FXUS64 KHUN 190836 AFDHUN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HUNTSVILLE AL 335 AM CDT SAT MAR 19 2011 .SHORT TERM...THROUGH MONDAY... WEAK SFC COLD FRONT IS SLOWLY EDGING ITS WAY INTO THE HUN CWFA THIS MORNING...STRETCHING ROUGHLY ALONG THE TN RIVER. REGIONAL MODIS/GOES SAT IMAGERY AND SFC OBS DO NOT INDICATE WIDESPREAD CLOUD COVER IMMEDIATELY AROUND THE FRONT...BUT THAT CHANGES NORTH OF I-40. MOST PCPN IS CONFINED EVEN FURTHER N ACROSS KY...THOUGH A FEW REMOTE SHRA HAVE BEEN HANGING AROUND IN NRN GA/SERN TN. THIS BOUNDARY WILL STALL OUT JUST SOUTH OF THE HUN CWFA TODAY... RESULTING IN A MOSTLY CLOUDY BUT NOT TERRIBLY WET DAY. DESPITE DECENT MOISTURE /PWATS ARND 1 INCH/...SYNOPTIC-SCALE LIFT AND CONVERGENCE WILL BE LACKING. CANNOT ENTIRELY RULE OUT A FEW STRAY SHRA...SO HAVE MAINTAINED 15-20 POPS AREAWIDE...BUT EXPECT TODAY TO BE FAR FROM A WASHOUT. AND DESPITE THE BROAD POSTFRONTAL NORTHERLY FLOW...LITTLE IF ANY COLD AIR ADVECTION IS EXPECTED...RESULTING IN CONTINUED ABOVE-NORMAL TEMPS /ALBEIT SLIGHTLY COOLER THAN FRIDAY/. THE FRONT WILL LIFT BACK NWD TONIGHT AS SWLY FLOW RESUMES ALOFT... BUT AGAIN NEGLIGIBLE LIFT EXISTS...LEADING TO A MOSTLY DRY BUT MILD FCST. THE BEST CHANCE FOR ANY MEASURABLE PRECIP...SUCH AS IT WILL BE...IS LIKELY TO COME SUNDAY IN RESPONSE TO SLIGHTLY ENHANCED UPPER FORCING AND INCREASED LOW-LVL CONVERGENCE ASSOCIATED WITH A WEDGE/BACKDOOR FRONT. FORCING IS STILL EXPECTED TO BE WEAK...AND MOS POPS ARE STILL BELOW 10 PCT...SO WILL STICK WITH ONLY 20 POPS ATTM. THE WEDGE FRONT MAY INTRODUCE A FAIRLY LARGE W-TO-E TEMP GRADIENT AS STRONG SWLY FLOW DEVELOPS FOR NW AL...AND E/SE FLOW IMPINGES FURTHER EAST. FOR NOW HAVE STUCK WITH HIGHS NEAR 80 WEST...NEAR 70 EAST...BUT THIS MAY BE TOO SUBTLE. RIDGING WILL BUILD IN FOR SUNDAY NIGHT/MONDAY...PLACING THE ENTIRE REGION UNDER ROBUST S/SW FLOW AND CLEARING SKIES. MILD OVERNIGHT CONDITIONS ARE EXPECTED...AND HIGHS MONDAY MAY RIVAL THOSE SEEN ON FRIDAY. .LONG TERM...TUESDAY THROUGH FRIDAY... UNSEASONABLY WARM CONDITIONS WILL CONTINUE UNTIL MID-WEEK...WHEN THE SYSTEM CURRENTLY COMING ASHORE ALONG THE W COAST ERODES THE SUBTROPICAL RIDGE. MOST OF THE ENERGY WITH THIS SYSTEM SHOULD STAY TO THE N...SO THE THREATS FOR HVY RAIN AND/OR SEVERE WX DO NOT LOOK HIGH ATTM. BUT THERE APPEARS TO BE INCREASING CONSENSUS ON A CHANCE OF SHRA/TSRA IN THE WED-THURS TIMEFRAME. A COLD FRONT WILL CROSS THE REGION WED NIGHT AND NW FLOW WILL PERSIST THROUGH THE REST OF THE EXTENDED...RESULTING IN COOLER IF NOT COLDER CONDITIONS. WHILE PREFRONTAL TEMPS ARE EXPECTED TO REMAIN 10-15 DEGREES ABOVE NORMAL...POSTFRONTAL CONDITIONS SHOULD BE MUCH CLOSER TO OR SLIGHTLY BELOW NORMAL. && .AVIATION...UNCHANGED FROM 06Z...A COLD FRONT WILL PUSH SOUTHWARD TOWARDS THE TERMINALS OVERNIGHT...ARRIVING JUST AFTER DAYBREAK. CLOUDS WILL INCREASE OVERNIGHT AND INTO SATURDAY AFTERNOON...WITH MVFR CEILINGS EXPECTED...ESPECIALLY AFTER 21Z. MOISTURE IS RATHER LIMITED WITH THIS FRONTAL PASSAGE...SO WILL ONLY INCLUDE VCSH TOWARDS THE END OF THE TAF PERIOD FOR NOW. && .PRELIMINARY POINT TEMPS/POPS... HUNTSVILLE 75 56 76 55 79 / 20 10 20 10 10 SHOALS 74 54 78 56 80 / 20 10 20 10 10 VINEMONT 72 54 72 53 76 / 20 10 20 10 10 FAYETTEVILLE 71 52 72 53 75 / 20 10 20 10 10 ALBERTVILLE 73 54 73 52 77 / 20 10 20 10 10 FORT PAYNE 73 54 71 50 76 / 20 10 20 10 10 && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ DISCUSSION...BCC AVIATION...12  FXUS64 KHUN 161009 AFDHUN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HUNTSVILLE AL 509 AM CDT THU MAY 16 2013 .DISCUSSION... MOST OF THE SENSIBLE WEATHER IMPACTS FOR THE TN VALLEY OVER THE SHORT TERM WILL BE EITHER DIRECTLY OR INDIRECTLY ASSOCIATED WITH A CLOSED UPR LOW NOW MOVING ACROSS THE RED RIVER VALLEY. THIS FEATURE WAS PARTIALLY RESPONSIBLE FOR SEVERE WEATHER INCLUDING TORNADOES JUST WEST OF THE DFW METRO YESTERDAY...BUT IS EXPECTED TO WEAKEN AS IT MOVES TOWARD THE TN VALLEY. SEVERE WEATHER CHANCES LOOK RATHER SMALL FOR OUR AREA THROUGH THE END OF THE WEEK AND INTO THE WEEKEND. WEATHER CONDITIONS FOR THE PERIOD BEYOND WILL BECOME INCREASINGLY WARM AS A RIDGE BUILDS OVER THE EASTERN CONUS. HOWEVER...CONFIDENCE IS BUILDING FOR ANOTHER TROUGH AND PERHAPS A SLIGHTLY COOLER AIRMASS FOR MID TO LATE WEEK. MORE DETAILS FOLLOW BELOW. EARLY MORNING ANALYSIS SHOWS THE MAIN BELT OF THE POLAR WESTERLIES CONFINED TO THE CANADIAN/CONUS BORDER...WHILE THE SUBTROPICAL JET EXTENDED ACROSS NORTH-CENTRAL MEXICO INTO THE WESTERN GOM. IN BETWEEN...A CLOSED UPR-LOW WAS MOVING SLOWLY EWRD ACROSS THE OK/TX BORDER REGION...WITH THE CENTER VERY NEAR OK CITY. STANDARD WATER VAPOR IMAGERY INDICATED A REGION OF DRIER AIR WRAPPING AROUND THE SOUTHERN FLANK OF THE LOW...WHICH WAS CORROBORATED BY 00Z SOUNDINGS AND OTHER MULTI-SPECTRAL MODIS/VIIRS AND RGB IMAGERY. REGIONAL RADARS AT 330 AM CDT SHOWED HEAVIER CONVECTION WAS GENERALLY CONFINED TO PORTIONS OF AR AND TX...WHILE A FEW SHOWERS WERE LOCATED IN THE MEMPHIS METRO AND ALONG A NARROW LINE STRETCHING FROM THE MISS DELTA INTO SW ALABAMA. THESE SHOWERS...IN ASSOC/WITH AN AREA OF SHEARED UPR VORTICITY WILL CONTINUE TO ADVANCE EWRD THROUGH THE MORNING. WHILE SOME OF THE RAIN MAY BE REACHING THE SFC...SOME OF THE LIGHTER SHOWERS ALOFT LIKELY ARE NOT REACHING THE SFC DUE TO THE PRESENCE OF A SUBSTANTIALLY DRY MID-LAYER. THIS FEATURE WILL BE PROGRESSIVE THROUGH THE MORNING...AND SHIFT TO OUR EAST BY THE AFTERNOON. HOWEVER...THE MAIN UPR LOW IS LIKELY TO BECOME INCREASINGLY SHEARED W-E AS THE DAY PROGRESSES...WITH WEAK UPR VORT MAXIMA ROTATING THROUGH THE REGION. THE PATTERN WITH THE SUITE OF GUIDANCE IS TOO CHAOTIC TO DISCERN A COHERENT FEATURE...BUT SUFFICE IT TO SAY THAT LIFT ON A SYNOPTIC SCALE WILL BE PRESENT BUT LIKELY WEAK. IN ADDITION...LOW-LEVEL FLOW LOOKS TO BE LARGELY DIFFLUENT IN NATURE. NEVERTHELESS...GIVEN THE CLOUD TRENDS OVER THE LAST SEVERAL HOURS...IT LOOKS AS THOUGH MORE CLEARING AND INSOLATION MAY BE REALIZED LATER THIS AFTERNOON THAN PREVIOUSLY THOUGHT. THIS WOULD LEAD TO GREATER DESTABILIZATION AND PRESENT A HIGHER THREAT OF SHRA/TSTM ACTIVITY...BUT WILL RETAIN THE SLIGHT CHANCE POPS FOR TODAY ATTM GIVEN THE OTHER COMPETING FACTORS. ALTHOUGH THE PARENT UPR LOW IS LIKELY TO WEAKEN OVER THE NEXT COUPLE OF DAYS...IT WILL KEEP A STEADY ADVANCE TO THE EAST. BY LATER TONIGHT...THE MAIN CORE OF THE UPR LOW WILL PROBABLY PUSH INTO WESTERN PORTIONS OF THE TN VALLEY. CONTINUING INSTABILITY AHEAD OF THE FEATURE WILL LIKELY RESULT IN ANOTHER AREA OF DEEP CONVECTION IN THE MID-MISS VALLEY LATER TODAY AHEAD OF THE UPR LOW. ALTHOUGH STEERING FLOW WILL BE SW-W...CONVECTION MAY BE PARTIALLY COLD-POOL DRIVEN...WITH THE POSSIBILITY FOR DEVELOPMENT INCREASING IN OUR AREA TONIGHT. POPS WERE RAISED A LITTLE MAINLY IN THE NW TO ACCOUNT FOR THIS SCENARIO...BUT WERE KEPT AT CHANCE CATEGORY UNTIL A CLEARER PICTURE EMERGES. CHANCES FOR SEVERE WEATHER LOOK RATHER SMALL FOR NOW WITH VERY LOW SHEAR AND MARGINAL CAPE. ON FRIDAY...AS DAYTIME HEATING COMMENCES ALBEIT UNDER A DENSER CLOUD CANOPY...THUNDERSTORM COVERAGE IS LIKELY TO INCREASE. POPS WERE ADJUSTED UPWARD TO ACCOUNT FOR THE GREATER INSTABILITY AND SYNOPTIC LIFT AVAILABLE. SHEAR WILL REMAIN RELATIVELY LOW WITH THIS FEATURE AS IT MOVES ACROSS THE REGION...HOWEVER BRIEF INTENSIFICATION OF THE LOW-LEVEL JET FRIDAY AFTERNOON INTO SAT MORNING MAY ALLOW FOR SOME ORGANIZATION OF STORMS ALONG THE SE FLANK OF THE UPR LOW. WHILE BETTER STORM ORGANIZATION IS MORE LIKELY TO OUR WEST OVER THE MID- MISS VALLEY OR THE WESTERN TN VALLEY...STORMS MAY MAINTAIN ORGANIZATION AS THEY MOVE EWRD INTO PORTIONS OF NW ALABAMA LATE FRIDAY AFTERNOON. SCTD STRONG STORMS WILL PROBABLY PERSIST ACROSS THE AREA INTO FRIDAY EVENING AND THE OVERNIGHT PERIOD. CONTINUED STORM ORGANIZATION IS POSSIBLE WITH AMPLE INSTABILITY...ALTHOUGH THE THREAT FOR SEVERE WEATHER IS LIKELY TO DECREASE WITH THE LOSS OF DAYTIME HEATING. KEPT POPS FOR SATURDAY AS ANOTHER UPSTREAM UPR-WAVE MOVES SWRD INTO THE REGION...PERHAPS MERGING WITH THE PRE-EXISTING UPR TROUGH. INSTABILITY MAY ACTUALLY BE HIGHEST ON THIS DAY...WITH CLOUD COVER THE OBVIOUS CAVEAT. NEVERTHELESS...FORECAST CAPE VALUES EXCEEDING 2000 J/KG SUGGEST STRONG UPDRAFT POTENTIAL. WHILE SHEAR REMAINS GENERALLY WEAK...MARGINALLY SEVERE HAIL COULD STILL OCCUR. THE EFFECTS OF THE COMBINED UPR-LVL SYSTEMS COULD IMPACT THE AREA THROUGH SAT NIGHT...AND PERHAPS INTO THE EARLY PART OF THE DAY ON SUNDAY IN THE EAST. DUE TO THE UNCERTAINTY WITH THE EVENTUAL MOVEMENT OF THE SYSTEM...A SLIGHT CHANCE POP WAS INTRODUCED IN THE EASTERN HALF OF THE AREA FOR SUNDAY. FOR MON-TUES...A RIDGE WILL BUILD QUICKLY IN THE EASTERN CONUS AS THE LARGE SCALE PATTERN BECOMES INCREASINGLY AMPLIFIED. GENERALLY HOT AND DRY WEATHER WILL LIKELY RESULT FOR THE REGION. CURRENTLY...HIGHS IN THE MID/UPR 80S ARE FORECAST FOR MOST LOCATIONS ON MON AND TUES. HOWEVER...SOME GUIDANCE IS INDICATING LOW 90S ARE POSSIBLE AS EARLY AS MONDAY. ALTHOUGH TYPICAL DIFFERENCES STILL EXIST WITH THE GLOBAL GUIDANCE DURING THE MIDDLE OF NEXT WEEK...CONFIDENCE IS SLOWLY INCREASING THAT A PROGRESSIVE TROUGH WILL MOVE INTO THE TN/OH VALLEY REGION BY ABOUT WED. THIS WOULD BRING A CHANCE OF SHOWERS/TSTMS TO THE AREA AND A CHANCE FOR COOLER CONDITIONS. KDW && .AVIATION... /ISSUED 1232 AM CDT THU MAY 16 2013/ FOR 06Z TAFS...EVEN AS MORE HIGH/MID LVL CLOUDS CONTINUE TO STREAM ACROSS THE TERMINALS THRU TOMORROW...VFR CONDITIONS ARE EXPECTED TO PERSIST THRU THE PERIOD. SCT/ISOL -RA MAY ALSO DEVELOP ACROSS AL/TN BTWN 14-18Z BUT SHOULD NOT IMPACT FLT CATEGORIES. AS THE SYSTEM TO OUR W PUSHES CLOSER LATE IN THE PERIOD...CIGS SHOULD START TO DROP BUT CAT DROPS ARE EXPECTED TO HOLD OFF UNTIL AFTER 06Z TOMORROW. CCC && .PRELIMINARY POINT TEMPS/POPS... HUNTSVILLE 84 65 82 67 / 20 30 50 40 SHOALS 85 62 79 68 / 20 30 50 40 VINEMONT 82 62 81 67 / 20 20 40 40 FAYETTEVILLE 82 59 81 65 / 20 30 50 40 ALBERTVILLE 82 63 81 66 / 20 20 40 40 FORT PAYNE 83 59 80 63 / 20 20 40 40 && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WEATHER.GOV/HUNTSVILLE.  FXUS64 KHUN 110732 AFDHUN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HUNTSVILLE AL 232 AM CDT SUN AUG 11 2013 .DISCUSSION... FOG AND LOW CLOUDS ARE ONCE AGAIN DEVELOPING THIS MORNING. CONDITIONS ARE A BIT MORE FAVORABLE (LESS HIGH CLOUD DEBRIS) FOR THE DEVELOPMENT OF WIDER SPREAD FOG THIS MORNING, SO WILL CONTINUE TO MONITOR GOES/MODIS SATELLITE TRENDS AND OBS. THUS FAR, NO OB SITES ARE REPORTING DENSE FOG SO WILL HOLD OFF ON ADVISORY AT THIS POINT. PWS ARE RUNNING ABOUT 0.10-0.20 INCH LOWER THAN YESTERDAY, BUT HAVE VERY LITTLE REASON TO BELIEVE WE SHOULD NOT SEE A SIMILAR OCCURRENCE OF NUMEROUS CLUSTERS OF THUNDERSTORMS. CONVECTIVE INSTABILITY MAY BE GREATER WITH THE LACK OF MORNING HIGH CLOUDS. A RIBBON OF HIGHER VORTICITY WILL BE LOCATED ACROSS NORTHERN AR EWD THRU TN AND KY. SO WE MAY SEE CONVECTION TO THE NORTH PRODUCE POSSIBLE OUTFLOW BOUNDARIES THAT PUSH SOUTH INTO OUR AREA AS WELL, INSTIGATING MORE CONVECTION INTO TONIGHT. THE THREAT OF MORE ORGANIZED AND WIDESPREAD CONVECTION WILL DEVELOP LATE MONDAY INTO TUESDAY AS A SERIES OF VORTICITY IMPULSES TRACK ESEWD. THE REPETITIVE NATURE OF THE THUNDERSTORMS WILL HAVE TO BE WATCHED CLOSELY FOR FLASH FLOOD POTENTIAL DUE TO THE DEEP MOIST ENVIRONMENT. THE GOOD NEWS IS THAT THERE WILL BE BRISKER MOVEMENT OF ACTIVITY WITH THE INCREASED MID-UPPER LEVEL FLOW. HAVE CONTINUED A MORE OR LESS SPLIT ON TEMPS FOR TODAY (ALTHOUGH THAT HINGES ON PRECIP/CLOUD DEVELOPMENT). KMSL HIT 93F YESTERDAY AFTER ALL. WE GRADUALLY LEAN CLOSER TO THE COOLER MET NUMBERS MON-WED GIVEN THE HIGHER CONFIDENCE IN WIDER SPREAD PRECIP. THE EXTENDED FORECAST JUST BECAME LESS CONFIDENT WITH THE 00Z GFS AND ECMWF. BOTH LET GO OF THE IDEA WE'LL SEE MUCH OF A DRIER PUSH OF AIR IN OUR AREA THIS WEEK WITH THE ARRIVAL OF A DEEPER UPPER LEVEL TROF AXIS. THIS TROF IS PROGGED TO MORE OR LESS PARK ITSELF SOMEWHERE OVER THE SE U.S. NEXT WEEKEND. WHETHER THE AXIS SHIFTS JUST FAR ENOUGH SE TO DRY US OUT IS STILL VERY DEBATABLE. AK && .AVIATION... /ISSUED 1237 AM CDT SUN AUG 11 2013/ FOR 06Z TAFS...NO CHANGES TO PREVIOUS AVIATION FORECAST REASONING. GENERALLY QUIET WX CONDS ARE ANTICIPATED AROUND HSV/MSL FOR THE REMAINDER OF THIS EVENING AND OVERNIGHT...WITH THE GREATEST NOCTURNAL CONCENTRATION OF SHRA/TSRA EXPECTED TO THE NORTH OF THE TERMINALS. THAT SAID...THE POTENTIAL DEVELOPMENT OF ISOLATED CONVECTION CANNOT BE ENTIRELY DISCOUNTED -- BUT CHANCES ARE TOO REMOTE TO INCLUDE IN TAF. FOG WILL CONTINUE TO DEVELOP AROUND THE REGION...WITH TEMPO INCLUDED FOR IFR VSBY BTWN 11/10-13Z. SHRA/TSRA WILL BEGIN TO DEVELOP INVOF TERMINALS ONCE AGAIN BTWN 11/14-15Z AND WILL CARRY VCTS/TSRA THRU 12/01Z. SFC WINDS WILL GENERALLY BE FROM THE SW AT 5-10 KNOTS. 70/DD && .PRELIMINARY POINT TEMPS/POPS... HUNTSVILLE 88 69 87 71 / 70 20 70 60 SHOALS 89 70 89 71 / 70 20 70 60 VINEMONT 86 68 85 70 / 70 20 70 60 FAYETTEVILLE 88 68 84 71 / 70 20 70 60 ALBERTVILLE 86 68 86 70 / 70 20 70 60 FORT PAYNE 85 69 85 69 / 70 20 70 60 && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WEATHER.GOV/HUNTSVILLE.  FXUS64 KHUN 270709 AFDHUN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HUNTSVILLE AL 209 AM CDT FRI SEP 27 2013 .DISCUSSION... A SPRAWLING SFC RIDGE OF HIGH PRESSURE ENCOMPASSING THE EASTERN CONUS WILL REMAIN INTACT OVER THE NEXT 2-3 DAYS. WITH TIME, RELATIVELY DRIER AIR WILL SPILL EAST OF THE APPALACHIAN MTNS AND INTO OUR REGION SATURDAY AND SUNDAY. THIS WILL ENABLE LOWERING DEW POINTS AND MOSTLY CLOUD FREE DAYS AFTER COMFORTABLY COOL MORNINGS. VALLEY FOG IS BECOMING PREVALENT THIS MORNING PER GOES AND MODIS IMAGERY, BUT MAY BE LESS OF CONCERN OVER THE COMING DAYS. WILL STAY FAIRLY CLOSE TO GFS MOS GUIDANCE +/- A DEGREE OR TWO DURING THIS PERIOD. THE LATEST MEDIUM RANGE GUIDANCE MAINTAINS THAT A COLD FRONT WILL WEAKEN AND/OR DISSIPATE OVER THE MS VALLEY AND WILL NOT REACH OUR FORECAST AREA SUNDAY INTO MONDAY. NONETHELESS, THE MODELS CONTINUE TO SHOW A SEGMENT OF VORTICITY THAT BREAKS OFF FROM THE DEPARTING MIDWEST/GREAT LAKES SHORTWAVE EARLY NEXT WEEK. THIS MAINTAINS AN 850 MB (LOW LEVEL) LOW AND CIRCULATION OVER THE ARKLATEX REGION WHICH GENERATES VERY MOIST SOUTHERLY FLOW OVER THE DEEP SOUTH AND LOWER MS VALLEY. THIS TENDS TO FOCUS MCS DEVELOPMENT TO OUR SW. INITIALLY, THE INFLUENCE OF THE RIDGE OVER THE EASTERN COASTAL AREAS WILL MAINTAIN LOW LEVEL DRY ADVECTION AND MAY PREVENT SIGNIFICANT PRECIP FROM OCCURRING IN OUR AREA THRU SUNDAY. BASED ON THIS UNCERTAINTY, HAVE NOT CHANGED THE LOW POPS WE HAVE GOING FOR MONDAY AND TUESDAY, BUT THIS IS CERTAINLY UP FOR ADJUSTMENTS IN LATER FORECASTS. AK && .AVIATION... /ISSUED 1207 AM CDT FRI SEP 27 2013/ FOR 06Z TAFS... WITH AN EXCEPTION OF A BRIEF PERIOD OF 6SM BR/HZ BEFORE DAYBREAK...VFR FLYING WEATHER SHOULD CONTINUE THE NEXT 24 HOURS. LIGHT/VARIABLE WINDS DURING THE NIGHT SHOULD BECOME ESE A FEW HOURS AFTER SUNRISE. WINDS AGAIN WILL BECOME VARIABLE IN DIRECTION AFTER DUSK FRI PM. RB && .PRELIMINARY POINT TEMPS/POPS... HUNTSVILLE 83 57 83 58 / 0 0 0 0 SHOALS 85 56 85 56 / 0 0 0 0 VINEMONT 81 54 80 56 / 0 0 0 0 FAYETTEVILLE 84 55 82 56 / 0 0 0 0 ALBERTVILLE 82 53 83 54 / 0 0 0 0 FORT PAYNE 83 55 83 54 / 0 0 0 0 && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WEATHER.GOV/HUNTSVILLE.  FXUS64 KHUN 020209 AAB AFDHUN AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE HUNTSVILLE AL 909 PM CDT TUE OCT 1 2013 .UPDATE... ADDED PATCHY FOG FOR THE LATE NIGHT...AND MINOR TEMPERATURE/DEWPOINT CHANGES. && .DISCUSSION... GENERALLY QUIET CONDITIONS PREVAILED ACROSS THE GREATER TENNESSEE VALLEY...AS WEAK HIGH PRESSURE SITUATED ACROSS THE SOUTHEAST CONTROLLED THE WEATHER. WITH A LOSS OF DAYTIME HEATING...SKIES HAVE CLEARED ACROSS THE AREA AS OF THIS WRITING. HOWEVER...AREAS OF SOME LOW CLOUDS/FOG AS SEEN IN THE FOG/LOW CLOUD LOOP...A 115Z MODIS PASS...AND OBSERVATIONS...WERE AFFECTING PARTS OF MIDDLE TENNESSEE. THE LOWER CLOUDS WERE MOVING IN A SOUTHERLY DIRECTION...WITH NW-N WINDS NOTED VIA DOPPLER RADAR VAD WIND PRODUCT. WITH THE ABOVE NOTED FOG AND MORE OF THIS PHENOMENA NOTED ON SATELLITE...HAVE ADDED PATCHY FOG TO THE GRIDS FOR THE LATE NIGHT. FOR THIS UPDATE...RESTRICTED FOG TO LOCATIONS NEAR MOST MAJOR BODIES OF WATER AND WIND SHELTERED VALLEYS. 300-305K ISENTROPIC UPGLIDE FROM THE RAP WAS FORECAST TO OCCUR MORE OVER NW ALABAMA...WHICH HINTS THAT FOG COULD BECOME A PROBLEM OVER THE NE...DUE TO FEWER CLOUDS. OTHERWISE...HIGHER ALTITUDE CLOUDS EMANATING FROM A WEAK GULF/LOWER MISSISSIPPI VALLEY SYSTEM SHOULD OVERSPREAD THE AREA DURING THE OVERNIGHT. SINCE THOSE CLOUDS WERE CIRRUS...STAYED WITH PARTLY CLOUDY RATHER THAN MOSTLY CLOUDY WORDING. NIGHT TIME LOW TEMPERATURES SHOULD REMAIN CLOSE TO FORECAST VALUES. MADE A FEW MINOR (MAINLY DOWNWARD) ADJUSTMENTS TO SOME OF OUR HIGHER ELEVATED SPOTS...ALONG WITH DEWPOINT TWEAKS. UPDATED TEXT/GRID FORECASTS HAVE BEEN SENT. GRAPHICAST WILL BE FRESHENED SOON. RB && .AVIATION... /ISSUED 646 PM CDT TUE OCT 1 2013/ FOR 00Z TAFS... VFR CONDITIONS SHOULD PREVAIL INTO THE LATE NIGHT. HOWEVER...THE SATELLITE VIEW AND SHORT-TERM MODEL OUTPUT WAS SUGGESTING A DECK OF MOSTLY VFR STRATUS FORMING AFTER MIDNIGHT. THE DEVELOPMENT SHOULD BE MORE OVER KHSV THAN KMSL. THUS THE KMSL TERMINAL WILL BE MORE SUBJECT TO MVFR FOG BEFORE DAYBREAK WED. DESPITE A CHANCE FOR MORE CLOUDS OVER KHSV...HAVE LEFT A TEMPO IN FOR FOG AROUND DAYBREAK. OTHERWISE... VFR SHOULD RETURN BY 14-15Z TIMEFRAME WED AM. DEEPER MOISTURE OVER NW AL COULD RESULT IN AN ISOLATED SHOWER OR THUNDERSTORM WED AFTERNOON. DID NOT INCLUDE IT IN THE 00Z TAF...PENDING REVIEW OF NEXT MODEL RUN. RB && .PREV DISCUSSION... /ISSUED 259 PM CDT TUE OCT 1 2013/ A QUASI-ZONAL FLOW CONTINUES ACROSS CENTRAL NORTH AMERICA TODAY WITH A WEAK LOW OVER E TX/LA SPREADING SHOWERS/STORMS ACROSS THE GULF COAST. IN ADDITION, THERE IS EVIDENCE OF A DIGGING TROUGH JUST OFF THE WEST COAST WHICH WILL IMPACT OUR WEATHER LATE IN THE WEEK. FURTHER TO THE SOUTH, OVER THE WESTERN CARIBBEAN SEA, A WEAK TROPICAL DISTURBANCE MAY BECOME BETTER ORGANIZED OVER THE NEXT FEW DAYS. BROKEN CLOUD COVER MAINLY ORIGINATING FROM THE GULF LOW AND DEEP MOISTURE TRANSPORT STRETCHING NORTHWARD TOWARDS THE OH RIVER VALLEY WILL REMAIN TONIGHT WITH SOMEWHAT HIGHER DEWPOINTS THAN LAST NIGHT. DUE TO THE WARMER DAY TODAY AND HIGHER DEWPOINTS (WITH LITTLE IN THE WAY OF CHANGE IN SENSIBLE WEATHER), TEMPERATURES WILL BE WARMER TONIGHT, AS WELL. THE MAIN QUESTION FOR THE NEXT COUPLE OF DAYS THEN CENTERS ON THE GULF LOW MOVING NNE ACROSS THE LOWER AND MIDDLE MS RIVER VALLEY. NAM/RAP MODEL OUTPUT INDICATE A SHEARING OF THE LOW AS IT MOVES ACROSS THE TN VALLEY AND A SLIGHT WOBBLE WEST. DUE TO ITS WEAK NATURE AND OVERALL STABLE FEATURES ACROSS MOST OF THE AREA, HAVE PULLED BACK POPS FOR TOMORROW AND THURSDAY. THERE IS NOT MUCH CONFIDENCE IN THE SKY COVER FORECAST AS CLOUD COVER ASSOCIATED WITH THE LOW HAS BEEN CHALLENGING TO INTERPRET IN THE LATEST MODEL RUNS AS THE LOW WEAKENS. ISENTROPIC ANALYSIS DOES SHOW A RIBBON OF UPGLIDE JUST TO OUR WEST WHICH IS WHY ADJUSTMENTS WERE MADE TO REFLECT MORE CLOUD COVER FURTHER WEST OVER NW AL THAN AREAS EAST. SIMILAR ADJUSTMENTS WERE ALSO MADE FOR THURSDAY WITH THE BREAKDOWN AND LIFTING OF THE WEAK "GULF" LOW TO THE NORTHEAST. BY FRIDAY, IT APPEARS LITTLE (IF ANY) EFFECT FROM THE GULF LOW IS NOTED AS IT MOVES OFF TO THE NE WITH THUNDERSTORMS REMOVED COMPLETELY FROM FRIDAY'S FORECAST DUE TO THE LACK OF A LIFTING MECHANISM. TEMPERATURES ARE EXPECTED TO BE WARMER THAN THURSDAY WITH DAYTIME HIGHS IN THE MIDDLE 80S. MEANWHILE, ON THURSDAY, THE AFOREMENTIONED DIGGING TROUGH OFF THE WEST COAST OF THE U.S. IS EXPECTED TO MOVE EAST ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. THE EFFECT FROM THIS VIGOROUS TROUGH WILL BE SPREADING WHAT COULD BE THE HEAVIEST SNOWFALL OF THE SEASON ACROSS THE NORTHERN PLAINS/NORTHERN ROCKIES. BY FRIDAY, SFC CYCLOGENESIS WILL HAVE OCCURRED OVER E CO, TRACKING NE ACROSS THE UPPER MS/MO RIVER VALLEYS BY FRIDAY NIGHT WITH THE PARENT TROUGH MOVING NE ACROSS WI/ONTARIO. THE ACCOMPANYING STRONG NW WILL PUSH A CP AIR MASS SOUTH/SOUTHEAST OVER THE PLAINS STATES. ALSO, THE TROPICAL DISTURBANCE NOTED OVER THE NW CARIBBEAN SEA MAY BE PULLED NORTHWARD ACROSS THE GULF COAST OF FL INTO GA/AL BY THE ONCOMING TROUGH. IT LOOKS TO THEN MERGE WITH THE TROUGH AS IT MOVES NORTHWARD. AS THE TROUGH LIFTS NORTHEAST, THE BULK OF THE PVA LIFTS TO THE NORTH LEAVING A SLOW MOVING FRONT AND CONVECTIVE THUNDERSTORMS/HEAVY RAINFALL OVER THE MS RIVER VALLEY BY SATURDAY. THE LATEST MED RANGE MODEL OUTPUT DOES ACTUALLY SHOW AN OVERALL SLOW PROGRESSION--LIKELY DUE TO A STRONGER RIDGE OVER THE SOUTHEAST. IN ADDITION, WHETHER IT IS BELIEVABLE OR NOT, THE MODELS DEPICT THAT THE SOUTHERN FLANK OF THE TROUGH BECOMES CUTOFF FROM THE PREVAILING WESTERLIES. THEREFORE, BEGAN SCALING BACK POPS ON SATURDAY MORNING INTO THE AFTERNOON AND LEFT SUNDAY POPS INTACT. HOWEVER, DID RETAIN POPS FOR A LONGER TIME PERIOD ON MONDAY GIVEN THIS TREND. FURTHER ADJUSTMENTS MAY BE NEEDED IF THE SUCCEEDING MODEL RUNS CONTINUE TO SHOW A SLOWING OF THE SYSTEM. TEMPERATURES WERE ALSO ADJUSTED IN THE LONG TERM TO REFLECT A SLOWER PROGRESSION SOUTHWARD WITH THE FRONT. THIS INCLUDES SOMEWHAT WARMER TEMPS THAN GUIDANCE. SL.77 && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WEATHER.GOV/HUNTSVILLE.  FXUS64 KHUN 180755 AFDHUN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HUNTSVILLE AL 255 AM CDT FRI OCT 18 2013 .DISCUSSION... AN UPPER FLOW PATTERN CHANGE IS EXPECTED OVER THE NEXT 7 DAYS- TRANSITIONING FROM A ZONAL FLOW PATTERN TO A MORE AMPLIFIED TROUGH PATTERN. FOR NOW, AN AMPLIFIED RIDGE AXIS STRETCHES FROM THE WEST COAST NORTHWARD TO NORTH ALASKA/YUKON TERRITORIES. MEANWHILE, A SUBTROPICAL JET STRETCHES FROM NORTHERN MEXICO NE TOWARDS THE OHIO RIVER AND FINALLY NEW ENGLAND. THIS SUBTROPICAL JET KEEPS SOUTHWESTERLY MID-UPPER FLOW ACROSS THE SOUTHEAST AND EAST. CONCURRENTLY, WITH THE FROPA THAT OCCURRED EARLIER YESTERDAY AND MUCH COOLER CONDITIONS THAN PREVIOUS NIGHT, RADIATIONAL COOLING AND LIGHT WINDS HAS LEAD TO THE DEVELOPMENT OF WIDESPREAD DENSE RADIATION FOG. OBS INDICATE VISIBILITIES HAVE ONLY BRIEFLY RISEN ABOVE 1/4 SM. OF PARTICULAR NOTE IS THE NASA-SPORT MODIS NIGHTTIME MICROPHYSICS IMAGERY (0423Z IMAGE) CONFIRMS THE DEVELOPMENT AND SPREADING OF VALLEY/RIVER FOG. THUS, WILL KEEP THE ONGOING DENSE FOG ADVISORY IN PLACE THROUGH 9AM. WITH SUNRISE, FOG WILL GRADUALLY EVAPORATE WITH TEMPERATURES EXPECTED TO WARM INTO THE UPPER 60S TO NEAR 70 DEGREES. MADE SOME VERY MINOR ADJUSTMENTS TO THE DAYTIME HIGHS TO ACCOUNT FOR THE COOLER START TO THE MORNING AND DELAY IN WARMING FROM FOG. DURING THE DAY TODAY INTO THIS EVENING, A MID-LEVEL SHORTWAVE TROUGH ENVELOPED IN THE BROAD TROUGH CENTERED OVER CANADA IS EXPECTED TO SWING DOWN FROM THE CENTRAL U.S. TOWARDS THE NEW ENGLAND STATES. AS THIS MID-LEVEL SHORTWAVE TROUGH MOVES EAST, IT WILL PUSH A SFC REINFORCING COLD FRONT SOUTHEAST FROM THE CORN BELT REGION SOUTHEAST TOWARDS THE TN VALLEY BY TOMORROW MORNING. A DRY COLUMN AND LITTLE IN THE WAY OF MOISTURE ADVECTION PRIOR TO ITS ARRIVAL SHOULD YIELD LITTLE IN THE WAY OF PRECIPITATION. MODEL CONSENSUS ALSO INDICATES A GENERALLY DRY FORECAST AS WELL. HOWEVER, CLOUDS SHOULD INCREASE LATE TONIGHT INTO TOMORROW MORNING. THE CLOUD COVER SHOULD KEEP TEMPERATURES MODERATED (ALONG WITH CAA BEHIND THE COLD FRONT) THROUGH THE DAY IN THE MID TO UPPER 60S. THEN, TEMPS SHOULD NOSEDIVE QUICKLY AS COLD/DRY AIR ADVECTS SOUTHWARD WITH DEWPOINTS DROPPING INTO THE MID-UPPER 30S/LOWER 40S. HAVE ADDED PATCHY DENSE FOG TO THE VALLEYS/RIVERS/LAKES, BUT MORE WIDESPREAD FOG IS POSSIBLE ESPECIALLY WITH A 10 DEGREE DIFFERENCE BTWN OVERNIGHT LOWS AND CROSSOVER TEMPS. IN ADDITION, SHELTERED LOCATIONS OF SOUTHERN MIDDLE TN AND NORTHEAST ALABAMA MAY DROP CLOSE TO THE MID-UPPER 30S SUNDAY MORNING YIELDING A POSSIBILITY FOR FROST. DRY CONDITIONS SHOULD THEN PREVAIL ON SUNDAY AND MONDAY AS THE UPPER FLOW PATTERN BEGINS TO AMPLIFY ACROSS CENTRAL NORTH AMERICA WITH A RIDGE OVER THE WESTERN HALF AND A DEEPENING TROUGH OVER THE EASTERN HALF. THIS CHANGE IN THE UPPER FLOW PATTERN WILL MEAN A PLUNGE OF WELL BELOW NORMAL TEMPERATURES ACROSS THE HEARTLAND INTO THE EASTERN HALF OF THE U.S. IN PARTICULAR, OVER THE TN VALLEY, TEMPS MAY BE 5- 10 DEGREES BELOW NORMAL FOR HIGHS AND LOWS, ESPECIALLY LATE IN THE FORECAST PERIOD. AN INITIAL MID-LEVEL SHORTWAVE TROUGH WILL SEND ANOTHER REINFORCING COLD FRONT EASTWARD ON TUESDAY WITH DEEP NW FLOW ALOFT SENDING VERY COLD AIR FROM OVER THE NORTHWEST TERRITORIES SOUTHEAST. SOME MODIFICATION OF THIS AIRMASS IS LIKELY, BUT GUIDANCE SUGGESTS A DROP INTO THE LOW TO MID 60S FOR HIGHS AND OVERNIGHT LOWS IN THE UPPER 30S. THEN, ANOTHER SURGE OF COLD AIR IS EXPECTED AHEAD OF ANOTHER MID-LEVEL VORTEX ROTATING AROUND THE PARENT TROUGH ACROSS THE CORN BELT REGION TO THE SOUTHEAST ON WEDNESDAY INTO THURSDAY. THERE ARE SOME TIMING DIFFERENCES BTWN THE MODELS (AND MODEL RUNS) ON THE THIRD SURGE OF COLD AIR. THUS, HAVE MAINLY INCORPORATED A TREND DOWNWARD RATHER THAN UTILIZING MODEL GUIDANCE NUMBERS FOR TEMPS. NEVERTHELESS, OVERNIGHT LOWS MAY DROP LOW ENOUGH FOR THE POSSIBILITY OF FROST ON THE MORNINGS OF TUE-THU WITH PERHAPS SHELTERED LOCATIONS DROPPING CLOSE TO FREEZING ON 1 OR 2 OF THE MORNINGS (MOST LIKELY THURSDAY). SL.77 && .AVIATION... /ISSUED 1203 AM CDT FRI OCT 18 2013/ FOR 06Z TAFS... AREAS OF DENSE FOG WILL LINGER AT BOTH TERMINALS THRU 14Z THIS MORNING, WITH CONDS HOVERING NEAR AIRPORT MINIMUMS (200FT CEILINGS AND 1/2SM VSBYS). CONDS WILL DETERIORATE RAPIDLY BETWEEN MIDNIGHT AND DAYBREAK. CONDITIONS WILL THEN IMPROVE AFTER SUNRISE WHEN MVFR CONDS ARE LIKELY, WITH VFR CONDS RETURNING TO BOTH SITES AFTER 18/14-15Z. 12 && .PRELIMINARY POINT TEMPS/POPS... HUNTSVILLE 70 49 70 42 / 0 10 10 0 SHOALS 70 48 68 41 / 0 10 10 0 VINEMONT 68 50 68 42 / 0 10 10 0 FAYETTEVILLE 70 47 68 40 / 0 10 10 0 ALBERTVILLE 69 49 68 43 / 0 10 10 0 FORT PAYNE 72 48 69 40 / 0 10 10 0 && .HUN WATCHES/WARNINGS/ADVISORIES... AL...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR ALZ001>010-016. TN...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR TNZ076-096-097. && $$ FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WEATHER.GOV/HUNTSVILLE.  FXUS64 KHUN 111008 AFDHUN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HUNTSVILLE AL 408 AM CST WED FEB 11 2015 .DISCUSSION... A HIGH AMPLITUDE PATTERN IS EXPECTED TO EVOLVE OVER THE NEXT 24 TO 48 HOURS AND REMAIN ESSENTIALLY ENTRENCHED ACROSS THE NORTH AMERICAN DOMAIN OVER THE FORECAST PERIOD. THIS PATTERN WILL BE CHARACTERIZED BY RIDGING AND WARMER THAN NORMAL TEMPS ALONG THE WEST COAST AND TROUGHING AND BELOW NORMAL TEMPS FOR MUCH OF THE CENTRAL/EAST CONUS. THREE DISTINCT INTRUSIONS OF MODIFIED ARCTIC AIR ENTERING THE TN VALLEY OVER THE NEXT SEVEN DAYS WILL RESULT IN A COLD PERIOD FOR THE REGION. PRECIPITATION WILL LIKELY BE VERY LIMITED IN OUR AREA IN ADVANCE OF THE FIRST TWO FRONTS...HOWEVER A DIFFERENT SETUP AHEAD OF THE THIRD FRONT EARLY NEXT WEEK MAY ALLOW FOR A HEAVIER PRECIPITATION EVENT. MORE DETAILS FOLLOW BELOW. CHANGES ARE ALREADY TAKING SHAPE WELL TO OUR WEST IN THE NE PAC WHICH WILL FORCE A COLD PATTERN FOR THE TN VALLEY FOR THE UPCOMING PERIOD. THE LATEST MULTI-SPECTRAL SAT IMAGERY SHOWS A SUBSTANTIAL RIDGE DEVELOPING ALONG THE WEST COAST WITH A DEEP MOIST PLUME EXTENDING INTO WRN CANADA AND THE ALASKA PANHANDLE. THIS IS FORCING DOWNSTREAM TROUGH DEVELOPMENT OVER THE CANADIAN PRAIRIE PROVINCES INTO THE UPR MIDWEST/NORTHERN PLAINS EARLY THIS MORNING. GOES WATER VAPOR AND MODIS AIRMASS IMAGERY INDICATE AT LEAST TWO PRIMARY FRONTAL BOUNDARIES PUSHING SWRD IN THIS REGION. THE LEADING EDGE IS LIKELY A MIX OF NE PAC AND CONTINENTAL/CANADIAN AIRMASSES...HOWEVER THE TRAILING AIRMASS IS MODIFIED ARCTIC. THE FIRST OF THESE WILL PUSH INTO OUR AREA LATE TONIGHT...AROUND MIDNIGHT...WHILE THE SECONDARY SHOT OF COLDER AIR ARRIVES ABOUT SIX HOURS OR SO LATER EARLY THURS MORNING. AFTER A RELATIVELY MILD DAY TODAY...TEMPS ON THURS WILL LIKELY STRUGGLE TO REACH THE MID 30S FOR MOST LOCATIONS. LOW CLOUDS ARE EXPECTED TO CROSS THE AREA IN ASSOC/W THE COLD AIRMASS AND CAN BE SEEN CURRENTLY IN SAT IMAGERY IN THE UPR MIDWEST/NORTHERN PLAINS. THIS WILL TEND TO LIMIT INSOLATION...HELPING TO SUPPRESS TEMP RISES THURS...BUT SUFFICIENT MOISTURE IN CONCERT WITH LOW-LEVEL CAA MAY LEAD TO SOME FLURRIES AND/OR LGT SNOW SHOWERS IN THE AREA. THE BEST CHANCES FOR SNOW SHOWERS WILL BE TO OUR NORTHEAST...OVER PORTIONS OF EAST TENN AND THE SOUTHERN APPS. HOWEVER...LIFT ALONG THE PLATEAU WARRANTS AT LEAST A 20 POP MENTION FOR NOW. AS THE ARCTIC HIGH SETTLES OVHD THE REGION FRIDAY MORNING...LOW TEMPS ARE LIKELY TO BOTTOM OUT IN THE LOW/MID TEENS. A FEW OF OUR NORMALLY COLDER VALLEY LOCATIONS WITH GOOD COLD AIR DRAINAGE MAY FALL INTO THE SINGLE DIGITS. WHILE BELOW NORMAL...THESE TEMPS WILL BE ABOVE RECORD VALUES FOR THE 13TH (-11F FOR MUSCLE SHOALS AND 7F FOR HUNTSVILLE). TEMPS WILL GRADUALLY MODIFY FROM FRIDAY INTO SATURDAY...ALTHOUGH YET ANOTHER TROUGH WILL BEGIN DIGGING INTO THE EASTERN CONUS. SUCCESSIVE LONG RANGE MODEL RUNS HAVE TENDED TO DECREASE THE AMPLITUDE OF THIS RESULTING TROUGH AND THE INTENSITY OF THE COLD AIR ADVECTION IN OUR AREA...PRIMARILY SHOVING THE BRUNT OF THE COLD AIR INTO THE MID- ATLANTIC. NEVERTHELESS...ANOTHER FRONTAL BOUNDARY IN ASSOC/W THIS MODIFIED ARCTIC AIRMASS WILL CROSS THE AREA PROBABLY BEGINNING SAT AFTERNOON. A NARROW LINE OF MOISTURE AND POSSIBLY EVEN WEAK ISENTROPIC ASCENT CENTERED ARND 850MB MAY ACCOMPANY THIS FRONT AS IT CROSSES THE AREA. A FEW FLURRIES ARE NOT OUT OF THE QUESTION...MAINLY IN THE HIGHER ALTITUDES. HOWEVER...DRY AIR ADVECTION AT/NEAR THE SFC MAY PREVENT ANY FLURRIES OR LGT SNOW SHOWERS FROM REACHING THE SFC. THUS...NO MENTION AT THIS TIME IN THE OFFICIAL FCST. TEMPS ON SUNDAY MAY STRUGGLE TO REACH THE LOW/MID 30S FOR MOST LOCATIONS DESPITE THE PROSPECT FOR GOOD INSOLATION FOR MOST OF THE DAY. FURTHER STEEPENING OF THE RIDGE IN THE NE PAC WILL LEAD TO REINFORCEMENT OF THE DOWNSTREAM TROUGH OVER THE CENTRAL/EASTERN CONUS BY EARLY NEXT WEEK...BUT EVEN THE LARGE SCALE DETAILS YET ARE FAR FROM CERTAIN. 00Z LONG RANGE GUIDANCE INDICATES A VERY SHORT WAVELENGTH RIDGE OVER THE EASTERN PAC...WHICH WOULD LEND SUPPORT TO SOLUTIONS SHOWING A STRONG SHORTWAVE TROUGH DIGGING INTO THE INTERMOUNTAIN WEST. SFC CYCLOGENESIS THEN TAKES PLACE IN THE SOUTHERN PLAINS AND RESULTS IN SW-NE TILTING OF THE POLAR FRONT AND STRONGER WAA OVER THE TN VALLEY REGION. IF THIS SCENARIO PANS OUT...THEN A RAPID WARMUP WOULD TAKE PLACE BEGINNING MONDAY INTO TUESDAY. HOWEVER...AN INSPECTION OF THE GFS ENSEMBLE MEMBERS SHOWS A WIDE RANGE OF SCENARIOS STILL POSSIBLE WITH THE PLACEMENT OF THE POLAR FRONT AND THUS THE MOVEMENT/TRACK OF ANY SUBSEQUENT SFC LOW. SOME TRACKS ARE STILL TO OUR SOUTH. ALTHOUGH...SEVERAL ARE CLUSTERED WITH TRACKS RIGHT ACROSS OUR AREA OR TO OUR NORTH...INCLUDING THE 00Z OPERATIONAL GFS/ECMWF. WITH ALL OF THIS SAID...THE MOST LIKELY SCENARIO AT THIS POINT PLACES THE LOW TRACK ACROSS THE MID-SOUTH AND TN VALLEY REGION. THE LATEST FORECAST UPDATE WILL REFLECT THIS THINKING. AT THE ONSET OF ISENTROPIC ASCENT AND MOISTURE ADVECTION ALOFT ON MONDAY AFTN...TEMPS MAY BE BRIEFLY COLD ENOUGH TO SUPPORT SOME SNOW FLAKES OR ICE PELLETS MIXING WITH RAIN. CHANCES APPEAR SLIM HOWEVER...AND THE DETAILS OF THE FCST FOR THIS PERIOD ARE STILL NOT CLEAR WITH RELATIVELY LOW CONFIDENCE. NEVERTHELESS...ROBUST WARM/MOIST ADVECTION ALOFT MAY LEAD TO SUFFICIENT ELEVATED INSTABILITY TO WARRANT A MENTION OF THUNDER MAINLY FOR ABOUT THE SOUTHERN HALF OF THE AREA ON TUESDAY. AS THE LOW DEPARTS AND DEEP/COLD ADVECTION BEGINS AROUND THE BACKSIDE OF THE LOW TUESDAY NIGHT...A BRIEF PERIOD OF -RA/-SN MIX COULD BE POSSIBLE AND WAS ADDED TO THE FORECAST. KDW && .AVIATION... /ISSUED 1119 PM CST TUE FEB 10 2015/ FOR 06Z TAFS... VFR CONDITIONS AT BOTH TERMINALS IS EXPECTED THROUGH THE TAF PERIOD. A DECK OF CLOUDS WITH CIGS AROUND 2 KFT CONTINUES ACROSS EAST-CENTRAL TENNESSEE THIS EVENING. THE SOUTHERN EDGE OF THESE CLOUDS HAVE MADE IT INTO SOUTHERN MIDDLE TENNESSEE WHERE THEY MAY LINGER AROUND UNTIL MORNING. EXPECT LIGHT AND VARIABLE WINDS THROUGH WEDNESDAY MORNING...THEN WINDS BEGIN TO INCREASE IN THE AFTERNOON AS A LOW PRESSURE SYSTEM MOVES CLOSER TO THE AREA. STUMPF && .PRELIMINARY POINT TEMPS/POPS... HUNTSVILLE 58 30 35 16 / 0 10 10 0 SHOALS 59 29 36 15 / 0 10 10 0 VINEMONT 58 31 36 14 / 0 10 10 0 FAYETTEVILLE 55 29 32 13 / 0 10 10 0 ALBERTVILLE 57 32 36 20 / 0 10 10 0 FORT PAYNE 57 31 36 16 / 0 10 10 0 && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WEATHER.GOV/HUNTSVILLE.  FXUS64 KHUN 240652 AFDHUN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HUNTSVILLE AL 152 AM CDT MON AUG 24 2015 .DISCUSSION... AT 06Z, A COLD FRONT WAS SITUATED FROM JUST EAST OF LEXINGTON TO JUST S OF NASHVILLE AND MEMPHIS. A PRE-FRONTAL TROF WAS FOUND FROM SRN MIDDLE TN THRU NWRN AL INTO CENTRAL MS. DEW POINTS WERE QUITE SOUPY THIS MORNING, SITTING IN THE L-M70S. AREAS OF CLOUDS WERE ON THE INCREASE ALONG AND NEAR THIS BOUNDARY AND THE COLD FRONT IN KY AND TN. LOCAL RADARS INDICATE A SMALL TSTM HAS POPPED UP IN LAWRENCE COUNTY DURING THE PAST HOUR AND WE COULD SEE MORE OF THESE THRU THE MORNING HOURS. THIS LINES UP WITH NAM AND HRRR RUNS THAT SHOWS NOCTURNAL CONVECTION THAT MAY PLAGUE A FEW AREAS THRU EARLY MONDAY MORNING (~15Z) BEFORE THE FRONT SLIPS SOUTHEAST. IN ADDITION, PATCHY THICK FOG HAS DEVELOPED, MAINLY IN SOME OF OUR RIVER VALLEYS IN SRN TN AND NERN AL. THE 03Z MODIS IMAGE PICKED UP ON THIS WITHIN THE PAINT ROCK VALLEY. FORT PAYNE (4A9) IS DOWN TO 1/2SM. WE HAVE ADDED PATCHY FOG THRU 15Z TO GO ALONG WITH THE SCHC OF TSRA ALONG THE COLD FRONT. FOR THE REST OF TODAY, WE WILL SEE DEW POINTS DROP INTO THE U50S-L60S WITH A NWLY BREEZE DEVELOPING. LOWS BY TUESDAY MORNING SHOULD DROP INTO THE L-M50S IN SRN TN, AND U50S- L60S IN NRN AL. FINE WEATHER WILL CONTINUE FOR THE NEXT SEVERAL DAYS THIS WEEK AS SPRAWLING HIGH PRESSURE FROM THE NORTHERN PLAINS EXTENDS INTO THE DEEP SOUTH. THIS COLD FRONT SHOULD ACTUALLY PENETRATE THE NORTHERN GULF OF MEXICO BY LATE TUESDAY INTO WEDNESDAY. TEMPS WEDNESDAY MORNING COULD APPROACH 50 IN A FEW OF OUR SRN TN VALLEYS. AS THE SRN EXTENT OF THE UPPER TROF BECOMES ANCHORED ACROSS THE SERN U.S., A SIMILAR PATTERN THAT OCCURRED A COUPLE WEEKS BACK, WE MAY SEE ANOTHER INVERTED SFC TROF DEVELOP OVER GA/FL WHICH TRACKS WEST THRU AL AND TN ON FRIDAY INTO SATURDAY. HOWEVER, IT APPEARS MOISTURE WILL BE SLOW TO RETURN WESTWARD, SO WE HAVE HELD OFF POPS ATTM. TEMPS SHOULD GRADUALLY WARM BACK TO SEASONAL OR JUST ABOVE BY THE WEEKEND IF NOT SOONER. AK && .AVIATION... /ISSUED 1155 PM CDT SUN AUG 23 2015/ FOR 06Z TAFS...CDFNT CONTINUES TO MOVE TOWARDS NW AL. LOCAL RADARS SHOW THAT ISOLATED SHRA/TSRA HAVE DISSIPATED. HOWEVER SCT/BKN CLOUDS ARND 6000 FT WILL CONTINUE TO MOVES ACROSS THE TAF SITES OVERNIGHT...ALONG WITH PATCHY FOG. OTHERWISE EXCEPT FOR THE PATCHY MVFR FOG...VFR CONDITIONS ARE EXPECTED THRU THE FCST PERIOD. 07 && .PRELIMINARY POINT TEMPS/POPS... HUNTSVILLE 87 59 83 58 / 10 0 0 0 SHOALS 87 60 83 57 / 10 0 0 0 VINEMONT 85 56 81 57 / 20 0 0 0 FAYETTEVILLE 82 57 80 52 / 10 0 0 0 ALBERTVILLE 84 59 81 55 / 20 0 0 0 FORT PAYNE 85 56 81 53 / 20 0 0 0 && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WEATHER.GOV/HUNTSVILLE.  FXUS64 KHUN 170652 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 152 AM CDT SUN JUL 17 2016 .DISCUSSION... A mostly clear sky combined with a moist near surface layer has provided a favorable environment for valley fog development. IR imagery (GOES and MODIS) are showing river valley fog in parts of Jackson and DeKalb Counties in northeast AL and Franklin County in TN. Observations at K4A9 and KMSL also indicate fog at this hour. The fog should dissipate rather quickly after sunrise so will carry it through ~13Z. Water vapor imagery and stream flow vectors indicate a shortwave trough has now pushed into central AL and GA, with slightly drier mid and upper levels helping to clear the sky in the TN valley. Nevertheless, forecast soundings indicate good potential for convective instability to develop readily again today. The best chance of thunderstorm development should take place along the higher terrain in the southeast portion of our forecast area. Will go with a chance POP in these areas, lowering to slight chance in our northwest areas. Forecast CAPE values are not as high as Saturday, but given some drier air in the mid and upper levels, some downdrafts could produce gusty winds again today. Will go ahead and forecast patchy fog again tonight given little change in atmospheric conditions expected from what we see this morning. Not much change in forecast thinking from yesterday with a broad longitudinal ridge building across the southern U.S., which strengthens into a well defined anti-cyclone over Kansas by Monday into Tuesday. This places our area in an eastward extension of a ridge axis. There will be considerable northwest flow bringing impulses southeast through the Ohio Valley that may round the ridge to the southwest and west into the deep South during the early part of this week. This will help keep at least low chances of thunderstorms in on Monday and Tuesday. The greater chance appears to be on Tuesday when a "back door" cold front drops south or southwest from the Ohio Valley with at least scattered thunderstorms along and ahead of it. Will we see the considerably drier surface dew point air that the GFS advects in behind this front on Thursday into Friday? The ECMWF is less optimistic on lowering dew points as much as the GFS and seems more reasonable. The 850 mb high position is also progged to be right over middle TN and north AL on Thursday. So, it will certainly be a hot weather period this week into next weekend. The question will be the humidity and resulting heat index values. Those will be highest in our NW Alabama counties which will flirt with 105 degrees, while other areas may experience mainly upper 90s to around 100 degrees. && .AVIATION... (Issued 1231 AM CDT SUN JUL 17 2016) For 06Z TAFs: Mostly clear skies continue at both TAF sites at this time. Very light winds will continue and new model guidance shows very little additional cloud cover developing. In fact, new guidance suggests VSBYS dropping to between 1 and 3 miles after 17/08Z or 17/09Z. Skeptical that KHSV will drop that low, since they had very little rain today at the terminal. Thus, VSBY values were dropped into the MVFR category at KHSV and to IFR at KMSL. Although cigs around 4000 feet will develop by 17/15Z, VFR conditions will return/continue through the rest of the TAF period. An isolated tsra is a possibility at both sites tomorrow afternoon, but left out due to low confidence of development. If one affects the TAF sites, lower CIGS and VSBYS are possible. KTW && .PRELIMINARY POINT TEMPS/POPS... Huntsville 93 73 94 73 / 30 20 20 20 Shoals 93 73 94 73 / 20 20 20 20 Vinemont 91 72 92 72 / 40 20 20 20 Fayetteville 92 72 93 72 / 30 20 20 20 Albertville 91 71 92 71 / 40 30 30 20 Fort Payne 90 70 92 70 / 40 30 30 20 && .HUN Watches/Warnings/Advisories... AL...NONE. TN...NONE. && $$ For more information please visit our website at weather.gov/huntsville.  FXUS64 KHUN 122056 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 256 PM CST Sat Nov 12 2016 .NEAR TERM...(Tonight) Issued at 255 PM CST Sat Nov 12 2016 An upper level shear axis extending from NE TX to the Mid-Atlantic states is in the process of becoming a cut-off low just to our west. With the weak system to our west tonight models are all in agreement in keeping winds out of the NE/E. MODIS satellite imagery this afternoon was a good indicator of just how much smoke has made it into the area from the wildfires across N GA/E TN/W NC. For tonight one concern is the potential for reduced visibilities due to smoke from the wildfires. Observations from this morning only indicated a reduction down to 6-7 miles due to the smoke but this was only in Jackson and DeKalb counties. Unless we start to see more easterly winds in N GA/NE AL believe that the visibilities will be similar to this morning of 6-7 miles. Latest Air Quality forecast has portions of Jackson and DeKalb counties in a "Unhealthy for sensitive groups". It is recommended that people with asthma or are sensitive the reduced air quality limit their time outdoors this evening. Mostly clear skies tonight and generally light winds will allow for temps to drop into the upper 30s. .SHORT TERM...(Sunday through Monday night) Issued at 255 PM CST Sat Nov 12 2016 The system mentioned above begins to shift eastward into NW GA during the day Sunday. The latest guidance continued to indicate that the cut-off low would be able to advect some moisture back to the west up through central GA and guidance still generates some light rain with the moisture advection. Expect a gradual increase in cloud cover as moisture in the mid-levels spreads into the eastern half of the area. However, with the amount of dry air over the region and the center of the upper level system over AL/GA any precip that does form over central GA will remain well to our east. While we miss out on any precip, the good news is that with winds becoming westerly will help to clear out some of the smoke. We will remain under a broad trough with a few shortwaves moving across the region Monday and Tuesday. But dry air is forecast to continue with PWATS less than 0.5 inches and dewpoints in the 30s. So, the most we can expect with any of the shortwaves is a brief increase in cloud cover. Expect high temperatures to warm a degree or two from Sunday (upper 60s) to Monday (lower 70s). Overnight lows will be in the middle to upper 30s each night. .LONG TERM...(Tuesday through Friday) Issued at 255 PM CST Sat Nov 12 2016 As the main trough axis deepens (trailing south from a surface/upper low moving east into the great lakes region) Monday night into Tuesday morning, an associated cool front will push east across the area. New runs are showing some very light showers being produced in southern/central Mississippi as the front pushes east Monday night. However, northern Alabama will likely not see the moisture return that may be seen further southwest, so not expecting any precipitation. Not much cooler air will follow behind the front. However, the departing front should keep highs in the mid to upper 60s to lower 70s in most locations on Tuesday. Longer range synoptic models continued to rebuild a strong upper level ridge behind this front and quickly move it eastward Wednesday into Thursday. This will lead to a warming trend both days. Highs in the lower 70s look reasonable on Wednesday. By Thursday, both models center this ridge over the Tennessee Valley and further amplify the ridge over the area. This should allow the 925 mb/850 mb temps to rise to between 15 to 18 degrees. High temperatures look to respond and jump into the mid 70s on Thursday. Long range models continue to develop a strong storm system over the midwestern U.S. Thursday night and into Friday. Latest GFS has slowed this system down (closer to previous ECMWF model run timing), as the upper ridge is stronger this run than previous runs with the GFS. If the approaching system slows down more due to the strong upper ridge, Friday's highs could climb into the mid 70s as well. However, the ridge looks too strong for any precipitation ahead of the front to affect the Tennessee Valley until Friday night into Saturday. Although, a strong upper level jet and a 30 kt 850 mb jet is progged by models, thunderstorms look very doubtful, as CAPE and instability aloft is non-existent. Given the strong forcing with this system, at least some isolated to scattered showers look possible though. Unfortunately, unless the upper ridging slows this system down more (allowing a longer period for moisture return), rain amounts will be very paltry (less than one half of an inch). && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 1121 AM CST Sat Nov 12 2016 An upper level trough has become centered over the area based on latest satellite imagery. This has allowed a slight increase in wind speeds along and south of the TN River but speeds should decrease through the afternoon and into the evening hours. VFR conditions are forecast but smoke from wildfires in N GA/E TN will cause some haze. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...Stumpf SHORT TERM...Stumpf LONG TERM...KTW AVIATION...Stumpf For more information please visit our website at weather.gov/huntsville.  FXUS64 KHUN 131848 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 1248 PM CST Sun Nov 13 2016 .NEAR TERM...(Tonight) Issued at 1245 PM CST Sun Nov 13 2016 Rather busy day here at the office as calls/tweets continue to roll in about the smoke across the area. The low level flow remains east to northeasterly, and visibilities have dropped to around 4-5 miles in spots across northeast Alabama. Midday shortwave IR imagery from MODIS shows several large fires/hotspots, with the largest being the Rough Ridge/Cohutta fire across north central GA. At last report, this fire has burned over 19k acres. Multiple fairly signficant fires evident across eastern Tennessee into western NC, showing up even through the midday cloud cover. Aside from the smoky conditions, clouds have cleared out this afternoon as the initial upper low ejects east (more on that in a bit). Temps recovered quickly from a chilly start, currently running in the low to middle 60s in most locations. Winds will decouple quickly tonight making for a rather smoky night. Through the smoke/haze, viewing of the super/mega/colossal moon should be decent if not optimal across the area. For reference, the supermoon will reach its closest point to earth tonight at 522 AM CST. Moon rise this evening will be around 440 PM CST with moon set around 610 AM CST. .SHORT TERM...(Monday through Tuesday) Issued at 1245 PM CST Sun Nov 13 2016 A messy split flow pattern will persit through the short term with a series of southern stream systems passing across the region over the next 48 hours. The first aforementioned upper tough/low will continue to push east toward the southeast United States coastline tonight. Although this feature did bring some cloudiness to the region earlier today, the rainfall remained well east of the Tennessee Valley. The next wave will weaken significantly as it approaches the area on Monday. Little in the way of low level moisture will be present with this sytem, and only expect an increase in mid/high clouds perhaps late Monday. One bit of good news, winds should slowly veer to a more westerly direction and help somewhat with the smoke/haze situation (at least temporarily). Refer to our recent social media posts (over the past couple of days) along with today's Public Information Statement on more details concerning the smoke/fires. Despite some increase in cloud cover late on Monday, the warm air advection and southerly flow should help temps reach a category or so above today's readings for high temperatures. A secondary shortwave trough will move across Monday night on the back edge of the larger scale longwave trough. This system will have a bit more lift associated with it, although moisture is still limited. The latest high resolution model guidance produces very light QPF across northern MS and northwest AL late Monday night into early Tuesday. Will continue dry forecast for now given already dry thermal profiles and little model continuity. The upper level ridge will sharpen acros the central/southern plains on Tuesday in response to some phasing of nrn/srn stream energy along the eastern seaboard. This will help to push a weak dry front across the Tennessee Valley. Really not much, if any, airmass change with this feature as thickness values remain at or above climatological norms. In fact, trends show a slightly less amplified eastern CONUS flow pattern than previous runs. .LONG TERM...(Wednesday through Sunday) Issued at 1235 PM CST Sun Nov 13 2016 To start this period, an upper ridge will be over the central portion of country with the TN valley in nw flow. By Thursday the upper ridge axis is progged to move over the sern US. This scenario will keep dry conditions along with a slight warming trend across the cwa. Aftn highs on Wednesday and Thursday will be in the low/mid 70s with mrng lows mainly in the mid 40s. These aftn/mrng temps will also continue into Friday. However Friday looks to be the last day of above normal temps as a fairly strong cdfnt will be approaching the TN valley. For now will lean a little more with the GFS for the timing of the cdfnt. As such the cdfnt should begin to affect the TN valley by late Friday night and into Saturday mrng. If the GFS is correct the cdfnt should be out of the cwa by the early evening hours on Saturday. Behind the cdfnt much more colder temps will push across the area on Sunday. Highs on Sunday will be in the mid 50s with a good chc of freezing temps by Sunday night/Monday mrng )based on GFS model soundings). As for any severe wx with this cdfnt, it looks to be a low cape/ high shear event, especially late Friday night and early Saturday mrng. However overall it does not look like a widespread severe event attm, due to speed of cdfnt and perhaps a lack of good moisture return. Thus for now will maintain slight chc wording for tsra on Friday night and just shra on Saturday. However may have to add a slight chc of thunder on Saturday for locations east of I65.This will all depend on the timing of the cdfnt. && .AVIATION...(For the 18Z TAFS through 18Z Monday afternoon) Issued at 1119 AM CST Sun Nov 13 2016 Weak ridging will persist across the Tennessee Valley through tonight helping to maintain general VFR conditions at both KHSV and KMSL. Light northeasterly flow does continue to advect in smoke from fires in Northern Georgia, with the smoke layer extending up to around 8 kft. This obscuration may reduce visibilities in isolated spots to around 5-6 statute miles. A weak system will approach the area on Monday resulting in a wind shift to the south and eventually southwest. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...15 SHORT TERM...15 LONG TERM...007 AVIATION...15 For more information please visit our website at weather.gov/huntsville.  FXUS64 KHUN 231025 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 425 AM CST Thu Feb 23 2017 .NEAR TERM...(Today) Issued at 400 AM CST Thu Feb 23 2017 Moisture advection and shallow isentropic ascent has led to low stratus development around 1.5 to 2.5 kft this morning in eastern areas, generally from Franklin County (TN) southward through much of Jackson and DeKalb Counties. Patchy fog had developed by late in the evening as indicated by several observation sites, however MODIS/VIIRS RGB satellite images have shown that the fog is very limited in coverage and largely located in narrow valleys adjacent to the plateau. Since the low stratus has developed and moved across the area, some, if not most, of this valley fog has dissipated. Elsewhere, patchy fog was present along/near the TN River channel around Wheeler/Wilson Lakes and nearby low-lying communities. Nevertheless, the fog does not appear to be sufficiently dense or widespread to warrant a dense fog advisory at this time. Temperatures have fallen into the mid to upper 50s at most locations early this morning, and will remain near stationary until sunrise. Any remaining fog will quickly dissipate after sunrise this morning. The low stratus currently in the east and in areas to our south will gradually spread farther westward, perhaps into the Huntsville/Decatur metro area later this morning. However, this cloud deck will tend to disperse during the afternoon. Temperatures this afternoon are likely to reach the low/mid 70s for most locations. The most likely adjustments made to the forecast later may be to address issues with cloud cover and impacts to temps though, since the timing of dissipation and extent of the low cloud deck remains a little uncertain. .SHORT TERM...(Tonight through Saturday) Issued at 400 AM CST Thu Feb 23 2017 A broad, partially closed upper low currently in the Western CONUS will move into the Plains states as it phases with a northern stream trough in central Canada tonight and Friday. In response, a surface low will develop and briefly strengthen along the baroclinic boundary stretching across the Plains and Upper Midwest while a surface cold front moves into the Mississippi Valley region. In the warm sector in advance of this front, temperatures may soar into the upper 70s across many locations in the Tennessee Valley. Temperatures as high as 80 degrees may occur particularly in NW Alabama closer to the main axis of strong temperature advection from the SW. Record high temperatures are likely to fall at some locations on Friday. Showers and thunderstorms are expected to develop along the advancing front on Friday, but a significant capping inversion centered around 700-800 mb will tend to keep development at bay in our area until late in the day. To our north, where better instability and dynamical forcing will be present, thunderstorm development is expected to occur earlier. Showers and storms are expected to then develop gradually southward along and ahead of the cold front as it moves across the area Friday evening. So, the best chances for shower/thunderstorm activity will be in the north. CAPE values may reach ~1000 J/KG while deep layer shear in the vicinity of ~50 kts suggests some storm organization will be possible. Sounding profiles suggest "thin" CAPE up through 700 mb, with most of the CAPE above 700 mb to the EL, and dry mid-level conditions with a relatively moist boundary layer. The threat for damaging winds and large hail will be present, but is marginal. Looping hodographs, marginally high effective inflow helicity, and LCLs around 1 km suggest a slight tornado threat during the evening. The threat for strong to severe storms will subside as the cold front moves across the area quickly during the overnight period. Much cooler, but sunny conditions will return for Saturday as a modified Canadian airmass moves into the area. .LONG TERM...(Saturday night through Wednesday) Issued at 400 AM CST Thu Feb 23 2017 Medium range guidance from the global models is in agreement that a zonal flow regime in place over the southern CONUS at the beginning of the extended forecast period will become more amplified on Sunday as a 500-mb trough digs southeastward into WA/OR. A shortwave disturbance crossing the southern Rockies late Sunday is forecast to weaken and eject east-northeastward into the upper OH valley by late Monday afternoon, as prevailing flow downstream from the western CONUS trough backs to the southwest. At the surface, the center of a Canadian surface high will be located across the TN valley on Sunday morning providing ingredients for strong radiational cooling. After morning lows in the u20s/l30s, highs will rebound into the u50s/l60s as the ridge shifts eastward off the Atlantic coast and southeasterly winds strengthen. Return flow will continue to increase Sunday evening, as the southern Rockies disturbance ejects into the Plains and a weak surface low forms near the Red River valley of OK/TX. Strong low-level warm/moist advection east of the low will support widespread showers from the southern Plains into the mid-South region early Monday morning, with this regime expected to impact our forecast area during the day. A few thunderstorms are possible based on amount of elevated CAPE in forecast soundings, but overall instability should be too meager to support a threat for severe convection even with deep-layer shear around 60 knots. The Red River valley surface low will likely begin to degenerate into a baroclinic trough as the parent wave weakens and lifts further into the OH valley late Monday. This boundary may serve as a focal point for additional convection on Monday night/Tuesday, but the influence of this feature should also dissipate with time as the western CONUS longwave begins to push eastward and a new surface low forms in the lee of the central Rockies. Due to uncertainties on where the boundary may lie, we have maintained a chance POP both periods. If clouds and precip are less than anticipated on Tuesday, temperatures could easily be several degrees warmer than values in the current forecast. Convection will likely become fairly widespread to the north/west of the region Tuesday night beneath an intense low-level jet attendant to deepening cyclone ejecting through the Great Lakes and into southern Ontario/Quebec. The trailing cold front is forecast to cross our region Wednesday afternoon, with showers and thunderstorms likely throughout the day. Although shear/instability parameters appear favorable for severe storms both Tuesday night and Wednesday, coverage/intensity of frontal convection will be dictated by coverage of precipitation Tuesday night. A cooler/drier airmass of north Pacific origin will be advected into the region in the wake of this front and linger through the end of the forecast period. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1130 PM CST Wed Feb 22 2017 Fog is expected to form during the overnight across the area, courtesy of clear skies, light winds, and residual moisture from recent rain. Although some of the fog could become locally dense - especially late tonight, the lowest I went in the TAF was 3/4SM. VFR weather should return shortly after daybreak Thu as an area of high pressure moves east of the region, bringing a SE-S wind in the late morning and afternoon. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...KDW SHORT TERM...KDW LONG TERM...70/DD AVIATION...RSB For more information please visit our website at weather.gov/huntsville.