FXUS65 KRIW 122127 AFDRIW AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 327 PM MDT SUN SEP 12 2010 SHORT TERM...TONIGHT THROUGH WEDNESDAY SEASONABLE DAY ACROSS THE AREA AS FLAT RIDGE AXIS PASSES OVHD. SUBTROPICAL CIRRUS BAND CONTINUES TO MOVE ACROSS THE RED DESERT AS THE CRAS IMAGERY WAS INDICATING YESTERDAY. OTHERWISE...JUST A FEW CU OVER THE HIGHER MTNS. WEAK DISTURBANCE...AREA OF MOISTURE WILL MOVE ENE TOWARDS NW WYOMING ON MONDAY WHICH MAY BE ENOUGH TO PRODUCE AN ISOLATED STORM OVER THE FAR NW LATE MONDAY. THE REST OF THE AREA WILL CONTINUE MILD TO WARM AND QUITE DRY BUT WITHOUT SIGNIFICANT WINDS. TROUGH APPROACHING NRN CA IS STILL EXPECTED TO MOVE SLOWLY TOWARDS THE AREA MONDAY INTO TUESDAY. GFS IS A LITTLE FASTER MOVING THE TROUGH AXIS THROUGH BY 12Z WEDNESDAY WITH THE NAM BEING AT LEAST 6 HOURS SLOWER. FORECAST IS FOLLOWING THE SLOWER SOLUTION FOR NOW. IT LOOKS LIKE COMBINATION OF STEEP LAPSE RATES AND NEUTRAL TO SLIGHTLY NEGATIVE LI'S AND INCREASE PW'S FROM .60 TO .80 WILL BRING AT LEAST ISOLATED STORMS TO THE LOWER ELEVATIONS TUESDAY INTO TUESDAY NIGHT AND WIDELY SCATTERED TO SCATTERED MTN STORMS. 18Z NAM IS SLIGHTLY SLOWER YET WITH PCPN BACK INTO THE WIND RIVER BASIN INTO EARLY WED AFTN. SOUNDINGS SHOW INSTABILITY TUESDAY AFTERNOON AND EVENING IN THE 300-500 J/KG RANGE WITH WEDNESDAY BEGINNING TO STABILIZE BUT PW'S HOLD IN THE .60 TO .80 RANGE. TEMPS SHOULD COOL AT LEAST 8 TO 12 DEGREES EAST OF THE DIVIDE FROM TUESDAY INTO WEDNESDAY. LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY MEDIUM RANGE MODELS AGREE THAT A REX BLOCK WILL BE IN PLACE ACROSS THE EASTERN PACIFIC/ALASKA WEDNESDAY AND COULD LAST MUCH OF THE EXTENDED WITH THE GFS FASTER IN BREAKING IT DOWN. AT THE SAME TIME MODELS ARE SHOWING A STRONG CLOSED LOW AFFECTING CENTRAL CANADA/SOUTHERN HUDSON BAY. THE ECMWF AND GEM CONTINUE TO SHOW A STRONG SHORTWAVE TROUGH...ASSOCIATED WITH THE ABOVE MENTIONED CLOSED LOW...DIVING SOUTHEAST ACROSS MANITOBA/SASKATCHEWAN WEDNESDAY NIGHT AND THURSDAY. THE ECMWF SENDS A DECENT COLD FRONT THROUGH THE AREA THURSDAY WHILE THE GFS HAS A MUCH WEAKER COLD FRONT. THE ECMWF SENDS ANOTHER COLD FRONT THROUGH FRIDAY NIGHT...AS ITS PLACEMENT OF THE HUDSON CLOSED LOW IS A BIT FARTHER SOUTHWEST THAN THE GFS. ALTHOUGH NO SIGNIFICANT STORMS ARE EXPECTED IN THE EXTENDED DUE TO THE REX BLOCK IN THE EASTERN PACIFIC...WEAK DISTURBANCES IN THE FLOW AND THEIR INTERACTION WITH SURFACE COLD FRONTS COULD BE SUFFICIENT FOR SOME PRECIPITATION FROM TIME TO TIME ACROSS...MAINLY ACROSS THE NORTH AND NORTHEAST WHERE A BETTER MOISTURE PROFILE WILL BE LOCATED. DURING THE WEEKEND...MODELS ARE HINTING AT DEEP WESTERLY FLOW DEVELOPING ON THE SOUTHERN PERIPHERY OF THE WEAKENING REX BLOCK...WITH A FETCH OF PACIFIC MOISTURE POSSIBLY BEING PUSHED INTO THE WESTERN MOUNTAINS. WILL KEEP AN EYE ON THIS SCENARIO...BUT KEEP CONDITIONS MAINLY DRY FOR NOW. HAVE GONE COOLER THAN MEX MOS GUIDANCE...WITH A TREND TOWARDS THE ECMWF ESPECIALLY EAST OF THE DIVIDE DUE TO THE POSSIBILITY OF THE STRONGER COLD FRONTS IN THE ECMWF SOLUTION. AVIATION... VFR CONDITIONS ARE EXPECTED THROUGH MONDAY. ONE EXCEPTION WILL BE WHERE ISOLATED THUNDERSTORMS PRODUCING LOCAL MVFR CONDITIONS OCCUR IN NORTHWEST WYOMING MONDAY AFTERNOON DUE TO A WEAK UPPER LEVEL DISTURBANCE TRACKING EAST ACROSS THE AREA. SOUTHWEST WINDS OF 10 TO 18 MPH WILL BLOW FROM EASTERN SWEETWATER COUNTY TO KCPR MONDAY AFTERNOON. FIRE WEATHER... IT WILL CONTINUE VERY DRY EAST OF THE DIVIDE INTO TUESDAY AFTERNOON WITH OCCASIONAL WEST TO SOUTHWEST WIND 10 TO 20 MPH. MINIMUM RH'S WILL CONTINUE IN THE TEENS TO AS LOW AS AROUND 10 PERCENT. ISOLATED LATE DAY THUNDERSTORMS ARE POSSIBLE ON MONDAY IN THE NORTHWEST MOUNTAINS. AN APPROACHING DISTURBANCE WILL BRING A BETTER CHANCE OF ISOLATED TO WIDELY SCATTERED THUNDERSTORMS ON TUESDAY OVER ALL OF THE WEST...GRADUALLY SPREADING EAST OF THE DIVIDE BY LATE TUESDAY AFTERNOON OR EVENING. THIS SYSTEM WILL MOVE EAST OF THE AREA BY WEDNESDAY AFTERNOON RESULTING IN DRIER CONDITIONS AGAIN FOR THURSDAY AND FRIDAY. && .RIW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...SKRBAC LONG TERM...WM AVIATION...LIPSON FIRE WEATHER...SKRBAC  FXUS65 KRIW 222030 AFDRIW AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 230 PM MDT WED SEP 22 2010 SHORT TERM...TONIGHT THROUGH SATURDAY FRONTAL BOUNDARY THAT SAGGED SOUTH OVERNIGHT HAD A STRONGER PUNCH THAN EXPECTED WITH LOW CLOUDS LINGERING THROUGH THE AFTERNOON AND KEEPING TEMPERATURES ONLY IN THE 50S TO LOWER 60S ACROSS ALL OF THE BIG HORN BASIN OVER TO JOHNSON COUNTY. IN FACT...CODY WAS STILL STRUGGLING TO HIT 50...48 DEGREES...AT 215 PM THIS AFTERNOON. IT WILL BE A BUSY EVENING AS APPROACHING TROUGH AND DYNAMICS PRODUCE WIDESPREAD SHOWERS AND SOME THUNDERSTORMS ACROSS A BIG PORTION OF THE AREA. THUNDERSTORMS HAVE BEEN FIRING THE PAST FEW HOURS OVER THE HIGHER TERRAIN OF UTAH WITH MOST OF THEM WEAKENING AS THEY MOVE INTO SWRN WYO DUE TO LESS INSTABILITY. SUBTROPICAL MOISTURE PLUME IS AIMED JUST EAST OF THE AREA BUT SHORTWAVE IS SEEN RAPIDLY DEVELOPING ON TOP OF THIS PLUME OVER WRN CO AND ERN UT. WITH INCREASING JET SUPPORT AND QG FORCING...THIS MAY WELL TURN INTO A BAROCLINIC LEAF AS INDICATED BY THE CRAS IMAGERY. STLT IMAGERY SHOWS SOME TRAPPED MTN WAVES OVER THE RED DESERT INDICATIVE OF INCREASING WINDS ALOFT AS OUR JET STREAK LIFTS NE OVHD. BAROCLINIC LEAF WILL LIKELY PRODUCE WIDESPREAD SHOWERS AND ISOLD TSTMS OVER THE SERN HALF OF THE AREA WITH ANOTHER AREA OF CONCENTRATED SHOWERS AROUND THE WIND RIVER BASIN UP INTO THE SRN BIG HORN BASIN AND OVER TO THE SERN ABASAROKAS WHERE COMBINATION OF QG FORCING...FRONTAL FORCING AND MID LEVEL DEFORMATION ALL ADD UP TO HIGH POPS. INCREASED POPS OVER THE SW THIS AFTERNOON AND ALL OF THE CENTRAL AND SERN ZONES THIS EVENING. GFS AND NAM ARE SHOWING THE H7 LOW TRACKING SOMEWHERE BETWEEN SERN AND CNTRAL FREMONT THIS EVENING. ODDS OF PCPN WILL INCREASE FURTHER NE AS THE LOW AND ASSOCIATED FORCING LIFTS NE LATER TONIGHT. SHOWERS WILL LIKELY LINGER IN THE FAR N AND ERN ZONES THURSDAY MORNING... ESPECIALLY THE NERN ZONES. ANOTHER PASSING SHORTWAVE CLIPS THE FAR NORTH LATE FRIDAY INTO FRIDAY EVENING BUT MAINLY WITH INCREASING CLOUDS AND NO MORE THAN AN ISOLATED LIGHT SHOWER IN THE FAR NRN MTNS. COLD FRONT SHOULD PUSH SOUTH BEHIND THIS SYSTEM FRIDAY NIGHT POSSIBLY WITH ENOUGH PUNCH TO PRODUCE SOME LOW CLOUDS BETWEEN BYG AND CPR SATURDAY MORNING. THE REST OF THE AREA WILL SEE A WARMUP AS HEIGHTS BUILD FOR THE WEEKEND AND H7 TEMPS RISE ABOVE 10C IN THE WRN HALF. LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY MUCH ABOVE NORMAL TEMPERATURES WITH DRY CONDITIONS EXPECTED IN THE FINAL WEEK OF SEPTEMBER. MEDIUM-RANGE GLOBAL MODELS IN OVERALL BETTER AGREEMENT THIS MORNING IN DEVELOPMENT OF HIGH AMPLITUDE PATTERN WITH UPPER RIDGE OVER THE WESTERN U.S. WITH LONGWAVE TROUGH OVER THE EASTERN PACIFIC. LATEST ECMWF HAS BACKED OFF ON PROGRESSION OF THIS RIDGE NEXT WEEK...MOVING TOWARD GFS SOLUTION THOUGH THE GFS OPS AND GEFS MEAN STILL REMAIN FURTHER WEST. ALL MODELS DEPICT SHORTWAVE MOVING OVER TOP OF RIDGE OVER CENTRAL CANADA SUNDAY DRIVING A WEAK...SHALLOW COLD FRONT SOUTH EAST OF THE DIVIDE SUNDAY NIGHT THOUGH THIS FRONT IS NOT EXPECTED TO HAVE MUCH OF AN IMPACT ON TEMPERATURES. THE OVERALL PICTURE WILL BE TEMPERATURES 10-15F ABOVE NORMAL SUNDAY THROUGH WEDNESDAY BUT WITH GENERALLY LIGHT WIND NOT QUITE IN RECORD HIGH TERRITORY. ALSO...CLEAR (AND LONGER) NIGHTS AND A DRY AIRMASS WILL RESULT IN DIURNAL TEMPERATURE DIFFERENCES NEAR 40F. AVIATION... MOISTURE AND INSTABILITY IN SOUTHWEST FLOW ALOFT AHEAD OF A PACIFIC TROUGH WILL INTERACT WITH TOPOGRAPHY ACROSS WESTERN AND CENTRAL WYOMING...AND WITH A COLD FRONTAL BOUNDARY EXTENDING FROM NORTHWEST TO SOUTHEAST ALONG THE CONTINENTAL DIVIDE. SHOWERS AND THUNDERSTORMS WILL SPREAD ACROSS THE AREA...BECOMING WIDESPREAD IN THE MOUNTAINS AND MORE SCATTERED OVER THE BASINS AND VALLEYS THIS EVENING...CONTINUING THROUGH THE NIGHT. WIDESPREAD MOUNTAIN OBSCURATIONS WILL OCCUR. MOST VALLEYS AND BASINS WILL DEVELOP MVFR CEILINGS WITH LOWER VISIBILITY IN PRECIPITATION. THROUGH THE NIGHT AFTER THE HEAVIER PRECIPITATION...LOCAL IFR CEILINGS AND VISIBILITIES WITH MIST WILL BE ENCOUNTERED OVER MUCH OF THE AREA. ALL OF THE TAF SIGHTS WILL BE IMPACTED WITH LOWER CLOUDS... PRECIPITATION AND AT LEAST MIST IN THE VICINITY OF THE AIRPORT. AS THE UPPER TROUGH PASSES THROUGH LATE TONIGHT AND EARLY THURSDAY MORNING...NORTHWEST FLOW WILL SPREAD FROM WEST TO EAST WITH DECREASING MOISTURE AND INCREASING STABILITY. CEILINGS WILL GRADUALLY LIFT THROUGH LATE MORNING INTO THURSDAY AFTERNOON. SHOWERS WILL LINGER OVER THE MOUNTAINS AND ACROSS THE EAST WITH SOME OBSCURATIONS CONTINUING. THE TAF LOCATIONS ARE EXPECTED TO BECOME VFR BY LATE MORNING 16Z TO 18Z. FIRE WEATHER... A SLIGHTLY UNSTABLE ATMOSPHERE WILL INTERACT WITH AN APPROACHING WEATHER SYSTEM TO PRODUCE WIDESPREAD SHOWERS AND ISOLATED TO WIDELY SCATTERED THUNDERSTORMS THROUGH TONIGHT ACROSS ALL BUT THE NORTHWEST PART OF THE DISTRICT. THE SHOWERS WILL LINGER INTO THURSDAY MORNING ACROSS THE FAR NORTH AND EASTERN PART OF THE DISTRICT. THE AIRMASS WILL DRY OUT FRIDAY INTO THE WEEKEND WITH ONLY A PASSING DISTURBANCE BRUSHING FAR NORTHERN WYOMING LATE FRIDAY. THIS WEAK DISTURBANCE FRIDAY AFTERNOON AND EVENING WILL BRING AN INCREASE IN CLOUDS TO THE FAR NORTH ALONG WITH A LIGHT SHOWER POSSIBLE IN THE NORTHERN MOUNTAINS. A COLD FRONT WILL ALSO SLIDE SOUTH WITH THIS DISTURBANCE POSSIBLY CAUSING SOME LOW CLOUDS SATURDAY MORNING BETWEEN BUFFALO AND CASPER. && .RIW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...SKRBAC LONG TERM...AEM AVIATION...C.BAKER FIRE WEATHER...SKRBAC  FXUS65 KRIW 232011 AFDRIW AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 211 PM MDT THU SEP 23 2010 SHORT TERM...TONIGHT THROUGH SUNDAY SYSTEM LAST NIGHT BROUGHT MEASURABLE PCPN TO MOST OF THE AREA WITH SOME SITES REPORTING AS MUCH AS .25 TO .40. THE AREA AROUND KAYCEE AND ELKHORN RAWS REPORTED THE MOST WITH AROUND .40 INCHES. LOW CLOUDS HAVE LINGERED MUCH OF THE DAY IN JOHNSON...WEST OF THP AND IN THE SOUTHEAST END OF THE BIG HORN BASIN. ENOUGH MOISTURE OVER THE MTN RANGES TO ALLOW MODERATE CU AND PC SKIES THIS AFTERNOON. MAIN FORECAST CHALLENGE FOR TONIGHT WILL BE OVERNIGHT LOWS AND WIND SPEEDS IN THE CODY FOOTHILLS. WEAK MTN WAVE SIGNATURE SHOWING UP ALONG THE EAST SLOPE OF THE ABSAROKA MTNS BETWEEN 06Z AND 15Z FRIDAY. LCL WRF IS GENERATING SOME 30-35KT SUSTAINED WINDS IN THE HIGHER FOOTHILLS AND 15-20 KTS BETWEEN CODY AND CLARK. INCREASED THE WINDS ACROSS THIS AREA TO ADJUST FOR THIS. RIDGE AXIS PASSES TO THE EAST OVERNIGHT AND JET NOSES INTO WRN MT WHICH IS USUALLY A GOOD SET-UP FOR A SOME MTN WAVE ACTION. CRAS IMAGERY ALSO SHOWING SOME LEE ENHANCEMENT IN OUR FAVORED AREA UP THERE SO INCREASED CLOUD COVER UP THERE LATE TONIGHT INTO FRIDAY MORNING. DRY THROUGH THE PERIOD UNLESS WE CAN SQUEEZE OUT A LATE DAY SHOWER FROM THE BEARTOOTH OVER TO THE NRN BIG HORNS. RIDGE BUILDS IN OVER THE WEEKEND FOR WARMING TEMPS AND LOWERING AFTERNOON RH'S. WINDS SHOULD NOT BE ENOUGH FOR FIRE WEATHER CONCERNS BUT MIN RH'S WILL LIKELY DROP BELOW 15 PERCENT EACH AFTERNOON ACROSS MOST OF THE LOWER ELEVATIONS AND EAST SLOPE OF THE MTN RANGES. DRY ATMOSPHERE SHOULD LEAD TO SOME PRETTY IMPRESSIVE DIURNAL SWINGS OF AT LEAST 40 TO 50 DEGREES. WEAK FRONTAL BOUNDARY THAT DROPS DOWN FRIDAY NIGHT LOOKS WEAKER THAN EARLIER RUNS INDICATED SO CHANCE OF LOW CLOUDS HAS DIMINISHED. TEMPERATURES WILL WARM EACH DAY WITH MANY LOWER ELEVATIONS IN THE UPPER 70S AND 80S BY SUNDAY WITH UPPER 50S AND 60S IN THE HIGH COUNTRY. LONG TERM...SUNDAY NIGHT THROUGH THURSDAY MUCH ABOVE NORMAL TEMPERATURES WITH DRY CONDITIONS EXPECTED IN THE FINAL WEEK OF SEPTEMBER. MEDIUM-RANGE GLOBAL MODELS CONTINUE TO ADVERTISE STRONG UPPER RIDGE OVER THE ROCKIES WITH UPSTREAM TROUGH OVER THE EASTERN PACIFIC BETWEEN 140-150W. SHORTWAVES TIMED TO TOP RIDGE ACROSS CENTRAL CANADA ON SUNDAY AND TUESDAY WITH ASSOCIATED WEAK SHALLOW BACKDOOR COLD FRONTS PUSHING SOUTH INTO CENTRAL WYOMING SUNDAY NIGHT AND TUESDAY NIGHT RESPECTIVELY. THESE COLD FRONTS WILL ONLY RESULT IN A FEW DEGREES OF COOLING ACROSS EASTERN ZONES MONDAY AND WEDNESDAY OTHERWISE A VERY DRY AND UNSEASONABLY WARM AIRMASS WILL PREVAIL UNDER THE UPPER RIDGE WITH TEMPERATURES 10-15F ABOVE NORMAL...CLOSE TO RECORD HIGHS BUT LIKELY TO STAY A FEW DEGREES BELOW AS WINDS WILL REMAIN GENERALLY LIGHT...AIRMASS NOT COMPLETELY MIXING OUT DURING THE SHORTER DAYS. CLEAR SKIES...A DRY AIRMASS AND LONGER NIGHTS WILL ALSO RESULT IN LARGE DIURNAL TEMPERATURE RANGES NEAR 40F. BOTH ECMWF AND GFS HOLD ON TO THIS STRONG RIDGE THROUGH THE FIRST WEEKEND IN OCTOBER WITH THE ECMWF SHOWING MORE AMPLITUDE OVER THE EASTERN PACIFIC AND NORTH AMERICA OR A STRONG BLOCKING PATTERN THAT WILL CONTINUE SEVERAL DAYS BEYOND. AVIATION... WEST NORTHWEST FLOW ALOFT WILL BRING COOLER...DRY AND STABLE AIR TO WESTERN AND CENTRAL WYOMING TONIGHT AND FRIDAY. GENERALLY VFR CONDITIONS WILL PREVAIL AT THE TAF LOCATIONS. WITH CLEARING AND RADIATIONAL COOLING...SOME STRATUS AND MIST IS EXPECTED TO FORM OVER LOW LYING AREAS WHERE PRECIPITATION OCCURRED YESTERDAY THROUGH THIS MORNING. THIS SHOULD BE LOCALIZED WITH LOCAL MVFR TO IFR CONDITIONS WITH LOW CEILINGS AND MIST IN THE VALLEYS...ESPECIALLY IN THE WEST WITH LOCAL TERRAIN OBSCURATIONS. BY MID MORNING CLEARING SHOULD OCCUR WITH BREEZY AREAS OF WEST TO SOUTHWEST WINDS DEVELOPING ALONG THE EAST SLOPES OVER THE MOUNTAINS AND ACROSS THE SOUTH FROM KRKS TO KCPR. FIRE WEATHER... A DRY FORECAST WILL DOMINATE THE AREA THROUGH THE WEEKEND AND MOST LIKELY THROUGH NEXT WEEK. THERE WILL BE A PASSING DISTURBANCE THAT BRUSHES THE FAR NORTH WITH ONLY A SLIGHT CHANCE OF A HIGH MOUNTAIN SHOWER LATE FRIDAY. OTHERWISE...IT WILL BE DRY WITH A WARMING AND DRYING TREND WITH MIN RH'S DROPPING BACK INTO THE TEENS ACROSS MANY LOWER ELEVATION AREAS FRIDAY...DRYING FURTHER THROUGH THE WEEKEND. BIG DIURNAL TEMPERATURE SWINGS WILL PREVAIL THROUGH THE WEEKEND AND INTO NEXT WEEK AS THE DRY AIRMASS ALLOWS FOR 40 TO 50 DEGREE DIURNAL SWINGS. THERE WILL BE SOME WINDY CONDITIONS IN THE CODY FOOTHILLS BETWEEN 06Z AND 15Z FRIDAY AND SOME BREEZY TO LOCALLY WINDY CONDITIONS IN THE WIND CORRIDOR FROM RKS TO CPR AGAIN FRIDAY. THE MOUNTAINS WILL ALSO BE BREEZY AT TIMES DURING THE AFTERNOON AND EVENING. && .RIW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...SKRBAC LONG TERM...AEM AVIATION...C.BAKER FIRE WEATHER...SKRBAC  FXUS65 KRIW 232216 AFDRIW AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 316 PM MST THU DEC 23 2010 SHORT TERM...TONIGHT THROUGH SUNDAY WEAK COLD FRONT PUSHED SE ACROSS THE AREA TODAY BEHIND OUR SHORTWAVE. LOW CLOUDS AND FOG DEVELOPED IN QUITE A FEW OF OUR ERN AND SRN ZONES AND CONTINUED OUT WEST. CPR WARMED TO ABOUT 40F EARLY THIS MORNING WHEN THE SHORTWAVE WENT THROUGH BUT THEN THE COLD FRONT PUSHED BACK SOUTH AND TEMPS WERE COLDER THE REST OF THE DAY ALONG WITH LOW CLOUDS AND FOG THAT WORKED ITS WAY SOUTH FROM TWENTYMILE HILL. FOG PERSISTED MUCH OF THE DAY IN THE UPPER GREEN AND JACKSON VALLEY. THE MAIN WEATHER CHALLENGE FOR THE NEXT 2 TO 3 DAYS WILL FOG AND ITS DURATION AND THICKNESS. SOUNDINGS LOOK PRETTY IMPRESSIVE FOR FOG OUT WEST TONIGHT AND MOST OF THE LOW LYING CENTRAL AND WRN AREAS FRIDAY NIGHT AND SATURDAY MORNING. THE SOUNDINGS LOOK CLASSIC BY SATURDAY MORNING WITH JUST TWO NEGATIVES TO BE CONCERNED WITH. ONE IS LACK OF SNOW COVER IN THE CENTRAL WIND RIVER BASIN WHILE OTHER AREAS GENERALLY HAVE SNOW. THE SECOND ITEM IS POTENTIAL FOR SOME MID AND HIGH CLOUDS INTO FRIDAY NIGHT. SOUNDINGS DON'T SUPPORT ANY THICKER HIGH CLOUDS BUT CRAS IMAGERY IS SHOWING SOME CLOUDS THROUGH THE PERIOD WITH EVEN SOME LEE ENHANCEMENT. LEANING TOWARDS THE FOG SCENARIO BASED ON TODAY'S TREND WITH FOG LINGERING ALL DAY IN SPOTS AND THE IMPRESSIVE WARMING ALOFT. CLOUDS MAY THICKEN ENOUGH BY SUNDAY MORNING TO BREAK UP THE FOG IN THE WEST EARLIER BUT IT COULD CONTINUE FURTHER EAST. MODELS ARE TRENDING WEAKER AND SLOWER WITH THIS SYSTEM BUT I DIDN'T CHANGE OUR SLIGHT CHANCES SUNDAY MORNING OR CHANCES SUNDAY AFTERNOON IN THE FAR WEST. LONG TERM...SUNDAY NIGHT THROUGH THURSDAY LONG RANGE MODELS ARE IN FAIRLY GOOD AGREEMENT AFTER MONDAY. THERE ARE MODEL DIFFERENCES WITH THE INCOMING TROUGH SUNDAY AFTERNOON AND SUNDAY NIGHT. THE ECMWF CONTINUES TO SPLIT THE TROUGH AND HAS MUCH LESS PRECIP IN THE FORECAST THAN THE GFS. THE GFS SWINGS A NEGATIVELY TILTED TROUGH INTO THE REGION WITH A DECENT SHOT OF PRECIP FOR THE WEST SUNDAY AFTERNOON AND NIGHT...THEN SCATTERED PRECIP IN THE EAST SUNDAY NIGHT INTO MON MORNING. THE CANADIAN MODEL SIDES WITH THE ECMWF MODEL. THE 06Z NAM SIDES WITH THE GFS SO THERE IS PLENTY OF UNCERTAINTY. WILL KEEP THE PRECIP IN THE FORECAST AND MADE ONLY SLIGHT ADJUSTMENTS SUNDAY NIGHT INTO MONDAY. ONCE THIS TROUGH EXITS THE WEATHER PATTERN QUICKLY GOES TO A MOIST WEST NORTHWEST FLOW FOR MONDAY NIGHT AND TUESDAY WITH SNOW RETURNING TO THE WESTERN MTS. THEN THE FLOW BACKS TO THE SW WED AS THE NEXT TROUGH DIVES INTO THE WESTERN U.S. AND THEN HEADS TOWARD THE GREAT BASIN/INTERMOUNTAIN WEST THURSDAY. GFS SEEMS TOO FAST WITH ITS TROUGH SPEED WHILE THE ECMWF IS DIGGING A SHARPER TROUGH...WHICH SEEMS TO BE THE BETTER IDEA THIS SEASON. SO THE WET WEATHER WILL CONTINUE THROUGH YEARS END IN THE WEST WHILE THE EAST STAYS MAINLY DRY NEXT MON THROUGH WED. THE EAST MAY SEE SOME PRECIP NEXT THURS. AS FOR TEMPS...A MILD DAY ON SUNDAY THEN COLDER FOR MONDAY...SEASONAL HIGHS AND LOWS NEXT TUE THROUGH THURS. AVIATION... A STABLE ATMOSPHERE WILL ENSUE THROUGH CHRISTMAS EVE. THIS WILL RESULT IN A PROPENSITY FOR OCCASIONAL FOG AND LOW CLOUDS. FOR THE REST OF THIS AFTERNOON A PATCHY LOW DECK OF CLOUDS BETWEEN 3 AND 4K AGL OVERLAYING ANOTHER LOWER CLOUD DECK AT AROUND 1K WEST OF THE DIVIDE WILL AFFECT KJAC...KRKS AND KAFO. ANOTHER AREA OF LOW CLOUDS WILL SLOWLY DISSIPATE AND EXIT THE INTERSTATE 25 CORRIDOR INCLUDING KCPR AND THE BIG HORN MTNS. THESE CLOUDS WILL RESULT IN AREAS OF MVFR AND IFR CONDITIONS AS WELL AS MTN OBSCURATIONS. AREAS OF FOG AND LOW CLOUDS WILL REFORM THIS EVENING AND EXPAND AFTER MIDNIGHT TONIGHT IN THE BASINS AND VALLEYS WEST OF THE DIVIDE. THE FOG AND LOW CLOUDS WILL PERSIST THROUGH 18Z FRIDAY. THE FOG AND LOW CLOUDS WILL AFFECT KRKS...KBPI...KPNA AND KJAC. PATCHY FOG WILL FORM IN THE WIND RIVER BASIN AND BIG HORN BASIN THIS EVENING AND PERSIST THROUGH THE REST OF TONIGHT AND LAST THROUGH 18Z FRIDAY. THE FOG IN THESE BASINS WILL BE CONCENTRATED PRIMARILY ALONG THE BIG HORN RIVER AND THE VICINITY OF BOYSEN RESERVOIR. THIS PATCHY FOG WILL AFFECT THE VICINITIES OF KWRL AND KRIW. AFTER THE FOG AND LOW CLOUDS DISSIPATE AFTER 18Z FRIDAY EXPECT VFR CONDITIONS. A WEST SOUTHWEST BREEZE OF 10 TO 15 MPH FROM KRKS TO KCPR WILL BE PRESENT THROUGH FRIDAY WITH WINDS INCREASING TO 15 TO 25 MPH FROM THE RED DESERT TO KCPR. FIRE WEATHER... STEEP BASIN AND VALLEY INVERSIONS WILL DEVELOP FRIDAY INTO SATURDAY AS A RIDGE OF HIGH PRESSURE BUILDS OVER THE STATE. NO PRECIPITATION IS EXPECTED FRIDAY OR SATURDAY. SOME WEST TO SOUTHWEST WINDS WILL BLOW AT TIMES FROM THE RED DESERT TO CASPER AND EAST SLOPE OF THE CENTRAL WYOMING MOUNTAINS. && .RIW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...SKRBAC LONG TERM...AR AVIATION...LIPSON FIRE WEATHER...SKRBAC