FXAK68 PAFC 161358 AFDAFC SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ANCHORAGE AK 458 AM AKST FRI JAN 16 2015 .ANALYSIS AND UPPER LEVELS... THE UPPER LEVELS HAVE TWO CLOSED LOWS WITH THE FIRST OVER THE BRISTOL BAY REGION AND THE SECOND LOW OVER THE EASTERN SIBERIA AREA. THERE IS GALE FORCE LOW REFLECTED AT THE SURFACE NEAR DILLINGHAM THIS MORNING WITH MULTIPLE SHORTWAVES PIN-WHEELING AROUND THIS LOW HEADING INTO THE WEEKEND. THIS WILL BRING RAIN TO THE BRISTOL BAY REGION WITH SURFACE TEMPERATURES IN THE MID 30S TO LOWER 40S. THE KUSKOKWIM DELTA AND LOWER KUSKOKWIM VALLEY CONTINUE WITH NORTHEASTERLY WINDS AT THE SURFACE. THIS IS BRINGING IN COOLER AIR THE AREA AND COINCIDES WITH THE SHORTWAVES PUSHING THROUGH THE REGION WILL RESULT IN LIGHT FREEZING RAIN THIS MORNING. AN UPPER LEVEL WAVE WILL FORM A LOW AT THE SURFACE LOCATED JUST SOUTH OF THE GULF OF ALASKA THIS MORNING. THE SOUTH TO NORTH MERIDIONAL 70 KNOT JET STREAK OVER THE EASTERN GULF WILL HELP TO TRACK THE LOW INTO THE GULF BY FRIDAY EVENING. THIS WILL BRING MORE SOUTHERLY FLOW AND WARM AIR ADVECTION INTO THE NORTHERN GULF BEFORE SPREADING INLAND. THE COPPER RIVER BASIN HAS STRATUS AND FOG WITH THE SPORT MODIS NIGHTTIME MICROPHYSICS SATELLITE PICKING UP THE IFR FOG THIS MORNING. THE EASTERN KENAI EXTENDING SOUTHWARD TO KODIAK WILL CONTINUE TO HAVE MORE PERIODS OF RAIN AS SHORTWAVES ROTATE AROUND THE SURFACE LOW NEAR CHIGNIK TODAY. THE BERING SEA WILL PREDOMINANTLY HAVE NORTHERLY WINDS FROM THE PRIBILOF ISLANDS WESTWARD WITH THE LOW IN THE BRISTOL BAY BECOMING ELONGATED HEADING INTO THE WEEKEND. THE PRESSURE GRADIENT THROUGH THE BERING STRAIT EXTENDING SOUTHWARD INTO THE CENTRAL BERING WILL REMAIN GUSTY AS MORE COLD AIR FILTERS INTO THE REGION. && .MODEL DISCUSSION... THE MODELS CONTINUE TO BE IN GOOD AGREEMENT WITH THE LOW OVER BRISTOL BAY REGION. THIS LOW WILL BEGIN TO BECOME ELONGATED BY FRIDAY EVENING WITH A LOW FORMING TO THE NORTH OF BETHEL BEFORE TRACKING NORTH INTO THE BERING STRAIT BY SATURDAY AFTERNOON. THE BRISTOL BAY AREA WILL HAVE THE REMNANTS OF A TROUGH HEADING INTO THE WEEKEND. THE MODELS ARE STRUGGLING OVER THE GULF WITH THE GFS BEING THE OUTLIER WITH KEEPING ONLY ONE LOW IN THE GULF...WHILE THE OTHER MODELS ARE DEPICTING TWO LOWS FORMING BY FRIDAY EVENING OVER THE GULF. THE PREFERRED MODELS OF CHOICE WERE THE ECMWF AND THE NAM. THE FORECAST CONFIDENCE REMAINS ABOVE AVERAGE EVEN THOUGH THE MODELS HAVE UNCERTAINTY WITH THE LOWS FORMING IN THE GULF. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)... RAIN SHOWERS WILL PERSIST ALONG THE NORTH GULF COAST THROUGH THE DAY WITH LEEWARD SIDES OF THE MOUNTAINS MISSING MOST OF THE PRECIPITATION. A LOW DEVELOPING IN THE SOUTHEAST GULF WILL MOVE OVER THE COPPER RIVER BASIN AND BRING SNOW TO THAT AREA TONIGHT THROUGH SATURDAY. AFTER THAT LOW MOVES THROUGH THE UPPER LEVEL FLOW OVER SOUTHCENTRAL ALASKA WILL THEN TRANSITION TO THE SOUTHWEST AND COOLER AIR WILL ACCOMPANY THIS CHANGE IN PATTERN. && .SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)... NUMEROUS RAIN SHOWERS WILL CONTINUE ACROSS MUCH OF THE SOUTHWEST MAINLAND THROUGH SUNDAY AFTERNOON. THE CROSS BARRIER FLOW KEEPING AREAS ON THE LEEWARD SIDE OF THE ALEUTIAN/ALASKA RANGE DOWNSLOPED AND DRIER WILL BEGIN TO DIMINISH SATURDAY...ALLOWING SOME SHOWERS TO FILL IN OVER AREAS ALONG THE ALEUTIAN RANGE. GENERALLY RAINFALL WILL CONTINUE ACROSS MUCH OF THE SOUTHWEST INTERIOR THROUGH SUNDAY AS AN AREA OF LOW PRESSURE REMAINS OVER THE SOUTHWEST COAST. FREEZING RAIN REMAINS A CONCERN FOR INLAND AREAS OF THE KUSKOKWIM DELTA AND WESTERN PORTION OF THE LOWER KUSKOKWIM VALLEY TODAY...WITH MUCH WARMER AIR ALOFT KEEPING RAIN THE DOMINANT PRECIPITATION TYPE AND COLDER NORTHERLY FLOW AT THE SURFACE KEEPING SURFACE TEMPS NEAR OR BELOW FREEZING. THE COASTAL REGIONS OF THE KUSKOKWIM DELTA WILL REMAIN ALL SNOW AS A MUCH COLDER AIR MASS BEGINS TO SLOWLY MOVE INLAND OVER THE DELTA TONIGHT. THIS MUCH COLDER AIR MASS WILL GRADUALLY MOVE INLAND THROUGH SUNDAY...CHANGING THE PRECIPITATION FROM RAIN TO SNOW...AND ELIMINATING THE THREAT OF FREEZING RAIN. THERE ARE SOME CONCERNS FOR WIND CHILLS OVER THE KUSKOKWIM DELTA OVER THE WEEKEND AS TEMPERATURES POSSIBLY BELOW ZERO AT NIGHT AND IN THE LOWER TEENS ARE ACCOMPANIED BY A STOUT NORTHERLY WIND. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)... A MUCH COLDER AIR MASS ORIGINATING OVER SIBERIA HAS PUSHED INTO THE NORTHERN BERING SEA. THIS AIR MASS WILL CONTINUE TO TRACK SOUTH THROUGH THE WEEK AND INTO THE WEEKEND AND BRING MUCH COOLER WEATHER TO THE BERING SEA ALONG WITH SNOW SHOWERS AND GUSTY WINDS. THE COLDER AIR MASS WILL CREATE DECENT MID-LEVEL LAPSE RATES THAT WOULD BE CONDUCIVE FOR SCATTERED SNOW SHOWERS ACROSS MUCH OF THE BERING SEA BY THIS EVENING. THE PRIBILOF ISLANDS HAVE ALREADY BEGUN TO FEEL THE EFFECTS OF THIS AIR MASS AS TEMPERATURES HAVE COOLED TO 32 DEGREES WITH PERIODS OF LIGHT TO MODERATE SNOW AND STRONG WINDS. HEAVY FREEZING SPRAY WILL BECOME AN ISSUE NORTH OF 58N AS GALE FORCE WINDS MIX WITH COLDER AMBIENT TEMPERATURES. WINDS BEGIN TO SHIFT BACK TO THE SOUTHWEST BY SUNDAY...HELPING TO MODIFY TEMPERATURES AND DIMINISH THE GUSTY WINDS OVER THE BERING. && .LONG TERM FORECAST (SUNDAY THROUGH THURSDAY)... THE ABOVE NORMAL TEMPERATURE PATTERN CONTINUES INTO THE EXTENDED FORECAST. ONE CHANGE FROM THE CURRENT STATE IS THAT THE CHANCES FOR PRECIPITATION LOOK TO BE A BIT BETTER THAN THE CURRENT SITUATION OVER THE COOK INLET REGION. LATE THIS WEEKEND THE LAST GASP OF THE CURRENT ALASKA PENINSULA TROUGH WILL BE LINGERING IN THE AREA KEEPING SOME SCATTERED RAIN/SNOW SHOWERS IN THE AREA. EARLY NEXT WEEK A DISTURBANCE MOVING INTO THE GULF FROM THE BERING SEA WILL BRING THE NEXT THREAT FOR PRECIPITATION TO THE MAINLAND. WHILE THE PATTERN NEXT WEEK IS NOT THAT DIFFERENT FROM THE CURRENT VARIATION A BLOCKING HIGH PRESSURE OVER THE ALEUTIANS IS CAUSING SOME DISCREPANCIES AMONG GUIDANCE AS TO HOW THE FLOW WILL LOOK OVER THE SOUTHERN MAINLAND. HOWEVER...SOME COMMON FEATURES CAN BE SEEN. IT APPEARS AS IF A TROUGH WILL SET UP JUST SOUTH OF THE ALEUTIANS ALONG WITH A BAROCLINIC ZONE STRETCHING INTO THE FAR SOUTHERN GULF. THE TAKE AWAY IS A CONTINUATION OF ABOVE NORMAL TEMPERATURES WITH INCREASING CHANCES FOR PRECIPITATION TOWARD THE MIDDLE OF NEXT WEEK. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...HEAVY FREEZING SPRAY 180 181 185 GALE 173 174 179 181 185. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...PD SOUTHCENTRAL ALASKA...EZ SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TP LONG TERM...MTL  FXAK68 PAFC 191425 AFDAFC SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ANCHORAGE AK 525 AM AKST MON JAN 19 2015 .ANALYSIS AND UPPER LEVELS... THERE IS AN UPPER LEVEL CLOSED LOW POSITIONED OVER THE BERING STRAIT WITH AN ASSOCIATED TROUGH EXTENDING TO THE SOUTHWEST JUST NORTHWEST OF THE WESTERN ALEUTIANS. THIS IS REFLECTED AT THE SURFACE WITH A WEAK LOW JUST SOUTH OF SAINT LAWRENCE ISLAND AND A SECOND WEAK LOW JUST NORTH OF SHEMYA. THE 300 MB IS SHOWING A 90 KNOT ZONAL JET STREAK LOCATED OVER THE WESTERN TO CENTRAL BERING SEA THIS MORNING. THE SOUTHCENTRAL ALASKA REGION EXTENDING SOUTH IN THE WESTERN GULF IS AN UPPER LEVEL RIDGE. THE SATELLITE IMAGERY IS SHOWING MOSTLY STRATUS IN THE GULF. THE SPORT MODIS NIGHTTIME MICROPHYSICS IMAGERY WAS PICKING UP THE LOW STRATUS AND FOG IN THE COPPER RIVER BASIN. THIS COINCIDES WITH THE SURFACE OBSERVATIONS IN THE AFOREMENTIONED REGION. THE EASTERN GULF AT 500 MB IS SHOWING A CLOSED LOW LOCATED OFF THE COAST NEAR SITKA. THE SURFACE ANALYSIS IS SHOWING A WEAK LOW JUST SOUTHWEST OF SITKA WITH THE ASCAT SCATTEROMETER WINDS SHOWING UPPER END SMALL CRAFT ADVISORY WINDS WITH THIS SYSTEM. THE OTHER KEY FEATURE IS AN UPPER LEVEL TROUGH OVER THE EASTERN ALEUTIANS NEAR COLD BAY. THE SATELLITE IMAGERY IS SHOWING AN AREA OF LOW CLOUDS ASSOCIATED WITH THIS TROUGH AND THE WATER VAPOR SATELLITE HAS THE BACK EDGE OF THE TROUGH JUST EAST OF COLD BAY THIS MORNING. && .MODEL DISCUSSION... THE MODELS HAVE SOME UNCERTAINTY WITH A NORTH PACIFIC LOW ENTERING THE GULF BY TUESDAY MORNING. THE NAM/GFS MODELS TRACK THE LOW FARTHER EAST IN THE EASTERN GULF. WHILE...THE GEM-REG/EC MODELS TRACK THE LOW MORE TOWARDS THE WEST INTO THE MIDDLE OF THE GULF. THIS LOW PRESSURE SYSTEM THEN MOVES INLAND BY TUESDAY EVENING. THE MODELS ARE STRUGGLING WITH THE COMPLEX NORTH PACIFIC LOW APPROACHING THE CENTRAL TO EASTERN ALEUTIANS. THE EC MODEL SEEMS TO HAVE HAD BETTER RUN-TO-RUN CONSISTENCY WITH THIS COMPLEX LOW PRESSURE SYSTEM. THE FORECAST CONFIDENCE REMAINS BELOW AVERAGE DUE TO THE UNCERTAINTY WITH TIMING AND LOCATION OF SYNOPTIC SYSTEMS. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)... A SHORT WAVE LIFTING NORTHEAST ACROSS SOUTHCENTRAL TONIGHT WILL BRING INCREASED CHANGES FOR LIGHT SNOW ACROSS COOK INLET...MAT- SU...AND THE KENAI PEN WITH A MIXTURE ALONG THE NORTH GULF COAST. GENERAL OFFSHORE FLOW SETS UP AFTER THE PASSAGE OF THE SHORT WAVE ON TUE. THIS WILL LEAD TO DECREASING CLOUDS...HOWEVER SOME LOW CLOUDS AND FOG MAY REFORM OVER THE COPPER RIVER BASIN TUE NIGHT. PRESSURE GRADIENTS WILL ALSO BUILD IN THE WAKE OF THE WAVE AND GIVE RISE TO BRISK OUTFLOW WINDS ACROSS THE NORTH GULF AND EASTERN KENAI PENINSULA TUE AND TUE NIGHT. && .SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)... WEAK HIGH PRESSURE WILL BUILD OVER THE REGION...WHICH WILL KEEP MOST LOCATIONS DRY THROUGH TUESDAY. THE EXCEPTION WILL BE A WEAK SURFACE CIRCULATION DISSIPATING AS IT MOVES OVER KODIAK ISLAND TONIGHT...BRINGING SOME SNOW SHOWERS NEAR THE ALASKA AND ALEUTIAN RANGES THROUGH TUESDAY. OTHERWISE...COLDER TEMPERATURES AND OFFSHORE FLOW WILL CONTINUE TO DOMINATE THE SOUTHWEST MAINLAND THROUGH MID WEEK. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)... A WEAKENING FRONTAL ZONE BRINGING SNOW SHOWERS AND GUSTY WINDS TO THE PRIBILOF ISLANDS THIS MORNING...WILL CONTINUE TO TRACK INTO THE NORTHERN BERING AND DISSIPATE TUESDAY. OTHERWISE...RATHER QUIESCENT WEATHER FOR THE BERING SEA WILL BE THE DOMINANT MODE AS WEAK HIGH PRESSURE ALOFT BUILDS OVER THE BERING MONDAY INTO TUESDAY. NEAR GALE FORCE EASTERLY WINDS AND SHOWERY CONDITIONS WILL DEVELOP ACROSS THE ALEUTIAN CHAIN TUESDAY AS A NORTH PACIFIC FRONT MOVES APPROACHES THE AREA. && .LONG TERM FORECAST (WEDNESDAY THROUGH SUNDAY)... THE MAJOR PLAYERS IN THE EXTENDED FORECAST REMAIN MUCH THE SAME. A LARGE COMPLEX STACKED LOW CENTER SITS JUST SOUTH OF THE ALEUTIANS WITH A BAROCLINIC ZONE STRETCHING NORTHEASTWARD INTO THE GULF. THESE FEATURES WILL BE THE FOCUS FOR ACTIVE WEATHER IN THE COMING WEEK. LIGHT WINDS AND NEAR SEASONABLE TEMPERATURES WILL HANG AROUND WEDNESDAY WHEN THE AFOREMENTIONED FRONT WILL SWING OVER THE COASTAL MOUNTAINS AND PUSH ONTO THE MAINLAND ON THURSDAY. BEYOND THAT TIME PERIOD MODEL GUIDANCE DIFFERS ON HOW TO HANDLE THESE FEATURES AS WELL AS A LINGERING UPPER LOW PRESSURE TO THE NORTH. IT APPEARS HOWEVER THAT A MORE ACTIVE WEATHER REGIME WILL SET UP AND CONTINUE FOR THE WEEKEND. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...HEAVY FREEZING SPRAY 185. GALE 155 172 173 174 175 176 177. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...PD SOUTHCENTRAL ALASKA...BC SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TP LONG TERM...MTL  FXAK68 PAFC 031259 AFDAFC SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ANCHORAGE AK 459 AM AKDT FRI JUL 3 2015 .ANALYSIS AND UPPER LEVELS... AN UPPER LEVEL CLOSED LOW REMAINS POSITIONED EAST OF THE SEWARD PENINSULA. THIS SYNOPTIC FEATURE WITH HAVE SHORTWAVE TROUGHS ROTATING AROUND THE LOW AND WILL PUSH THROUGH THE UPPER SOUTHWEST ALASKA REGION AND SPILLOVER INTO THE MATSU VALLEY REGION. THE RADAR IMAGERY IS SHOWING NUMEROUS SHOWERS MOVING EASTWARD THROUGH THE UPPER KUSKOKWIM VALLEY AND APPROACHING THE MCGRATH AREA THIS MORNING. THE SOUTHWEST ALASKA REGION HAS WEAK ONSHORE FLOW AT THE SURFACE AND A 70 KNOT ZONAL JET STREAK THROUGH THE BRISTOL BAY INTERIOR. THE SATELLITE IMAGERY IS SHOWING LOW STRATUS SITTING OFFSHORE IN THE KUSKOKWIM BAY AND STARTING TO GRADUALLY MOVE ONSHORE. WHILE...THE ALASKA PENINSULA REGION THROUGH THE GULF HAS A FLAT RIDGE OF HIGH PRESSURE WITH ANOTHER SMALL RIDGE EXTENDING INTO THE EASTERN COPPER RIVER BASIN. THE MAJORITY OF THE SOUTHCENTRAL ALASKA REGION AT THE SURFACE HAS WEAK OFFSHORE FLOW AND THE CENTRAL GULF HAS SOUTHWESTERLY FLOW. THE SPORT MODIS NIGHTTIME MICROPHYSICS SATELLITE IMAGERY IS PICKING UP THE AREAS OF FOG OVER THE KENAI AREA AND THE MATSU VALLEY REGION. THE CENTRAL ALEUTIANS NEAR ADAK HAS A WEAK NORTH PACIFIC LOW AND A SECONDARY LOW SOUTH OF THE DUTCH HARBOR REGION THIS MORNING. THIS IS RESULTING IN EAST TO SOUTHEASTERLY SMALL CRAFT WINDS THROUGH THE EASTERN ALEUTAINS EXTENDING INTO THE BERING SEA. THE SATELLITE IMAGERY IS SHOWING A LARGE SWATH OF MOISTURE OVER THE AFOREMENTIONED REGION WITH STRATUS AND PATCHY FOG STREAMING INTO THE CENTRAL BERING SEA. && .MODEL DISCUSSION... THE MODELS ARE IN GOOD AGREEMENT THROUGH THE SHORT TERM FORECAST EXCEPT FOR THE ECWMF BRINGING THE NORTH PACIFIC LOW FARTHER EAST ALONG THE CHAIN THAN THE GFS/NAM MODELS. THE PREFERRED MODEL OF CHOICE WAS THE NAM FOR THE SOUTHCENTRAL ALASKA REGION AND THE GFS FOR THE SOUTHWEST ALASKA/BERING SEA REGION. BY FRIDAY AFTERNOON THE TWO NORTH PACIFIC LOWS BEGIN TO MERGE TOGETHER OVER THE CENTRAL ALEUTIANS. THERE WILL BE A FRONTAL BOUNDARY ASSOCIATED WITH THIS SYSTEM APPROACHING THE EASTERN ALEUTIANS AND THE KODIAK ISLAND REGION. THIS SYSTEM WILL MOVE INTO THE SOUHTWEST AND THE SOUTHCENTRAL ALASKA INTERIOR BEFORE DISSIPATING OVER THE WEEKEND. THIS WILL BRING SOUTH TO SOUTHEASTERLY WINDS THROUGH THE GULF AND ONSHORE FLOW TO THE NORTHERN GULF MARINE AREAS. THE TURNAGAIN ARM AND PORTAGE/WHITTIER WINDS WILL STRENGTHEN WITH THIS FRONTAL BOUNDARY OVER THE WEEKEND BEFORE DIMINISHING BY LATE SATURDAY AS THE PRESSURE GRADIENT WEAKENS. THIS WILL BRING RAIN AND GUSTY WINDS TO THE COASTAL MARINE AREAS WITH SCATTERED SHOWERS INLAND. THE EASTERN GULF WILL HAVE THE REMAINS OF THE UPPER LEVEL RIDGE OF HIGH PRESSURE THAT WILL REMAIN THROUGH THE WEEKEND. && .FIRE WEATHER... THE ONSHORE FLOW OVER THE SOUTHWEST ALASKA REGION WILL HELP TO PRODUCE A STABLE ENVIRONMENT OVER THE REGION. THIS IS DUE TO DIFFERENT AREAS OF OFFSHORE STRATUS BEGINNING TO MOVE ONSHORE THIS MORNING. THE SATELLITE IMAGERY IS ALSO SHOWING AREAS FOG IN THE LOWER KUSKOKWIM VALLEY. BY SATURDAY A WEATHER FRONT WILL MOVE INTO THE AREA. THIS WILL BRING WETTING RAINS AND GUSTY WINDS THROUGH SATURDAY BEFORE TAPERING OFF TO SCATTERED SHOWERS BY SUNDAY. THE HUMIDITY VALUES WILL CLIMB WELL ABOVE ANY CRITICAL FIRE WEATHER LEVELS THROUGH THE WEEKEND. THE SOUTHCENTRAL ALASKA REGION WILL HAVE ISOLATED WET THUNDERSTORMS FRIDAY AFTERNOON/EVENING HOURS. THESE WET THUNDERSTORMS WILL MAINLY BE OVER THE ALASKA RANGE...TALKEETNA MOUNTAINS AND ALONG THE WRANGELL MOUNTAINS IN THE COPPER RIVER BASIN. THESE WET THUNDERSTORMS WILL GRADUALLY MOVE OFF THE MOUNTAINS AND BECOME SHOWERS INLAND OVER THE SOUTHCENTRAL. THE UPPER LEVEL RIDGE OVER THE REGION WILL KEEP THE HUMIDITIES FAIRLY LOW BUT WITH THE ARRIVAL OF THE WEATHER FRONT BY SATURDAY THE HUMIDITIES WILL RECOVER. THE MARINE COASTAL HUMIDITIES WILL SEE THE LARGEST RECOVERIES. THE INLAND AREAS WILL HAVE HUMIDITY RECOVERIES JUST NOT AS MUCH DUE TO MOUNTAINS KEEPING MAJORITY OF PRECIPITATION ALONG THE COAST. THE HUMIDITIES WILL CONTINUE TO RISE ABOVE ANY CRITICAL FIRE WEATHER LEVEL THROUGH THE WEEKEND. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)... BROAD SOUTHWESTERLY FLOW ALOFT AND MINOR SHORT WAVES WILL PROVIDE FOR THE DEVELOPMENT OF SHOWERS ACROSS SOUTHCENTRAL THIS AFTERNOON AND TONIGHT. THE POSITIONING OF THE THERMAL TROUGH...DRAPED ACROSS THE COPPER RIVER BASIN AND SUSITNA VALLEY...COMBINED WITH FORCING FROM UPPER SHORT WAVES AND MARGINAL STABILITY INDICES SHOULD ALLOW FOR DEVELOPMENT OF ISOLATED AFTERNOON AND EVENING THUNDERSTORMS OVER THE NORTHERN AND EASTERN SUSITNA VALLEY AND MAINLY MOUNTAINS OF THE COPPER RIVER BASIN. SATURDAY SHOULD BE MORE STABLE OVERALL AS COOLER AIR AND ABUNDANT CLOUD COVER SPREAD NORTH ACROSS SOUTHCENTRAL AHEAD OF AN APPROACHING WEATHER FRONT. A WEATHER FRONT MOVING NORTH ACROSS THE GULF WILL BRING RAIN TO KODIAK ISLAND THIS EVENING. RAIN WILL SPREAD TO THE NORTH GULF COAST AND KENAI PEN SATURDAY. MINIMUM EASTERLY GALES ARE EXPECTED WITH AND AHEAD OF THE FRONT AS IT MOVES NORTH THROUGH THE GULF. BRISK GAP WINDS ARE EXPECTED ACROSS TURNAGAIN ARM/PORTAGE VALLEY THIS AFTERNOON AND TO A LESSER EXTENT THE COPPER RIVER AND KNIK ARM. GAP FLOWS WILL INCREASE ACROSS THESE AREAS ON SATURDAY AS THE COASTAL RIDGE BUILDS. && .SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)... A WET AND WINDY PATTERN WILL BE RETURNING TO SOUTHWEST ALASKA STARTING LATE TONIGHT AS THE FRONT CURRENTLY SOUTH OF THE ALASKA PENINSULA WILL PUSH NORTHWARD INTO THE REGION. SCATTERED SHOWERS ARE EXPECTED ALONG THE LOWER KUSKOKWIM VALLEY TODAY AS A WEAK SHORTWAVE PASSES THROUGH THE AREA...BUT OTHERWISE PARTLY SUNNY SKIES WITH WARMER TEMPERATURES ARE EXPECTED. AREAS OF DENSE FOG OVER THE KUSKOKWIM DELTA WILL DISSIPATE BY MID MORNING ALTHOUGH PATCHY COASTAL FOG MAY CONTINUE THROUGH THE DAY ALONG THE WESTERN COAST. AS WITH PREVIOUS DAYS...AREAS OF SMOKE ARE EXPECTED IN THE OVERNIGHT AND EARLY MORNING HOURS WITH THE HEAVIEST SMOKE IN VALLEY LOCATIONS NEAR ACTIVE FIRES. THE FRONT WILL BEGIN TO IMPACT THE BRISTOL BAY REGION IN EARNEST EARLY SATURDAY MORNING BEFORE RAPIDLY MOVING NORTHWARD TO THE KUSKOKWIM VALLEY/DELTA BY SATURDAY AFTERNOON. THERE WILL BE MOIST SOUTHERLY FLOW WITH THIS SYSTEM...SO THE HEAVIEST RAINFALL IS EXPECTED OVER THE AHKLUN MOUNTAINS WITH LESSER AMOUNTS IN THE LEEWARD SIDE OF THE ALEUTIAN RANGE AND THE KILBUCK MOUNTAINS. AS THIS FRONT PUSHES THROUGH...WINDS WILL BEGIN TO INCREASE OVER THE WESTERN TWO-THIRDS OF THE AREA. LOCAL GUSTS TO 35 MPH ARE POSSIBLE STARTING THIS AFTERNOON WITH THE STRONGEST GUSTS THROUGH CHANNELED TERRAIN. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)... THE FRONT THAT IS ASSOCIATED WITH THE LOW NEAR ADAK HAS PUSHED INTO THE BERING SEA OVERNIGHT WHILE THE NEXT FRONT...ASSOCIATED WITH THE LOW IN THE NORTH PACIFIC...WILL BEGIN TO MOVE INTO THE ALASKA PENINSULA THIS AFTERNOON AND TO THE PRIBILOF ISLANDS BY LATE TONIGHT. RAIN AND WINDS TO NEAR GALE FORCE ARE EXPECTED TO CONTINUE ALONG THE FRONT AS IT MOVES NORTHWARD THROUGH EARLY SATURDAY MORNING. WITH THE DEEP SOUTHERLY FLOW...RAIN WILL CONTINUE OVER THE ALASKA PENINSULA THROUGH SATURDAY NIGHT. BY LATE SATURDAY NIGHT...ANOTHER FRONT WILL APPROACH THE EASTERN ALEUTIANS AND ALASKA PENINSULA...BRINGING MORE RAIN TO THE AREA. && .LONG TERM FORECAST (DAYS 3 THROUGH 7)... FOR THE START OF THE WEEKEND A RIDGE TRANSITS THE GULF AND SOUTH CENTRAL SUPPRESSING RAIN EXCEPT FOR ALONG THE MOUNTAIN RANGES OF THE SUSITNA AND AND COPPER RIVER VALLEYS WHERE AFTERNOON SHOWERS DEVELOP ALONG A TROUGH THAT MOVES ACROSS THE INTERIOR. TO THE WEST...A LOW PRESSURE SYSTEM OVER THE WESTERN ALEUTIAN CHAIN PULLS A FRONT NORTH FROM THE PACIFIC. THIS FRONT IS EXPECTED TO MOVE TO THE ALASKA PENINSULA AND SOUTHERN GULF EARLY SATURDAY MORNING. THE NORTHWARD PROGRESSION STILL REMAINS UNCERTAIN AS MODEL SOLUTIONS STILL LACK AGREEMENT. THE ALASKA PENINSULA...KODIAK ISLAND AND THE EASTERN KENAI WILL SEE THE HIGHEST PRECIPITATION AMOUNTS FROM THIS FRONT DURING THE WEEKEND. MODELS DO AGREE ON BRINGING A SWATH OF RAIN ACROSS BRISTOL BAY SATURDAY NIGHT AND INTO THE KUSKOKWIM ON SUNDAY. INCREASED CLOUD COVER CAN BE EXPECTED ACROSS THE REST OF THE SOUTHERN MAINLAND THIS WEEKEND WITH SCATTERED SHOWERS MAINLY ALONG THE MOUNTAINS. OVERALL FORECAST CONFIDENCE DECREASES IN TIME AS MODELS HAVE STRUGGLED WITH HANDLING THE UPPER TROUGH DEEPENING ACROSS THE INTERIOR THROUGH THE WEEKEND. THE GFS AND ECMWF WERE USED TO UPDATE THE WEEKEND FORECAST WITH NO SIGNIFICANT CHANGES MADE BEYOND MONDAY. THE BEGINNING OF NEXT WEEK MODELS ARE SUGGESTING THAT A RIDGE AMPLIFIES ACROSS EASTERN ALASKA KEEPING SOUTHCENTRAL DRY ON MONDAY. LOW PRESSURE IN THE BERING BRINGS ANOTHER REINFORCING FRONT LATE SUNDAY SPREADING RAIN TO THE SOUTHWEST MAINLAND AND BERING INTO MONDAY. THIS LOW PRESSURE SYSTEM WILL BE THE PATTERN TO WATCH NEXT WEEK AS IT MAY BECOME THE DOMINATING SYSTEM THAT BRINGS A REGULAR PATTERN OF CLOUDS AND RAIN. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...GALE WARNING...120 130 131 132 138. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...PLD SOUTHCENTRAL ALASKA...BC SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...RF LONG TERM...KH  FXAK68 PAFC 031406 AFDAFC SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ANCHORAGE AK 506 AM AKST THU DEC 3 2015 .ANALYSIS... THE UPPER LEVELS HAVE A WEAK NEGATIVE TILTED TROUGH OVER THE BRISTOL BAY INTERIOR EXTENDING ACROSS THE ALEUTIAN RANGE INTO THE BARREN ISLANDS REGION. THIS SYNOPTIC FEATURE WILL AFFECT ANCHORAGE BY TONIGHT AS THE WEAK RIDGE OVER SOUTHCENTRAL MOVES TO THE NORTH. THE SATELLITE IMAGERY IS SHOWING THIS FEATURE WITH A SWATH OF MOISTURE ALONG THE SOUTHWEST ALASKA COASTLINE WITH SURFACE OBSERVATIONS REPORTING LIGHT SNOW SHOWERS. THE MODIS NIGHTTIME MICROPHYSICS IMAGERY IS SHOWING AREAS OF FOG ACCOMPANIED BY LOW STRATUS THROUGH THE UPPER COOK INLET ALONG THE TURNAGAIN ARM...THE LOWER SUSITNA VALLEY...THE MATANUSKA VALLEY AND THE INTERIOR OF THE WESTERN KENAI PENINSULA THIS MORNING. WHILE THE SOUTHWEST INTERIOR WILL BE UNDER THE INFLUENCE OF OFFSHORE FLOW AND COOLER TEMPERATURES WITH MOSTLY CLEAR SKIES. THE EASTERN ALEUTIANS/BERING SEA HAS A RIDGE AXIS JUST EAST OF SAINT MATTHEW ISLAND EXTENDING THROUGH THE EASTERN ALEUTIANS INTO THE NORTH PACIFIC. FARTHER UPSTREAM IS A BROAD CLOSED LOW NEAR ADAK WITH AN ASSOCIATED TROUGH EXTENDING SOUTHWARD NEAR 40N. ON THE BACKSIDE OF THIS SYSTEM AT 300 MB THERE IS A STRONG 185 KNOT NORTHWESTERLY JET STREAM DIGGING INTO THE BASE OF THE LONGWAVE TROUGH. REFLECTED AT THE SURFACE IS AN OCCLUDED 965 MB LOW JUST SOUTH OF SHEMYA WITH THE OCCLUDED FRONT EXTENDING THROUGH THE WESTERN TO CENTRAL BERING SEA BEFORE EXTENDING THROUGH DUTCH HARBOR. THIS IS BRINGING TEMPERATURES IN THE MID TO UPPER 30S TO THE CHAIN AND THE SOUTHERN BERING SEA. THE SATELLITE IMAGERY IS SHOWING A SHOWERY REGIME BEHIND THE OCCLUDED FRONT WITH THE SOUTHWESTERLY WINDS REFLECTED AT THE SURFACE. .MODEL DISCUSSION... THE MODELS ARE IN GOOD AGREEMENT WITH THE NORTH PACIFIC LOW LOCATED SOUTH OF SHEMYA IN THE EARLY PERIOD...BUT BY THURSDAY NIGHT THE MODELS TRANSITION THIS LOW INTO A COMPLEX LOW WITH MULTIPLE LOW CENTERS JUST SOUTH OF DUTCH HARBOR. THIS SYSTEM CONTINUES TO MOVE EASTWARD AND REMAINS SOUTH OF THE GULF OF ALASKA HEADING INTO THE WEEKEND. THE MODELS ARE STRUGGLING WITH PLACEMENT OF THIS SYSTEM. BY FRIDAY ANOTHER SYSTEM TRACKS NEAR THE KAMCHATKA PENINSULA AND REMAINS SOUTH OF THE WESTERN ALEUTIANS. THE MODELS ARE HAVING DIFFICULTY WITH THE PLACEMENT AND STRENGTH OF THIS SYSTEM AS WE HEAD INTO THE WEEKEND. THE FORECAST CONFIDENCE IS AVERAGE BEFORE DIMINISHING AS THE NORTH PACIFIC LOW BECOMES A BROAD COMPLEX LOW BY END OF THE WEEK. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)... ALL GUIDANCE IS QUICKLY TRENDING TOWARD A MINOR SNOWFALL OVER MUCH OF SOUTHCENTRAL ALASKA THIS AFTERNOON THROUGH TONIGHT. AN INVERTED TROUGH EXTENDING FROM A DEEP LOW OVER THE NORTHEAST PACIFIC EXTENDS NORTHWARD ACROSS THE CENTRAL GULF. THIS TROUGH IS MOVING SLOWLY WESTWARD SPREADING MOISTURE NORTH AND WEST TOWARD SOUTHCENTRAL. MEANWHILE...AN UPPER LEVEL TROUGH IS SWINGING THROUGH BRISTOL BAY AND BEGINNING TO LIFT NORTHWARD AS IT HITS THE OPPOSING FLOW OVER THE GULF. THIS TROUGH WILL TAKE ADVANTAGE OF THE MOISTURE IN PLACE AS WELL AS DEEP LAYER WEAK INSTABILITY (AS SEEN IN THE ANCHORAGE SOUNDING) TO PRODUCE WIDESPREAD SNOW SHOWERS. ALTHOUGH SNOW ACCUMULATION IS EXPECTED TO BE LIGHT...IT DOES LOOK FAVORABLE FOR MESOSCALE BANDS OF HEAVIER SNOW TO BRIEFLY SET UP SOMEWHERE OVER THE WESTERN KENAI TO ANCHORAGE AREA. THUS THERE LIKELY WILL BE SOME AREAS WHICH SEE SEVERAL INCHES OF SNOW. IN ADDITION...A SURFACE LOW IS EXPECTED TO FORM OVER THE NORTHERN GULF AND DRIFT INTO PRINCE WILLIAM SOUND. HEAVIER PRECIPITATION IS LIKELY IN THE VICINITY OF THIS LOW. ALTHOUGH PRECIP WILL BE IN THE FORM OF SNOW MOST PLACES...IT IS WARM ENOUGH IN THE CORDOVA AREA TO PRODUCE ALL RAIN. ANOTHER MUCH WEAKER UPPER WAVE WILL FOLLOW DURING THE DAY FRIDAY KEEPING A CHANCE OF SHOWERS IN THE FORECAST FOR MOST OF THE REGION. && .SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)... A LINGERING UPPER TROUGH OVER THE BRISTOL BAY AREA WILL BRING AREAS OF LIGHT SNOW TO MAINLY AREAS NORTH AND EAST OF KING SALMON TODAY. THAT WILL BE THE ONLY THREAT OF PRECIPITATION OVER THE NEXT COUPLE DAYS. LOW STRATUS HAS FILTERED INTO THE KUSKOKWIM VALLEY AND DELTA WITHIN THE LIGHT NORTHERLY FLOW AND SHOULD CONTINUE TO HANG AROUND AS THE WEAK OUTFLOW PATTERN CONTINUES THROUGH SATURDAY. EXPECT GENERALLY LIGHT WINDS AND BELOW NORMAL TEMPERATURES THROUGH THE SHORT TERM. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)... THE DEEP LOW PRESSURE SYSTEM WILL PULL SOUTH OF THE CHAIN TODAY AS A FRONTAL BOUNDARY ASSOCIATED WITH IT WEAKENS AS IT MOVES OVER THE ALASKA PENINSULA AND PRIBILOF ISLANDS. SOME ACCUMULATING SNOW IS POSSIBLE IN THESE PLACES...BEST CHANCES OVER SAINT GEORGE ISLAND. ARCTIC AIR FILTERING IN BEHIND THIS FRONT OVER THE WESTERN AND CENTRAL BERING WILL KEEP SCATTERED SNOW SHOWERS OVER MUCH OF THE AREA. MOSTLY BENIGN CONDITIONS...WEAK FLOW AND NO MAJOR FRONTS...WILL REMAIN IN PLACE THROUGH SATURDAY AS THE JET STAYS WELL SOUTH OF THE CHAIN. && .LONG TERM FORECAST (DAYS 3 THROUGH 7)... THE FORECAST FOR THIS WEEKEND INTO NEXT WEEK IS CHARACTERIZED BY BELOW AVERAGE CONFIDENCE AS MODELS CONTINUE TO STRUGGLE GREATLY WITH THE EVOLUTION OF AN ELONGATED AREA OF LOW PRESSURE SOUTH OF THE ALEUTIAN CHAIN. THERE IS A GENERAL CONSENSUS FOR THE DEVELOPMENT OF A DOMINANT LOW CENTER WITHIN THE BROADER COMPLEX LOW...HOWEVER 00Z GUIDANCE DIFFERS ON THE PLACEMENT OF THIS FEATURE BY UPWARDS OF 400 MILES...MAKING IT VERY DIFFICULT TO NARROW DOWN ANY SPECIFIC FORECAST DETAILS. THERE IS ALSO GENERAL AGREEMENT ON A DEEP LOW APPROACHING THE SOUTHERN GULF EARLY TO MID NEXT WEEK AS THE LONGWAVE TROUGH SHIFTS TO THE EAST...BUT THIS SYSTEM IS ALSO POORLY HANDLED BY THE MODELS AT THIS TIME. THIS PATTERN IS GENERALLY EXPECTED TO YIELD BENIGN CONDITIONS ACROSS SOUTHERN ALASKA THROUGH MUCH OF THE NEXT WEEK AS THE MAIN UPPER LEVEL JET REMAINS OVER THE NORTH PACIFIC SOUTH OF 50N AND KEEPS THE STORM TRACK WELL TO THE SOUTH OF THE MAINLAND. THE BEST CHANCES FOR PRECIPITATION WILL THEREFORE REMAIN CONFINED TO THE GULF COAST...WITH INLAND AREAS OF SOUTHCENTRAL STAYING MOSTLY DRY WITH TEMPERATURES NEAR SEASONAL NORMAL VALUES. OUT WEST...THE BULK OF THE ACTIVITY SHOULD REMAIN CONFINED TO THE ALEUTIAN CHAIN IN CLOSER PROXIMITY TO THE COMPLEX LOW...WITH A MORE SHOWERY REGIME OVER THE REST OF THE BERING BENEATH BROAD CYCLONIC FLOW. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE MARINE...GALE WARNING 178 HEAVY FREEZING SPRAY 160 180 181 && $$ SYNOPSIS AND MODEL DISCUSSION...PLD SOUTHCENTRAL ALASKA...SEB SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MTL LONG TERM...CB  FXAK68 PAFC 101333 AFDAFC SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ANCHORAGE AK 533 AM AKDT TUE MAY 10 2016 .ANALYSIS AND UPPER LEVELS... THE WESTERN BERING HAS AN UPPER LEVEL CLOSED LOW WITH A LONGWAVE TROUGH EXTENDING THROUGH THE CENTRAL ALEUTIANS INTO THE NORTH PACIFIC OCEAN. THIS SYNOPTIC FEATURE IS REFLECTED AT THE SURFACE WITH A 991 MB LOW OVER THE WESTERN BERING SEA. THE FLOW AHEAD OF THIS SYSTEM REMAINS SOUTHERLY AND COINCIDES WITH A STRONG 110 KNOT SOUTHWESTERLY JET STREAM OVER THE EASTERN BERING THROUGH THE Y-K DELTA REGION THIS MORNING. THE RADAR IS SHOWING A SWATH OF MOISTURE MOVING THROUGH THE KUSKOKWIM DELTA AND THE BRISTOL BAY REGION THIS MORNING. ON THE EAST SIDE AT THE SURFACE THERE IS A 1035 MB HIGH PRESSURE OVER THE GULF WITH AN ASSOCIATED AMPLIFIED RIDGE IN THE UPPER LEVELS EXTENDING FROM THE NORTHERN GULF NORTHWARD INTO THE BEAUFORT SEA. THE ASCAT SCATTEROMETER WIND IMAGERY IS SHOWING THE WEAK ANTI-CYCLONIC FLOW WITH SOUTHERLY WINDS ON THE WESTERN SIDE OF THE GULF AND WESTERLY WINDS FROM THE NORTHERN TO EASTERN GULF THIS MORNING. THE SATELLITE IMAGERY IS SHOWING A LARGE AREA OF STRATUS AND FOG OVER THE CENTRAL GULF REGION. WHILE THE MODIS NIGHTTIME MICROPHYSICS SATELLITE IMAGERY IS SHOWING LOW CLOUDS OVER THE MAT-SU VALLEYS AND THROUGH THE COPPER RIVER BASIN. && .MODEL DISCUSSION... THE MODELS CONTINUE TO BE IN GOOD AGREEMENT AND THE NAM WAS THE PREFERRED MODEL OF CHOICE. THE FORECAST CONFIDENCE REMAINS HIGH. && .AVIATION...(FOR THE 12Z TAFS THROUGH 18Z WEDNESDAY MORNING)... PANC...THE WINDS WILL REMAIN LIGHT AND VARIABLE THIS MORNING BEFORE WE START GETTING STRONGER SOUTHERLY WINDS COMING OFF THE TURNAGAIN ARM BY THIS AFTERNOON. THESE WINDS WILL DIMINISH BY LATE EVENING TONIGHT AS A HIGH PRESSURE RIDGE BUILDS INTO THE REGION. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)... A HIGH PRESSURE RIDGE EXTENDS FROM THE GULF OF ALASKA NORTH TO OVER THE COPPER RIVER BASIN. AREAS WEST OF THE COPPER RIVER BASIN WILL HOLD UNDER GENERALLY BROAD SOUTHERLY FLOW THROUGH WED AFTERNOON. THIS WILL ALLOW MOISTURE FROM A WEAKENING FRONTAL SYSTEM WEST OF THE ALASKA RANGE TO SPREAD NORTH ACROSS AREAS WEST OF THE COPPER RIVER BASIN. THE DYNAMICS ARE PRETTY WEAK...HOWEVER THERE WILL BE INCREASED CHANCES OF LIGHT RAIN ALONG THE KENAI AND SUSITNA VALLEY TODAY THROUGH WED MORNING WITH SPRINKLES TOWARD THE ANCHORAGE BOWL/MAT VALLEY TONIGHT AND WED. THE RIDGE BUILDS WEST SOME WED NIGHT AND THU...SO ANY LINGERING RAIN SHOULD BE PUSHED WEST. LOCAL GAP FLOWS (TURNAGAIN ARM/PORTAGE VALLEY/COPPER RIVER/KNIK) WILL PERSIST DURING THE AFTERNOON AND EVENING HOURS THROUGH WED...THOUGH THE TURNAGAIN WIND WILL LIKELY CONTINUE THROUGH THE OVERNIGHT HOURS TONIGHT. && .SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2...TUE AND WED)... THE AREA WILL REMAIN PINCHED BETWEEN A BROAD TROUGH OVER THE BERING AND A RIDGE BUILDING OVER SOUTH CENTRAL. WITH SOME FAIRLY STRONG UPPER LEVEL JET SUPPORT...THE REGION WILL BE IN THE SWEET SPOT FOR GUSTY WINDS AND A HEALTHY AMOUNT OF RAIN. THE FLOW WILL FAVOR SOUTH FACING SLOPES WHERE UP TO 2 INCHES OF RAINFALL IS NOT OUT OF THE QUESTION BY THU EVENING. THE GOOD NEWS IS...RAIN SHOULD COME AS STEADY PRECIPITATION AND NOT BE OVERLY HEAVY AT ANY ONE TIME. THUS...HYDROLOGIC CONCERNS ARE RELATIVELY LOW AT THIS TIME. BUT THE BAD NEWS IS THAT THIS BOUNDARY ESSENTIALLY STALLS OVER SW ALASKA AND WAVE AFTER WAVE OF UPPER LEVEL ENERGY WILL RIDE FROM SOUTH TO NORTH ALONG IT. EACH WAVE WILL BRING ANOTHER ROUND OF GUSTY WINDS AND RAIN. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2...TUE AND WED)...BROAD CYCLONIC CIRCULATION WILL DOMINATE THE BERING. ON THE EASTERN HALF...ABUNDANT MOISTURE WILL RIDE ALONG THE JET FROM SOUTH TO NORTH. THIS WILL KEEP RAIN FALLING ACROSS MUCH OF THE AREA...FAVORING THE SOUTH SIDE OF THE CHAIN. IT WILL ALSO PUMP UP SOME WARMER AIR CREATING DECENT FOG POTENTIAL...ESPECIALLY OVER COOLER WATERS AND THE ICE PACK. ON THE WESTERN HALF...COOLER AND CALMER CONDITIONS WILL BE THE RULE. NORTHWEST FLOW WILL BRING DOWN SOME SLIGHTLY COOLER TEMPERATURES TO THE WESTERN ALEUTIANS POSSIBLY ALLOWING A LITTLE SNOW TO MIX IN WITH THE RAIN. THE ANCHOR LOW WITHIN THE CIRCULATION WILL DRIFT SLIGHTLY EAST OVER THE NEXT FEW DAYS. THIS WILL ALLOW NORTHWEST WINDS TO BECOME MORE WESTERLY AND SOUTHWESTERLY...HELPING TO BRING AN END TO SOME OF THE SHOWERS OVER THE WESTERN ALEUTIANS. && .LONG TERM FORECAST (DAYS 3 THROUGH 7)... A CONSOLIDATED BLOCKING HIGH WILL FORM OVER THE EASTERN PART OF THE STATE AND ELONGATE AND BUILD TO THE WEST LATE THURSDAY. THIS WILL CLEAR OUT THE SKIES AND RESULT IN WARM AND SUNNY AFTERNOONS THROUGH SUNDAY. TEMPERATURES WILL SOAR TO THEIR HIGHEST LEVELS THIS YEAR ON SATURDAY AND SUNDAY. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...PD SOUTHCENTRAL ALASKA...BC SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MO LONG TERM...DK  FXAK68 PAFC 131326 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 526 AM AKDT FRI MAY 13 2016 .ANALYSIS AND UPPER LEVELS... The upper levels are depicting a closed high at 500 mb over the eastern Alaska Range. With an associated ridge extending through the Southcentral region into the eastern Aleutians. This synoptic feature is reflected at the surface with a 1030 mb high pressure over the Yukon Territory and a 1031 mb high in the northern Gulf of Alaska this morning. This coincides with the MODIS Nighttime Microphysics satellite imagery showing low stratus and fog in the Central Gulf. While the Southcentral region has some high cirrus clouds spilling over the ridge into the AOR. At 300 mb there is a strong 90 knot southerly jet stream extending through the eastern Bering northward into the Y-K Delta region towards the North Slope. The radar imagery is showing a steady onshore flow with rain echoes through the aforementioned region. The rest of the Bering Sea is under weak easterly to northeasterly flow, and high pressure is positioned over the Bering Strait. The strongest winds along the Aleutian Chain are over the Unalaska region with small craft advisory winds on the Pacific side due to a gale force low south of the Central Aleutians. && .MODEL DISCUSSION... The models continue to remain in good agreement except for the timing of an upper level trough that will be swinging through the Western Gulf of Alaska into the Southwest Alaska region this weekend. The ecmwf is slightly faster than the gfs/nam with this feature. This synoptic feature combined with the thermal trough will enhance the possiblities of producing isolated thunderstorms over the Southwest region for Saturday afternoon/evening timeframe. The forecast confidence remains high through the weekend. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)... With a strong ridge overhead expect a hot and dry day across Southcentral Alaska. The main forecast challenge is timing and strength of sea breezes. As the 850 mb ridge lifts northward into interior Alaska today offshore flow of 5 to 10 knots will develop. This will be enough to at least delay the onset of sea breezes, especially along prince william sound and the north gulf coast. therefore, have bumped up high temps at least a few degrees area-wide (and correspondingly lowered relative humidities). Winds on Saturday look quite a bit different. As the upper level ridge moves inland a well defined thermal trough will set up beneath it. This will aid in development of the very typical east- west oriented surface ridge along the north Gulf Coast which will promote development of stronger sea breezes moving in earlier in the day. Development of gusty gap winds is expected along Turnagain Arm and into south to west Anchorage, and also along the Knik River Valley into Palmer and along the Copper River. The sea breezes and gap winds will help moderate temperatures, so forecast highs have been lowered just a bit. Meanwhile, an upper level trough will approach Southcentral Saturday afternoon then move through Saturday night into Sunday. The air mass out ahead of it will start out very dry and stable. Surface-based stability parameters look favorable for convection...mainly over the western Kenai Peninsula, Talkeetna Mountains and northern Susitna Valley. Based on the limiting factors of moisture and stability it seems convective initiation is most likely to occur over the mountains where there is always some moisture to work with (in the form of melting snow). Have maintained a slight chance of thunderstorms for the western Kenai Peninsula, but with warmer low level temps inland the best chance for showers and thunderstorms will be over the Talkeetna mountains. Southeasterly flow will advect whatever does form across the northern Susitna Valley. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... A few lingering showers will be seen across the Kuskokwim Delta and Lower Kuskokwim Valley this morning as the building upper level ridge shifts the upper level trough anchored over the Bering Sea and North pacific westward. By midday, the remaining lift along the eastern periphery of the upper level trough will shift into the Bering Sea and allow sky cover to quickly diminish. Temperatures at 850 mb will warm 2 to 5 degrees Celsius over the next 24 to 36 hours as the ridge moves overhead. These warmer temperatures aloft coupled with developing offshore flow will easily bring some of the warmest temperatures observed so far this year. Temperatures today will warm into the mid 50s across the Kuskokwim Delta to the lower to mid 60s across the Lower Kuskokwim Valley and into the mid 60s to lower 70s across all of southwest Alaska on Saturday. Thunderstorms look likely on Saturday but will be isolated due to the lack of sufficient moisture. Thermal profiles show lapse rates of 7 to 8 degrees C/km with sfc based CAPE values upwards to 500 J/kg. An easterly wave will be pushing across the northern Bristol Bay area and southern portions of the Lower Kuskokwim Valley Saturday afternoon which will act as the lifting mechanism that will help utilize the instability and what little moisture is available. On Sunday, a similar setup to Saturday will be in place once again. However, there will be a few differences in the ingredients in place Sunday afternoon. The biggest plus for thunderstorms will be a stronger lifting mechanism on Sunday in the form of another upper level easterly wave moving across southwest Alaska. The negatives include somewhat less surface-based instability on Sunday due to cooler temperatures resulting from more cloud cover, and less moisture in place. Thermal lapse rates will be around 7 degrees C/km with forecast model soundings indicating CAPE values of 200-300 J/kg. Dew points are expected to be in the 40s. Thus, the fundamental question will be if the stronger wave will be able to overcome a less favorable environment. The current thinking is the best chance for storms will be along the Kilbuck and Ahklun Mountains, extending north into parts of the Kuskokwim Valley as the topography aids in lifting the moist, unstable air mass in place. The timing of the upper level easterly wave is also such that it will be moving into this region at the most favorable time of day (late afternoon) when the greatest amount of heating can occur prior to convective initiation. If thunderstorms develop, an environment featuring weak steering- level winds should mean the storms will move very little from where they form. This means the storms will choke themselves off from their source of warm, moist air as they create their own cold pools. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... High pressure will be the main story across much of the Bering Sea through the weekend. An area of low pressure in the North Pacific will drive a front through the eastern and central Aleutians this afternoon before stalling just west of Adak Saturday night as it clashes with the high pressure over the Bering Sea. The front will bring some decent rainfall to the eastern and central Aleutians as well as small craft winds and seas. The front will help displace the high pressure over the Bering Sea which will allow for broad cyclonic flow to re-develop over the Bering Sea by the beginning of next week and bring the return of isolated to scattered rain showers. Fog will be possible across much of the Bering with high pressure moving overhead but should decrease drastically in coverage as the aforementioned front displaces the high pressure. && .LONG TERM FORECAST (Days 3 through 7)... High pressure over the area will begin to diminish sunday night with low pressure building back over the gulf and eastern bering...causing increasing cloudiness along the coast and parts of the southern mainland. By early to mid next week...models continue to struggle with how they want to handle various systems that will move through the area. This results in lower forecast confidence moving into mid week with some models bringing in showers to the area...especially during the afternoon with daytime heating. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...None. MARINE...None. && $$ SYNOPSIS AND MODEL DISCUSSION...PD SOUTHCENTRAL ALASKA...SB SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MC/JW LONG TERM...TP  FXAK68 PAFC 121756 CCA AFDAFC Southcentral and Southwest Alaska Forecast Discussion...CORRECTED National Weather Service Anchorage AK 956 AM AKDT SUN JUN 12 2016 .ANALYSIS AND UPPER LEVELS... The closed upper level low continues to move eastward, and is reflected at the surface as a weak low positioned over the lower southwestern Gulf this morning. While, a 1008 mb low pressure system is approaching the Southeast Panhandle near Sitka with a 100 knot southwesterly jet streaking just south of the Dixon Entrance. The moisture from this system is streaming northward bringing numerous showers into the northern Gulf coastal communities, except for some moisture spilling over the mountains with periods of light rain filtering into the Southcentral region. While, another weak shortwave is over the Kuskokwim Delta, and is reflected at the surface with a weak cyclonic circulation west of Bethel. The radar imagery is picking this feature up well, and is depicting the cyclonic circulation associated with this low. Plus, numerous showers over the Kuskokwim Delta coastline from Kipnuk northward, and scattered rain showers over the Kuskokwim Mountains. The MODIS Nighttime Microphysics satellite imagery is picking up the low stratus along the southwest coastline from Kipnuk eastward. This feature is being aided by the onshore flow helping to transfer the stratus inland this morning. The Western Aleutians have a comma cloud shield streaming from the Pacific Ocean associated with the 1000 mb North Pacific Low located southwest of Shemya. && .MODEL DISCUSSION... Models remain in good agreement as the North Pacific Low approaches Shemya, and as the ridge of high pressure builds into the Bering Sea. Looks like the Southwest Alaska region will have a nice warming trend as the high pressure builds, and begins to extend into Southcentral Alaska area. Plus, the northwesterly flow will result in drier conditions. The models in the Gulf keep weak diffuse lows moving across the region keeping moisture mainly along the coast. The forecast confidence is average as we head into the early work week. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)... The surface flow will remain fairly weak through tonight with surface ridging across the Bering and a trough along the eastern Gulf. An upper level low currently centered near Kodiak drifts slowly east across the southern gulf waters through the afternoon. This system pinwheels easterly shortwaves across the southern mainland and gulf bringing continued shower activity until ridging builds in from the southwest which should diminish rain activity by Tuesday. Isolated thunderstorms are possible late this afternoon and tonight along the Talkeetna Mountains during peak heating, with the focus shifting to the mountains along the Copper River on Monday as a thermal trough extends south from the Yukon. Offshore flow develops across the Eastern Kenai on Monday with gusty conditions developing early Tuesday. North to westerly flow sets up across all of Southcentral by late Tuesday with stronger gusts across channeled terrain and gap locations along the coastal areas. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... A showery regime will hang around for one more day before a much drier, and then a warmer air mass comes around on Tuesday. Today the forecast starts out with a strong shortwave trough withing the larger cyclonic circulation taking up most of southern Alaska. The steady rain over the Kuskokwim Delta will continue this morning, mainly west of Bethel before tapering off this afternoon. The rest of the mainland will see afternoon showers and thunderstorms associated with the cold air aloft. The best chance for thunder to accompany showers will be in eastern portions of the Bristol Bay zone. That system exits to the east tonight and will be replaced with a northwesterly flow regime aloft. Monday night into Tuesday a disturbance in this flow will bring a chance of rain to northern areas of the mainland. High pressure builds in on Tuesday bringing much drier and warmer conditions. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... One front weakens over the Bering today, and another approaches. The Eastern Aleutians will see spotty rain today as the front overhead falls apart. Most of the Bering will see generally weak westerly flow with some areas of fog. An east-west frontal boundary will stretch across the north Pacific, and will spread over the Western and Central Aleutians on Monday afternoon while weakening. A triple point low pressure system will develop on this front late Monday evening, affecting the Central and Eastern Aleutians with steady moderate rainfall. && .LONG TERM FORECAST (Days 3 through 7)... Beginning the long term period, a ridge over the Bering Sea will be building ahead of a North Pacific low with a northerly shortwave trough moving into the Gulf of Alaska. With the remnants of the previous Gulf low moving southeast, this pattern will promote strong offshore flow and rapid drying across southern Alaska. Rapid warming will occur Tuesday with Wednesday and Thursday looking to be the warmest days of the year thus far across many locations as 850 hpa temperatures rise to 8 to 12C, 2 to 3 standard deviations above normal. By late Thursday into Friday, uncertainty rises with respect the Bering low and how quickly the front moves into southwest Alaska (and eventually Southcentral). The ECMWF, GFS, and Canadian GDPS all differ with respect to timing and how much phase interaction there is with the subtropics, which impacts dramatically how quickly and how wet the eventual front is as it moves eastward. For now, a WPC ensemble approach was favored which features increasing trends for precipitation and gradually moderating temps (back towards normal) from the end of the week into the weekend. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...NONE. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...PD SOUTHCENTRAL ALASKA...KH SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ML LONG TERM...JA