FXAK68 PAFC 131326 AAA AFDAFC SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ANCHORAGE AK 526 AM AKDT TUE MAY 13 2014 .UPDATE... UPDATED ANCHORAGE... DENSE FOG ADVISORY ISSUED FOR ANCHORAGE AREA. IT APPEARS FOG DEPTH MAY NOT BE QUITE AS DEEP AS OVER THE KENAI PENINSULA...BUT IT IS DENSE NONETHELESS. THINKING SOME HEATING WILL HELP VISIBILITY IMPROVE BY MID TO LATE MORNING. JAM && .PREV DISCUSSION... /ISSUED 501 AM AKDT TUE MAY 13 2014/ ANALYSIS AND UPPER LEVELS... THE MOST SIGNIFICANT WEATHER THIS MORNING IN THE AOR IS THE MARINE LAYER IN THE GULF/UPPER COOK INLET AND OUT IN THE BERING SEA. WITH REGARDS TO FEATURES...A STRONG SHORTWAVE TROUGH OVER NW AK IS QUICKLY TRACKING SOUTHEAST THROUGH THE SOUTHERN MAINLAND. THIS TROUGH IS DAMPENING THE RIDGING AND HIGH PRESSURE THAT HAS BEEN DOMINANT OVER THE AOR THE LAST SEVERAL DAYS. UPPER-RIDGING DOES HOWEVER REMAIN STRONG OVER THE EASTERN BERING SEA AND AKPEN BETWEEN A NEAR STATIONARY UPPER-LOW IN THE NE PACIFIC AND A LOW NEAR SHEMYA. THE LOW IN THE NE PACIFIC HAS SPAWNED OFF A PIECE OF ENERGY THAT IS TRACKING TO FAR EASTERN REACHES OF THE GULF AND THE AK PANHANDLE. THE 999 MB LOW NEAR SHEMYA IS MOVING NORTH WHILE THE ASSOCIATED FRONT IS STALLED OVER THE WESTERN CHAIN...UNABLE TO MAKE EASTWARD PROGRESS DUE TO AFOREMENTIONED RIDGING DOWNSTREAM IN THE EASTERN BERING. MODEL DISCUSSION... REASONABLY CLOSE MODEL AGREEMENT WITH THE MAIN WEATHER FEATURES IN THE AOR. AS THE SHARP UPPER TROUGH CLEARS SOUTHCENTRAL AK LATE TONIGHT...THERE ARE SOME DIFFERENCES WITH HOW IT INTERACTS WITH THE RESIDUAL LOBE OF ENERGY ROTATING UP TOWARDS SE AK ON WED...BUT THE SUBSTANCE OF THESE AREN'T TOO IMPACTFUL ON THE AOR. IN GENERAL...MODELS SHOW THE CYCLONIC FLOW FROM THE TROUGH ALOFT MIGRATING OVER THE NORTHERN GULF WITH A SURFACE TROUGH/LOW FORMING NEAR CAPE SUCKLING LATE TONIGHT. THIS LOW IS SHOWN DRIFTING TO AROUND 200 MI E OF KODIAK CITY ON THU WHERE IT DISSIPATES. THE UPPER-RIDGING IN THE EASTERN BERING IS DEPICTED PINCHING OFF AN UPPER-HIGH CENTER TONIGHT NEAR UNALASKA...WHICH THEN SNEAKS TO NEAR THE WESTERN CAPES OF BRISTOL BAY ON THU. THE GFS PUSHES THIS UPPER HIGH A BIT FURTHER INTO THE SW MAINLAND THOUGH THE REMAINING MODELS KEEP IT OUT OVER THE EASTERN BERING SEA. REGARDLESS OF SOLUTION THOUGH...WARM AND DRY CONDITIONS WOULD BE EXPECTED OVER SOUTHCENTRAL/SOUTHWEST AK THE REMAINDER OF THE WEEK. FURTHER WEST...THE LOW NEAR SHEMYA IS SHOWN MOVING TO AROUND 600 MILES WEST OF SAINT MATTHEW ISLAND WED AFTERNOON BEFORE PUSHING INTO EASTERN SIBERIA AND DISSIPATING ON THU. THERE IS GOOD MODEL AGREEMENT WITH THAT TREND. SHORT TERM FORECAST... SOUTHCENTRAL TO SOUTHWEST ALASKA/GULF... FOG HAS BEEN RATHER THICK OVER COOK INLET THIS MORNING AS THE LAST OF THE UP INLET FLOW HANGS ON. THIS WILL CHANGE MARKEDLY WITH THE APPROACH OF THE TROUGH THIS AFTERNOON/EVENING. ACROSS SOUTHCENTRAL... THE PREEXISTING AIRMASS OVER UPPER COOK INLET IS ADDING CONSIDERABLE MOISTURE TO THE LOWER LEVELS OF THE ATMOSPHERE. AS SUCH...WHEN THE STRONG DRY WINDS ARRIVE TO THE REGION (ESPECIALLY THE WESTERN KENAI PENINSULA)...IT WILL LIKELY TAKE LONGER FOR CRITICAL FIRE WEATHER CONDITIONS TO DEVELOP. WE WILL PUSH BACK THE START TIMES OF RED FLAG WARNINGS TO LATE WED MORNING FOR THE MATANUSKA VALLEY AND WESTERN KENAI PENINSULA...EVEN THOUGH WINDS WILL BE GUSTY BY LATE THIS EVENING. THE FIRE DANGER ON THURSDAY SEEMS TO BE REDUCED A BIT IN SOUTHCENTRAL AS WELL BECAUSE THE UPPER RIDGING/HIGH DOES NOT BUILD IN QUITE AS FAR INTO THE MAINLAND. ASIDE FROM FIRE WEATHER THREAT...OUTFLOW GAP WINDS WILL DEVELOP AS THE TROUGH DEVELOPS IN THE NORTHERN GULF. THESE WINDS WILL BE STRONGEST THROUGH TYPICAL GAPS SUCH AS THOMPSON PASS AND CHANNELED AREAS OF PRINCE WILLIAM SOUND. AMPLE SUNSHINE IS EXPECTED IN THE COMING DAYS FOR THE SOUTHERN MAINLAND. SW AK FIRE DANGER WILL BEGIN THIS AFTERNOON. IT WILL LIKELY PERSIST INTO THU DUE TO STRONGER COMPRESSIONAL WARMING/SUBSIDENCE PROVIDING FOR MORE AND A LONGER DURATION OF DRY AIR. THOUGH TROUGH PASSAGE WILL BE WELL TO THE NORTH...KODIAK ISLAND WILL ALSO LIKELY BENEFIT FROM A MORE OFF- SHORE FLOW COMPONENT TO THE FLOW ALLOWING FOR MORE SUNSHINE AND LESS LOW CLOUDS/FOG. BERING SEA/ALEUTIANS/AKPEN... LITTLE CHANGES ANTICIPATED OUT WEST AS STRONG HIGH PRESSURE MOVES LITTLE FROM THE EASTERN BERING SEA. THE STABLE AIRMASS SUGGESTS PERSISTENT TYPICAL FOG/STRATUS. THE WESTERN TO CENTRAL CHAIN WILL SEE THE HEAVIEST RAINS AND STRONGEST WINDS EBB BY TONIGHT AND WED AS THE FRONT DISSIPATES IN PLACE AND THE PARENT LOW PRESSURE SYSTEM TRACKS TO E RUSSIA. LONG TERM FORECAST... STILL ANTICIPATING A SIZABLE LOBE OF ENERGY DROPPING FROM THE HIGH ARCTIC TO THE SOUTHERN MAINLAND/GULF LATE WEEKEND INTO EARLY NEXT WEEK. THE DETAILS OF THIS REMAIN FUZZY...BUT SUFFICE TO SAY A SIZABLE PATTERN SHIFT APPEARS ON THE HORIZON. WELL ABOVE TEMPERATURES AND DRY WEATHER INCREASINGLY LOOKS TO TREND CLOUDIER AND COOLER WITH MORE SIZABLE CHANCES FOR WETTING RAINS AS THIS LARGE LOW MEANDERS AROUND WITH IT'S CYCLONIC FLOW ALOFT. FEW CHANGES OVERALL TO THE SENSIBLE WEATHER IN THE BERING SEA/ALEUTIAN REGION. THE UPPER HIGH IN THE EASTERN PART OF THE BERING SLIDES TO THE WESTERN PORTION OR WEAKENS A BIT...BUT DOESN'T BREAK COMPLETELY. THUS TYPICAL CLIMATOLOGICAL WEATHER (MORE FOG/STRATUS) CAN BE ANTICIPATED. AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...DENSE FOG ADVISORY...101 121 MARINE...GALE...177 411 413 FIRE WEATHER...RED FLAG WARNING...121 141 145 152 161 $$ JAM  FXAK68 PAFC 241344 AFDAFC SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ANCHORAGE AK 444 AM AKST TUE FEB 24 2015 .ANALYSIS AND UPPER LEVELS... AN UPPER LEVEL CLOSED LOW IS LOCATED OVER THE EASTERN RUSSIA WITH AN ASSOCIATED TROUGH EXTENDING THROUGH SAINT MATTHEW ISLAND INTO THE EASTERN BERING SEA. AT THE SURFACE THIS IS REFLECTED AS A WEAK LOW NEAR 65N 178E WITH A WEATHER FRONT THROUGH THE WESTERN BERING SEA/ALEUTIANS AND A TROUGH OVER THE NUNIVAK ISLAND AREA. THE SATELLITE IMAGERY IS SHOWING A SWATH OF LOWER CLOUDS ASSOCIATED WITH THE AFOREMENTIONED TROUGH WHICH IS PRODUCING SNOW SHOWERS. THE MAJORITY OF THE BERING SEA AND ALEUTIANS WILL BE UNDER SOUTHWESTERLY FLOW WITH THE WEATHER FRONT AT THE SURFACE PUSHING INTO THE WESTERN BERING SEA AND ALEUTIANS TODAY. THE SURFACE OBSERVATIONS OVER THE WESTERN ALEUTIANS ARE REPORTING SNOW SHOWERS. THE SOUTHWEST ALASKA REGION IS BEING INFLUENCED BY ONSHORE FLOW. THIS IS RESULTING IN LOW STRATUS/FOG IN THE BRISTOL BAY REGION AND IS BEING SHOWN ON THE GOES IFR PROBABILITY SATELLITE PRODUCT. THE SURFACE OBSERVATIONS FROM KING SALMON NORTHWARD INTO THE BRISTOL BAY INTERIOR ARE REPORTING LOW STRATUS AND FOG THIS MORNING. THE GULF AND THE SOUTHCENTRAL ALASKA REGION ARE SITTING UNDER THE HIGH PRESSURE RIDGE WITH LIGHT WINDS FOR MAJORITY OF SOUTHCENTRAL THIS MORNING. THIS IS RESULTING IN LOW STRATUS AND FOG COVERING THE NORTHERN GULF...AND SPREADING INTO THE CORDOVA AND VALDEZ AREAS. UPSTREAM THERE IS A CLOSED UPPER LEVEL LOW SOUTH OF THE SHUMAGIN ISLANDS...AND REFLECTED WITH A GALE FORCE SURFACE LOW NEAR 50N 156W. THE ASSOCIATED WEATHER FRONT WITH THIS SYSTEM IS APPROACHING THE SOUTHWESTERN GULF THIS MORNING. && .MODEL DISCUSSION... THE MODELS ARE IN GOOD AGREEMENT HEADING INTO THE MIDWEEK TIME FRAME. THE PREFERRED MODELS OF CHOICE WERE THE GEM-REG/ECMWF. THE NAM CONTINUES TO BE THE OUTLIER WITH THE NORTH PACIFIC LOW TRACKING JUST SOUTH OF THE WESTERN GULF THIS MORNING. THE NAM KEEPS THE LOW PRESSURE SYSTEM FARTHER WEST THAN THE OTHER MODELS. THE FORECAST CONFIDENCE CONTINUES TO REMAIN ABOVE AVERAGE THROUGH THE MIDWEEK TIME FRAME. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)... A FEW SHOWERS LINGER THIS MORNING AS AN UPPER LEVEL LOW EXITS THE AREA. OTHERWISE...DRY WEATHER IS ON TAP FOR THE NEXT COUPLE OF DAYS OVER MAINLAND SOUTH CENTRAL ALASKA AS A RIDGE BUILDS OVER THE AREA. A LOW PRESSURE SYSTEM WILL MOVE INTO THE GULF OF ALASKA FROM THE SOUTHWEST TODAY AND THEN TRAVERSE EASTWARD ACROSS THE GULF WEDNESDAY THEN WELL SOUTHEAST OF THE AREA WEDNESDAY NIGHT. BEHIND THIS THE RIDGE WILL STRENGTHEN OVER SOUTHERN ALASKA AND INCREASE THE OFFSHORE GRADIENTS...THUS INCREASING THE WINDS THROUGH THE FAVORED GAPS. && .SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)... A FRONTAL ZONE IS TRACKING INTO THE KUSKOKWIM DELTA THIS MORNING...BRINGING SNOW SHOWERS TO THE AREA. ELSEWHERE...CLEARING SKIES BEHIND THE LAST LOW PRESSURE SYSTEM HAS ALLOWED FOR AREAS OF FOG TO DEVELOP...ESPECIALLY IN SHALLOW BASINS AND VALLEYS. THIS FOG SHOULD DIMINISH BY THIS AFTERNOON AS NORTHERLY OFFSHORE WINDS INCREASE...AND SOLAR RADIATION BURNS THE REMAINDER OFF. HIGH PRESSURE WILL THEN SETTLE IN THROUGH THURSDAY...WITH COOLING OVERNIGHT TEMPERATURES AND CLEARING SKIES. PATCHY FOG CAN NOT BE RULED OUT ACROSS THE KUSKOKWIM DELTA...ESPECIALLY DURING THE OVERNIGHT AND MORNING PERIODS. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)... WEAK HIGH PRESSURE WILL DOMINATE THE CENTRAL AND EASTERN ALEUTIANS HEADING INTO THURSDAY...WITH A SLOW MOVING FRONTAL ZONE OVER THE WESTERN ALEUTIANS BRINGING STRONG GALE FORCE WINDS AND PERIODS OF RAIN AND SNOW...EVENTUALLY BECOMING ALL RAIN. THIS FRONT WILL SLOWLY TRACK EAST TOWARD THE CENTRAL ALEUTIANS ON THURSDAY. && .LONG TERM FORECAST (DAYS 3 THROUGH 7)... THE SURFACE LOW CROSSING THE GULF WILL BE EAST AND CLEAR OF THE AREA THURSDAY MORNING AS IT TRACKS OVER HAIDA GWAII. UPPER LEVEL RIDGING WILL BUILD RAPIDLY OVER THE GULF BEHIND IT PUSHING INTO SOUTHWEST AND SOUTHCENTRAL ALASKA THURSDAY MAKING FOR A RATHER NICE AND SUNNY DAY. OFFSHORE NORTHERLY SURFACE WINDS OVER SOUTH CENTRAL ALASKA WILL PERSIST THROUGH MUCH OF THE DAY THURSDAY THEN GRADUALLY TAPER OFF OVERNIGHT. THESE WINDS SHOULD STILL BE ENOUGH HOWEVER TO PREVENT FOG AND LOW STRATUS IN MOST SOUTH CENTRAL AREAS THURSDAY NIGHT BUT DO HAVE CONCERNS FOR FRIDAY AS THE WINDS WILL BE MUCH LIGHTER WITH THE RIDGE AXIS DIRECTLY OVERHEAD. THE NEXT PACIFIC FRONTAL SYSTEM WILL LIFT NORTH UP THE WEST SIDE OF THE UPPER LEVEL RIDGE ON FRIDAY REACHING THE ALASKA PENINSULA IN THE AFTERNOON. THE LOW WILL THEN CURVE NORTHEAST UP THE GULF COAST AS IT GETS PICKED UP BY THE STRONG WESTERLY FLOW ALOFT TO THE NORTH AND CARRIED UP AND OVER TOP THE RIDGE FRIDAY NIGHT AND SATURDAY. CURRENTLY THERE IS SOME MODEL DIFFERENCES IN THE TRACK OF THE LOW WITH THE GFS FURTHEST NORTH FOLLOWING THE COAST BUT JUST INLAND...THE CANADIAN REMAINING OFFSHORE AND TRACKING THROUGH THE NORTHERN GULF BUT DEEPEST WITH THE SURFACE LOW AND THE EUROPEAN ALSO SOUTH AND OFFSHORE BUT WITH A SIGNIFICANTLY WEAKER LOW. GIVEN THE INTERACTION OF THE LOW WITH THE STRONG UPPER LEVEL SHORTWAVE AND BAROCLINIC ZONE TO THE NORTH AND THE LARGE RIDGE FOR IT TO RIDE UP AND OVER I TEND TO FAVOR THE MORE NORTHERLY AND STRONGER SOLUTIONS. HOWEVER GIVEN THE UNCERTAINTY OUT AT DAY 5 OF THE FORECAST HAVE CHOSEN TO AVERAGE THE POSITIONS AND STRENGTH FOR TODAYS FORECAST PACKAGE. RIDGING WILL RETURN SUNDAY CLEARING THINGS OUT AGAIN RATHER RAPIDLY WITH DRY WEATHER FOR MOST OF THE AREA THROUGH MONDAY. OUT IN THE ALEUTIANS AND BERING SE...STORMIER WEATHER WILL PERSIST FOR THE DURATION. BY THURSDAY THE CURRENT FRONTAL SYSTEM WILL HAVE TRACKED TO THE CENTRAL ALEUTIANS AND BE WEAKENING SOMEWHAT WHILE WESTERLY FLOW BRINGS COOL SHOWERY WEATHER TO THE WESTERN ALEUTIANS. THE NEXT RATHER STRONG LOOKING FRONTAL SYSTEM WILL REACH THE WESTERN END OF THE CHAIN FRIDAY NIGHT OR SATURDAY MORNING BRINGING AT LEAST WIDESPREAD GALES AND THE POTENTIAL FOR STORMS. THE FRONT WILL CONTINUE EAST TO THE CENTRAL ALEUTIANS THROUGH SUNDAY WHILE THE LARGE PARENT LOW MOVES UP INTO THE BERING. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...GALE WARNING 132 150 155 175 177 178 185. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...PD SOUTHCENTRAL ALASKA...BL SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JA LONG TERM...JER  FXAK68 PAFC 011239 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 439 AM AKDT MON AUG 1 2016 .ANALYSIS AND UPPER LEVELS... The primary weather feature this morning is a vertically stacked low off the Southwest Alaska coast that is slowing shifting southeastward towards Bristol Bay. A stream of moisture is wrapping northward around the east side of the low, bringing steady precipitation to the Alaska Peninsula and Bristol Bay area. Drier weather is in place over Southcentral with weak ridging aloft, however midlevel moisture spilling over the ridge is keeping some clouds over the area. Further west, a drier airmass from the north is advancing southward around the backside of the low over the Bering Sea. This is shown on morning satellite imagery as a pronounced dry slot wrapping into the low. && .MODEL DISCUSSION... Models are in good agreement synoptically with the track of the low as it moves into the Gulf of Alaska Tuesday. Recent runs of the higher resolution models have trended towards a slightly drier solution for interior Southcentral as the moisture from this low moves into the area in the short term. The indication of stronger northern Gulf coastal ridging supports more downsloping of the moisture west of the Chugach. This results in a trend towards slightly lighter precipitation over Anchorage and the western Kenai. The higher resolution models were used in the morning package to best capture these mesoscale features. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2..through Tue)... A low pressure center moving east across Bristol Bay into the Gulf and its associated frontal trough will bring increased chances of rain and locally windy conditions through Tuesday. Southeast cross-barrier flow will hold the lions share of rain along the coasts and southeast exposures today. The cross-barrier flow weakens overnight and Tuesday with the frontal zone which will allow rain to spread inland. Precipitation will taper off from the west Monday afternoon/evening clearing much of Cook inlet, Anchorage Bowl, and MATSU Valleys by evening. The upper low and associated waves moving across the gulf will increase the convective potential on Tuesday. This center will bring with it a -24C cold pool aloft. As this passes over the warm Gulf waters, it could be enough to produce a few thunderstorms. It also pushes a few impulses of energy up into the Copper River Basin where conditions have been very warm and moist. So we have introduced a slight chance of thunderstorms for both these areas. The low and associated front will also bring windy conditions. Southerly winds to small craft strength will be evident with and in advance of the frontal system across the gulf with a weak southeast barrier jet setting up along the North Gulf Coast late tonight and Tuesday. Pressure gradients associated with the aforementioned weather makers will also bring locally brisk and gusty gap flows to favored locals (Turnagain arm, Knik Valley, Copper River) today which should then diminish overnight. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... The low pressure system is located in the Kuskokwim Bay near 58N 165W with the associated weather front approaching the Bristol Bay coastline this morning. The satellite imagery is depicting a large swath of moisture streaming south to north into the Southwest Alaska region. The surface observations are showing temperatures in the lower to mid 50s with the radar imagery displaying widespread rain accompanied by fog. As this low drop farther south into the Bristol Bay the cooler pool aloft will aid in enhancing unstable condition by this afternoon. Therefore, look for isolated thunderstorms forming in the Bristol Bay area with southerly storm motion carrying them inland in the afternoon/evening time- frame. By Tuesday, as the system exits the region into the Gulf, the showery precipitation will taper-off as the upstream ridge builds into the Southwest Alaska region. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... The eastern Bering has the upper level closed low tracking eastward before exiting the region by Tuesday morning. This morning the Scatterometer Wind imagery is showing small craft advisory northerly winds on the backside of this low pressure system located between Nunivak Island, and Saint Paul Island. While, upstream a high pressure ridge is over the central/western Bering/Aleutians region. There is a weak wave just southwest of Adak with the satellite imagery showing a plume of moisture streaming into the Adak region. The GOES IFR Probability satellite imagery is showing widespread stratus/fog over the Western Aleutians extending into the Central Aleutians. The Scatterometer Wind imagery is displaying southeasterly flow which is streaming moisture into the Bering. By Tuesday the ridge of high pressure moves farther eastward, and the Western Aleutians is influenced by a weak trough. Overall, the Bering and Aleutians will see the usual stratus/fog as we head into Tuesday. && .LONG TERM FORECAST (Days 3 through 7)... The big story moving into the later part of the week is the broad troughing over the Bering that will form a consolidated low center over the northeastern Bering Thursday night. This setup will pull up moisture from the south and the southwest flow produced by the low will bring widespread rain to Southwest and Southcentral Alaska for the end of the week into the weekend. Guidance is coming more in line with this overall pattern which is increasing confidence but there still remains variations in how the upper low will move. If it tracks south into the Gulf instead of staying along the coast as some models are indicating then rain amounts will be more limited for inland locations. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...NONE. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...RD SOUTHCENTRAL ALASKA...BC SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PD LONG TERM...DK