FXAK68 PAFC 051407 AFDAFC SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ANCHORAGE AK 507 AM AKST SAT DEC 5 2015 .ANALYSIS AND UPPER LEVELS... THE MAIN NORTH PACIFIC JET STREAM CONTINUES TO REMAIN SOUTH OF THE REGION...KEEPING THE ALASKA REGION OUT OF THE ACTIVE STORM TRACK. A STRONG AND VERY LARGE LOW EXISTS ACROSS THE NORTHEAST PACIFIC JUST SOUTH OF THE GULF OF ALASKA...WITH AN ELONGATED TROUGH SOUTH OF THE KAMCHATKA PENINSULA EXTENDING EASTWARD TO JUST SOUTH OF THE WESTERN ALEUTIAN ISLANDS. OVER THE WESTERN BERING SEA...THERE IS A WEAK AND BROAD UPPER LEVEL TROUGH AXIS...WITH A WEAK SHORTWAVE RIDGE BUILDING INTO THE EASTERN BERING SEA. OVER SOUTHCENTRAL...A SERIES OF WEAK UPPER SHORTWAVE TROUGHS ARE MOVING NORTHEAST ACROSS SOUTHCENTRAL...AND WILL REACH THE CANADIAN BORDER BY LATE THIS MORNING. WITH THE WEAKENING OCCLUDED FRONT ASSOCIATED WITH THE STRONG NORTHEAST PACIFIC LOW MOVING INTO THE GULF TODAY THROUGH TONIGHT...AND INCREASING PRESSURE BUILDING ACROSS SOUTHERN ALASKA...OFFSHORE FLOW WILL INCREASE HEADING THROUGH THE WEEKEND. OUT WEST...THE NORTH PACIFIC JET STREAM WILL STRENGTHEN TO AN IMPRESSIVE 190 KTS AND MOVE EAST...WITH WAVINESS ALONG THE JET RESULTING IN A SERIES OF LOWS TRACKING INTO THE NORTH CENTRAL PACIFIC AND EVENTUALLY INTO THE GULF OF ALASKA BY TUESDAY. && .MODEL DISCUSSION... THE MODELS ARE IN EXCELLENT AGREEMENT WITH THE LARGE SCALE HEMISPHERIC PATTERN INTO NEXT WEEKEND...AND ARE IN GOOD AGREEMENT WITH THE GENERAL IMPACTS REGION WIDE INTO NEXT WEEK...BUT THEY BEGIN TO DIVERGE WITH THE DEVELOPING DEEP LOW MOVING INTO THE GULF OF ALASKA LATE MONDAY EVENING INTO TUESDAY. THEY ALSO DIVERGE RATHER QUICKLY ACROSS THE BERING WITH RESPECT TO NUMEROUS SMALL MESOSCALE LOWS WRAPPING AROUND/ALONG THE FRONT INTO THE BERING SEA SUNDAY AND MONDAY. HOWEVER...THESE IMPACTS ARE MUCH LOWER AND OVERALL DO NOT IMPACT THE FORECAST ALL THAT MUCH. THE ECMWF AND GFS TENDED TO AGREE WITH THE OVERALL PRESSURE PATTERN AND UPPER LEVEL PATTERN THE BEST...SO THEY WERE FAVORED FOR BOTH THE SHORT TERM AND EXTENDED...ALTHOUGH SOME NAM WAS FAVORED ACROSS SOUTHCENTRAL TO BETTER HANDLE OFFSHORE GAP WINDS HEADING THROUGH THE WEEKEND. FOR THE DEEP LOW LATE MONDAY INTO TUESDAY...A TREND TOWARD THE GFS AND ECMWF WAS FAVORED...BUT LARGE UNCERTAINTY STILL CLOUDS THE DEVELOPMENT OF THAT LOW...ALTHOUGH THERE IS NOW MODERATE TO HIGH CONFIDENCE THAT THE LOW WILL EXIST SOMEWHERE IN THE GULF...JUST LOW CONFIDENCE ON TRACK. NONETHELESS...THAT LOW WILL LARGELY BE A MARINE IMPACT...WITH A CONTINUED OFFSHORE PRESSURE GRADIENT KEEPING INLAND LOCATIONS LARGELY DRY THROUGH TUESDAY BEFORE THE REMNANTS OF THE LOW MOVE INLAND. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)... THE LAST OF A SERIES OF UPPER SHORT-WAVES IS EXITING TO THE NORTH TODAY. WITH THE LOSS OF MID AND UPPER LEVEL MOISTURE AND DEVELOPMENT OF SURFACE-BASED TEMPERATURE INVERSIONS...AREAS OF STRATUS AND FOG HAVE FORMED. A RECENT SUOMI-VIIRS NIGHTTIME MICROPHYSICS RGB SATELLITE IMAGE SHOWS A WELL DEFINED AREA AREA OF STRATUS/FOG FROM THE WESTERN KENAI WITH A NARROW STRIP BANKED UP AGAINST THE CHUGACH MOUNTAINS FROM ANCHORAGE TO EKLUTNA. THERE LIKELY ARE OTHER AREAS ACROSS INTERIOR SOUTHCENTRAL...BUT MID LEVEL CLOUDS ARE BLOCKING THE VIEW. THE LOW SUN ANGLE THIS TIME OF YEAR USUALLY MEANS THIS STUFF WILL HANG AROUND FOR A WHILE. HOWEVER...EXPECT INCREASING NORTHERLY WINDS LATER TODAY THROUGH TONIGHT IN RESPONSE TO A WARM FRONT MOVING UP FROM THE PACIFIC AND TRACKING WESTWARD ACROSS THE GULF TO KODIAK ISLAND. THUS...GENERALLY EXPECT DIMINISHING CLOUDS ACROSS SOUTHCENTRAL AND AT LEAST PARTIAL EROSION OF FOG/STRATUS WITH THE INCREASE IN VERTICAL MIXING. HIGH PRESSURE WILL BUILD OVER SOUTHCENTRAL THROUGH THE REMAINDER OF THE WEEKEND INTO EARLY NEXT WEEK...WITH A CUT-OFF HIGH SETTING UP DIRECTLY OVERHEAD. WITH MOSTLY CLEAR SKIES THIS WILL BE IDEAL CONDITIONS FOR SIGNIFICANT COOLING OF THE AIR MASS. EXPECT COOLING TEMPERATURES REGION-WIDE...WITH THE COLDEST TEMPERATURES IN THE COPPER RIVER BASIN. CONTINUED ACTIVITY ACROSS THE GULF OF ALASKA AND NORTHEAST PACIFIC COMBINED WITH COOLING OVER INTERIOR SOUTHCENTRAL WILL LEAD TO TIGHTENING PRESSURE GRADIENTS AND DEVELOPMENT OF GAP WINDS ALONG PRINCE WILLIAM SOUND AND THE NORTH GULF COAST. THERE WILL NOT BE MUCH IN THE WAY OF UPPER LEVEL SUPPORT TO ADVECT THE COLDER AIR OFFSHORE. THEREFORE...GENERALLY EXPECT THIS TO BE A WEAK EVENT WITH THE STRONGEST WINDS THROUGH THE GAPS AND IN THE IMMEDIATE EXIT OF THE GAPS...BUT NOT MUCH FARTHER. WITH THE COLDEST AIR SETTING UP IN THE COPPER RIVER BASIN...THE VALDEZ TO THOMPSON PASS AREA CAN EXPECT SOME OF THE STRONGEST GAP WINDS. && .SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)... THE SOUTHWEST WILL CONTINUE WITH DRY CONDITIONS WITH AN UPPER LEVEL RIDGE POSITIONED OVER THE REGION. COOLER TEMPERATURES WILL FILTER IN FROM THE NORTH AND COINCIDE WITH OFFSHORE FLOW THROUGH SATURDAY. BY SUNDAY A FRONTAL BOUNDARY WILL BE POSITIONED IN THE BRISTOL BAY REGION WITH INCREASED CLOUD COVER PRODUCING WARMER TEMPERATURES ALONG THE SOUTHWEST COASTLINES. THE COLDEST TEMPERATURES WILL BE FARTHER INLAND THROUGH THE LOWER KUSKOKWIM VALLEY AND THE KUSKOKWIM DELTA. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)... THE BROAD COMPLEX LOW PRESSURE SYSTEM REMAINS SOUTH OF THE WESTERN TO CENTRAL ALEUTIAN CHAIN THIS MORNING. THE STRONG 175 KNOT NORTHWESTERLY ZONAL JET STREAM LOCATED IN THE NORTH PACIFIC CONTINUES TO DIG INTO THE BASE OF THE LONGWAVE TROUGH BEFORE TRANSITIONING TO ZONAL FLOW SOUTH OF THE CENTRAL ALEUTIANS. THIS WILL KEEP STORMS SOUTH OF THE CHAIN THROUGH THE WEEKEND. OTHERWISE...THE BERING IS PREDOMINANTLY NORTHEASTERLY FLOW AND LOOK FOR THE WINDS TO INCREASE TO GALE FORCE OVER THE WESTERN BERING BY LATE TONIGHT. BY SUNDAY NIGHT THERE WILL BE INCREASED PRESSURE GRADIENT OVER THE WESTERN BERING SEA AND THE GALE FORCE WINDS WILL INCREASE TO STORM FORCE WINDS. THE BERING AND THE ALEUTIANS WILL BE UNDER A SHOWERY WEATHER REGIME THROUGH THE WEEKEND. && .LONG TERM FORECAST (DAYS 3 THROUGH 7...MON THROUGH FRI)... A BROAD LONG WAVE PATTERN CENTERS NEAR THE EASTERN ALEUTIANS FOR THE EXTENDED FORECAST ON MONDAY...SHIFTING SLOWLY EAST THROUGH THE WEEK. THE MOST ACTIVE WEATHER AT THE BEGINNING OF THE WEEK WILL BE FOCUSED AROUND THE LOW CENTER THAT DEVELOPS IN THE EASTERN PACIFIC ON MONDAY. A STRONG STORM SYSTEM IS EXPECTED TO QUICKLY SPIN UP FROM THIS SYSTEM AND MOVE INTO THE SOUTHERN GULF MONDAY NIGHT. MODELS CONTINUE TO STRUGGLE WITH THE STRENGTH AND TRACK OF THIS SYSTEM...THEREFORE ONLY MINOR EDITS WERE MADE TO INCREASE WINDS AND PRECIPITATION CHANCES USING INFLUENCE FROM THE ECMWF WHICH HAD THE BEST RUN TO RUN CONSISTENCY. THE 06Z GFS IS STARTING TO ALIGN BETTER WITH THE ECMWF AND BOTH ARE BRINGING A SURFACE LOW BETWEEN 950-955MB INTO THE EASTERN GULF EARLY TUESDAY MORNING. THIS STORM IS CURRENTLY EXPECTED TO TRACK INTO THE NORTHEASTERN GULF ON WEDNESDAY MORNING...THEN WEAKEN AS IT MOVES TOWARD THE KENAI. ANOTHER STRONG WAVE ENTERS THE WESTERN BERING EARLY WEDNESDAY AND IS PROJECTED TO MERGE WITH A PACIFIC WAVE WHICH ESSENTIALLY AMPLIFIES THE LONG WAVE AND SETS A NEW PATTERN INTO MOTION. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...HEAVY FREEZING SPRAY 160 180 181 185. GALES 130 138 177 178 185. && $$ SYNOPSIS AND MODEL DISCUSSION...JA SOUTHCENTRAL ALASKA...SB SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PD LONG TERM...KH  FXAK68 PAFC 060144 AFDAFC SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ANCHORAGE AK 444 PM AKST SAT DEC 5 2015 .ANALYSIS AND UPPER LEVELS... THERE IS AN UPPER LEVEL TROUGH OVER THE WESTERN BERING SEA. ASSOCIATED WITH THIS ARE TWO VERTICALLY STACKED LOWS...ONE SOUTH OF THE WESTERN ALEUTIANS AND ONE SOUTH OF THE EASTERN ALEUTIANS. THERE IS ALSO A WEAK SHORT-WAVE OVER THE SOUTHEAST BERING AND ALASKA PENINSULA...WHICH IS ESSENTIALLY A "BACK DOOR" WARM FRONT MOVING TOWARD THE NORTHWEST. FURTHER EAST THERE IS AN UPPER LEVEL RIDGE OVER SOUTHERN ALASKA WITH WEAK OFFSHORE FLOW AT THE LOWER LEVELS. THERE IS AN UPPER LOW OVER THE SOUTHERN GULF OF ALASKA WITH A SHORTWAVE TROUGH OVER THE EAST CENTRAL GULF MOVING TOWARDS THE WEST. THERE IS ENOUGH MOISTURE OVER THE GULF TO BRING SOME SHOWERS TO KODIAK ISLAND IN NORTHEAST FLOW. OF NOTE FROM A LARGER WEATHER/CLIMATE PERSPECTIVE IS THE VERY EXTENDED EAST ASIAN JET (EAJ). THIS IS RUNNING ALMOST DUE EAST BETWEEN 35 AND 40 DEGREES NORTH LATITUDE FROM KOREA TO ABOUT 140 DEGREES WEST LONGITUDE. THE WINDS IN THIS JET EXCEED 190 KTS IN PORTIONS OF THE WESTERN PACIFIC. THIS EXTENDED EAJ IS A COMMON OCCURRENCE DURING EL NINO YEARS AND IS A SIGN THAT THE CURRENT EL NINO IS WELL COUPLED WITH THE MID LATITUDE WEATHER AT THIS TIME. && .MODEL DISCUSSION... THE NUMERICAL MODELS ARE IN REASONABLY GOOD AGREEMENT FOR THE SHORT TERM PORTION OF THE FORECAST. THERE ARE SOME DIFFERENCES IN HOW THEY HANDLE THE INTERACTION OF THE VARIOUS LOWS OVER AND JUST SOUTH OF THE EASTERN/CENTRAL ALEUTIANS AND ALASKA PENINSULA FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON. THIS DOES NOT HAVE A LARGE IMPACT ON THE WEATHER FORECAST...BUT DOES INTRODUCE SOME UNCERTAINTY. WITH THIS IN MIND...THE FORECAST CONFIDENCE IS NEAR NORMAL FOR THE ALEUTIANS AND BERING SEA AND A BIT ABOVE NORMAL FOR THE SOUTHWEST AND SOUTH CENTRAL ALASKA MAINLAND. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)... AN UPPER LEVEL JET STREAK AND ATTENDANT SHORTWAVE DISTURBANCE WILL USHER HIGH LEVEL CLOUDS ACROSS THE REGION TONIGHT. DEPENDING ON THE AMOUNT OF INSOLATION PROVIDED...FOG WHICH HAS DEVELOPED AROUND SUNSET THIS AFTERNOON...OR IN SOME PLACES HAS PERSISTED SINCE THIS MORNING...MAY DIMINISH IN COVERAGE AS THESE CLOUDS MOVE OVERHEAD TONIGHT. AS OF 3 PM...VIIRS NPP POLAR SATELLITE DETECTED THIS FOG EXTENDING FROM THE KNIK AND LOWER MATANUSKA RIVER VALLEYS SOUTH ALONG THE WESTERN CHUGACH RANGE TO EAST ANCHORAGE...THEN DEVELOPS AGAIN FROM POTTER MARSH THROUGH TURNAGAIN ARM DOWN TO PORTAGE AND PERHAPS TURNAGAIN PASS. ANOTHER BATCH OF LOW CLOUDS AND FOG EXISTS ALONG THE STERLING HIGHWAY FROM NEAR SOLDOTNA EAST TO NEAR COOPER LANDING. A DENSE FOG ADVISORY HAS BEEN ISSUED FOR THE IMPACTED AREAS IN ANCHORAGE AND THE MATANUSKA VALLEY UNTIL 6 AM AKST TO ACCOUNT FOR THIS FOG...WITH THE MAIN IMPACTS BEING SLICK ROADS FROM THE FOG DEPOSITING ICE ON THE ROADWAYS...MAINLY ALONG THE GLENN HIGHWAY...AND REDUCED VISIBILITY. HIGH PRESSURE WILL BUILD OVER SOUTHCENTRAL THROUGH THE REMAINDER OF THE WEEKEND INTO EARLY NEXT WEEK...WITH A CUT-OFF HIGH SETTING UP DIRECTLY OVER THE NORTH GULF COAST. WITH MOSTLY CLEAR SKIES THIS WILL BE IDEAL CONDITIONS FOR SIGNIFICANT COOLING OF THE AIR MASS. EXPECT COOLING TEMPERATURES REGION-WIDE...WITH THE COLDEST TEMPERATURES IN THE COPPER RIVER BASIN SUNDAY NIGHT AND MONDAY MORNING. CONTINUED ACTIVITY ACROSS THE GULF OF ALASKA AND NORTHEAST PACIFIC COMBINED WITH COOLING OVER INTERIOR SOUTHCENTRAL IS LEADING TO TIGHTENING PRESSURE GRADIENTS AND DEVELOPMENT OF GAP WINDS ALONG PRINCE WILLIAM SOUND AND THE NORTH GULF COAST. THERE WILL NOT BE MUCH IN THE WAY OF UPPER LEVEL SUPPORT TO ADVECT THE COLDER AIR OFFSHORE. THEREFORE...GENERALLY EXPECT THIS TO BE A WEAK EVENT WITH THE STRONGEST WINDS THROUGH THE GAPS AND IN THE IMMEDIATE EXIT OF THE GAPS...BUT NOT MUCH FARTHER. WITH THE COLDEST AIR SETTING UP IN THE COPPER RIVER BASIN...THE VALDEZ TO THOMPSON PASS AREA CAN EXPECT SOME OF THE STRONGEST GAP WINDS. && .SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2...SUN AND MON)...WEATHER WILL REMAIN COLD AND RELATIVELY CALM...ESPECIALLY FOR DECEMBER...FOR THE NEXT COUPLE OF DAYS. AS THE BROAD LONGWAVE TROUGH REMAINS OVER THE CENTRAL ALEUTIANS...A WEAK SHORTWAVE RIDGE WILL ACTUALLY BUILD OVER THE MAINLAND. WITH THE COLD AIR ALREADY IN PLACE OVER THE SOUTHWEST...THIS WILL CREATE A MODERATE OFFSHORE SURFACE GRADIENT. THIS WILL CAUSE THE NORTH TO EAST WINDS TO CREEP UP SLOWLY OVER THE NEXT 24 HOURS...ESPECIALLY ALONG THE WESTERN CAPES OF BRISTOL BAY AND THE ALASKA PENINSULA. A WEAK WARM FRONT WILL SLIDE THROUGH THE EASTERN ALEUTIANS AND ALASKA PENINSULA LATE SUN INTO MONDAY. THIS COULD BRING A SHOT OF LIGHT SNOW INTO THOSE AREAS. BUT AS IT USHERS IN THE WARMER AIR...EXPECT THE SNOW TO CHANGE QUICKLY TO RAIN. THIS FRONT WILL ALSO HELP TEMPERATURES OVER THE MAINLAND TO SLOWLY MODIFY TO START THE WEEK. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2...SUN AND MON)...THE BEST WAY TO SUM UP THE WEATHER FOR THE NEXT COUPLE OF DAYS IS COMPLICATED BUT LOW-IMPACT. A BROAD UPPER LEVEL LOW WILL SET-UP IN THE VICINITY OF DUTCH HARBOR. ON THE EAST SIDE OF THE LOW THERE WILL BE SOUTH TO SOUTHEAST WINDS AND WARMER AIR BEING ADVECTED FROM THE NORTH PACIFIC. SNOW SHOWERS WILL TURN TO RAIN SHOWERS AS FAR NORTH AS THE PRIBILOF ISLANDS. ON THE WEST SIDE...THERE WILL BE COLD AIR SNOW SHOWERS AND GUSTY NORTH TO NORTHEAST WINDS. SEVERAL WEAK PIECES OF ENERGY WILL ROTATE ACROSS THE BERING IN A CYCLONIC/COUNTER-CLOCKWISE FASHION AROUND THE LOW CENTER. MODELS ARE SHOWING THAT SOME OF THIS ENERGY COULD PRODUCE A POLAR LOW OVER THE NORTHWEST BERING ON SUNDAY. THIS WILL LIKELY BRING A NARROW BAND OF STORM FORCE WINDS AND HEAVIER SNOW SHOWERS THROUGH THE WESTERN ALEUTIANS LATE SUN. && .LONG TERM FORECAST (DAYS 3 THROUGH 7...MON THROUGH FRI)... THE LONG WAVE TROUGH OVER THE EASTERN BERING THAT HAS BEEN A SEMI-PERMANENT FEATURE LATELY WILL BEGIN TO SHIFT INTO THE GULF AND DEEPEN EARLY NEXT WEEK. THIS WILL BRING A GALE (OR POTENTIALLY STORM FORCE) LOW INTO THE GULF BY LATE MONDAY WHICH WILL PERSIST IN THE GULF AND SLOWLY WEAKEN OVER THE COURSE OF NEXT WEEK UNDER THE UPPER LEVEL TROUGH. THIS WILL KEEP MUCH OF THE ACTIVE WEATHER CONFINED TO THE GULF AND EASTERN BERING THROUGH THE MIDDLE OF NEXT WEEK. OVER SOUTHCENTRAL THIS WILL BRING GENERALLY OFFSHORE FLOW AND CLEAR SKIES FOR MUCH OF SOUTHCENTRAL...WHILE OVER THE BERING...BROAD NORTHERLY GALE FORCE WINDS WILL BRING COLD AIR ADVECTION SNOW SHOWERS TO THE AREA. BY LATE NEXT WEEK THERE IS VERY GOOD MODEL AGREEMENT THAT THE GULF LOW WILL DISSIPATE SOMEWHERE AROUND THE NORTH GULF COAST...BRINGING INCREASING CHANCES FOR SNOWFALL TO THE SOUTH MAINLAND. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...DENSE FOG 101 111. MARINE...GALES 130 138 160 177 178 180 181 185 HEAVY FREEZING SPRAY 160 180 181 185. && $$ SYNOPSIS AND MODEL DISCUSSION...BL SOUTHCENTRAL ALASKA...CC SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MO LONG TERM...DEK  FXAK68 PAFC 011349 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 449 AM AKST Sun Jan 1 2017 .ANALYSIS AND UPPER LEVELS... A large upper level low is over the central and western Bering Sea while a large upper level ridge extends from the Gulf of Alaska over the mainland. The front associated with the Bering Sea storm extends along 170W through the Eastern Bering Sea through the Unalaska area to a wave along the front that will cross the eastern Aleutians later this morning. A low formed south of Shemya and is quickly moving to the northeast around the base of the main low. The airmass looks rather convective in the satellite imagery across the Bering Sea west of the front. Between the Bering Sea low and the ridge of high pressure over the mainland is a tight pressure gradient that continues to produce gale force winds along and ahead of the front. Over the mainland under the high pressure, subsidence and radiational cooling is resulting in inversions setting up increasing the likelihood of fog in the valleys. The large high pressure over the Gulf of Alaska will also increase the likelihood of fog over the Gulf over the next few days. && .MODEL DISCUSSION... Models are in excellent agreement with respect to the synoptic scale features in the short term. The GFS and NAM were used to fine tune the forecast this morning. && .AVIATION... PANC...VFR conditions and light winds will persist. The one area of uncertainty is with respect to fog over the Inlet that could drift over the airfield. At this point it looks unlikely, but is something we will be watching for. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)... An impressive inversion is present in the morning sounding, with small dewpoint depressions across the Anchorage Bowl indicating the availability of some surface moisture. However, ASCAT satellite data continues to show persistent offshore flow down Cook Inlet that is currently limiting fog development by mixing much drier air into the boundary layer. The latest VIIRS pass however, does show some fog in sheltered areas of Kenai Peninsula, and it is possible for some additional patchy fog to develop before morning. With an impressive upper level ridge becoming further established across much of mainland Alaska, fog development will remain the main forecast challenge over the next few days. The presence of low level jets across Cook Inlet and also Prince William Sound should limit the intensity and coverage of fog across most of south central Alaska Sunday night as well. However, Monday morning models indicate winds could lighten up enough to allow some fog development. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... A meandering frontal boundary will bring rain and snow to mainly the Kuskokwim Delta through Tuesday. The flow pattern will remain steady state for the time being as a blocking high pressure over the Gulf prevents a north/south oriented front in the Bering Sea from making too much eastward progress. Southerly flow will encompass most of the mainland with the strongest winds along the west coast. The front looks to linger west of Bethel along the coast today and Monday, followed by an enhancement by a couple of shortwave troughs late Monday into Tuesday. There is uncertainty in the forecast in that the front could waggle from west to east across the area, with higher confidence that it will not make it past Bethel due to the blocking high pressure. Rain will be the predominant precipitation type, but some areas of snow remain possible, especially near Hooper Bay and the far western edge of the front that will not be in the warmer southerly flow. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... A frontal boundary will stall over the eastern Bering for the next two days and linger as several disturbances ride overhead. The Pribilof Islands will be right on the western side of the front today, making snow likely. The front will move to the east overnight tonight as high pressure sits over the central Bering Sea. A compact low pressure system is approaching the western Aleutians this morning with gale and possibly some isolated storm force winds. The current track of the system looks to put Shemya in a bullseye for decent accumulating snow. The deformation band is passing right overhead and should linger through the morning. && .LONG TERM FORECAST (Days 3 through 7/Monday night through Saturday)... An anomalously strong blocking ridge centered over the Gulf of Alaska early next week will retrograde westward as energy rides over the top of it Tuesday and Wednesday. It will then connect up with a separate ridge moving into the Bering Sea Wednesday night, ending up as an equally strong blocking ridge over the Eastern Bering Sea. The primary uncertainty with this pattern is with handling of short-wave moving over the ridge Tuesday/Tuesday night, advecting the remnants of the front along the Southwest coast inland to interior Alaska. With a fairly narrow zone of precipitation along the front, there is some question about where this zone will be as it all heads inland. Elsewhere, there is high confidence in a prolonged dry spell over Southcentral Alaska and Kodiak Island, on the order of 7 days or longer. The air mass underneath the ridge will be quite mild early to mid week, so expect temperatures near or slightly above normal. The wild card will be fog/stratus, which will likely form over the Gulf of Alaska and Cook Inlet regions. This would limit radiational cooling and maintain a very narrow diurnal temperature range. As the ridge becomes repositioned farther west mid to late next week that will open the gates for some arctic air to advect southward into Southcentral, though models continue to differ on the extent of cooling. In any case expect colder temps later in the week along with development of offshore flow and gap winds. Meanwhile, the storm track will remain over the far west, from the northwest Pacific to western Bering Sea, the eastern periphery of systems clipping the western Aleutians. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...None. MARINE...Gale 165, 170, 172, 177,178, 180, 185, 411, 412, 413, 414. && $$ SYNOPSIS AND MODEL DISCUSSION...Sam SOUTHCENTRAL ALASKA...EN SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ML LONG TERM...SEB  FXAK68 PAFC 191303 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 403 AM AKST Fri Jan 19 2018 .ANALYSIS AND UPPER LEVELS... There are 2 main features across Alaska today. The first is a decaying low over the Gulf of Alaska which continues to produce showers that are detectable on the Middleton Island radar. A another low south of the aforementioned low continues to push eastward along 50N which will not directly impact South Central but it will interact with the remnants of the low just outside Prince William Sound. The other primary feature is a strengthening surface high near the Gulf of Anadyr. This surface high has been over Siberia will continue to migrate towards the Central Bering. Anomalously cold air is trapped in this feature and this will have a major impact on the region as the forecast period unfolds. && .MODEL DISCUSSION... There is good model consensus with the synoptic features and good run to run continuity. That said, there are a few areas of uncertainty regarding timing of fog dissipation and pinpointing the temperatures as we head into a much cooler pattern. && .AVIATION... PANC...Fog has moved down Knik Arm and has reduced visibility and cigs. The latest VIIRS image has a large area of stratus spanning from Knik Arm and down Cook Inlet which is camouflaging the fog. Looking at the models, the MOS guidance is anticipating overcast conditions at PANC for the next 24 hrs with the fog ebbing and flowing around the airport. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)... Though there is an upper low currently parked over Southcentral Alaska, shallow inversions and low level moisture have given rise to areas of fog from Cook Inlet/Western Kenai, Anchorage Bowl, to over the Matanuska Valley (especially Knik Arm). Stratus and fog are more widespread across the Copper River Basin. Except for the Copper River Basin, where the low conditions are expected to linger into Saturday, the other aforementioned areas should see a lessening of these conditions tonight with a little more mixing. That said, there may be some patchy fog which redevelops/holds overnight through the Knik Valley. Pressure and temperature gradients will increase across Southcentral tonight as cold air butts up against the interior side of Alaska Range and Copper River Basin and flows through gaps. Other than along the range, a noticeable increase in outflow winds will be evident across the northern and Western Gulf, including the eastern Kenai peninsula overnight which should continue through Saturday night. && .SHORT TERM FORECAST SOUTHWEST ALASKA... With high pressure settling in over the Bering, dry, northerly winds will dominate southwest Alaska through the weekend. This setup will pull down Arctic air over the area dropping temperatures to around -30 F for interior locations Saturday and Sunday night. Winds look to be relatively light over the weekend for low lying areas, but if they do pickup wind chills could become a concern. However, there remains uncertainty with how strong the winds will get. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS... High pressure will dominate the Bering through the weekend with the eastern side pulling down cold air over the eastern Bering and Aleutians. These winds look to be around small craft strength which will be enough combined with the cold air to bring freezing spray to much of the eastern Bering. Out west, a North Pacific system will approach the western Aleutians tonight but will be stalled by the Bering high. This will keep its front and any precip associated with it over the central and western Aleutians. && .LONG TERM FORECAST (Days 3 through 7)... The long term begins Sunday night and Monday with a high amplitude upper high over the Bering Sea and a trough to the east, which includes a closed low in the Gulf of Alaska and another over northern Alaska. There is weak ridging in between the two lows over Southcentral. Strong northerly flow will be over the Alaska west coast and Alaska Peninsula. During the first half of next week the Gulf low will slide east, and the Bering high will weaken. This will allow the north Alaska low to dive southward, reaching southern Alaska around the middle of next week. The exact path and timing of this southward traversing low is not agreed upon exactly by the models, but agreement is good enough for a fairly high confidence forecast for this time range. The end result of all of this is a fairly cold regime with temperatures below normal over mainland southern Alaska. Some precipitation is possible through the period for the Gulf coastal areas. There is a chance some precipitation could get further inland, depending on how the Gulf low behaves, but confidence in this is low. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...None. MARINE...Gale 411 150 177 178 180 130. Heavy Freezing Spray 160 180 181 185. && $$ SYNOPSIS AND MODEL DISCUSSION...PJS SOUTHCENTRAL ALASKA...BC SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK LONG TERM...BL  FXAK68 PAFC 081341 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 441 AM AKST Thu Feb 8 2018 .ANALYSIS AND UPPER LEVELS... The main weather feature is a broad trough driving the active weather pattern across the Bering with several strong short waves within its flow evident on Water Vapor satellite imagery. A closed low center spinning within the trough is over Shemya early this morning. Abundant moisture is streaming up through the central and eastern Bering between this low and a ridge over mainland Alaska. At the surface, ridging remains dominant over the southern mainland returning colder than normal temperatures along with weak offshore flow. Gusty southerly flow is predominant across much of the Bering with a surface low crossing to the Bering over the central Aleutians. This system is re-enforcing a warm front across the eastern half of the Bering. && .MODEL DISCUSSION... Models continue in relatively good agreement with the synoptic pattern through the end of the work week. Changes were made to increase winds across the Bering as confidence increased for storm force marine winds as the pressure gradient tightens between the Bering low and ridge to its east. Blowing snow was also added along the Kuskokwim Delta coast as the frontal boundary shifts closer Thursday night into Friday. && .AVIATION... PANC...IFR to LIFR visibilities may briefly occur this morning as a steep inversion just of the surface is trapping low level moisture along the northern inlet. Patchy fog may redevelop tonight as low level moisture increases in a continued stable environment. Light winds persist through the TAF package with a dominant surface ridge over the central mainland. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)... The Suomi (polar orbiting satellite) VIIRS RGB Nighttime Microphysics imagery clearly shows some localized areas of fog/stratus along the Knik River Valley into Palmer, along Knik Arm, along the east end of Turnagain Arm (and nearby valleys including Girdwood), and portions of the Copper River Basin along the south to west side of the Wrangell Mountains. Otherwise, clear skies dominate Southcentral this morning under an offshore flow regime. An upper level short- wave which dropped southward across the eastern Copper Basin overnight led to an upswing in gap winds in Valdez/Thompson Pass as well as along the Copper River Delta into the northern Gulf. These winds will gradually diminish today as pressure and thermal gradients slacken. Aside from a continued threat for localized areas of fog and stratus, dry clear and seasonably cool conditions will continue into Friday. A strong frontal system taking shape out west will then approach Kodiak Island on Friday with rain and gale force winds spreading northward across the western Gulf. Precip will reach the southern tip of the Kenai Peninsula Friday night, with clouds spreading northward across the rest of Southcentral. && .SHORT TERM FORECAST SOUTHWEST ALASKA... Warm southerly flow will continue over southwest Alaska with ridging to the east and a longwave trough to the west. Late tonight a front will move in and will at first bring precip to areas along the coast and then will spread inland on Friday. However, the majority of the heaviest precip will stay along the coast. Precip looks to start as snow for most locations and transition to rain, with the exception of farther inland locations that will stay as snow. Winds will also increase throughout southwest Alaska as the front pushes in. Along the Kuskokwim Delta coast the initial onset of snow combined with winds will bring blowing snow conditions to the coastline Friday. Friday night both precip and winds will start to diminish and Saturday will continue to see improving conditions. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS... With the longwave trough extending over the western Bering, multiple systems look to track north into the central and eastern Bering through Saturday. These systems will bring warm air, rain and winds to the eastern Aleutians and Bering as they move through. Marine areas around eastern portions of the Alaska Peninsula look to see storm force winds Friday. Further west, temperatures will stay colder without the influence of the North Pacific systems bringing in warmer air from the south. This will result in light snow showers for locations around the Western Aleutians into the weekend. && .LONG TERM FORECAST (Days 3 through 7)... Saturday will be a day the pattern is shifting to a warmer one over Southcentral and Southwest Alaska due to an amplifying upper level ridge along the West coast of North America. The low in the Bering Sea will push into this ridge over the weekend and start a somewhat progressive upper level pattern over the state for next week. Models are struggling quite a bit with the progressive pattern, but in spite of the noise, it looks like we can get a reasonable idea as to where the longwaves will set up and those will be the basis for everything else. In general, the highly amplified ridge/trough pattern has been dampened a bit on the long term guidance which is to keep the forecast from fluctuating too far as some of the details become more clear. This will also keep a lot of 'chance of' POPs to remain in the long term forecast. Overall, next week will be much more mild with many locations experiencing temperatures above freezing. Precipitation type will be an issue with this situation, and the details will not come into focus until we get closer to these systems moving through the area. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...None. MARINE...Storm Warning 150 160 180. Gale Warning 130-132 136-138 155 165 171-173 179 181 185. && $$ SYNOPSIS AND MODEL DISCUSSION...KH SOUTHCENTRAL ALASKA...SEB SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK LONG TERM...EZ  FXAK68 PAFC 301254 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 454 AM AKDT Sun Sep 30 2018 .ANALYSIS AND UPPER LEVELS... A ridge of high pressure remains parked over the state today, continuing the trend for fair weather across much of the Mainland. The area of low pressure responsible for the gusty southeasterly winds across the central and eastern Aleutians yesterday has now moved into the northwestern Bering. A strong gradient between the high over the mainland and the low pressure over the Bering Sea is maintaining the strong south to southeast wind along the Bering Sea coast and over the eastern Bering Sea. An upper level North Pacific low is currently situated just south of Dutch Harbor. The leading front associated with this low will continue to bring southeasterly winds along the eastern Aleutians and AKPEN. Radar imagery this morning indicates rain and low level stratus and fog along the coastal areas of Southwest Alaska as the front approaches. && .MODEL DISCUSSION... Overall, models remain in good synoptic agreement through the next 48 hours. Differences arise by Tue morning as the remnants of typhoon Trami enter the western Bering. Models currently agree on the phasing of the upper level low currently south of Dutch Harbor with the upper level remnants of Trami beginning Mon evening over the central Bering. At this time, the GFS/EC solution shows a slightly faster track while the NAM keeps the low further west. With large uncertainties in timing and position, GFS was still preferred with this morning's forecast package. && .AVIATION... The main issue will be with the potential for stratus and fog this morning and again overnight tonight. The latest satellite imagery (nighttime microphysics) did not show any stratus in the northern Inlet, although that was from around 1030Z. At this point we will stick some IFR Cigs and Vsby in for this morning then VCFG for the late night and morning hours again tonight and Mon morning, though generally keeping the prevailing conditions VFR with light wind. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)... High pressure will continue to dominate the weather over the region for the next two days with the only exception being Kodiak which will see a front move over that area tomorrow. With the high pressure, the only real question will be the development of fog. A nighttime microphysics pass from the VIIRS satellite taken around 2:30 AM AKDT shows the development of fog in the river valleys of the eastern Kenai Peninsula, eastern Turnagain Arm, as well as in the Eagle River and Eklutna River valleys. The Copper River Basin, which had some extensive fog and stratus yesterday is almost completely clear of fog at this time. Fog should overall be less than yesterday, with some areas developing again Sunday night into Monday morning. Temperatures will remain well above normal today and tomorrow for most of southcentral Alaska with a cooling trend back toward normal after that. A front will move over Kodiak Island from the southwest tomorrow and bring back rain to the area as well as strong southeast winds. This front will then slowly progress northward through Tuesday. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3)... Winds will remain the focus across Southwest Alaska through Monday as a tight pressure gradient lingers over the region. The gradient is the result of a stationary ridge situated downstream in the northern Gulf and a trough upstream extending across the eastern Bering. As the next surface low begins to track northeast toward the AKPEN today, the gradient will tighten and the southeasterly winds will increase, especially across Bristol Bay and the Kuskokwim Delta with the highest speeds along the coasts. Scattered showers will also develop along the coast later today and continue through Monday as the low dissipates and transitions to an open wave. For upslope areas of the AKPEN, the persistent southerly flow will bring periods of moderate to heavy rain. Any lingering showers from the now dissipating trough will move inland on Tuesday as an occluded front extending from a strong storm system over the western Bering advances toward the Southwest with another shot of rain and gusty southerly winds. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)... A low well south of Atka will move toward Dutch Harbor today. The rain and gusty southeasterly winds that developed overnight across the eastern Bering will continue through early Monday before diminishing as the low tracks north and fills in. Over the central Bering, gusty northerly flow will increase tonight around the back side of the low passing to the south and east. Then all eyes turn to the remnants of typhoon Trami as it tracks quickly toward the western Aleutians. This system will transition to a powerful extratropical storm as it taps into a cold air mass over the Kamchatka Peninsula. Storm-force winds will move over Shemya and Attu Monday as its associated front sweeps across the western Aleutians. There is still some uncertainty as to the exact track of this low once it passes west of Attu; however, current guidance continues to place the center of circulation well north and west of the Aleutians. If this trend holds, it is looking more likely that the core of strongest winds associated with the colder air wrapping underneath the low will remain over the open waters of the western and central Bering through Tuesday where gusts could approach 70 kts. && .LONG TERM FORECAST (Days 3 through 7)... (Wednesday through Saturday) A very unsettled pattern will persist for the middle to latter part of the week, as the remnants of the former Super Typhoon Trami, which is currently near Japan, move northeast towards the western Bering Sea. It is expected to then turn eastward as it merges with a trough coming off the Kamchatka Peninsula. The numerical models all agree in this scenario, but they differ in speed and strength as the system bumps into a persistent ridge stretching from the North Slope through the Kenai Peninsula, and into the Gulf. Initially, the models are in good agreement with the pattern aloft on Wednesday, but they quickly begin to diverge some 24 hours later, as the GFS looks to have a faster progression with the system as the ridge slides off to the east while weakening. This storm will be unusually strong for the Bering Sea for this time of year, as it will be 3 to 4 standard deviations above normal. Most of the region along and north of the western Aleutians will see storm force winds with hurricane force gusts likely. An associated occluded front will cross into southwestern parts of the state by evening, with widespread rainfall accompanying it, with another low developing near Kodiak. This rainfall will also spread northeast during the evening and into Thursday for most of Southcentral and the Kenai/Prince William Sound region. Meanwhile, another north Pacific low will strengthen as it crosses the central portions of the chain, lifting north towards Saint Matthew Island on Friday, while sending another front through the southwest with more rainfall developing. Similar to its predecessor, another Kodiak low will form Friday evening, reaching Prince William Sound late Saturday, spreading widespread rainfall across all of Southcentral and into the Copper River Basin. However, it's important to note that as we approach next weekend, model diversity increases somewhat, which is typical given its 5 to 7 days out. Added to the mix is that everything is dependent on if the models handle the first extra-tropical system correctly, so forecast changes are probable for the latter half of the week. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...None. MARINE...Gale 150-170 172 174 177 180 181. Storm 178. && $$ SYNOPSIS AND MODEL DISCUSSION...KO/SA SOUTHCENTRAL ALASKA...EZ SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TM LONG TERM...PD  FXAK68 PAFC 151423 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 523 AM AKST Thu Nov 15 2018 .ANALYSIS AND UPPER LEVELS... An upper level ridge is building over Southwest Alaska and toward Southcentral Alaska. Mostly clear skies and light winds across much of this region has produced fairly steep surface-based inversions as seen on areas soundings. This in turn has led to development of areas of fog. Recent VIIRS nighttime microphysics imagery shows dense fog in Anchorage spreading southward to the western Kenai Peninsula. Other areas of fog are noted in the Copper River Basin and Bristol bay regions. Upstream of the ridge an upper low is lifting northward across the northern Bering Sea, with a trough axis extending southward across the eastern Bering. An inverted surface trough is right underneath the upper trough and is the focus for rain and snow showers. Meanwhile, a large vertically stacked gale force low is lifting northward from the North Pacific toward the Alaska Peninsula and Kodiak Island. Lastly, a deep low is elongating to the southwest of the Western Aleutians. An occluded front is nearing the Aleutians, with rain and gale force winds spreading north and east along the chain. && .MODEL DISCUSSION... Models are in fairly good agreement with large scale features. There are some minor differences with position/strength of the North Pacific low as it approaches the Alaska Peninsula on Friday, but there is good agreement in the progression of the occluded front and associated precipitation out ahead of it. The main forecast challenge is determining the extent of freezing rain as warm air once again rides overtop of Southwest and Southcentral Alaska the next couple days. && .AVIATION... PANC...Dense fog (with LIFR conditions) remains the primary concern. Fog in the Anchorage area is more extensive compared to 24 hours ago. With very little change in winds until this afternoon expect fog will hold in through the morning hours. A slight increase in winds this afternoon should help mix out some of the fog, or perhaps even advect it southward away from the terminal. The fog seems like it will come right back after sunset late this afternoon. However, there will be more wind in the vicinity and winds along Turnagain Arm and on the mountains will steadily increase overnight, making fog less and less likely. Therefore, if fog does return, it should not be as long-lived as it has been the past couple nights. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2/Today through Friday night)... Areas of fog will persist today, with some improvement expected in Anchorage and the western Kenai Peninsula this afternoon as northerly winds increase just a bit. The fog could return after sunset later today, but pressure gradients will tighten overnight as a front moves into the Gulf of Alaska. Increasing low level flow and mixing should help erode any fog for good by late tonight. Areas not in the fog will see another sunny day. The aforementioned front will lift northward to Kodiak Island tonight, with heavy rain and strong winds spreading northward across Kodiak and the western Gulf. As the front lifts northward to the Gulf coast and Prince William Sound on Friday, strong low level southeast flow looks like it will keep the western Kenai, Anchorage, and the Matanuska Valley mostly dry. A series of waves moving through the upper flow could produce a little precipitation, but if anything does fall expect it to be very light with little accumulation. Coastal areas can expect moderate to heavy precipitation as the upper trough becomes strongly negatively tilted and heads right for the Prince William Sound region. Marginally warmer air will advect northward with this storm system. The 12Z Anchorage sounding shows an above freezing warm nose remaining from the warm-up this past weekend. Thus, it won't take much warm advection to lead to precipitation falling in the form of rain. With persistent northerly winds at the surface, this again looks like a situation where surface temperatures will be slow to rise above freezing. Thus, there is potential for freezing rain from the western Kenai Peninsula to Anchorage and the Matanuska Valley Friday through Friday night. However, as mentioned above, downsloping should keep these areas mostly dry. Thus, have only included a chance of freezing rain in the forecast. If something does fall, it may be so light that there won't be any impacts. Plus, roads are already quite icy and it might not make any difference. In any case, will continue to evaluate this threat moving forward. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... (Today through Friday) The weather pattern looks to become more active over the next 24 to 36 hours, as a series of fronts brings precipitation to the region. The real question though for some locations will be what type of precipitation falls and how quickly does it change over to rain. More on that in a minute. Early this morning the latest nighttime microphysics satellite imagery shows some fog and low stratus has developed across some of the coastal locations, especially Bristol Bay, and the interior valleys east of the Kilbuck Mountains. This may briefly intensify near sunrise before burning off by mid to late morning. Heading into the afternoon, a weak warm front attached to a Bering Sea low will lift northward across the region, with precipitation developing along it. The low-level winds will continue to be northeasterly along and ahead of the front, will just a few thousand feet above the ground southeasterly winds will advect above freezing temperatures and moisture into the region. This warmer/moist flow will also get a boost from a low in the Pacific heading towards the AKPEN. Taking a closer look at point soundings show the colder surface air will remain entrenched for the first hours or so along the coast, and a little bit longer inland, allowing for a period of snow to transition to a mix of or change over to freezing rain. Should this occur, any ice accumulations are expected to be just a few hundredths of an inch at most. Still, this could cause some travel impacts. For now, we decided to hold off on an advisory and await the next couple of model runs before deciding on any headlines. For your Friday, the Pacific low will reach the peninsula by early evening, bringing a reinforcing shot of warm air to the area. This type, all precipitation looks to be rain west of the Kilbuck Mountains, and south of the Nushagak Hills. Further northeast of these areas, wintry type precipitation will hold on longer as the colder air remains more terrain locked (almost like a mesoscale cold air damming effect), which could again lead to some headline concerns for freezing rain. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... (Today through Friday) The tale of two air masses in battle sums up much of the Bering Sea, as a pair of weak lows sits across the northern Bering and Pribilof Islands respectively this morning. To the east of these features, southerly flow is helping to draw warm air northward, while along and to the west of the lows a northerly flow dominates. This is allowing any precipitation to fall in the form of snow compared to points further east. Meanwhile, a front attached to a Kamchatka low is entering the western Aleutians, helping to advecting warmer air into this part of the Bering. This front will continue to move north and eastward through Friday morning as the parent low dives southeast towards this area while weakening, while the system begins to fill as it becomes vertically stacked and the front weakens. As for the sensible weather related to these features, snow will gradually transition to a mix of rain and snow for locations along and south of 55N, as the warmer air starts to take hold. The interesting part of this is several disturbances in the flow aloft will interact with the warmer tropical fetch advecting into the western Aleutians. This moisture-laden airmass moving over the cooler marine waters looks to create sufficient instability for a few thunderstorms to develop near and south of the Chain. As for winds, look for gale force winds along the front today to decrease to small craft criteria by Friday morning, as the pressure gradient weakens. Our attention then turns to a Pacific low heading towards the AKPEN on Friday. Model disagreement remains moderate with respect to strength of the low itself and the associated wind field strength, but, overall we expect widespread precipitation will develop along and ahead of this feature and its associated warm front, with sustained gales expected. && .LONG TERM FORECAST (Days 4 through 7)... The long-term forecast begins Saturday night with a surface low weakening east of Kodiak Island and its associated occluded front draped along the coast bringing another round of mixed wintry precipitation to Southcentral Alaska. A second trough follows on the heels of the first moving through the Gulf and impacting the Southcentral coast Sunday. Yet another trough slides across the Gulf on Monday, with the GFS bringing it closer to Southcentral while the EC slides the system farther east toward the Alaska Panhandle. All of this is in response to an upper-level trough situated along the western Alaska coast ejecting a series of shortwaves through the Gulf as it slowly moves across the mainland over the weekend. Confidence remains above average that conditions will remain wet and unsettled across southern Alaska through the weekend while under the influence of the long-wave trough. There is less confidence, however, in the timing of the mid-level shortwaves and associated surface features (and hence precipitation and wind along the coast) as the GFS and EC continue to disagree in their exact track through the Gulf. Guidance then goes completely off the rails moving into early next week with very low confidence in any solution overall. The main issue is with the upper-level solutions between the GFS and EC, specifically with the development of an upper-level low over eastern Russia and a shortwave tracking across the Aleutians. The EC is much faster in moving the Aleutian shortwave east and while suppressing the ridge over the the central and eastern Bering as it tracks well south of the AKPEN and shears apart by Tuesday in conjunction with the trailing upper level low now in the Bering. The GFS keeps the eastern Russia low in place on Monday allowing the Aleutian shortwave to intensify and move quickly into the Bering while pushing an amplified ridge over southwest Alaska. The shortwave then reaches the west coast by late Monday. A secondary low then develops south of the AKPEN and moves into the Gulf for mid-week. The GFS has had the better run to run consistency of the suite of long-term guidance and is favored over the EC. This would keep wet weather over the southern mainland through the weekend with a brief drying trend late Sunday through late Monday across the southwest and Monday through late Tuesday across Southcentral (especially the interior) before more wet weather returns. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...Dense Fog Advisory 101 121. MARINE...Gale Warnings 119 120 130 131 132 136 137 138 139 150 177 178 351 352 411. && $$ SYNOPSIS AND MODEL DISCUSSION...SEB/ALH SOUTHCENTRAL ALASKA...SEB SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PD LONG TERM...TM