000 FXAK68 PAFC 042159 AFDAFC AREA FORECAST DISCUSSION SOUTHCENTRAL AND SOUTHWEST ALASKA 1255 PM AKST THU DEC 4 2008 .ANALYSIS AND UPPER LEVELS...THERE ARE NOW TWO VERTICALLY STACKED LOWS EMBEDDED WITHIN A HIGH AMPLITUDE TROUGH CENTERED OVER THE BERING SEA/NORTH PACIFIC. ONE IS CENTERED SOUTH OF THE EASTERN ALEUTIANS AND THE OTHER IS JUST NORTH OF THE PRIBILOF ISLANDS. THERE IS VERY LITTLE MOVEMENT RIGHT NOW...BUT THESE LOWS WILL BEGIN TO FUJIWARA WITH THE PACIFIC LOW TRACKING NORTHEASTWARD AND THE BERING LOW DROPPING SOUTHWESTWARD. A HIGH AMPLITUDE RIDGE EXTENDS ACROSS THE NORTHEAST PACIFIC UP TOWARD BRITISH COLUMBIA. THE UPPER JET HAS NOW SLID EAST OF SOUTHCENTRAL AND IS POINTED TOWARD SOUTHEAST ALASKA. WHAT IS LEFT BEHIND ARE WEAK UPPER WAVES ROTATING AROUND THE WESTERN TROUGH NORTHWARD ACROSS MAINLAND ALASKA AND THE EASTERN BERING SEA. ONE UPPER WAVE IS CURRENTLY EXITING THE COPPER BASIN. SNOWFALL CONTINUES ACROSS MUCH OF THE BASIN...ENHANCED BY UPSLOPE FLOW ALONG THE ALASKA RANGE. A WINTER WEATHER ADVISORY FOR SNOW IS IN EFFECT FOR THIS AREA THROUGH 4 PM AND IT LOOKS LIKE WE WILL BE ABLE TO LET THAT EXPIRE ON SCHEDULE. ALSO OF NOTE...THE ARCTIC FRONT HAS PUSHED NORTHWEST ACROSS SOUTHWEST ALASKA TO THE KUSKOKWIM MOUNTAINS. WARM AIR CONTINUES TO ADVECT NORTHWARD ACROSS THE SOUTHERN MAINLAND. MOST COASTAL AREAS HAVE CHANGED TO ALL RAIN...BUT INLAND LOCATIONS ARE STILL ALL SNOW. 00Z SOUNDING FROM THIS AFTERNOON WILL BE KEY IN DETERMINING HOW MUCH THE ATMOSPHERE HAS WARMED AND WHAT THE POTENTIAL FOR FREEZING RAIN WILL BE OVER INLAND LOCATIONS. FINALLY...GALE TO STORM FORCE NORTHERLIES CONTINUE WEST OF THE UPPER TROUGH OVER THE CENTRAL TO WESTERN BERING SEA. AIR TEMPERATURES HAVE STEADILY DROPPED THE PAST 24 HOURS (BUOY 46035 IS DOWN TO 30 DEGREES) AND FREEZING SPRAY IS EXTENDING SOUTHWARD ACROSS THE NORTHERN BERING SEA. .MODEL DISCUSSION...12Z MODELS INITIALIZED WELL AND ARE IN VERY GOOD AGREEMENT THROUGH THE SHORT-TERM PERIOD. WILL FINE-TUNE CURRENT FORECAST WITH NO MAJOR CHANGES. GFS AND ECMWF HAVE ALSO CONVERGED ON A SOLUTION WITH MAJOR LOW MOVING INTO GULF MONDAY...SO WILL TREND TOWARD THAT SOLUTION. .SHORT TERM FORECAST... SOUTHERN MAINLAND/ALASKA PENINSULA...WEAK WAVES WILL CONTINUE TO ROTATE ACROSS THE SOUTHERN MAINLAND...ALASKA PENINSULA...AND EASTERN BERING TONIGHT INTO FRIDAY. CHARACTER OF PRECIPITATION WILL PREDOMINANTLY BE SHOWERY. HOWEVER...UPSLOPE AREAS AND INLAND VALLEYS WHERE OVERRUNNING DOMINATES WILL SEE STEADIER PRECIPITATION AS THESE WAVES MOVE THROUGH. PRECIPITATION WILL GENERALLY BE LIGHT AND SHORT-LIVED. HOWEVER...AS MENTIONED ABOVE THERE IS A THREAT FOR FREEZING RAIN ACROSS MUCH OF INTERIOR SOUTHERN ALASKA THIS AFTERNOON THROUGH TONIGHT. WILL NEED TO LOOK AT 00Z SOUNDINGS BEFORE MAKING A FINAL DECISION...BUT FOR NOW SINCE DON`T EXPECT WIDESPREAD OR STEADY PRECIPITATION PLAN TO DOWNPLAY THE THREAT AND FORECAST A CHANCE OF FREEZING RAIN OR ISOLATED AREAS OF FREEZING RAIN. AS THE LOW SOUTH OF THE ALEUTIANS (AND UPPER TROUGH AXIS) MOVE TOWARD KODIAK ISLAND FRIDAY AND SATURDAY...STEADIER PRECIPITATION WILL SPREAD NORTHWARD ACROSS THE GULF AND THEN DIMINISH AS IT MOVES INLAND OVER SOUTHCENTRAL AND SOUTHWEST ALASKA. THIS LOW WILL QUICKLY WEAKEN OVER THE GULF SUNDAY WHILE A RIDGE BUILDS FROM THE WESTERN BERING TOWARD NORTHWEST ALASKA...HELPING TO GRADUALLY END PRECIPITATION AND ADVECT COLDER AIR BACK ACROSS THE REGION SATURDAY NIGHT THROUGH SUNDAY NIGHT. BERING SEA/ALEUTIANS...AS THE LOW NEAR THE PRIBILOF ISLANDS DROPS SOUTHWARD TONIGHT THROUGH FRIDAY NIGHT AN ALREADY TIGHT PRESSURE GRADIENT WILL TIGHTEN FURTHER ON THE WEST SIDE OF THE LOW. THEREFORE...EXPECT SOLID STORM FORCE WINDS CAN BE EXPECTED FROM THE NORTH CENTRAL BERING SOUTHWARD TO THE VICINITY OF ADAK. TEMPERATURES WILL CONTINUE TO COOL ACROSS THE CENTRAL TO WESTERN BERING AND FREEZING SPRAY WILL SPREAD SOUTHWARD. AFTER THIS LOW DROPS SOUTH OF THE ALEUTIAN CHAIN FRIDAY NIGHT WINDS WILL GRADUALLY DIMINISH THROUGH SATURDAY NIGHT. A GALE FORCE FRONT WILL MOVE INTO THE WESTERN ALEUTIANS SUNDAY AND THEN WEAKEN AS IT TRACKS EASTWARD. ALL IN ALL ITS LOOKING LIKE A FAIRLY CALM PERIOD ACROSS THE BERING SEA AND ALEUTIANS. .LONG TERM FORECAST...CONFIDENCE IS SLOWLY BUILDING FOR THE EXTENDED FORECAST PERIOD. A MEAN RIDGE WILL SET UP FROM THE WESTERN BERING TO NORTHERN ALASKA WITH A MEAN TROUGH OVER THE GULF. THUS...ITS LOOKING LIKE AN EXTENDED CALM PERIOD OVER THE BERING SEA/ALEUTIANS AND MAINLY DRY AND COLD OVER MAINLAND ALASKA WITH PERHAPS SOME PRECIPITATION ALONG THE GULF COAST. MODELS ARE NOW INDICATING A BLOCKING RIDGE SETTING UP OVER THE BERING THE END OF NEXT WEEK...WHICH WOULD RESULT IN STRONG COLD ADVECTION ACROSS MAINLAND ALASKA ALONG WITH STRONG NORTHERLY WINDS IN THE USUAL LOCATIONS. .AER/ALU...WATCH/WARNING SUMMARY PUBLIC...NONE. MARINE...STORM WARNING...172 175. GALE WARNING...176 185. HEAVY FREEZING SPRAY WARNING...185. FIRE WEATHER...NONE. SEB DEC 08