FXAK68 PAFC 081257
AFDAFC

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
400 AM AKST TUE DEC 8 2009

.ANALYSIS AND UPPER LEVELS...
AN INCREDIBLY STRONG AREA OF HIGH PRESSURE AT THE CENTER OF A LARGE
SCALE OMEGA BLOCK IS CENTERED RIGHT OVER THE ANCHORAGE BOWL AND IS
LEADING TO EXTREMELY QUIET WEATHER FOR THE MAINLAND WITH LIGHT WINDS
AND CLEAR SKIES. VERY STRONG TEMPERATURES INVERSIONS ARE
PRESENT...WITH AS MUCH AS AROUND 50 DEGREE TEMPERATURE VARIATIONS
FROM RIDGETOP TO VALLEY FLOOR. TEMPERATURES AT 3000 TO 4000 FOOT
ELEVATION ARE RUNNING 45 TO 50 DEGREES F EARLY THIS MORNING...WITH
VALLEY TEMPERATURES RUNNING FROM ABOUT 5 BELOW TO 15 ABOVE ZERO. IT
IS EVEN ABOVE FREEZING ALL THE WAY UP TO 10000 FEET. SLIGHTLY WARMER
VALLEY TEMPS FROM BRISTOL BAY TO THE KUSKOKWIM DELTA WHERE A WEAK
PRESSURE GRADIENT IS STILL PRESENT PREVENTING COMPLETE DECOUPLING.
LOCALLY DENSE VALLEY FOG HAS SET UP OVER SOME AREAS...WITH GENERALLY
THE WORST FOG IN NORTHERN COOK INLET AND TURNAGAIN ARM.

OUT WEST...THE SEEMINGLY ENDLESS STRING OF STRONG LOW PRESSURE
SYSTEMS IS COMING TO AN END. WINDS ARE EASING FROM SOUTH TO NORTH
THIS MORNING AS THE LOW JUST NORTH OF ATTU MOVES TOWARD 
SIBERIA...AND FINALLY THERE ARE NO HIGH WIND WARNINGS IN EFFECT
ANYMORE. STILL THOUGH THERE IS BROAD UPPER LEVEL LOW PRESSURE OUT
WEST ON THE WEST LEG OF THE OMEGA BLOCK.

.MODEL DISCUSSION...
MODELS ARE IN GOOD AGREEMENT OVERALL. GFS HAS TRENDED TO THE ECMWF
REGARDING THE EVOLUTION OF INDIVIDUAL LOW CENTERS OUT IN THE
BERING/ALEUTIANS IN THE SHORT TERM. IN THE EXTENDED...ALL MODELS NOW
TAKE THE THRUST OF THE COLD AIR INTO BC AND SOUTHEAST ALASKA...AND
NOT INTO THE MAINLAND. INHERITED FORECASTS REFLECTED THIS
ALREADY...SO ONLY SMALL TWEAKS WERE MADE. 

.SHORT TERM FORECAST...
SOUTHERN MAINLAND...
AS MENTIONED ABOVE...STRONG HIGH PRESSURE IS PRESENT OVER THE
MAINLAND AND VERY LITTLE CHANGE IS EXPECTED THROUGH FRIDAY. MOSTLY
CLEAR SKIES AND STRONG INVERSIONS WILL CONTINUE WITH WARM
TEMPERATURES IN THE MOUNTAINS...COLD TEMPERATURES IN THE
VALLEYS...AND AREAS OF FOG IN THE VALLEYS. A SUBTLE CHANGE IS THAT
THE UPPER LEVEL HIGH CENTER WILL MOVE WEST SLIGHTLY THROUGH THE WEEK
FROM SOUTHCENTRAL TODAY TO THE KUSKOKWIM VALLEY FRIDAY. AS THIS
HAPPENS...A WEAK SURFACE TROUGH WILL DEVELOP ALONG THE NORTH GULF
COAST WHICH WILL HELP TO INCREASE LOCALIZED OFFSHORE WINDS A BIT.

BERING/ALEUTIANS...
A LOW JUST NORTH OF ATTU THIS MORNING WILL MOVE TOWARD SIBERIA AND
WEAKEN. THIS IS ALLOWING SOUTHERLY WINDS TO RAPIDLY DIMINISH ACROSS
THE REGION. HOWEVER...A COMPLEX LOW CENTERED IN THE NORTH PACIFIC
WILL GRADUALLY BE DRIVEN NORTH BY THE SOUTHEASTERLY UPPER LEVEL
JET...ALLOWING WINDS TO QUICKLY PICK BACK UP OVER THE REGION AND 
RAIN TO RETURN. HOWEVER...ONLY A FEW GALES ARE EXPECTED OVER THE 
NEXT FEW DAYS...A FAR CRY FROM WHAT THE BERING/ALEUTIAN REGION HAS
BEEN SEEING.

.LONG TERM FORECAST...
AS MENTIONED IN THE MODEL DISCUSSION...IT NOW APPEARS THAT THE MAIN
PUSH OF THE EXTREMELY COLD AIR OVER NORTHERN CANADA WILL GO INTO
SOUTHEAST ALASKA OVER THE WEEKEND AND EARLY NEXT WEEK...AND THE
MAINLAND WILL ONLY GET A GLANCING BLOW. HIGH PRESSURE WILL CONTINUE
TO MOVE WEST AND INTO THE BERING SEA FOR THE WEEKEND WITH TRANQUIL
WEATHER DEVELOPING THERE. OVER SOUTHCENTRAL FOR THE WEEKEND INTO
EARLY NEXT WEEK...IT LOOKS FAIRLY TRANQUIL AS WELL WITH PROBABLY 
JUST SOME SHOWERS RIGHT ALONG THE COAST AND SEASONABLY COLD
TEMPERATURES INLAND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE WARNING 155 165 170 171 172 179 185 411 412 413 414
FIRE WEATHER...NONE

FOISY DEC 09