FXAK68 PAFC 071258
AFDAFC

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKST MON DEC 7 2009

.ANALYSIS AND UPPER LEVELS...
MASSIVE OMEGA BLOCK OVER THE REGION...WITH THE CENTER OF THE OMEGA
BLOCK BEING A STRONG AREA OF BOTH UPPER LEVEL AND SURFACE HIGH
PRESSURE CENTERED OVER SOUTHCENTRAL. LOOKING AT STANDARDIZED
ANOMALIES...500 MB HEIGHTS ARE 3.5 STANDARD DEVIATIONS ABOVE NORMAL
(THAT'S A LOT)...WITH UNUSUALLY WARM AIR ALOFT. THE HIGHER 
ELEVATIONS ARE BAKING OVER THE MAINLAND...CASE IN POINT SUNBURST
WEATHER STATION AT 4000 FEET ELEVATION IN THE MOUNTAINS ABOVE
TURNAGAIN PASS...WHICH IS 41 DEGREES F EARLY THIS MORNING. ALSO VERY
DRY AIR ALOFT WITH RELATIVE HUMIDITY AROUND 10 PERCENT AT SUNBURST
AND MOST OTHER HIGHER ELEVATIONS OF THE SOUTHERN MAINLAND. IN OTHER
WORDS...NO PRECIPITATION EXPECTED. VALLEY INVERSIONS ARE
STRENGTHENING AS THE HIGH PRESSURE BECOMES MORE FIRMLY ENTRENCHED. 

ON THE WEST LEG OF THE OMEGA BLOCK IS A FAIRLY STRONG LOW JUST SOUTH
OF ATKA THIS MORNING...WITH THE STRONGEST WINDS ON THE EAST SIDE OF
THE LOW OVER THE EASTERN BERING/ALEUTIANS.

.MODEL DISCUSSION...
MODELS ARE DOING WELL IN THE IMMEDIATE SHORT TERM...BUT DETAILS IN
THE FORECAST FALL APART OUT WEST BEGINNING AROUND WEDNESDAY 
REGARDING THE EVOLUTION OF INDIVIDUAL SURFACE LOWS AROUND THE 
OVERALL UPPER LEVEL LOW CIRCULATION ENCOMPASSING THE NORTHERN
PACIFIC/SOUTHERN BERING. HOWEVER...NONE OF THESE SYSTEMS WILL BE
NEARLY AS STRONG AS THE RECENT SYSTEMS SO THE MODEL DISAGREEMENT IS
NOT A HUGE DEAL.

FOR NEXT WEEKEND...SOME DISAGREEMENT REGARDING A POTENTIAL MAJOR 
COLD OUTBREAK. GFS BRINGS EXTREMELY COLD AIR INTO THE MAINLAND WHILE
THE ECMWF SENDS THE THRUST OF MOST OF THE COLD AIR TO OUR EAST INTO
BC AND SOUTHEAST ALASKA. HONESTLY...NOT SURE WHICH MODEL TO TRUST SO
PLAYED IT CONSERVATIVELY FOR NOW.

.SHORT TERM FORECAST...
SOUTHERN MAINLAND...
SEVERE CLEAR OVER THE MAINLAND THROUGH THE WHOLE WORKWEEK WITH HIGH
PRESSURE PARKED OVERHEAD. STRONG INVERSIONS WILL PERSIST WITH
SEASONABLY COLD TEMPERATURES IN THE VALLEYS...BUT DOWNRIGHT MILD
TEMPERATURES OVER HIGHER ELEVATIONS. THE MILD AIR WILL HAVE THE BEST
CHANCE TO MIX DOWN TO THE SURFACE IN WINDIER AREAS. THIS INCLUDES
AREAS ALONG THE NORTH GULF COAST WHICH WILL HAVE LOCAL OFFSHORE 
WINDS SUCH AS WHITTIER SEWARD AND VALDEZ. IT IS ALSO QUITE MILD 
TODAY OVER BRISTOL BAY AND THE KUSKOKWIM DELTA WHERE DOWNSLOPE
EASTERLY WINDS ARE STILL BLOWING ON THE WEST SIDE OF THE HIGH
PRESSURE. THESE WINDS WILL EASE AS THE HIGH STRENGTHENS. BETHEL'S 
AND KING SALMON'S SNOW DEPTH IS ACTUALLY DOWN TO A TRACE NOW WITH 
ALL THE MILD WEATHER LATELY. SOME LOW LYING FOG DEVELOPING THIS
MORNING...AND WILL NEED TO KEEP AN EYE ON THIS IN THE UPCOMING DAYS.

BERING/ALEUTIANS...
LOW PRESSURE SOUTH OF ATKA THIS MORNING WILL CROSS NEAR ATKA AND 
MOVE INTO THE BERING LATER TODAY...THEN BE ABSORBED INTO ANOTHER LOW
TONIGHT DEVELOPING A BIT NORTH OF ATTU. STRONGEST WINDS WILL 
CONTINUE TO BE WELL EAST OF THE LOW...WITH HIGH WIND WARNINGS FOR 
THE EASTERN ALEUTIANS AND THE PRIBILOFS ASSOCIATED WITH THE TAIL END
OF THE TROUGH MOVING NORTH THROUGH DUTCH AND THE PRIBILOFS LATER
TODAY. AFTER THIS...SOMEWHAT UNSETTLED WEATHER WILL PERSIST FOR THE
SOUTHERN AND WESTERN HALF OF THE REGION...BUT NOT AS UNSETTLED AS IT
HAS BEEN.

.LONG TERM FORECAST...
TOWARD NEXT WEEKEND THE UPPER LEVEL HIGH OVER THE MAINLAND SHOULD
RETROGRADE INTO THE BERING...AND COLDER AIR SHOULD MOVE INTO THE
MAINLAND. JUST HOW COLD IT GETS IS THE QUESTION WITH THE GFS BEING A
LOT COLDER THAN THE ECMWF. IT STILL LOOKS GENERALLY DRY IN THE
EXTENDED EXCEPT MAYBE NEAR THE GULF COAST.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING ZONE 185 195
MARINE...STORM WARNING ZONES 155 160 165 170 171 172 179 180 185 412 
           413 414
         GALE WARNING ZONES 150 175 176 411
FIRE WEATHER...NONE

FOISY DEC 09