FXAK68 PAFC 012348
AFDAFC

AREA FORECAST DISCUSSION 
SOUTHCENTRAL AND SOUTHWEST ALASKA
300 PM AKST TUE DEC 1 2009

.MODEL DISCUSSION...MODELS ARE DOING WELL IN THE SHORT TERM WITH A
SLIGHT FAVORING TOWARD THE NAM IN THE EASTERN PART OF THE AREA.
MODELS HOLD TOGETHER WELL IN THE EAST WITH A RIDGE BUILDING IN LATER
IN THE WEEK BUT ARE STRUGGLING WITH A STRONG LOW THAT WILL MOVE INTO
THE ALEUTIANS THURSDAY AND FRIDAY. IT IS A STRONG FEATURE ON ALL THE
MODELS BY WEDNESDAY NIGHT BUT THEY VARY IN LOCATION OF THE MAIN
CENTER BY ALMOST 700 MILES DIFFER IN PRESSURE BY NEARLY 20 MB AT THAT
TIME.

.ANALYSIS AND UPPER LEVELS...THE DEEP UPPER LEVEL TROUGH EXTENDS OVER
THE ENTIRE WESTERN COAST OF THE STATE WITH THE LOW CENTERED OVER THE
ALASKA PENINSULA. A STRENGTHENING UPPER LEVEL HIGH IS OVER SOUTHEAST
ALASKA WITH A BRANCH OF THE JET STREAM BETWEEN THEM BRINGING STRONG
DUE SOUTH WINDS OVER MOST OF THE MAINLAND PART OF THE STATE. THE MAIN
JET EXITS ASIA OVER JAPAN AND HEADS DUE EAST UNTIL IT STARTS TO BEND
NORTHWARD BETWEEN THE 150W AND 170W MERIDIANS...AND WEAKENS FRO ITS
PEAK AS IT REACHES THE GULF OF ALASKA. THE JET STREAM LOCATION OVER
THE STATE IS SEEN CLEAREST IN THE IR SATELLITE IMAGES.

.SHORT TERM FORECAST...WHILE THE STORM IS WEAKENING THERE IS STILL A
LOT OF WEATHER IN THE SHORT TERM. THE PARENT LOW OVER THE ALASKA
PENINSULA IS BRINGING SOME INTENSE SNOW SHOWERS TO NEARBY AREAS. THE
ENTIRE BERING SEA REGION IS IN NORTH TO WEST FLOW AND COLD AIR
ADVECTION.
SOUTH CENTRAL ALASKA HAS SEEN A LOT OF AREA NEAR SEA LEVEL WITH RAIN
BUT THAT SHOULD BE TURNING BACK TO SNOW OVERNIGHT AS THE WARM AIR
MOVES EASTWARD AND COLDER AIR FILTERS BACK INTO THE AREA. MOUNTAIN
PASSES WILL REMAIN HAZARDOUS IN SNOW AND DRIFTING SNOW. 

.LONG TERM FORECAST...WHILE THE HEMISPHERIC LONG WAVE PATTERN WILL
NOT CHANGE MUCH OVER THE COURSE OF THE WEEK THE RETROGRESSION OF THE
ALEUTIAN LOW AND BUILDING OF THE UPPER LEVEL RIDGE ALONG THE ALCAN
BORDER WILL CAUSE A CHANGE IN THE WEATHER OF MOST OF THE AREA. THIS
WARM CORE RIDGE WILL REDUCE CLOUD COVER OVER THE EASTERN  YET THE
WARMER TEMPERATURES ALOFT WILL LIMIT HOW COLD IT WILL GET AT NIGHT.
THIS SHIFT WILL ALSO PUT THE BERING SEA IN THE CROSS HAIRS OF THE
STORM TRACK FROM THE DUE SOUTH.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...WINTER STORM WARNING 145.
MARINE...STORM 120 125.
         GALE 129 132 165.
         HEAVY FREEZING SPRAY 179 180 185.
FIRE WEATHER...NONE.

DEC 09