Blizzard in Alaska, December 27, 2007

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM AST THU DEC 27 2007

.MODEL DISCUSSION...
MODELS ARE IN FAIR AGREEMENT. OVERALL WE WILL BE GOING WITH THE GFS
SOLUTION BECAUSE ITS IN BETTER AGREEMENT WITH THE OTHER HEMISPHERIC
MODELS THAN THE NAM. THE MODELS STILL HAVE A RUN-TO-RUN CONSISTENCY
ISSUE, SO CONFIDENCE IS MODERATE.

.ANALYSIS AND UPPER LEVELS...
UPPER AIR...
THE UPPER RIDGE ALONG SOUTHEAST ALASKA AND OVER EASTERN AND NORTHERN
ALASKA IS CONTINUING TO DRIFT EAST. THE UPPER LOW COMPLEX OVER THE
BERING SEA HAS NOT MOVED MUCH IN THE LAST 24 HOURS BUT THE UPPER
TROUGH CONTINUES TO DIG ACROSS BRISTOL BAY INTO THE GULF OF ALASKA.

AT SURFACE...
A MODERATE LOW NEAR KODIAK IS TAKING A MORE EASTERLY TRACK THAN
PROGGED WITH THE MAIN WEATHER FRONT REMAINING OVER THE GULF
STRETCHING EAST AND WEAKENING. MOST OF THE SHOWERS ASSOCIATED WITH
THIS SYSTEM WILL REMAIN OVER THE GULF AND THE ADJACENT COAST. A
WEAKER LOW OVER BRISTOL BAY CONTINUES TO WEAKEN. ANOTHER MODERATE LOW
OVER THE NORTHERN BERING SEA IS DRIFTING EAST. RADAR AND SATELLITE
LOOPS SHOW A BAROCLINIC AREA LINKING THE BRISTOL BAY LOW TO THE ONE
IN THE BERING SEA.

.SHORT TERM FORECAST...
SOUTH CENTRAL AND GULF...
THE LOW NEAR KODIAK ISLAND WILL MOVE INTO THE CENTRAL GULF FRIDAY
THEN DRIFT ONTO THE EASTERN GULF WITH A POSSIBLE WEAKER LOW
DEVELOPING OVER THE WESTERN GULF SATURDAY. MOST OF THE WEATHER
ASSOCIATED WITH THE LOW ALONG THE COAST THROUGH SATURDAY. AN UPPER
TROUGH OVER SOUTHWEST ALASKA WILL MOVE EAST THROUGH KODIAK ISLAND
LATE TONIGHT AND WILL WEAKEN OVER THE SUSITNA VALLEY FRIDAY NIGHT.
SNOW SHOWERS OVER KODIAK WILL END FRIDAY MORNING. SNOW SHOWERS WILL
DEVELOP OVER THE SUSITNA VALLEY AND COOK INLET FRIDAY. COLD AIR
ADVECTION INTO THE WESTERN GULF FRIDAY NIGHT AND SATURDAY WILL CREATE
STRONG NORTHWEST WINDS ESPECIALLY THE CHANNELED TERRAIN ALONG THE
ALEUTIAN RANGE AND KODIAK ISLAND SATURDAY.

SOUTHWEST ALASKA...
AN UPPER TROUGH OVER BRISTOL BAY AND THE KUSKOKWIM DELTA WILL MOVE
EAST AND CROSS OVER INTO SOUTH CENTRAL ALASKA FRIDAY. AN AREA OF SNOW
SHOWERS ALONG THE COAST WILL MOVE EAST THROUGH THE SOUTHWEST INTERIOR
TONIGHT AND FRIDAY. A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE AREA
FRIDAY NIGHT AND SATURDAY SHOULD CLEAR OUT CLOUDS OVER THE EASTERN
HALF OF THE REGION BUT VARIABLE CLOUDS WILL REMAIN ALONG THE COAST.

BERING SEA AND ALEUTIANS...
THE MAIN LOW PRESSURE SYSTEM OVER THE NORTHERN BERING SEA WILL MOVE
TO JUST WEST OF SAINT LAWRENCE ISLAND SATURDAY. A SYSTEM RIDING ALONG
THE CENTRAL ALEUTIANS WILL BRING SNOW AND BLOWING SNOW TO DROP
VISIBILITIES SIGNIFICANTLY...THEREFORE A BLIZZARD WARNING WILL BE
ISSUED FOR THAT PART OF THE CHAIN FOR TONIGHT. SCATTERED SNOW
SHOWERS WILL REMAIN OVER THE BERING THROUGH SATURDAY. ANOTHER LOW
PRESSURE SYSTEM 300 MILES SOUTH OF THE CENTRAL ALEUTIANS WILL MOVE
TO 150 MILES SOUTH OF THE EASTERN ALEUTIANS TONIGHT THEN CONTINUE
EASTWARD AND DISSIPATE OVER THE SOUTHWESTERN GULF FRIDAY NIGHT.

.LONG TERM FORECAST...
AN UPPER RIDGE DEVELOPING SOUTH OF THE AK PEN SATURDAY WILL MOVE INTO
THE GULF SUNDAY THEN TURN NORTHEAST TO LIE ALONG SOUTHEAST ALASKA AND
THE CENTRAL GULF COAST MONDAY. THE UPPER LOW OVER THE BERING SEA WILL
SLOWLY WEAKEN THEN DISSIPATE MONDAY.

AT THE SURFACE, THE AREA OF LOW PRESSURE OVER THE GULF SAT NIGHT WILL
WEAKEN AND BE PUSHED THE EAST AS THE SURFACE REFLECTION OF THE UPPER
RIDGE MOVES INTO THE GULF SUNDAY THEN INTO BRITISH COLUMBIA MONDAY. A
LARGE LOW PRESSURE SYSTEM DEVELOPS OVER THE NORTHEAST PACIFIC MONDAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING FOR THE CENTRAL ALEUTIANS
      ...COASTAL FLOOD ADVISORY FOR BRISTOL BAY.
MARINE...STORM 132
         GALE 120, 130, 138, 140, 150, 155, 160, 165, 170
FIRE WEATHER...NONE.

NM DEC 07