Blizzard in Alaska, December 31, 2010

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 PM AKST THU DEC 30 2010

.MODEL DISCUSSION...
MODELS ARE IN GOOD AGREEMENT THROUGH SATURDAY NIGHT. NAM DOES A
SLIGHTLY BETTER JOB ON THE WINDS OVER THE MAINLAND AND ALONG THE
COAST AND THE GFS IS ACCEPTABLE OVER THE GULF AND BERING SEA.

.ANALYSIS AND UPPER LEVELS...
.UPPER LEVELS...THE UPPER RIDGE OVER THE EASTERN GULF AND WESTERN
CANADA CONTINUES TO MOVE EAST. THE MAIN UPPER LOW OVER THE NORTHERN
BERING IS SLOWLY DRIFTING SOUTH. THE SOUTH TO SOUTHWEST FLOW FORMED
BY THIS PATTERN HAS MOVED A WARM, MOIST MARINE AIRMASS INTO THE
SOUTHERN MAINLAND. A SHORT-WAVE TROUGH OVER THE SOUTHEASTERN BERING
AND THE ALASKA PENINSULA IS MOVING IS PIVOTING NORTHEAST AROUND THE
UPPER LOW.

.AT THE SURFACE...THE WARM FRONT OVER THE GULF OF ALASKA MOVED ONTO
THE CENTRAL GULF COAST THEN DISSIPATE THIS MORNING. A MODERATE LOW
DEVELOPED SOUTH OF KODIAK ISLAND THIS MORNING AND IS CURRENTLY MOVING
NORTH. ANOTHER LOW NEAR DUTCH HARBOR HAS BECOME NEARLY STATIONARY AND
CONTINUES TO WEAKEN THROUGH TODAY. AREAS OF SNOW HAD DEVELOPED
OVERNIGHT ALONG THE CENTRAL GULF COAST, THE KENAI PENINSULA AND
ANCHORAGE BUT THESE CHANGED TO SHOWERS BY EARLY MORNING. SNOW
CONTINUES TO FALL OVER THE SUSITNA VALLEY WHILE RAIN AND SNOW FALLS
OVER THE EASTERN KENAI PENINSULA. THE OCCLUDED FRONT OVER BRISTOL
WEDNESDAY DISSIPATED OVER SOUTHWEST ALASKA WEDNESDAY NIGHT.

.SHORT TERM FORECAST...
THE UPPER LOW WILL BECOME NEARLY STATIONARY OVER THE CENTRAL BERING
FRIDAY. THE UPPER RIDGE WILL REMAIN OVER WESTERN CANADA THROUGH
SATURDAY. THIS WILL KEEP A SOUTH TO SOUTHWEST FLOW OVER THE SOUTHERN
MAINLAND. THE UPPER SHORT-WAVE TROUGH WILL MOVE INTO THE KUSKOKWIM
DELTA, BRISTOL BAY AND KODIAK ISLAND TONIGHT THEN THROUGH
SOUTHCENTRAL ALASKA FRIDAY.

SOUTHCENTRAL ALASKA...THE SURFACE SOUTH OF KODIAK ISLAND WILL MOVE
NORTH INTO THE KENAI PENINSULA TONIGHT THEN DISSIPATE OVER CENTRAL
INTERIOR FRIDAY EVENING. MORE RAIN AND SNOW WILL DEVELOP ALONG THE
CENTRAL GULF COAST AND KENAI PENINSULA THIS EVENING. THE SNOW OVER
THE SUSITNA VALLEY WILL INTENSIFY TONIGHT AND SATURDAY WITH HIGHEST
ACCUMULATIONS EXPECTED ALONG THE WEST SIDE OF THE VALLEY. THE
PRECIPITATION WILL BECOME SHOWERS FRIDAY NIGHT BUT RAIN AND  SNOW
WILL REDEVELOP ALONG THE GULF COAST AS THE SOUTHERLY FLOW STRENGTHEN
AGAIN OVER THE GULF.

SOUTHWEST ALASKA...AREAS OF SNOW WILL DEVELOP OVER BRISTOL BAY AND
THE LOWER KUSKOKWIM VALLEY TONIGHT AND EARLY FRIDAY. MORE SNOW IS
EXPECTED FRIDAY NIGHT AND SATURDAY AS A LOW PRESSURE SYSTEM NEAR
DUTCH HARBOR FRIDAY EVENING MOVES INTO THE KUSKOKWIM DELTA COAST
SATURDAY. GUSTY EAST TO SOUTHEAST WINDS WILL ALSO DEVELOP OVER THE
REGION SATURDAY AND PRODUCE AREAS OF BLOWING SNOW.

BERING SEA...NORTH TO NORTHEAST FLOW WILL CONTINUE OVER THE CENTRAL
AND WESTERN BERING THROUGH SATURDAY. A LOW SOUTH OF THE CENTRAL
ALEUTIANS WILL CURVE NORTH ACROSS THE EASTERN ALEUTIANS FRIDAY
EVENING AND MOVE ONTO THE DELTA COAST SATURDAY. RAIN WILL MOVE INTO
THE EASTERN ALEUTIANS AND THE ALASKA PENINSULA FRIDAY AND FRIDAY
NIGHT THEN BECOME SHOWERS SATURDAY.

.LONG TERM FORECAST...
THE OVERALL UPPER LEVEL PATTERN DOES NOT CHANGE MUCH INTO THE
BEGINNING OF NEXT WEEK, SO THE WETTER WARMER WEATHER WILL PERSIST.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HEAVY SNOW WARNING FOR SUSITNA VALLEY.
MARINE...GALE 120 125 127 128 129 130 132 138 150 185
FIRE WEATHER...NONE.

NM DEC 10