Blizzard Watch 38, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM AKST FRI DEC 18 2009

.ANALYSIS AND UPPER LEVELS...
UPPER LEVELS...A UPPER LOW OVER THE LOWER YUKON VALLEY EXTENDS A
TROUGH SOUTHEASTWARD THROUGH THE KUSKOKWIM VALLEY, SUSITNA VALLEY AND
PRINCE WILLIAM SOUND. ANOTHER LOW OVER THE WESTERN ALEUTIANS EXTENDS
A TROUGH ACROSS THE SOUTHERN BERING SEA.
AT THE SURFACE...AN AREA OF HIGH PRESSURE OVER SOUTHWEST ALASKA AND
THE WESTERN GULF CONTINUES TO MOVE EAST. A STRONG 964 MB LOW IS
VERTICALLY STACK BENEATH THE UPPER LOW. AN OCCLUDED FRONT LIES ACROSS
THE SOUTHERN BERING SEA AND ACROSS THE ALASKA PENINSULA. A WEAK LOW
JUST SOUTH OF PRINCE WILLIAM SOUND WILL DISSIPATE THIS EVENING.

.MODEL DISCUSSION...
THE MODELS ARE IN GENERALLY GOOD AGREEMENT, THOUGH THE NAM DOES A
BETTER JOB IN THE FINE-SCALE FEATURES AROUND SOUTH-CENTRAL ALASKA.

.SHORT TERM FORECAST...
UPPER LEVELS...THE LOW OVER WESTERN ALASKA WILL MOVE INTO THE
NORTHERN BERING SEA SATURDAY THEN MOVE INTO SIBERIA SUNDAY. THE
ASSOCIATED TROUGH OVER SOUTHERN ALASKA WILL SWING NORTH INTO THE
NORTHERN INTERIOR SATURDAY AND INTO THE BEAUFORT SEA SUNDAY. A RIDGE
DEVELOPING OVER THE GULF OF ALASKA TONIGHT WILL CONTINUE TO BUILD
INTO THE EASTERN MAINLAND THROUGH SUNDAY. A STRONG SOUTHERLY FLOW
WILL DEVELOP OVER THE WESTERN MAINLAND OVER THE WEEKEND.

SOUTH-CENTRAL ALASKA AND THE GULF OF ALASKA...
A WEATHER FRONT WILL OVER THE BERING SEA WILL MOVE INTO KODIAK ISLAND
AND THE WESTERN GULF SATURDAY MORNING THEN WILL WEAKEN AS IT MOVES
INTO PRINCE WILLIAM SOUND AND THE EASTERN GULF SATURDAY NIGHT THEN
WILL DISSIPATE SUNDAY. AREA OF SNOW MAINLY ASSOCIATED WITH THE FRONT
WILL MOVE THROUGH KODIAK ISLAND TONIGHT AND MOVE INTO THE CENTRAL
GULF COAST, KENAI PENINSULA AND SUSITNA VALLEY SATURDAY THROUGH
SUNDAY.

SOUTHWEST ALASKA...THE WEATHER FRONT OVER THE BERING WILL MOVE
THROUGH SOUTHWEST ALASKA TONIGHT AND SATURDAY. AREAS OF SNOW AHEAD OF
THE FRONT WILL BECOME SCATTERED SNOW SHOWERS BEHIND IT. ANOTHER
WEATHER FRONT WILL MOVE INTO THE AREA LATE SATURDAY NIGHT AND SUNDAY.
MORE SNOW IS ALSO EXPECTED WITH THE FRONT.

BERING SEA AND ALEUTIANS...
THE SURFACE LOW OVER THE WESTERN ALEUTIANS WILL REMAIN NEARLY
STATIONARY THROUGH SUNDAY. THE WEATHER FRONT OVER THE SOUTHEAST
BERING WILL MOVE INTO SOUTHWEST ALASKA EARLY SATURDAY. A DEVELOPING
LOW SOUTH OF THE WESTERN ALEUTIANS WILL MOVE INTO THE SOUTHEAST
BERING SEA LATE SATURDAY AND WILL MOVE INTO THE NORTHERN BERING
SUNDAY.

.LONG TERM FORECAST...
THE UPPER RIDGE WILL REMAIN OVER THE EASTERN MAINLAND AND AN UPPER
LOW PRESSURE WILL REMAIN OVER THE WESTERN BERING THROUGH TUESDAY.
STRONG SOUTHERLY FLOW WILL REMAIN OVER WESTERN ALASKA INTO THE FIRST
HALF OF THE WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 120 130 132 150 155 160 165 170 172 175 176
FIRE WEATHER...NONE.

NM DEC 09