Small Craft Advisory 178, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM AKST SAT FEB 21 2009

.MODEL DISCUSSION...
MODELS ARE IN GOOD AGREEMENT THROUGH MONDAY NIGHT EXCEPT OVER THE
BERING SEA WHERE THE SOLUTIONS RAPIDLY DIVERGE AFTER SUNDAY NIGHT.
CONFIDENCE IN THE MODELS IS FAIRLY HIGH OVER MAIN LAND ALASKA THROUGH
THE SHORT TERM PERIOD. CONFIDENCE OVER THE BERING SEA IS HIGH THROUGH
SUNDAY NIGHT BUT BECOMES MODERATE MONDAY.

.ANALYSIS AND UPPER LEVELS...
THE UPPER RIDGE OVER WESTERN ALASKA CONTINUES TO BUILDS AS IT DRIFTS
EAST. AN STRONG SOUTHERLY JET IS BEGINNING TO MOVE INTO THE CENTRAL
BERING SEA.

AT THE SURFACE...HIGH PRESSURE OVER THE CENTRAL AND NORTHERN INTERIOR
HAS KEPT CENTRAL AND EASTERN ALASKA MOSTLY CLEAR. AREAS OF STRONG
NORTH WINDS BLOWING THROUGH CHANNELED TERRAIN ALONG THE CENTRAL GULF
COAST. A WEAKENING WEATHER FRONT OVER THE EASTERN BERING SEA IS
APPROACHING THE KUSKOKWIM DELTA COAST AND WESTERN BRISTOL BAY. GUSTY
WINDS AND AREAS OF BLOWING SNOW HAVE DEVELOPED ALONG THE DELTA COAST.

.SHORT TERM FORECAST...
UPPER AIR..THE UPPER RIDGE OVER WESTERN ALASKA WILL DRIFT INTO
EASTERN MAINLAND MONDAY AND WILL CONTINUE TO PROTECT SOUTHCENTRAL
ALASKA FROM ANY SIGNIFICANT WEATHER. THE SOUTHERLY JET WILL MOVE INTO
THE CENTRAL BERING TONIGHT THEN GRADUALLY DRIFT EASTWARD INTO THE
WEST COAST OF ALASKA BY MONDAY.

AT THE SURFACE...
SOUTHCENTRAL ALASKA...THE AREA OF HIGH PRESSURE WILL GRADUALLY WEAKEN
THROUGH MONDAY. GUSTY WINDS ALONG THE CENTRAL GULF COAST WILL SLOWLY
DIMINISH THROUGH TONIGHT AND SUNDAY.

SOUTHWEST ALASKA...THE WEAKENING WEATHER FRONT IS EXPECTED TO MOVE
INTO THE KUSKOKWIM DELTA THIS EVENING THEN DISSIPATE LATE TONIGHT.
MOST OF THE SNOW WILL NOT GO ANY FURTHER INLAND THAN THE WESTERN
KUSKOKWIM VALLEY AND WESTERN BRISTOL BAY. BLIZZARD CONDITIONS ALONG
THE DELTA COAST SHOULD IMPROVE BY EARLY EVENING AS WINDS BEGIN TO
DIMINISH. ANOTHER WEATHER FRONT IS EXPECTED TO MOVE ONTO THE COAST
SUNDAY NIGHT AND WEAKEN OVER THE SOUTHWEST INTERIOR MONDAY. MORE
GUSTY SOUTH WINDS AHEAD OF THE FRONT WILL DEVELOP ALONG THE COAST AND
PRODUCE AREAS OF BLOWING SNOW LATE SUNDAY. THE SNOW WITH THIS FRONT
WILL PENETRATE A LITTLE FURTHER EAST THAN THE PREVIOUS FRONT.

BERING SEA...A INTENSE LOW PRESSURE SYSTEM JUST EAST OF THE KAMCHATKA
PENINSULA WILL MOVE NORTH INTO THE RUSSIAN FAR EAST SUNDAY EVENING. A
LARGE AREA OF GALE FORCE WINDS OVER THE WESTERN BERING WILL MOVE INTO
THE CENTRAL BERING TONIGHT AND EASTERN BERING SUNDAY. A SECOND LOW
DEVELOPING OVER THE NORTHWEST PACIFIC SUNDAY WILL MOVE INTO THE
SOUTHERN BERING MONDAY. GALE FORCE TO POSSIBLE STORM FORCE WINDS WILL
MOVE INTO THE WESTERN ALEUTIANS SUNDAY NIGHT THEN SPREAD INTO THE
CENTRAL ALEUTIANS AND SOUTHERN BERING SEA MONDAY.

.LONG TERM FORECAST...
THE UPPER RIDGE BECOMES NEARLY STATIONARY ALONG THE ALCAN BORDER AND
WEAKENS A BIT TUESDAY AND WEDNESDAY. THE 300 MB JET ALONG THE WEST
COAST WILL WEAKEN A BIT AS IT MOVES INTO THE CENTRAL MAINLAND.
WEDNESDAY. THIS CHANGE IN THE PATTERN WILL ALLOW CLOUDS AND WEATHER
TO SPREAD INTO SOUTHCENTRAL ALASKA FROM THE WEST.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING FOR THE KUSKOKWIM DELTA COAST THROUGH THIS
EVENING.
MARINE...STORM 175, 176
         GALE 172, 180, 185
FIRE WEATHER...NONE.

NM FEB 09