Brisk Wind Advisory 19, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM AKST WED FEB 4 2009

.MODEL DISCUSSION...
MODELS BECOME PROBLEMATIC OVER THE GULF AND BERING SEA BY FRIDAY
AFTERNOON. IN THE GULF, THE GFS AND ECMWF ARE IN GOOD AGREEMENT IN
POSITION OF THE LOW MOVING TOWARD THE GULF FRIDAY NIGHT BUT THE GFS
TENDS TO BE 10 TO 12 MB DEEPER THAN AN OF THE OTHER MODELS. IN THE
BERING SEA, THE MODELS ARE INTO GOOD AGREEMENT WITH THE STRENGTH OF
THE LOW, BUT GFS MOVES THE SYSTEM INTO SEWARD PENINSULA WHILE THE
ECMWF KEEPS IT NEAR NUNIVAK ISLAND FRIDAY AFTERNOON. WE HAVE DECIDED
TO STICK WITH THE GFS SOLUTION SINCE IT IS SIMILAR TO THE HPC
GUIDANCE BUT WILL TONE DOWN THE STRENGTH OF THE GULF LOW BY ABOUT 10
MB FRIDAY AND FRIDAY NIGHT.

.ANALYSIS AND UPPER LEVELS...
A LOW OVER THE WESTERN GULF CONTINUES TO MOVE EAST. EASTERLY FLOW
ACROSS PRINCE WILLIAM SOUND AND THE KENAI PENINSULA PRODUCED AREAS OF
SNOW ALONG THE CENTRAL GULF COAST, WESTERN SOUTHCENTRAL. THE BERING
SEA LOW CONTINUES TO MOVE EAST WITH THE WEATHER FRONT OVER THE
SOUTHEAST BERING AND ALASKA PENINSULA.

THE MAIN UPPER LOW OVER THE NORTHERN BERING HAS STRENGTHENED A BIT
OVERNIGHT BUT HAS NOT MOVED MUCH IN THE LAST 24 HOURS. OTHERWISE,
WEST TO SOUTHWEST FLOW CONTINUES OVER THE SOUTHERN BERING AND MOST OF
MAINLAND ALASKA TODAY.

.SHORT TERM FORECAST...
THE WEAK LOW IN THE WESTERN GULF WILL CONTINUE TO MOVE EAST AND
DISSIPATE OVER THE EASTERN GULF BY THURSDAY MORNING. SNOW ALONG THE
CENTRAL GULF COAST, KODIAK ISLAND AND THE SUSITNA VALLEY WILL BECOME
SNOW SHOWERS TONIGHT. THE WEATHER FRONT OVER THE BERING SEA WILL MOVE
INTO THE SUSITNA VALLEY AND KENAI PENINSULA BY THURSDAY AFTERNOON
THEN DISSIPATE OVER THE COPPER RIVER BASIN LATE THURSDAY NIGHT OR
EARLY FRIDAY MORNING. MORE SNOW IS EXPECTED OVER SOUTHCENTRAL WITH
THIS FRONT. THE NEXT LOW MOVING TOWARD THE GULF FRIDAY WILL STRONGER
WINDS INTO THE GULF THAN ORIGINALLY FORECAST. MOST OF THE SNOW
ASSOCIATED WITH THIS SYSTEM WILL GO INTO PRINCE WILLIAM SOUND AND THE
COPPER RIVER BASIN THOUGH SOME SNOW MAY FALL OVER ANCHORAGE AND THE
MATANUSKA AND SUSITNA VALLEYS.

OUT OVER THE WESTERN DOMAIN, THE FRONT OVER THE EASTERN BERING SEA
WILL MOVE INTO THE DELTA COAST AND BRISTOL BAY TONIGHT THEN CROSS
OVER THE ALEUTIAN RANGE INTO SOUTHCENTRAL ALASKA THURSDAY AFTERNOON.
SNOW WILL CONTINUE OVER MOST OF THE SOUTHWEST MAINLAND TONIGHT AND
BECOME SNOW SHOWERS BEHIND THE FRONT THURSDAY. THE EVOLUTION OF THE
LOW PRESSURE SYSTEM STILL REMAIN IN DOUBT, WILL PROBABLY END UP AS A
COMPLEX LOW WITH ONE CENTER OVER THE SEWARD PENINSULA AND THE OTHER
NEAR NUNIVAK ISLAND FRIDAY AFTERNOON. UNDER THIS CONFIGURATION,
NORTHERLY FLOW WILL RETURN TO THE BERING BY FRIDAY.

.LONG TERM FORECAST...
MODEL INDICATE THAT THE LOW OVER THE CENTRAL GULF FRIDAY NIGHT WILL
CONTINUE NORTHEAST INTO THE YUKON TERRITORY SATURDAY NIGHT, BUT WILL
LEAVE A RESIDUAL LOW OVER THE NORTHERN GULF THROUGH SUNDAY. COLD AIR
MOVING INTO SOUTHWEST ALASKA FRIDAY NIGHT AND INTO THE WESTERN GULF
SATURDAY WILL PRODUCE STRONG GAP WINDS ALONG THE ALEUTIAN RANGE
SATURDAY AND SATURDAY NIGHT. ANOTHER STRONG STORM SYSTEM DEVELOPING
OVER THE NORTHWEST PACIFIC WILL FRIDAY IS EXPECTED TO MOVE NORTHEAST
AND BECOME NEARLY STATIONARY SOUTH OF THE WESTERN ALEUTIANS SUNDAY.
GALE TO POSSIBLE STORM FORCE WINDS WILL MOVE INTO THE CENTRAL AND
WESTERN ALEUTIANS SATURDAY AND MOVE INTO THE SOUTHERN BERING AND
EASTERN ALEUTIANS SUNDAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 155, 160, 165, 170, 171, 172, 175, 176, 179, 185
FIRE WEATHER...NONE.

NM FEB 09