Brisk Wind Advisory 15, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
1250 PM AST WED FEB 27 2008

.ANALYSIS AND UPPER LEVELS...REX BLOCK IN PLACE WITH CUT-OFF HIGH
CENTERED OVER EASTERN SIBERIA/CHUKCHI SEA AND A LARGE CLOSED LOW
TO THE SOUTH FROM THE EASTERN BERING TO THE NORTH PACIFIC. ANOTHER
LARGE CLOSED LOW IS CENTERED JUST SOUTH OF THE KAMCHATKA PENINSULA.
THERE ARE MULTIPLE SURFACE LOWS EMBEDDED WITHIN THE EASTERN BERING
TO NORTH PACIFIC CIRCULATION. THE FIRST IS OVER THE SOUTHERN BERING
TRACKING SOUTHWESTWARD. BASED ON OBSERVATIONS AT BUOYS 46035 AND
46073 THE LOW IS A LITTLE STRONGER THAN MODELS INDICATE. A LOW SOUTH
OF THE EASTERN ALEUTIANS IS NEARLY STATIONARY UNDERNEATH THE UPPER
CENTER. AN OCCLUDED FRONT EXTENDS EASTWARD ALONG 50N TO ANOTHER WEAK
LOW AND THEN FURTHER EAST TO A TRIPLE POINT WHICH SHOWS SIGNS OF
DEVELOPING INTO A LOW. NORTH OF THE FRONT OVER THE SOUTHWEST GULF IS
A YET ANOTHER WEAK LOW TRACKING WESTWARD. A WARM OCCLUSION EXTENDS
NORTHWARD FROM THE LOW...MOVING WESTWARD TOWARD KODIAK ISLAND AND
THE SOUTHERN KENAI PENINSULA. SNOW IS CURRENTLY BEING OBSERVED FROM
KODIAK ISLAND TO WESTERN PRINCE WILLIAM SOUND AND AROUND KACHEMAK
BAY. KENAI RADAR SHOWS WEAK ECHOES COVERING COOK INLET AND THE
SOUTHERN SUSITNA VALLEY...BUT PRECIPITATION IS SUBLIMATING AS IT
FALLS INTO VERY DRY LOW-LEVEL AIR (AS SEEN IN THE 12Z ANCHORAGE
SOUNDING).

.MODEL DISCUSSION...ALL MODELS WERE TOO WEAK AND A BIT OFF ON
LOCATION OF SOUTHERN BERING LOW. OTHERWISE...MODEL INITIALIZATION
LOOKED GOOD. MODELS DONT USUALLY HANDLE MULTIPLE LOWS AROUND A
MAIN CENTER VERY WELL. HOWEVER...THIS MORNINGS SOLUTIONS ARE ALL
GROUPED CLOSE TOGETHER THROUGH ABOUT 48 HOURS AND LITTLE CHANGE
WILL BE MADE TO THE CURRENT FORECAST. AFTER THIS SOLUTIONS DIVERGE
SIGNIFICANTLY IN STRENGTH AND PLACEMENT OF LOWS FORMING ALONG THE
FRONT JUST SOUTH AND WEST OF THE ALEUTIANS. WILL TREND TOWARD THIS
FORECAST THROUGH ABOUT SATURDAY BECAUSE CURRENT FORECAST JUST
INDICATES A FRONT WITH NO WELL DEFINED LOW. THERE IS ALSO POOR
RUN-TO-RUN CONSISTENCY BACK OVER MAINLAND ALASKA WITH UPPER TROUGH
MOVING SOUTHWARD ACROSS THE STATE THURSDAY NIGHT THROUGH FRIDAY
NIGHT. THEREFORE...WILL KEEP FORECAST AS IS FOR NOW.

.SHORT TERM FORECAST...

CUT-OFF HIGH WILL RETROGRADE WESTWARD OVER EASTERN SIBERIA A BIT
THE NEXT FEW DAYS AS A SHORT-WAVE TROUGH DROPS SOUTHWARD FROM THE
POLE ACROSS MAINLAND ALASKA AND THE TROUGH AXIS EXTENDING SOUTHWARD
FROM THE KAMCHATKA LOW ROTATES NORTHEASTWARD TO ALONG THE
ALEUTIANS...EVENTUALLY CONNECTING UP TO THE MAINLAND TROUGH. THIS
IN TURN PUSHES THE EASTERN BERING/NORTH PACIFIC CLOSED LOW EASTWARD
ACROSS THE GULF.

THE WARM OCCLUSION AFFECTING PORTIONS OF SOUTHCENTRAL WILL WASH OUT
AS THE FRONT TO THE SOUTH ALONG WITH WEAK FRONTAL LOWS MOVE UP INTO
THE GULF THIS EVENING AND THEN WEAKEN OVER THE NORTHERN GULF
THURSDAY. SHORT-WAVE DROPPING SOUTHWARD ACROSS THE STATE WILL KEEP
FRONT FROM PUSHING INLAND SO PRECIPITATION WILL AGAIN BE CONFINED
MAINLY TO KODIAK ISLAND AND COASTAL AREAS. A SURGE OF ARCTIC AIR
WILL ACCOMPANY THE UPPER TROUGH AS IT MOVES TO THE SOUTHERN MAINLAND
FRIDAY. THE SUB-TROPICAL JET WILL LIFT NORTHWARD AHEAD OF THIS
SHORT-WAVE AND STALL IT OVER THE SOUTHERN MAINLAND AND PREVENT
ARCTIC AIR FROM STREAMING SOUTHWARD ACROSS THE GULF. COLD ADVECTION
AND TIGHT SURFACE PRESSURE GRADIENT WILL PROVIDE STRONG NORTHERLY
WINDS THROUGH THE USUAL CHANNELED AREAS OF SOUTHCENTRAL AND SOUTHWEST
ALASKA...BUT WITHOUT PASSAGE OF UPPER TROUGH DO NOT EXPECT TO HAVE
UPPER SUPPORT NEEDED FOR WARNING LEVEL WINDS. THE SIBERIAN RIDGE
WILL HELP AMPLIFY THE TROUGH OVER THE EASTERN BERING. THIS WILL
RESULT IN STRONG COLD ADVECTION WESTWARD ACROSS THE BERING SEA AND
PRIBILOFS FRIDAY NIGHT AND SATURDAY...LIKELY MAINTAINING OR EXTENDING
THE SEA ICE EDGE. EXPECT TEMPERATURES ACROSS THE SOUTHERN MAINLAND
AND EASTERN BERING TO DROP BELOW NORMAL FOR AT LEAST A FEW DAYS AS
ALL OF THIS ARCTIC AIR MOVES IN. MEANWHILE...THE STORM TRACK WILL BE
ACTIVE ALONG AND SOUTH OF THE ALEUTIANS AND SOUTHERN ALASKA PENINSULA
THROUGH THE SHORT-TERM PERIOD.

.LONG TERM FORECAST...GFS 500MB 5-WAVE SHOWS HIGH AMPLITUDE TROUGH
SETTING UP OVER THE BERING AND RIDGE OVER THE NORTHEAST PACIFIC
DURING THE EXTENDED PERIOD. THEREFORE...TEMPERATURES OVER THE
SOUTHERN MAINLAND WILL QUICKLY MODERATE BY EARLY NEXT WEEK AS STORM
TRACK SHIFTS. STORMS DEVELOPING ALONG OR SOUTH OF THE ALEUTIANS
WILL BEGIN TO TRACK NORTHWARD TOWARD MAINLAND ALASKA...BRINGING A
RETURN TO MORE WINDS AND PRECIPITATION ALONG WITH WARMER AIR.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM WARNING 176.
         GALE WARNING 120 130 138 172 175.
         HEAVY FREEZING SPRAY 165 179 185.
FIRE WEATHER...NONE.

SEB FEB 08