Small Craft Advisory 233, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKDT SAT MAR 14 2009

.ANALYSIS AND UPPER LEVELS...
A STRONG WESTERLY UPPER LEVEL JET STRETCHES ACROSS THE ALEUTIANS AND
INTO THE SOUTHERN GULF OF ALASKA THIS MORNING...BUT WITH VERY LITTLE
ACTIVITY ALONG THE JET AT THE SURFACE. THERE IS JUST A WEAK LOW
SPINNING THROUGH THE PRIBILOFS. JUST SOUTHWEST OF MIDDLETON ISLAND
IS A VERTICALLY STACKED LOW PRESSURE WITH SOME LIGHT SNOW SHOWER
ACTIVITY PERSISTING AROUND THE LOW AND INTO THE COOK INLET REGION.
VERY COLD AIR IS STARTING TO SPILL SOUTH THROUGH THE INTERIOR...A
SIGN OF THINGS TO COME...SEE SHORT TERM FORECAST BELOW.

.MODEL DISCUSSION...
MODELS CONTINUE TO BE IN GOOD AGREEMENT. OPERATIONAL MOS DATA HAS
BEEN HANDLING THE UPCOMING COLD SNAP PRETTY POORLY AS IS USUALLY THE
CASE WITH BIG PATTERN CHANGES...THOUGH MOS HAS BEEN TRENDING COLDER
AND CLOSER TO REALITY AS THE TIME GETS CLOSER. ENSEMBLE MOS DATA HAS
BEEN DOING MUCH BETTER...AND OUR FORECAST HAS GENERALLY FAVORED THE
COLDER ENSEMBLE MOS OVER THE OPERATIONAL MEX. UPCOMING FORECASTERS
ARE ENCOURAGED TO STAY ON THE COLD SIDE OF GUIDANCE...PARTICULARLY
FOR DAILY HIGH TEMPERATURES.

.SHORT TERM FORECAST...
SOUTHCENTRAL...
THE LOW OVER THE NORTHERN GULF WILL SHIFT SOUTHWARD QUICKLY TODAY
AND BE ABSORBED INTO A LARGER LOW JUST OFF THE SOUTHERN PANHANDLE.
MEANWHILE...A RIDGE WILL QUICKLY AMPLIFY OVER THE CENTRAL BERING.
ALL OF THIS WILL ALLOW VERY COLD DRY AIR TO SPILL SOUTH ACROSS THE
ALASKA RANGE AND INTO SOUTHCENTRAL. THE OFFSHORE PRESSURE GRADIENT
WILL ALSO INCREASE...ALLOWING FOR VERY GUSTY WINDS THROUGH THE USUAL
CHANNELED TERRAIN WITH HEAVY FREEZING SPRAY AROUND THE COAST. THE
UPPER LEVELS NEVER QUITE ALIGN WITH THE OFFSHORE PRESSURE
GRADIENT...SO NOT EXPECTING ANY WINDS REACHING WARNING LEVEL. SUNDAY
NIGHT THROUGH MONDAY NIGHT...THE LOW COMPLEX OFF THE PANHANDLE
DRIFTS NORTHWEST INTO THE NORTHERN GULF...PERHAPS ALLOWING THE COLD
TEMPERATURES TO MODERATE SOMEWHAT AND BRINGING A GLANCING BLOW OF
PRECIP TO SOUTHERN PORTIONS OF SOUTHCENTRAL BEFORE THE COLD AIR
MOVES BACK IN ON TUESDAY AND THINGS DRY OUT AGAIN.

SOUTHWEST MAINLAND...
TEMPERATURES WILL PROGRESSIVELY DROP OVER THE SOUTHWEST MAINLAND AS
THE RIDGE BUILDS IN THE BERING. CONDITIONS WILL REMAIN BREEZY OVER
MOST AREAS THROUGH MONDAY...WHICH WILL ALLOW SURFACE TEMPERATURES
NOT TO GET TOO COLD. HOWEVER...WIND CHILLS COULD BE AN ISSUE...AS
SOME AREAS COULD BE PUSHING WIND CHILL ADVISORY CRITERIA SUNDAY
NIGHT. THE SOUTHWEST MAINLAND WILL SEE LITTLE IF ANY WARMING FROM
THE LOW IN THE GULF OF ALASKA MONDAY UNLESS THE SYSTEM PUSHES
FURTHER WEST THAN EXPECTED.

BERING SEA/ALEUTIANS...
THE ZONAL JET QUICKLY AMPLIFIES INTO A MONSTER RIDGE OVER THE BERING
THIS WEEKEND...WITH THE JET STREAM NEARLY MAKING IT NORTH TO THE
NORTH POLE. BY SUNDAY...THE REGION WILL BE DIVIDED WITH MILD WET
WEATHER TO THE WEST OF THE CENTRAL BERING RIDGE...AND VERY COLD
NORTHERLY FLOW EAST OF THE RIDGE IN THE EASTERN BERING/ALEUTIANS AND
AKPEN. SOME SNOW SHOWERS FORMING OFF THE ICE EDGE CAN BE EXPECTED
OVER THE SAME AREA ALONG WITH GUSTY WINDS ESPECIALLY THROUGH
CHANNELED TERRAIN OF THE AKPEN. THE ICE EDGE CAN BE EXPECTED TO
ADVANCE BACK SOUTH AFTER ITS SIGNIFICANT RETREAT IN THE PAST MONTH.

.LONG TERM FORECAST...
NOT MUCH CHANGE BEYOND MONDAY WITH THE VERY STRONG BLOCKING RIDGE
PERSISTING IN THE BERING AND THE PERMANENT COMPLEX LOW IN THE GULF
OF ALASKA. THE EASTERN BERING AND MAINLAND WILL REMAIN COLD AND
GENERALLY DRY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM WARNING ZONE 150.
         GALE WARNING ZONES 121 129 130 132 138 155 160 165 170 172
          175 176 180 351 352 411 414.
         HEAVY FREEZING SPRAY WARNING ZONES 121 125 129 130 132 138
          140 141 150 155 160 165 179 180 185 412 413 414.
FIRE WEATHER...NONE.

FOISY MAR 09