Small Craft Advisory 91, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AKST MON JAN 26 2009

.MODEL DISCUSSION...
MODELS CONTINUE TO DISAGREE ON DETAILS REGARDING THE EVOLUTION OF LOW
CENTERS IN BOTH THE GULF OF ALASKA AND THE NORTH PACIFIC.
INITIALIZATION FOR THE LOW IN THE GULF OF ALASKA IS PARTICULARLY POOR
THIS AFTERNOON...WITH THE ACTUAL LOW WELL SOUTH AND EAST OF THE
INITIALIZED POSITIONS. PERFORMANCE IS BETTER THAN THE PAST SEVERAL
DAYS HOWEVER...WITH MODELS COMING INTO BETTER AGREEMENT ON THE TRACK
OF THE LOW SOUTH OF ADAK. THE 26/12Z GFS IS THE OPERATIONAL MODEL OF
CHOICE THIS AFTERNOON...DUE TO GOOD RUN TO RUN CONSISTENCY.

.ANALYSIS AND UPPER LEVELS...
UPPER LEVEL ZONAL FLOW EXISTS ACROSS THE ALEUTIANS AND SOUTHERN
MAINLAND OF ALASKA. AT THE SURFACE A 996 MB LOW IS LOCATED NEAR 56N
146W. A 998 MB LOW IS LOCATED NEAR 50N 174W...OR ABOUT 100 NM SOUTH
OF ADAK.

.SHORT TERM FORECAST...

.SOUTHCENTRAL...
GENERALLY BENIGN WEATHER WILL EXIST ACROSS SOUTHCENTRAL THROUGH
TUESDAY...WITH PARTLY TO MOSTLY CLOUDY SKIES AND LIGHT WINDS. GUSTY
WINDS THROUGH CHANNELED TERRAIN WILL CONTINUE THROUGH
TUESDAY...BEFORE DIMINISHING AS THE LOW IN THE EASTERN GULF DEPARTS
INTO CANADA. PATCHY FOG WILL AFFECT LOCATIONS ALONG COOK INLET AND
PARTS OF THE MATANUSKA VALLEY THROUGH TUESDAY. AFTER TUESDAY MODELS
ARE TRENDING TOWARD THE SOLUTION OF THE LOW NEAR ADAK MOVING ALONG
THE ALASKA PENINSULA...AND UP COOK INLET BY THURSDAY MORNING. THIS
TREND IS LIKELY DUE TO THE FACT THAT INSTEAD OF UPPER LEVEL ZONAL
FLOW...A WEAK RIDGE IS NOW FORECAST TO BUILD INTO THE GULF OF ALASKA
WITH A TROUGH DIGGING OVER THE CENTRAL BERING SEA. WITH THIS LOW
TRACK SOUTHCENTRAL COULD SEE AN INCREASED THREAT OF PRECIPITATION BY
WEDNESDAY...WITH A DECENT OVERRUNNING EVENT SETTING UP AHEAD OF THE
LOW. ACCORDINGLY...THE POSSIBILITY OF SNOW HAS BEEN ADDED TO THE
FORECAST BEGINNING TUESDAY NIGHT. IF MODELS HANG ON TO THIS SOLUTION
IN FUTURE RUNS...CHANCES OF PRECIPITATION MAY HAVE TO BE INCREASED
FURTHER.

.SOUTHWEST...
SCATTERED SNOW SHOWERS AND LIGHT WINDS WILL CONTINUE OVER SOUTHWEST
THROUGH TUESDAY. SNOW AND RAIN WILL BEGIN TO OVERSPREAD THE AK
PENINSULA TUESDAY NIGHT AS THE LOW MOVES INTO THE AREA. PRECIPITATION
WILL ALSO BE ON THE INCREASE OVER THE SOUTHERN PORTIONS OF BRISTOL
BAY...WITH PRECIPITATION REMAINING ALL SNOW. PRECIPITATION WILL
CONTINUE OVER THE SAME AREAS THROUGH WEDNESDAY...WITH LOCATIONS ON
THE BACK SIDE OF THE LOW CHANGING BACK TO ALL SNOW. ELSEWHERE ACROSS
SOUTHWEST...EXPECT SCATTERED SNOW SHOWERS TO CONTINUE WITH NORTHERLY
FLOW DEVELOPING BY MID WEEK.

.BERING SEA AND ALEUTIANS...
THE AFOREMENTIONED LOW NEAR ADAK WILL MOVE EAST ACROSS THE
CHAIN...REACHING THE ALASKA PENINSULA BY WEDNESDAY MORNING. WARM AIR
ADVECTION AHEAD OF THE LOW WILL RESULT IN A SNOW AND RAIN MIX FOR THE
ALEUTIAN ISLANDS...REMAINING ALL SNOW FOR THE PRIBILOFS. AS THE LOW
EXITS TO THE EAST...COLD AIR ADVECTION WILL BRING GALE FORCE
NORTHERLY FLOW AND WIDESPREAD SNOW SHOWERS. MAIN PRECIPITATION BULK
ASSOCIATED WITH THE LOW WILL MOVE ACROSS THE EASTERN ALEUTIANS
TONIGHT INTO TOMORROW.

.LONG TERM FORECAST...
THE STRENGTHENING ALEUTIAN LOW IS EXPECTED TO CONTINUE MOVING
EASTWARD...ACROSS THE ALASKA PENINSULA AND INTO THE GULF OF ALASKA BY
THE END OF THE WEEK. COLD AIR ADVECTION WILL BE STRONG ON THE
BACKSIDE OF THIS LOW...BRINGING MUCH COLDER AIR INTO SOUTHCENTRAL AND
SOUTHWESTERN ALASKA FOR THE WEEKEND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 130 170 172 175
         HEAVY FREEZING SPRAY 160 179
FIRE WEATHER...NONE

NRH JAN 09