Small Craft Advisory 948, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
300 PM AKST SAT NOV 29 2008

.MODEL DISCUSSION...MODELS ARE DOING WELL IN THE BIG PICTURE BUT WERE
ALL OFF ON THE DETAILS OF THE CURRENT SYSTEM NEAR PRINCE WILLIAM
SOUND. THEY ALL HAD THE LOW TOO FAR WEST. THIS IS BEGINNING TO BE
CORRECTED AND THE 12Z NAM LOOKS BETTER THAN THE 12Z GFS WHICH STILL
IS TOO FAR WEST. WHAT IS KEY AT THIS POINT IS THAT EACH MODEL HAS
PICKED UP ON AN IMPORTANT PART OF THE MOVEMENT OF THIS LOW BUT
NEITHER HAS THE FULL STORY. THE GFS HAS THE LOW BLASTING INTO THE
COPPER RIVER BASIN...WHICH IS WHERE IT IS HEADING RIGHT NOW. HOWEVER
THIS LOW WILL QUICKLY DISSIPATE AS A SECONDARY LOW DEVELOPS EAST OF
SEWARD AND MOVES INTO THE SOUND TONIGHT. THE NAM HAS THIS. COMBINE
THEM AND THAT IS WHAT WILL LIKELY HAPPEN.
IN THE WEST THE MODELS ARE ARE HANDLING THE LARGE LOW SOUTH OF THE
ALEUTIANS PRETTY GOOD.

.ANALYSIS AND UPPER LEVELS AND SHORT TERM FORECAST...AS MENTIONED IN
THE PREVIOUS SECTION THE LOW IS PUSHING THROUGH PRINCE WILLIAM SOUND
BUT IS EXPECTED TO RAPIDLY WEAKEN THIS EVENING AS A SECONDARY LOW
DEVELOPS EAST OF SEWARD AND MOVES INTO THE SOUND OVERNIGHT AS THE
MAIN LOW.
COLD ADVECTION MOVING UP COOK INLET FROM THE SOUTHWEST IS CAUSING
SOME GUSTY WINDS IN THE REGION AS THE PRESSURE SURGE FOLLOWS THE LOW
NORTHWARD. THESE WINDS WILL DIMINISH BY THE EVENING AND A GOOD
OVERRUNNING SNOW EVENT IN THE ANCHORAGE IS EXPECTED...RESULTING IN
THE CURRENT WINTER WEATHER ADVISORY. 6 TO 12 INCHES OF SNOW IS
EXPECTED IN THE ANCHORAGE AREA BY LATE SUNDAY AFTERNOON.

IN THE WEST A LARGE LOW SOUTH OF THE ALEUTIANS IS BRINGING IN MORE
STRONG WINDS AND A MIXED BAG OF PRECIPITATION. THERE SHOULD BE SNOW
IN THE BEGINNING OF THIS SYSTEM FOR THE EASTERN ALEUTIANS AND ALASKA
PENINSULA AS COLD AIR IS ALREADY IN PLACE. PRECIPITATION SHOULD TURN
TO RAIN AS THE WARM CORE MOVES NORTHWARD. THERE IS A POSSIBILITY OF
BLIZZARD CONDITIONS IN THE WESTERN ALEUTIANS SUNDAY OR SUNDAY NIGHT
WITH COLD AIR ADVECTION ON THE WEST SIDE OF THIS LOW. THE EASTERN
ALEUTIANS AND ALASKA PENINSULA WILL PROBABLY NOT SEE AS MUCH BLOWING
SNOW AS THE PAST TWO DAYS SINCE THEY WILL BE IN THE WARM SECTOR OF
THE SYSTEM WITH SOUTHEAST FLOW AND WARM ADVECTION.

THERE IS ALSO A SMALL BUT INTENSE POLAR VORTEX TRACKING JUST NORTH OF
THE PRIBILOF ISLANDS IS BRINGING SNOW AND BLOWING SNOW TO THOSE
ISLANDS. THIS LOW IS SMALL IN SCALE AND IS AFFECTING ST PAUL MUCH
MORE THAN ST GEORGE. THIS LOW WILL MOVE OUT OF THE AREA BY EARLY
EVENING AND CONDITIONS WILL IMPROVE BY THEN.

.LONG TERM FORECAST...THE STRONG AND NEARLY STATIONARY LOW SOUTH OF
THE ALEUTIANS WILL BE THE MAJOR WEATHER FEATURE INTO THE MIDDLE OF
NEXT WEEK. HIGH PRESSURE WILL BUILD OVER THE MAINLAND PART OF THE
STATE BY LATE IN THE WEEKEND AND REMAIN UNTIL THE MIDDLE OF NEXT WEEK
WHEN THE LOW SOUTH OF THE ALEUTIANS FINALLY MOVES INTO THE GULF OF
ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WATCH FOR THE PRIBILOFS.
MARINE...GALE 120 121 125 150 155 165 171 176.
         STORM 130 132 138 170 172 175.
         HEAVY FREEZING SPRAY 130 138 140 160.
FIRE WEATHER...NONE.

NOV 08