Storm Warning 246, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT SUN OCT 31 2010

.MODEL DISCUSSION...MODELS ARE IN GOOD SYNOPTIC SCALE AGREEMENT
THROUGH LATE TUE NIGHT. BEYOND THIS MODELS DIFFER ON HANDLING OF
DEVELOPING LOW CENTER MOVING INTO THE GULF ON WED AFTERNOON. THE
ECMWF STILL APPEARS TO BE THE MOST PROGRESSIVE. AVAILABLE GFS
ENSEMBLE MEMBERS TEND TO TREND TOWARD THE ECMWF. HOWEVER...MODEL
TRACK AND TIMING ARE STILL UNCERTAIN...SO WILL MAKE SLIGHT BLEND WED
AFTERNOON AND LEAVE EXTENDED GRIDS AS IS UNTIL NEXT RUN.

.ANALYSIS...

UPPER LEVELS
OLD STACKED LOW SOUTHWEST OF THE GULF OF ALASKA MOVES OVER THE KENAI
PENINSULA LATE MON NIGHT. A SECOND SURGE OF COLD AIR ADVECTION INTO
THE NORTH PACIFIC DIGS THE LONG WAVE SOUTH ALONG 150-160W TUE. A
SECONDARY CENTER FORMS AT THE BASE OF THE TROUGH THEN MOVES RAPIDLY
NORTH TOWARD THE WESTERN GULF WED. WARM ADVECTION OUT WEST BUILDS THE
RIDGE OVER THE WESTERN BERING SEA MON. THE RIDGE AXIS SHIFTS TO THE
CENTRAL BERING SEA WED. A RELATIVELY SHALLOW WAVE MOVES TO THE
WESTERN BERING SEA ON WED.

SURFACE...A 940S STACKED LOW OVER THE NORTHEAST PACIFIC WEAKENS AS IT
MOVES OVER THE KENAI PENINSULA EARLY TUE MORNING. THE ASSOCIATED
OCCLUDED FRONT CURRENTLY STRETCHES ACROSS THE SOUTHERN GULF OF ALASKA
AND HAS STORM FORCE WINDS NEAR ITS LEADING EDGE. THIS FRONT WILL MOVE
TO THE NORTHERN GULF LATE TONIGHT AND WEAKENS AS IT SPREADS CLOUDS
AND MAYBE A LITTLE SNOW TO WESTERN ALASKA MON. A WEAK 980S LOW
CURRENTLY WEST OF NUNIVAK ISLAND MOVES SOUTH OF THE AK PEN TONIGHT
AND WEAKENS. THE NEXT LOW CENTER TO IMPACT THE GULF DEVELOPS OVER THE
EASTERN PACIFIC AT THE BASE OF DIGGING UPPER TROUGH TUE AND HEADS TO
THE NORTH GULF ON WED. THIS CENTER IS STILL A WAYS OUT AND TIMING AND
INTENSITY ARE STILL ISSUES. HOWEVER...THIS CENTER WILL LIKELY BE
SIGNIFICANT ENOUGH AND BRING STORMS/GALES INTO THE GULF WATERS.

.SHORT TERM FORECAST...

SOUTHCENTRAL...
EXPECT STORMS THE NORTH GULF TONIGHT AS STORM TRACKS NORTH. WINDS
LIKELY TO DIMINISH OVER THE WESTERN GULF SOME MON AS FRONT MOVES WEST
AND NORTH...HOWEVER COULD SEE STORMS CONTINUING INTO MON AFTERNOON IN
THE NORTH CENTRAL COASTAL WATERS AS STACKED LOW CENTER TRACKS NORTH.
BUILDING PRESSURE GRADIENTS WITH APPROACHING FRONT AND LOW CENTER
LIKELY TO PRODUCE STRONG GAP WINDS ACROSS ACROSS SOUTHCENTRAL. WARM
ADVECTION AHEAD OF FRONT SPREADS NORTH AND WEST ACROSS THE GULF AND
INTO SOUTHCENTRAL ALASKA. SHOULD SEE GENERALLY RAIN ALONG THE GULF
THROUGH TONIGHT AND MIXED INLAND AREAS...EXCEPT THE COPPER RIVER
BASIN WITH WILL MOST LIKELY REMAIN COLD ENOUGH FOR SNOW THROUGH
TONIGHT...BUT WARMER MON. THE BRUNT OF THE PRECIPITATION THROUGH MON
NIGHT WILL BE CONFINED TO THE COASTAL REGIONS. PRECIPITATION LIKELY
TO SPREAD INLAND FURTHER TUE AS LOW CENTER MOVES NW ACROSS THE KENAI
PEN...MAY SEE A QUICK SHOT AT SNOW AS IT MOVES RAPIDLY NW INTO THE
INTERIOR. NEXT LOW MOVING INTO THE GULF WED LIKELY TO BRING ANOTHER
ROUND OF RAIN AND WINDS TO THE GULF.

.SOUTHWEST ALASKA...
NORTHERLY FLOW INCREASES ACROSS THE REGION THROUGH TONIGHT. EXPECT
LOCAL BRISK NORTHERLY WINDS TO HOLD THROUGH MON. GENERALLY DRY
CONDITIONS WILL PREVAIL ACROSS THE AREA TONIGHT WITH NORTHERLY
FLOW...MAY SEE A CHANCE OF SNOW MON AS WEAKENING OCCLUDED FRONT MOVES
WEST ACROSS THE AREA.

AK PEN/AK PEN...BERING SEA...
BRISK NORTHERLY WINDS WITH RAIN AND SNOW SHOWERS WILL HOLD THROUGH
MON...THEN WEAKEN OVER THE WESTERN ALEUTIANS MON NIGHT AND TUE AS THE
RIDGE BUILDS EAST. WINDS AND SHOWERS DIMINISH ACROSS THE EASTERN
ALEUTIANS AND EAST BERING SEA TUE NIGHT AND WED. SOUTHERLY WINDS
INCREASE ACROSS THE WESTERN ALEUTIANS TUE AND WED WITH THE APPROACH
OF A STRONG WEATHER FRONT.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM...120 130
         GALE...125 129 132 138 140 150 155 172 175 176 180 185
              AND 179.

FIRE WEATHER...NONE.

RMC OCT 10