Blizzard and Coastal Flood in Alaska, November 7 to 9, 2011

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKST MON NOV 7 2011

.ANALYSIS AND UPPER LEVELS...
HIGHLY AMPLIFIED AND PROGRESSIVE PATTERN CONTINUES WITH ONE TROUGH
AXIS OVER CENTRAL ALASKA WITH TWO DISTINCT SURFACE LOWS ASSOCIATED
WITH IT. HIGH PRESSURE IS BRIEFLY IN CONTROL OF SOUTHWEST ALASKA
AHEAD OF THE MAJOR DEVELOPING STORM SYSTEM THAT IS TAKING SHAPE OVER
THE NORTH PACIFIC THIS AFTERNOON.

AS A RESULT OF THE COLD AIR ADVECTING THROUGH THE ALASKA AND CHUGACH
RANGES...LEE-SIDE CYCLOGENESIS IS NOW EVIDENT NEAR PRINCE WILLIAM
SOUND. A 993 MB LOW QUICKLY DEVELOPED THIS MORNING WHICH IS HELPING
TO FURTHER ENHANCE PRECIPITATION AROUND SOUTHCENTRAL AK. ANOTHER LOW
ROTATING AROUND THE BASE OF THE TROF NEAR THE ALASKA PENINSULA WILL
INTENSIFY OVERNIGHT AS IT MOVES TOWARD THE NORTHEAST GULF.

.MODEL DISCUSSION...
MODELS DOING AN EXCELLENT JOB CONSIDERING THE PROGRESSIVE PATTERN.
HAVE BEEN VERY PLEASED WITH THE CONSISTENCY FROM RUN TO RUN REGARDING
THE VERY STRONG OUT WEST...ALLOWING MAXIMUM LEAD TIME ON THE WATCHES
AND WARNINGS. OVERALL...ONLY MINOR CHANGES TO THE SHORT TERM AND NO
CHANGES TO THE MEDIUM AND LONG RANGE FORECAST AS WE CONCENTRATE OUR
EFFORTS ON THE MAJOR STORM OUT WEST.

.SHORT TERM FORECAST...
SOUTHCENTRAL...
LINGERING SNOW SHOWERS CONTINUE ALTHOUGH MOST OF THE DYNAMICS HAVE
SHIFTED EAST. IMPRESSIVE LOW LEVEL INSTABILITY COUPLED WITH SURFACE
CONVERGENCE LED TO ONE LAST HEAVY SNOW BAND THAT HIT THE ANCHORAGE
BOWL DURING RUSH HOUR THIS MORNING. ONLY EXPECTING FLURRIES OR LIGHT
SNOW SHOWERS MAINLY ALONG THE MOUNTAINS OVER NIGHT AS THE NEWLY
DEVELOPED LOW WEAKENS AND DRIFTS SOUTHEAST.

THIS LOW WILL MERGE WITH THE SECONDARY LOW SOUTH OF THE AKPEN AND
INTENSIFY IN THE NORTHEASTERN GULF TUESDAY AFTERNOON. THIS NEW
DEVELOPMENT WILL STRENGTHEN THE GRADIENT ALONG THE GULF
COAST...LEADING TO STRONG WINDS THROUGH THE NORMAL CHANNELED TERRAIN.
RECENT SNOWFALL THROUGH THOMPSON PASS COULD BE PICKED UP AND BLOWN
LEADING TO A GROUND BLIZZARD AS THE WINDS INCREASE EARLY TUESDAY
MORNING.

FAIR WEATHER BUILDS OVER SOUTHCENTRAL TUESDAY THANKS TO HIGH PRESSURE
AHEAD OF THE NEXT STORM SYSTEM. THE GRADIENT ALONG THE GULF COAST
WEAKENS LATE TUESDAY NIGHT...THEN INCREASING CLOUDS WITH THE NEXT
CHANCE OF LIGHT SNOW BY WEDNESDAY AFTERNOON.

SOUTHWEST...
ATTENTION TURNS OUT WEST WITH THE VERY STRONG LOW TO DEVELOP TONIGHT
AND MOVE INTO THE WESTERN BERING. WIDESPREAD HURRICANE FORCE WIND
WARNINGS AND HIGH WIND WARNINGS HAVE BEEN POSTED FOR THE MAJORITY OF
THE BERING SEA AND ALEUTIAN RANGE. WHILE THE MAJORITY OF THE IMPACTS
IN OUR DOMAIN WILL BE WIND RELATED...A BLIZZARD WATCH HAS ALSO BEEN
POSTED FOR THE KUSKOKWIM DELTA WHERE TEMPERATURES WILL REMAIN JUST
COOL ENOUGH TO SUPPORT BLIZZARD CONDITIONS. A CHALLENGE HAS BEEN
EXPECTED WINDS ALONG THE COAST WITH 80 MPH POSSIBLE ALONG THE
IMMEDIATE COAST OF THE DELTA IN CONJUNCTION WITH THE BLIZZARD
CONDITIONS. BLIZZARD CONDITIONS DIMINISH TUESDAY EVENING ONCE WARMER
AIR ARRIVES ONSHORE...BUT THE 80 MPH GUSTS WILL CONTINUE THROUGH THE
NIGHT.

ANOTHER CONSIDERATION FOR THE KUSKOKWIM DELTA HAS BEEN THE THREAT FOR
COASTAL FLOODING...BEACH EROSION...OR AT THE MINIMUM HIGH SURF. AT
THIS POINT...ALL MODEL GUIDANCE SUGGESTS THAT THERE WILL NOT BE ANY
SIGNIFICANT HIGH SURF AND THEREFORE NO COASTAL FLOODING. WILL
CONTINUE TO CLOSELY MONITOR AS THE STORM DEVELOPS TONIGHT.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING...187 191 195
         BLIZZARD WARNING...131 155
MARINE...HURRICANE FORCE WIND WARNING...172 175 176 179 180 185 411
          412 413 414
         STORM WARNING...165 170
         GALE WARNING...120 127 129 130 132 138 150 155 160 171
FIRE WEATHER...NONE

AB NOV 11