Coastal Flood Warning 1, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
315 PM AKST TUE NOV 8 2011

.ANALYSIS AND UPPER LEVELS...
THE HIGHLY AMPLIFIED PATTERN ACROSS THE STATE IS RESULTING IN A MAJOR
STORM OVER THE WESTERN BERING SEA. OUT EAST...A SHARP TROF HAS HELPED
TO DEVELOP A POTENT SURFACE LOW JUST SOUTHEAST OF MIDDLETON ISLAND
THIS AFTERNOON. THIS TROF AXIS WHICH IS LOCATED OVER PRINCE WILLIAM
SOUND WILL BEGIN TO RAPIDLY MOVE TO THE EAST THIS EVENING IN RESPONSE
TO THE APPROACHING SYSTEM FROM THE WEST.

A TRANSIENT RIDGE IS PROVIDING MUCH OF SOUTHCENTRAL AND THE
SOUTHWESTERN INTERIOR FAIR WEATHER TODAY WITH TEMPERATURES RANGING 5
TO 10 DEGREES BELOW NORMAL FOR THIS TIME OF YEAR.

THE REAL STORY IS THE INTENSIFYING MAJOR STORM IN THE WESTERN BERING.
ALL INDICATIONS TODAY ON SATELLITE AND FROM THE FEW OBSERVATIONS
AVAILABLE ACROSS THE BERING SEA ARE THAT THIS STORM IS AS
ADVERTISED...A MAJOR STORM WITH THE POTENTIAL FOR SIGNIFICANT
IMPACTS.

.MODEL DISCUSSION...
OUT EAST...THE MODELS DID NOT INITIALIZE WELL ON THE DEFORMATION ZONE
EXTENDING FROM THE LOW NEAR MIDDLETON ISLAND. THE POSITION OF THIS
BAND AND THE SURFACE LOW ARE FURTHER WEST THAN THE MODELS DEPICT.
FORECAST ADJUSTMENTS INCLUDE MORE SNOW FALLING OVER SOUTHEASTERN
COPPER RIVER BASIN AND SOUTHEASTERN PRINCE WILLIAM SOUND. THE
PRESSURE GRADIENT TOOK A BIT LONGER TO INCREASE ALONG THE
SOUND...DELAYING OUR BLIZZARD WARNING THROUGH THOMPSON PASS SEVERAL
HOURS.

WHILE THE INITIALIZATION IS POOR...MODELS ARE IN RELATIVELY GOOD
AGREEMENT WITH ALL MAJOR FEATURES. THE FOCUS FOR THIS FORECAST
PACKAGE IS THE SHORT TERM AND THE WARNINGS/IMPACTS ASSOCIATED WITH
THE BERING LOW.

.SHORT TERM FORECAST...
SOUTHCENTRAL...
AS MENTIONED BEFORE...SOME MINOR MODIFICATIONS TO THE SHORT TERM
FORECAST BASED ON THE RADAR AND SATELLITE TRENDS. THE SNOW AND WIND
ASSOCIATED WITH THE LOW IN THE NORTHEASTERN GULF WILL QUICKLY
DIMINISH AND MOVE EAST THIS EVENING. THE ONLY FORECAST CHALLENGE FOR
THE EAST IS THE REMNANTS OF THE TROF OUT WEST AS IT CROSSES THE
ALASKA RANGE AND OVER SOUTHCENTRAL. THE SYSTEM WILL BE WELL OCCLUDED
BY THIS TIME. A TRIPLE POINT LOW WILL DEVELOP NEAR KODIAK ISLAND
WEDNESDAY AFTERNOON AND MOVE INTO THE NORTHWESTERN GULF OVERNIGHT.
THE STRONG SOUTHWESTERLY FLOW ALOFT AND ABUNDANT MOISTURE ASSOCIATED
WITH THE REMNANTS OF THIS HUGE SYSTEM WILL BE ENOUGH TO SPREAD SNOW
UP COOK INLET.

AT THIS TIME...EXPECTING LIGHT SNOW TO DEVELOP OVER THE SOUTHERN
KENAI PENINSULA WEDNESDAY MORNING AND SPREAD NORTH DURING THE DAY.
LIKE THE PREVIOUS STORMS...THERE COULD BE A BRIEF PERIOD OF HEAVIER
SNOW BUT THERE ARE NO CLEAR INDICATIONS OF WHERE OR WHEN THAT WOULD
BE. SO FOR NOW...OUR FORECAST WILL MENTION ONLY LIGHT ACCUMULATIONS
THROUGH MID WEEK.

HIGH PRESSURE ON THE BACKSIDE OF THIS SYSTEM BUILDS THURSDAY
AFTERNOON AS THE NEXT STORM DEVELOPS OVER THE EASTERN
ALEUTIANS...BRINGING ANOTHER CHANCE OF SNOW BACK TO THE REGION LATE
IN THE WEEK AND OVER THE WEEKEND.

SOUTHWEST AND BERING SEA...
ALL THE ATTENTION SHOULD BE OUT WEST WHERE A 945 MB LOW RAPIDLY MOVES
TOWARD THE CHUKCHI SEA. WHILE THE MOST SIGNIFICANT IMPACTS WITH THIS
STORM WILL PLAY OUT IN FAIRBANKS AREA OF RESPONSIBILITY...STILL WORTH
MENTIONING THAT THIS IS A MAJOR STORM BRINGING HURRICANE FORCE WINDS
AND WAVES APPROACHING 40 FEET TO A GOOD PORTION OF THE BERING SEA.

CONDITIONS WILL RAPIDLY DETERIORATE OVER THE DELTA LATE THIS
AFTERNOON AS WINDS INCREASE AND SNOW BEGINS TO FALL. FEELING THAT
THERE IS STILL A VERY GOOD CHANCE OF BLIZZARD CONDITIONS FOR THE
INTERIOR PORTIONS OF THE KUSKOKWIM DELTA SO ISSUED A BLIZZARD WARNING
FOR THAT AREA WHILE LEAVING A HIGH WIND WARNING FOR THE COASTAL
COMMUNITIES. ALL MODEL GUIDANCE SUGGESTS TEMPERATURES WILL REMAIN IN
THE LOWER TO MID 20S THROUGH MIDNIGHT AS THE WINDS INCREASE TO 45 TO
60 MPH. ABOUT 6 INCHES OF SNOW ON THE GROUND HAS NOT FULLY CRUSTED
OVER WHICH WILL ALSO HELP REDUCE VISIBILITY AS WINDS INCREASE LATE
THIS AFTERNOON.

AS WINDS SHIFT FROM SOUTHEAST TO SOUTHWEST...WARMER AIR FLOWING OFF
THE OPEN WATER WILL FINALLY PUSH TEMPERATURES OVER FREEZING ENDING
THE THREAT FOR THE BLIZZARD. WINDS WILL REMAIN GUSTY...BUT DIMINISH
BELOW WARNING CRITERIA BY MORNING.

BRISTOL BAY WILL MOSTLY ESCAPE THIS STORM...WITH THE EXCEPTION OF A
BRIEF PERIOD OF SNOW AND BLOWING SNOW AS THE FRONT MOVES ONSHORE LATE
THIS EVENING. WINDS WILL BE GUSTY...BUT NOT NEARLY THE IMPACT THAT
AREAS NORTH WILL SEE.

THE ALEUTIANS AND BERING SEA ARE SEEING THE WORST OF IT RIGHT NOW.
HIGH WIND WARNINGS ARE VERIFYING AS THE STORM AND ASSOCIATED FRONT
MARCH ACROSS THE REGION. CONDITIONS SLOWLY IMPROVE ACROSS THE BERING
OVER THE NEXT 48 HOURS. THE NEXT LOW...ONLY PROGGED TO BE AT APPROX
985 MB WILL DEVELOP NEAR THE EASTERN ALEUTIANS LATER IN THE
WEEK...ALLOWING TIME FOR COASTAL COMMUNITIES IMPACTED BY THE MAJOR
STORM TO ASSESS ANY DAMAGE AND BEGIN THE CLEANUP PROCESS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING...155 195
         BLIZZARD WARNING...131 155
MARINE...HURRICANE FORCE WIND WARNING...180 185 412
         STORM WARNING...170 411 413 414
         GALE WARNING...120 127 128 129 130 132 150 155 160 165 171
                        172 175 176 179
FIRE WEATHER...NONE

AB NOV 11