Blizzard Watch 38, NWS Anchorage, AK

454 
WWAK41 PAFC 141351
WSWAER

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE ANCHORAGE AK
451 AM AKST FRI DEC 14 2012

AKZ131-141500-
/X.CAN.PAFC.BZ.A.0038.121214T1800Z-121215T0900Z/
NORTHEAST PRINCE WILLIAM SOUND-
INCLUDING THE CITIES OF...VALDEZ...THOMPSON PASS
451 AM AKST FRI DEC 14 2012

...BLIZZARD WATCH IS CANCELLED FOR THOMPSON PASS...

THE NATIONAL WEATHER SERVICE IN ANCHORAGE HAS CANCELLED THE
BLIZZARD WATCH. 

SCATTERED SNOW SHOWERS WILL MOVE THROUGH THOMPSON PASS TODAY AND
COMBINE WITH STRENGTHENING NORTHERLY WINDS TO PRODUCE AREAS OF
BLOWING SNOW. HOWEVER...WITH THE STEADY SNOW REMAINING SOUTH OF
THE AREA THERE WILL NOT BE ENOUGH SNOW TO CREATE BLIZZARD
CONDITIONS. 

$$

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKST THU DEC 13 2012

.ANALYSIS AND UPPER LEVELS...
THE STORM YESTERDAY USHERED IN A NEW OVERALL WEATHER PATTERN THAT
FEATURES A STRONG ZONAL JET STREAM SOUTH OF THE ALEUTIANS THAT
CONTINUES ACROSS THE SOUTHERN GULF AND INTO THE COAST OF BRITISH
COLUMBIA. THIS JET STREAM IS LOCATED ALONG THE TOP OF A VERY BROAD
NORTH PACIFIC RIDGE. SEVERAL DISTURBANCES ARE MOVING THROUGH THIS
PATTERN...AND ALL ARE GENERALLY ON THE WEAK SIDE. A COMPACT 990 MB
LOW IN THE CENTRAL BERING IS ADVANCING QUICKLY TOWARD SOUTHWEST
ALASKA. FURTHER SOUTH...A 1000 MB LOW IS FORMING NEAR DUTCH HARBOR
WITH THE HELP OF THE 100+ KT JET TO THE SOUTH. THE SOUTHERN LOW IS
INTENSIFYING AT THE EXPENSE OF THE NORTHERN LOW...A TREND THAT WILL
CONTINUE AS THE PAIR CONTINUE TO HEAD EASTWARD TOWARD THE GULF.
FURTHER EAST...WEAK EMBEDDED WAVES IN THE WESTERLY FLOW ARE CONTINUE
TO GENERATE SOME AREAS OF LIGHT SNOW ALONG WEST-FACING MOUNTAINS
AROUND COOK INLET AND PRINCE WILLIAM SOUND.

.MODEL DISCUSSION...
MODELS ARE IN REASONABLE AGREEMENT TODAY. THE MAIN DISCREPANCY
INVOLVES THE DEVELOPING LOW NEAR DUTCH HARBOR. THE EUROPEAN MODELS
(ECMWF AND UKMET) AND THE CANADIAN GEM FAVOR A MORE SOUTHERLY TRACK
THAT WOULD KEEP THE LOW FAR ENOUGH SOUTH IN THE GULF THAT IT WOULD
NOT SIGNIFICANTLY AFFECT THE NORTH GULF COAST. MEANWHILE...THE
AMERICAN NAM AND GFS (ESPECIALLY THE NAM) HAVE MORE NORTHERLY
SOLUTIONS WHICH WOULD BRING SNOWFALL MUCH FURTHER NORTH AND WEST INTO
WHITTIER AND THE VALDEZ AREA. CONSIDERING THE STRONG ZONAL JET STREAM
WELL SOUTH OF THE STATE...A FURTHER SOUTH SOLUTION SEEMS MUCH MORE
LIKELY AND WILL PROBABLY LIMIT ANY IMPACTS TO COASTAL AREAS ON
FRIDAY.

.SHORT TERM FORECAST...
SOUTHWESTERLY FLOW WITH LOW CLOUDS AND FLURRIES WILL BE SLOW TO
DIMINISH TONIGHT...ESPECIALLY AROUND WEST-FACING MOUNTAIN RANGES
INCLUDING ANCHORAGE. GUSTY SOUTHERLY WINDS IN COOK INLET WILL
DIMINISH OVERNIGHT AS THE LOW CURRENTLY NEAR DUTCH HARBOR INTENSIFIES
AND MOVES INTO THE WESTERN GULF. THIS WILL START TO PULL WINDS DOWN
THROUGH COOK INLET AND SWITCH WINDS AT MANY AREAS AROUND TO THE
NORTH. HOWEVER...WINDS WILL NOT BECOME VERY STRONG OUT OF THE
NORTH...AND WITH RECENT HEAVY SNOWFALL IT SEEMS LIKELY THAT SOME
AREAS OF FOG WILL DEVELOP AROUND COOK INLET OVERNIGHT...ESPECIALLY IF
THE HIGHER CLOUDS START TO BREAK UP A BIT. FOR FRIDAY...AS MENTIONED
IN THE MODEL DISCUSSION...IT NOW LOOKS LIKE MOST OF THE IMPACT FROM
THE GULF LOW WILL REMAIN SOUTH OF THE AREA...AND ANY IMPACTS WILL BE
LIMITED TO THE COAST. IF THE TRACK SHIFTS EVEN SLIGHTLY FURTHER NORTH
AND WEST...BLOWING SNOW ISSUES WILL LIKELY DEVELOP AROUND THOMPSON
PASS AND WHITTIER AS OFFSHORE WINDS INCREASE DRAMATICALLY ON FRIDAY.

SOUTHWEST...
WESTERLY WINDS...SNOW SHOWERS...AND COOLING TEMPERATURES WILL
CONTINUE ACROSS MOST OF THE REGION THROUGH THE WEEKEND. NOT EXPECTING
ANY SIGNIFICANT ACCUMULATIONS OF SNOW AS DYNAMIC FORCING REMAINS WEAK
AND FAST-MOVING. MOST AREAS WILL START TO SEE INCREASING AMOUNTS OF
SUNSHINE EACH DAY THROUGH THE WEEKEND AS THE GENERAL PATTERN
GRADUALLY DRIES OUT.

BERING SEA AND ALEUTIANS...FAIRLY BENIGN CONDITIONS WILL CONTINUE
WITH WESTERLY WINDS AND COOLING TEMPERATURES. A FEW WEAK LOWS ARE
SCATTERED AROUND THE BERING SEA...WITH THE STRONGEST LOCATED NORTH OF
THE PRIBILOFS. THESE LOWS ARE SEPARATED FROM THE ENERGY OF THE JET
STREAM TO THE SOUTH AND WILL GENERATE LITTLE MORE THAN LOCALIZED
GUSTY WINDS AND SNOW SHOWERS. A MORE SUBSTANTIAL LOW IS DEVELOPING
JUST SOUTH OF DUTCH HARBOR...BUT THE ASSOCIATED PRECIPITATION SHIELD
WILL IMPACT PRIMARILY THE BERING SIDE OF THE EASTERN ALEUTIAN ISLANDS
AND ALASKA PENINSULA AS THE JET STREAM REMAINS TO THE SOUTH.

.LONG TERM FORECAST...
MOST OF THE MAINLAND WILL SEE THE RETURN OF MUCH COLDER AIR FOR THE
WEEKEND. LONG RANGE MODELS ARE IN GOOD AGREEMENT THAT THE OVERALL
WEATHER PATTERN WILL REMAIN ZONAL WITH THE JET STREAM RELATED STAYING
WELL SOUTH OF THE MAINLAND THROUGH THE MIDDLE OF NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WATCH 131
MARINE...GALE WARNING 129 130 132 150 155 160 170 171 172 175 176
FIRE WEATHER...NONE

DIXON DEC 12