Blizzard in Alaska, January 5, 2012

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKST THU JAN 5 2012

.MODEL DISCUSSION...

PREFERRED THE UKMET AND EC SOLUTIONS AS THEY BOTH INITIALIZED WELL
AND HAVE GOOD CONSISTENCY WITH INHERITED PACKAGE. NAM IS STRUGGLING
TO RESOLVE THE SMALL LOW DEVELOPING NORTHEAST OF KODIAK ISLAND THIS
MORNING AND THE GFS IS TOO SLOW IN MOVING IN THE FIRST NORTH PACIFIC
SYSTEM INTO THE GULF.

.UPPER LEVELS...
UPPER LEVEL PATTERN IS DOMINATED BY A COLD CORE LOW CENTERED OVER THE
NORTHWEST CORNER OF THE BERING SEA. THE LOW IS SURROUNDED BY MULTIPLE
SHORTWAVES EMBEDDED IN THE CYCLONIC FLOW. TWO PARTICULARLY POTENT
WAVES WILL TRAVERSE SOUTHCENTRAL ALASKA OVER THE NEXT 24 HOURS
ENHANCING PRECIPITATION OVER THE AREA...THE FIRST ARRIVES THIS
MORNING...AND THE SECOND LATE TONIGHT. THE PRIMARY LOW GRADUALLY
MIGRATES NORTHWESTWARD INTO THE RUSSIAN FAR EAST BY SAT AFTERNOON
WHILE AN UPPER LEVEL RIDGE OF HIGH PRESSURE BUILDS ALONG THE WEST
COAST OF THE CONTIGUOUS US...ENHANCING SOUTHWESTERLY FLOW OVER
MAINLAND ALASKA AND WESTERN CANADA IN THE PROCESS.

.ANALYSIS AND NEAR TERM FORECAST...

OLD LOW OVER SOUTHWEST ALASKA IS RAPIDLY DETERIORATING BUT A NEW
SECONDARY LOW HAS ALREADY BEGUN TO FORM NEAR THE BARREN ISLANDS.
LIGHT SNOW AND SNOW SHOWERS OVER KODIAK ISLAND AND SOUTHWEST ALASKA
THIS MORNING WILL TAPER OFF THROUGH THE DAY. DANGEROUSLY LOW WIND
CHILLS OVER THE KUSKOKWIM DELTA THIS MORNING WILL ABATE LATER TODAY
AS WIND SPEEDS DROP BELOW 15 MPH.

THE DEVELOPMENT OF A 994 MB SURFACE LOW NEAR BARREN ISLANDS THIS
MORNING IS HELPING TO PULL LOW LEVEL MOISTURE FROM THE GULF OF ALASKA
TOWARDS THE MAINLAND. SNOW HAS ALREADY BEGUN TO MOVE OVER THE KENAI
PENINSULA THIS MORNING AND WILL ENGULF MOST OF SOUTHCENTRAL BY LATE
AFTERNOON.

PRESSURE GRADIENT ALONG GULF COAST BRIEFLY TIGHTENS TODAY WITH
DEVELOPMENT OF LOW NEAR BARREN ISLAND BUT RELAXES AGAIN AROUND
MIDNIGHT TONIGHT WHEN LOW RECENTERS ITSELF OVER NORTHERN PRINCE
WILLIAM SOUND. BRIEF WHITE OUT CONDITIONS POSSIBLE THROUGH PORTAGE
VALLEY AND ALONG TURNAGAIN ARM THIS AFTERNOON UNDER SOUTHEASTERLY
FLOW. BLIZZARD CONDITIONS WILL DEVELOP THROUGH THOMPSON PASS THIS
MORNING AND CONTINUE THROUGH MOST OF THE NIGHT.

BARREN ISLAND LOW MOVES INTO NORTHERN PRINCE WILLIAM SOUND LATE
TONIGHT...THEN WEAKENS AND MOVES INLAND ON FRIDAY. HEAVY SNOW IS
EXPECTED TO CONTINUE ACROSS EASTERN PRINCE WILLIAM SOUND AND THE
COPPER RIVER BASIN THROUGH FRIDAY MORNING.

A SMALL 1001 MB LOW HAS FORMED IN THE EASTERN BERING BETWEEN THE
PRIBILOF ISLAND AND THE ALASKA PENINSULA. NUMEROUS SNOW
SHOWERS...SOME HEAVY...ASSOCIATED WITH THIS FEATURE. LOW MAINTAINS
ITS INTENSITY AS IT PASSES OVER THE ALASKA PENINSULA THIS EVENING BUT
DISSIPATES NEAR THE WESTERN EDGE OF KODIAK ISLAND BY TOMORROW
MORNING.

.MID AND LONG TERM FORECAST...

A LARGE 965 MB NORTH PACIFIC PASSES JUST SOUTH OF THE ALEUTIAN CHAIN
THURSDAY NIGHT AND FRIDAY AND WILL SPREAD GUSTY NORTHEAST WINDS AND
BANDS OF SNOW SHOWERS ACROSS THE CHAIN. THE LOW ARCS NORTHEASTWARD
FRIDAY NIGHT AND HEADS TOWARD KODIAK ISLAND. HEAVY SNOW AND STRONG
WINDS ALONG AND IN ADVANCE OF THE FRONT WILL REACH THE NORTH GULF
COAST...KODIAK ISLAND...AND ALASKA PENINSULA EARLY SATURDAY MORNING.
STORM IS LARGE STRONG AND RELATIVELY SLOW MOVING...GIVING IT THE
POTENTIAL TO CREATE WIDESPREAD HAZARDOUS WINTER CONDITIONS ACROSS
SOUTHCENTRAL AND SOUTHWESTERN ALASKA OVER THE WEEKEND.

UPPER LEVEL STEERING FLOW WILL CONTINUE TO BE FAVORABLE FOR NORTH
PACIFIC STORMS TO MOVE DIRECTLY INTO THE SOUTHERN MAINLAND. EVEN MORE
SNOW AND WIND LIKELY IN THE FORECAST FOR SOUTHCENTRAL AND
SOUTHWESTERN ALASKA THROUGH AT LEAST THE FIRST HALF OF THE COMING
WEEK.

BROAD NORTHEASTERLY TO NORTHWESTERLY FLOW SHOULD ESTABLISH ITSELF
OVER THE BERING SEA AND ALEUTIAN CHAIN BY SATURDAY NIGHT AND SHOULD
PERSIST THROUGH MIDWEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 131
         BLIZZARD WATCH 181
MARINE...GALE 120 125 130 132 150 165 170 172 351 352
         STORM 155
         HEAVY SPRAY 121 130 132 138 140 141 150 165 179 185 412 414
FIRE WEATHER...NONE.

ASB JAN 12

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ANCHORAGE AK
630 AM AKST THU JAN 5 2012

AKZ101-051800-

...BRIEF PERIOD OF MODERATE SNOW WILL AFFECT RUSH HOUR THIS MORNING
IN ANCHORAGE...

A BAND OF MODERATE SNOW WILL MOVE ACROSS ANCHORAGE BETWEEN 630 AM
AND 800 AM. WITH VERY COLD TEMPERATURES IN PLACE THE SNOW THAT FALLS
WILL BE LIGHT AND FLUFFY WHICH MEANS IT WILL EASILY BE BLOWN AROUND
BY THE MOVEMENT OF VEHICLES ON THE ROAD. THEREFORE...EXPECT
SIGNIFICANTLY REDUCED VISIBILITIES IN THE FALLING AND BLOWING SNOW.
STRONG WINDS ALONG TURNAGAIN ARM  AND HIGHER ELEVATIONS WILL ALSO
CONTRIBUTE TO TEMPORARILY VERY LOW VISIBILITIES IN THOSE LOCATIONS.

AFTER THIS BAND OF SNOW MOVES THROUGH EXPECT SCATTERED SNOW SHOWERS
UNTIL STEADY SNOW REDEVELOPS DURING THE MID AFTERNOON HOURS.

SEB

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ANCHORAGE AK
643 AM AKST THU JAN 5 2012

AKZ101-051645-