Blizzard in Alaska, February 12 to 14, 2008

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
100 PM AST TUE FEB 12 2008

.ANALYSIS AND UPPER LEVELS...SATELLITE IMAGERY SHOWS A VERY STRONG
VERTICALLY STACKED LOW ABOUT 600 MILES SOUTH OF THE ALEUTIANS.
OCCLUSION HAS WRAPPED A FEW TIMES AROUND THE LOW CENTER. WINDS NORTH
OF THE LOW AND AHEAD OF THE FRONT ARE BEGINNING TO INCREASE ACROSS
THE CENTRAL AND EASTERN ALEUTIANS. LIGHT SNOW HAS ALSO BEGUN IN
DUTCH HARBOR. BLOWING SNOW QUICKLY DROPPED VISIBILITIES TO AROUND 1
1/2 MILES. A BLIZZARD WARNING IS IN EFFECT FOR THE EASTERN ALEUTIANS
BEGINNING LATE THIS AFTERNOON AND A BLIZZARD WATCH IS IN EFFECT FOR
THE ALASKA PENINSULA.

A QUASI-STATIONARY UPPER LOW IS CENTERED NEAR THE TIP OF THE SEWARD
PENINSULA. ONE TROUGH AXIS EXTENDS FROM THE LOW SOUTHEASTWARD ACROSS
SOUTHWEST ALASKA TO COOK INLET AND INTO THE GULF. THIS AXIS IS
PROGRESSING NORTHEASTWARD...WITH DRIER AIR MOVING IN BEHIND IT.
AHEAD OF THE TROUGH AXIS IS A SURFACE LOW OVER SOUTHEAST ALASKA WITH
A SURFACE TROUGH EXTENDING NORTHWESTWARD TO SOUTHCENTRAL. SNOW IS
FALLING ACROSS PORTIONS OF SOUTHCENTRAL...BUT IS GRADUALLY ENDING
FROM SOUTHWEST TO NORTHEAST. FREEZING RAIN AND FREEZING DRIZZLE HAVE
ALSO BEEN REPORTED IN ANCHORAGE AND THE MATANUSKA VALLEY. THE UPPER
LEVELS HAVE DRIED OVER THIS AREA...BUT LOW LEVEL MOISTURE IN THE
FORM OF SUPER COOLED WATER DROPLETS ARE LEADING TO THE FREEZING
PRECIPITATION. VISIBLE SATELLITE SHOWS THE CLEARING LINE MOVING UP
THE INLET SO EXPECT PRECIPITATION WILL END
BY EARLY AFTERNOON.

.MODEL DISCUSSION...MODELS INITIALIZED WELL WITH NORTH PACIFIC LOW
AND ARE IN GOOD AGREEMENT WITH THE PROGRESSION OF THIS LOW TO KODIAK
ISLAND THURSDAY MORNING. THERE IS SLIGHT DIVERGENCE IN LOW TRACKS
AS THE LOW THEN MOVES INLAND...BUT SOLUTIONS ARE CENTERED AROUND
COOK INLET...AND FORECAST WOULD VARY MUCH WITH ANY OF THESE
SOLUTIONS...SO DECIDED TO STICK CLOSE TO THE GFS TRACK. CONFIDENCE
QUICKLY DROPS BEHIND THIS SYSTEM AS MODEL SOLUTIONS RAPIDLY DIVERGE.
THEREFORE...WILL STICK CLOSE TO CURRENT FORECAST FROM THIS POINT
ONWARD.

.SHORT TERM FORECAST...

BERING SEA/ALEUTIANS/AKPENN...THE PACIFIC LOW WILL TRACK
NORTHEASTWARD TOWARD KODIAK ISLAND TONIGHT AND WEDNESDAY WHILE THE
OCCLUDED FRONT PIVOTS NORTHWESTWARD TOWARD THE EASTERN ALEUTIANS
AND ALASKA PENINSULA. LOOKS LIKE THE FRONT WILL REMAIN SOUTH AND
EAST OF THE EASTERN ALEUTIANS SO THEY WILL STAY ALL SNOW AND BLIZZARD
CONDITIONS CAN BE EXPECTED AS PRECIPITATION INTENSIFIES THIS EVENING
AND WINDS INCREASE FURTHER. THE FRONT WILL MOVE ACROSS A PORTION OF
THE ALASKA PENINSULA...COMING VERY CLOSE TO COLD BAY BY WEDNESDAY
MORNING. AREAS EAST OF COLD BAY WILL LIKELY CHANGE TO RAIN WEDNESDAY
MORNING. IF COLD BAY STAYS AHEAD OF THE FRONT AS EXPECTED LOW LEVEL
FLOW WILL REMAIN NORTHEASTERLY THROUGH WEDNESDAY MORNING AND THEN
BACK TO THE NORTH WEDNESDAY AFTERNOON AS THE LOW PULLS THE FRONT
BACK EASTWARD. THIS WOULD KEEP PRECIPITATION IN COLD BAY ALL SNOW
FOR THE EVENT. CURRENT TEMPERATURES ARE AROUND 10 DEGREES...SO EXPECT
BLIZZARD CONDITIONS ARE LIKELY AT THE BEGINNING OF THE EVENT...AND
MAY CONTINUE INTO WEDNESDAY DEPENDING ON HOW HIGH TEMPERATURE GETS.
WILL UPGRADE THE BLIZZARD WATCH TO A WARNING FOR THE ALASKA PENINSULA
ZONE AND SPECIFY MAINLY COLD BAY WESTWARD. STRONG COLD ADVECTION
BEHIND THE SYSTEM WILL RESULT IN SNOW SHOWERS AND BLOWING SNOW ACROSS
THE CENTRAL TO EASTERN BERING AND ALEUTIANS AS WELL AS THE SOUTHERN
ALASKA PENINSULA. STORM FORCE GUSTS ARE LIKELY THROUGH CHANNELED
AREAS WEDNESDAY. THE ICE EDGE WILL ALSO CONTINUE ITS MARCH SOUTHWARD.
CONDITIONS WILL GRADUALLY IMPROVE WEDNESDAY NIGHT THROUGH THURSDAY
NIGHT AS THE LOW WEAKENS OVER INLAND SOUTHWEST ALASKA. THE NEXT STORM
SYSTEM WILL MOVE TO SOUTH OF THE ALEUTIANS THURSDAY AND REMAIN THERE
FRIDAY. THE MAIN IMPACT WILL BE GALE FORCE EASTERLIES ALONG THE
ALEUTIANS.

SOUTHWEST ALASKA...THE FRONT ASSOCIATED WITH THE PACIFIC LOW WILL
MOVE FROM EAST TO WEST ACROSS SOUTHWEST ALASKA WEDNESDAY...BRINGING
WARM AIR ALOFT OVER EASTERN PORTIONS OF BRISTOL BAY AND THE KUSKOKWIM
VALLEY. AREAS IMMEDIATELY ALONG THE MOUNTAINS WILL SEE DOWNSLOPE
DRYING SO DO NOT EXPECT ANY SIGNIFICANT PRECIPITATION. FARTHER FROM
THE MOUNTAINS THERE IS THE POTENTIAL FOR FREEZING RAIN AS LOW LEVEL
NORTHERLY FLOW MAINTAINS BELOW FREEZING SURFACE TEMPERATURES. FOR
NOW WILL ADD IN A CHANCE OF FREEZING RAIN AND EVALUATE NEW MODELS
AND LOCAL SOUNDINGS TONIGHT TO DETERMINE WHETHER ICE ACCUMULATION
WILL OCCUR. WESTERN PORTIONS OF SOUTHWEST ALASKA WILL SEE ALL SNOW
AND GUSTY WINDS WILL RESULT IN REDUCED VISIBILITIES DUE TO BLOWING
SNOW. THERE IS THE SMALL POSSIBILITY OF BLIZZARD CONDITIONS ALONG
THE SOUTHWEST COAST WEDNESDAY NIGHT INTO THURSDAY...BUT AT THIS
POINT LOOKS LIKE BULK OF PRECIPITATION WILL REMAIN EAST OF
THERE...WITH MAINLY SNOW SHOWERS ALONG THE COAST...SO WILL NOT ISSUE
A WATCH BUT WILL RE-EVALUATE WITH NEW MODEL RUNS. COLD AIR WILL MOVE
BACK INTO ALL OF SOUTHWEST ALASKA THURSDAY NIGHT CHANGING ALL
PRECIPITATION BACK TO SNOW. SNOW AND WINDS WILL GRADUALLY END FRIDAY
AS THE LOW MOVES TO NORTHERN ALASKA.

SOUTHCENTRAL ALASKA...SOUTHCENTRAL ALASKA WILL BE ON THE WARM SIDE
OF THE STORM SYSTEM. MOST AREAS MAY SEE A BRIEF PERIOD OF SNOW AHEAD
OF THE FRONT BEFORE WINDS COME UP. STRONG EASTERLIES WILL THEN
DEVELOP AS THE FRONT NEARS WEDNESDAY AND PRODUCE DOWNSLOPE DRYING
ALONG THE LEE SIDE OF THE MOUNTAINS. WARM AIR ADVECTION WILL TURN
PRECIPITATION TO MAINLY RAIN FOR COASTAL AREAS BY WEDNESDAY
AFTERNOON. WARM AIR WILL ALSO MOVE OVER TOP OF THE SURFACE COLD LAYER
INLAND...SO PRECIPITATION AT HIGHER ELEVATIONS MAY TURN TO RAIN LATE
WEDNESDAY AND LOW LEVELS MAY SEE SOME AREAS OF FREEZING RAIN. COLD
AIR WILL QUICKLY MOVE BACK IN THURSDAY NIGHT CHANGING ALL
PRECIPITATION BACK TO SNOW. ALSO EXPECT VERY STRONG WINDS ACROSS THE
KODIAK ISLAND WATERS AS THE COLD AIR ADVECTS BACK IN. SNOW WILL BEGIN
TO TAPER OFF FRIDAY...BUT NEXT FRONT WILL BE ON THE WAY WITH ANOTHER
CHANCE OF SNOW BY FRIDAY NIGHT.

.LONG TERM FORECAST...LONG-WAVE PATTERN OF TROUGH CENTERED OVER THE
BERING AND RIDGE OVER WESTERN NORTH AMERICA LOOKS LIKE IT WILL HOLD
THROUGH THE EXTENDED PERIOD. THEREFORE...STORM TRACK WILL REMAIN
SIMILAR WITH LOWS TRACKING SOUTH OF THE ALEUTIANS AND THEN MOVING
NORTH ACROSS THE GULF AND SOUTHCENTRAL. THIS WILL KEEP THE BERING
COLD AND BRING A CHANCE OF PRECIPITATION EVERY 2 TO 3 DAYS ALONG THE
STORM TRACK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING ZONE 181 AND 185.
MARINE...STORM WARNING 120 130 155 170 172.
         GALE WARNING 125 132 138 140 141 150 160 165 171 175 179.
         HEAVY FREEZING SPRAY...130 138 140 141 165 179 185.
FIRE WEATHER...NONE.

SEB FEB 08