Blizzard in Alaska, March 4 to 5, 2012

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKST SUN MAR 4 2012

.ANALYSIS AND UPPER LEVELS...
AN UPPER LEVEL TROUGH IS QUICKLY MOVING EASTWARD ACROSS MAINLAND
ALASKA THIS MORNING...WITH A RIDGE FOLLOWING CLOSE BEHIND. AT THE
SURFACE...THE SURFACE LOW THAT HAS BEEN IN THE NORTHERN GULF IS STILL
IN GENERALLY THE SAME AREA. THERE IS HIGH PRESSURE IN THE EASTERN
BERING AND SOUTHWEST MAINLAND...WHILE STRENGTHENING LOW IS MOVING
NORTHWARD THROUGH THE WESTERN BERING. LIGHT SNOW HAS CONTINUED
OVERNIGHT ACROSS MUCH OF THE KENAI PENINSULA AND PRINCE WILLIAM
SOUND...AS WELL AS ACROSS THE ANCHORAGE BOWL.

.MODEL DISCUSSION...
THE SHORT TERM MODELS ARE IN DECENT AGREEMENT. THE GFS HAS STRUGGLED
THE MOST WITH THE LOW POSITION IN THE GULF...BUT THE NAM AND ECMWF
HAVE IT ANALYZED WELL. THEREFORE THE NAM AND ECMWF WERE USED FOR
SOUTH CENTRAL AREA. THE GFS HAS HAD THE BEST HANDLE ON THE BERING AND
ALEUTIANS...SO IT WAS USED ON THE WEST SIDE.

.SHORT TERM FORECAST...

SOUTHCENTRAL...
LIGHT SNOW AND SNOW SHOWERS ACROSS THE SOUTH CENTRAL MAINLAND WILL
GRADUALLY COME TO AN END THIS MORNING AS THE UPPER TROUGH PUSHES
EASTWARD. SKIES WILL BECOME CLEAR ACROSS MUCH OF THIS AREA TODAY AND
TONIGHT...FOR A BRIEF TIME BEFORE THE NEXT FRONT/SYSTEM APPROACHES
FROM THE WEST. SNOW WILL ONCE AGAIN SPREAD ACROSS SOUTH CENTRAL
ALASKA ON MONDAY AFTERNOON AND MONDAY NIGHT...ADDING TO THE ALREADY
MUCH ABOVE NORMAL SNOWFALL THIS AREA HAS RECEIVED THIS SEASON.
TEMPERATURES DO LOOK TO BE COLD ENOUGH FOR SNOW WITH THE NEXT STORM
ACROSS THIS PART OF THE STATE...ALTHOUGH THE SOUTHERN PART OF KODIAK
ISLAND COULD SEE SOME RAIN.

SOUTHWEST/BERING SEA/ALEUTIANS...
A FRONT WILL WORK ITS WAY EASTWARD ALONG THE CENTRAL AND EASTERN
ALEUTIAN ISLANDS TODAY...BRINGING RAIN AND SNOW TO THE AREA. MODELS
ARE SHOWING WARM AIR MAKING IT WELL NORTH OF THE PRIBILOF ISLANDS
TODAY AND TONIGHT...SO EVEN THOUGH PRECIPITATION WILL LIKELY START
OUT AS SNOW...THE EXPECTED RAPID WARMING SHOULD CAUSE THE SNOW TO
QUICKLY CHANGE TO RAIN. THEREFORE WE WILL HOLD OFF ON A BLIZZARD
WARNING AT THIS TIME FOR THE PRIBILOFS...ALTHOUGH IF TEMPERATURES DO
NOT WARM AS MUCH AS EXPECTED A BLIZZARD WARNING MAY BE NEEDED.

AS THE PRECIPITATION MOVES INTO THE SOUTHWEST MAINLAND...SURFACE
TEMPERATURES WILL BE MUCH COLDER SO THE WARM UP WILL NOT BE ENOUGH TO
CHANGE PRECIPITATION TO RAIN. WINDS WILL BE STRONG ALONG THE
COAST...BUT THERE IS LESS CERTAINTY HOW STRONG WINDS WILL BE INLAND.
FOR NOW WE WILL ISSUE A BLIZZARD WATCH FOR THE COASTS OF THE
KUSKOKWIM DELTA AND BRISTOL BAY FOR TONIGHT.

.LONG TERM FORECAST...
THE MODELS SEEM TO BE GETTING A HANDLE ON THE WEATHER FOR THE END OF
THE WEEK AND NEXT WEEKEND...WITH THE 04/00Z ECMWF AND THE 04/00Z GFS
BOTH NOW SHOWING A SIMILAR TRACK OF A SURFACE LOW NORTHWARD ACROSS
THE CENTRAL AND EASTERN GULF. THERE ARE STILL PLENTY OF DETAILS TO
WORK OUT WITH THIS SYSTEM HOWEVER. IN THE WEST...A LOW WILL MOVE
EASTWARD THROUGH THE BERING DURING THE LATTER PART OF THE WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WATCH...155 161
MARINE...STORMS...185 411 412
         GALES...130 132 138 170 172 175 176 179 180 413 414
         HEAVY FREEZING SPRAY...121 129 130 132 150 165 412
FIRE WEATHER...NONE.