Heavy Freezing Spray Warning 52, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 PM AKST WED FEB 9 2011

.ANALYSIS AND UPPER LEVELS...
A RELATIVELY ZONAL FLOW PATTERN EXISTS ACROSS THE REGION THIS
AFTERNOON WITH A FEW WEAK SHORTWAVES EMBEDDED IN THE FLOW. THE FIRST
OF THESE IS A QUICKLY MOVING FRONT TRACKING EASTWARD INTO
SOUTHCENTRAL...WHICH IS HELPING TO EJECT A DECAYING SURFACE WEATHER
FRONT CURRENTLY OVER THE REGION NORTHEASTWARD INTO THE COPPER RIVER
BASIN. PRECIPITATION ASSOCIATED WITH THIS WEAKENING SYSTEM IS
LIKEWISE LIFTING NORTHWARD AND QUICKLY LESSENING IN INTENSITY AND
COVERAGE.

SCATTERED SNOW SHOWERS ARE ALSO ACCOMPANYING THE AFOREMENTIONED UPPER
LEVEL SHORTWAVE TROUGH AS IT PUSHES THROUGH INLAND AREAS OF SOUTHWEST
ALASKA. OUT WEST...COLD AIR ADVECTION ON THE BACKSIDE OF THE FRONT IS
GENERATING SNOW SHOWERS ACROSS THE EASTERN BERING SEA AND THE
AKPEN/EASTERN ALEUTIANS. A WEAK UPPER LEVEL TROUGH IS TRACKING
THROUGH THE CENTRAL BERING ALONG WITH A 1008 MB SURFACE LOW THAT IS
SLOWLY DISSIPATING AS IT LOSES ITS UPPER LEVEL SUPPORT.

.MODEL DISCUSSION...
MODELS OVERALL IN EXCELLENT AGREEMENT THROUGH THE SHORT TERM ON THE
KEY SYNOPTIC FEATURES ACROSS THE REGION. THERE ARE SOME MINOR
STRUCTURAL DIFFERENCES BETWEEN THE MODELS WITH REGARDS TO THE
DISSIPATING BERING SEA LOW AND ANOTHER LOW THAT TRACKS NORTH INTO THE
GULF ON THURSDAY NIGHT...BUT THESE SHOULD HAVE LITTLE IMPACT ON THE
FORECAST. THUS THIS AFTERNOON'S FORECAST USED THE NAM FOR DETAIL OVER
LAND AND THE GFS OUT OVER THE BERING SEA.

.SHORT TERM FORECAST...SNOW IN SOUTH CENTRAL ALASKA IS ON THE
DOWNWARD TREND AS THE LOW MOVING UP COOK INLET HAS DISSIPATED AND THE
SOUTHWEST FLOW OVER THE NORTH GULF COAST HAS WEAKENED. AREAS EAST OF
THE ALASKA RANGE ARE GENERALLY WARM BUT WILL DROP QUICKLY IN
SOUTHWEST ALASKA AS A MUCH COLDER AIRMASS MOVES INTO THAT AREA.
NORTHERLY WINDS OVER THE EASTERN BERING SEA WILL KEEP SNOW SHOWERS
ALONG THE ALASKA PENINSULA. THE PRIBILOF ISLANDS WILL CONTINUE TO SEE
PERIODS OF LIGHT SNOW AND FREEZING DRIZZLE THROUGH THE NIGHT.
THERE IS A SIGNIFICANT CHANGE COMING TO THE GULF REGION AS A SURFACE
LOW DEVELOPS JUST SOUTHEAST OF MIDDLETON ISLAND THURSDAY NIGHT. THIS
WILL SIGNIFICANTLY INCREASE WINDS ALONG THE NORTH GULF COAST AND
KODIAK ISLAND BY FRIDAY.

.LONG TERM FORECAST...THE PROGRESSIVE WEATHER PATTERN THAT HAS BEEN
OCCURRING THIS WEEK WILL SETTLE DOWN SOME THIS WEEKEND AS A LARGE
UPPER LEVEL TROUGH ENTRENCHES ITSELF OVER THE MAINLAND PART OF THE
STATE WITH A PRONOUNCED UPPER LEVEL RIDGE OVER THE BERING SEA.
THE IMPACT OF THIS WILL BE FOR MOST OF MAINLAND ALASKA TO SEE CLEAR
AND VERY COLD TEMPERATURES. THE NORTH GULF COAST AND KODIAK ISLAND
WILL ALSO SEE STRONG OFFSHORE WINDS AS A SURFACE LOW DEVELOPS IN THE
NORTHERN GULF FRIDAY AND PERSISTS INTO EARLY NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 130 132 138 150 155 170 175 176 185.
         HEAVY FREEZING SPRAY...160 165 185.
FIRE WEATHER...NONE.

FEB 11