Blizzard in Alaska, January 4, 2010

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKST MON JAN 4 2010

.ANALYSIS AND UPPER LEVELS...
THE LONGWAVE TROUGH HAS MOVED OVER THE BERING SEA WITH THE LONGWAVE
RIDGE BUILDING IN OVER THE EASTERN GULF OF ALASKA THIS MORNING.  AN
UPPER LEVEL CLOSED LOW HAS MOVED INTO THE BASE OF THE TROUGH.  THIS
FEATURE IS REFLECTED DOWN TO THE SURFACE WITH A STRONG 966 MB LOW
JUST SOUTH OF DUTCH HARBOR THIS MORNING.  THE SURFACE HIGH IS
CENTERED A LITTLE FURTHER EAST THAN THE UPPER LEVEL RIDGE AND IS
LOCATED OVER WESTERN CANADA THIS MORNING.  THE TIGHT GRADIENT BETWEEN
THESE TWO FEATURES IS EXHIBITED IN THE STRONG WINDS MOVING THROUGH
THE AK PEN THIS MORNING...WHERE SOUTHEAST FLOW FROM THE NORTHERN
PACIFIC IS PUMPING PLENTY OF WARM AIR INTO THE STATE.

.MODEL DISCUSSION...
MODEL SOLUTIONS THIS MORNING APPEAR TO BE IN GOOD AGREEMENT ON THE
POSITION OF THE LOW IN THE ALEUTIANS BUT DIFFER SLIGHTLY ON THE
STRENGTH IN THE SHORT TERM.  THE GFS IS A LITTLE STRONGER THAN THE
NAM AND ECMWF SOLUTIONS.  THIS RESULTS IN STRONGER WINDS IN THE GFS
SOLUTION...WHICH SEEMS TO BE A BETTER CHOICE GIVEN THE OBSERVED WINDS
THIS MORNING. MODELS START TO DIVERGE ON TIMING ON TUESDAY AND
WEDNESDAY WITH THE NEXT FRONT MOVING INTO THE GULF OF ALASKA.  NAM
SEEMED TO BE THE OUTLIER ON THIS SO THE GFS WAS USED FOR THIS
TIMEFRAME AS WELL.

.SHORT TERM FORECAST...
IN THE EAST...A QUICK BATCH OF SNOW WILL MOVE THROUGH TODAY AS THE
WARM FRONT PROGRESSES UP FROM THE SOUTH.  MOST OF THE PRECIPITATION
WILL FALL IN THE SUSITNA VALLEY SINCE EASTERLY FLOW WILL CAUSE
DOWNSLOPING FOR THE ANCHORAGE BOWL AND KENAI PENINSULA.
HOWEVER...THE FRONT IS EXPECTED TO MOVE THROUGH RELATIVELY QUICKLY
AND THE SNOW SHOULD REMAIN BELOW ADVISORY LEVEL.  AS USUAL STRONG
WINDS ARE IN THE FORECAST WITH THE SOUTHEASTERLY FLOW BUT ARE
EXPECTED TO TAPER OFF AS THE GRADIENT SLACKENS.  TONIGHT AND INTO
EARLY TOMORROW THE RIDGE WILL BUILD IN AGAIN TEMPORARILY AND SKIES
WILL CLEAR...BUT THIS WILL CHANGE QUICKLY AS A NEW FRONT MOVES INTO
THE REGION.

WEST OF THE AK RANGE...MOST OF THE NASTY WEATHER WILL OCCUR IN THE
WEST THIS MORNING.  WARM AIR HAS MOVED IN ALOFT BUT AT THE SURFACE
COLD AIR REMAINS TRAPPED IN A LOT OF LOCATIONS...IN PARTICULAR WITH
THE NORTHEASTERLY FLOW AHEAD OF THE FRONT.  THIS MORNINGS UPPER AIR
SOUNDING AT BETHEL SHOWED A STRONG INVERSION JUST ABOVE THE SURFACE.
AS THE WARM FRONT MOVES NORTHWARD THIS INCREASES THE CHANCE FOR
WIDESPREAD FREEZING RAIN...HOWEVER AHEAD OF THE FRONT SNOW AND STRONG
WINDS WILL BRING BLIZZARD CONDITIONS TO THE COAST.  BY THIS AFTERNOON
CONDITIONS SHOULD IMPROVE AS THE WARMER TEMPERATURES WILL FINALLY MIX
DOWN TO THE SURFACE AND BRING MORE RAIN TO THE ENTIRE REGION.

ALEUTIANS AND BERING...EXPECT BLIZZARD CONDITIONS FOR THE PRIBILOFS
THIS MORNING WITH THE APPROACH OF THE COLD FRONT FROM THE SOUTH...BUT
SIMILAR TO THE WEST COAST...BY THIS AFTERNOON WARMER TEMPERATURES
SHOULD ELIMINATE THE BLIZZARD CONDITIONS.  IN THE ALEUTIANS STRONG
WINDS ARE PREVAILING THIS MORNING BUT RAIN IS THE NAME OF THE GAME
FOR THE EASTERN AND CENTRAL ALEUTIANS WITH ALL THAT WARM AIR ALOFT.
EXPECT STORMS IN THE BERING AND NORTHWARD WITH FRONTAL PASSAGE BUT
AFTERWARDS GALE FORCE WINDS SHOULD BE THE DOMINANT WEATHER FEATURE.

.LONG TERM FORECAST...
MORE OF THE SAME IN THE LONG TERM.  MODELS REMAIN UNCERTAIN IN THE
MID TO LONG RANGE SO CONFIDENCE IS LOW...ESPECIALLY WITH REGARDS TO
TIMING.  HOWEVER AT THIS POINT THE PATTERN LOOKS LIKE IT WILL
MAINTAIN A LOW IN THE EASTERN ALEUTIANS TO AK PEN REGIONS...WHICH
WILL CONTINUE TO BRING WARM AIR TO MOST OF THE MAINLAND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 155 AND 195
MARINE...STORMS 185 179
         GALES 130 132 138 140 150 155
               160 165 180 170 171 172 175 176
         HEAVY FREEZING SPRAY 180
FIRE WEATHER...NONE

LEWF JAN 10