Blizzard and High Wind in Alaska, February 12 to 15, 2009

AREA FORECAST DISCUSSION...CORRECTED
SOUTHCENTRAL AND SOUTHWEST ALASKA
530 AM AKST THU FEB 12 2009

.ANALYSIS AND UPPER LEVELS....
A COLD UPPER LEVEL LOW SLOWLY MOVES NORTHEAST OVER THE NORTHERN PART
OF THE STATE. A SHORTWAVE TROUGH EXTENDS SOUTHEAST FROM THE KUSKOKWIM
DELTA THROUGH THE GULF. A SECOND TROUGH EXTENDS SOUTHWEST FROM THE
LOW ACROSS THE WESTERN BERING AND REMAINS NEARLY STATIONARY. AN UPPER
LEVEL RIDGE SEPARATES THE TWO TROUGHS AND WILL GRADUALLY SHIFT EAST.

AT THE SURFACE...A LOW THAT RAPIDLY DEVELOPED YESTERDAY AHEAD OF
FIRST TROUGH CONTINUES TO SHEAR APART OVER THE GULF. HIGH PRESSURE
OVER THE YUKON FLATS CONTINUES TO MOVE EAST. A STRONG SURFACE LOW HAS
CROSSED THE WESTERN ALEUTIANS AND CONTINUES TO DEEPEN AND WILL REMAIN
THE KEY FOCUS FOR THE WESTERN HALF OF THE STATE OVER COMING DAYS.

.MODEL DISCUSSION...
MODELS ARE DOING REMARKABLY WELL THOUGH WEEKEND. ALL OF THE MODELS
HANDLE THE LOW CROSSING THE WESTERN CHAIN SIMILARLY...MOVING IT NORTH
AND EAST ACROSS THE BERING...EVENTUALLY ONSHORE NEAR NORTON SOUND
LATE FRIDAY NIGHT...WHILE ITS ASSOCIATED FRONT ADVANCES EAST AND
STALLS NEAR BRISTOL BAY. THE MODELS ALSO RAPIDLY SPIN UP A SECONDARY
SURFACE LOW NORTH OF DUTCH LATE TONIGHT AS THE JET DIPS SOUTH. THE
MODELS DO HAVE DIFFERENCES ON HOW THEY HANDLE THE SECOND LOW...THE
GFS HAS BEEN TRENDING AN INTACT CLOSED FURTHER SOUTH AND NOW ACROSS
THE AKPEN FRIDAY NIGHT. THE NAM - ECMWF AND UKMET ALL WEAKEN THE LOW
THROUGH BRISTOL BAY AND EVENTUALLY TROUGH IT OUT AS IT MOVES
INLAND...THAT SAID...THE GFS WAS SOMEWHAT OF AN OUTLIER AND THE
FORECAST THROUGH THAT TIME IS TRENDED TOWARDS THE NAM. BEHIND THE
SECOND LOW A WEAK RIDGE WILL NUDGE IN AND ACROSS THE ALEUTIANS ...
GIVING A BRIEF BREAK FROM THE ACTIVE WEATHER. BEYOND THE WEEKEND ALL
OF THE MODELS BRING UP ANOTHER STRONG SURFACE LOW ACROSS ADAK AND
INTO BRISTOL BAY.

.SHORT TERM FORECAST...

.SOUTHCENTRAL...
THE MAJORITY OF THE MOISTURE AND LIFT OVER PARTS OF SOUTHCENTRAL WILL
COME TO AN END LATE THIS MORNING AS AN UPPER LEVEL TROUGH SWINGS
SOUTH AND EAST ACROSS THE AREA. SKIES ARE CLEARING TO THE WEST AND
WILL CONTINUE THE DOWNWARD TREND IN THROUGH TODAY FROM WEST TO
EAST...BUT CLOUDS WILL CONTINUE TO LOOM. MOISTURE WILL REMAIN PRESENT
THROUGH PRINCE WILLIAM SOUND AND THE PACIFIC SIDE OF THE PENINSULA
WITH THE CONTINUED SOUTH TO SOUTHEAST FLOW. AS THE LOW IN THE BERING
LIFTS NORTH...ITS ASSOCIATED FRONT WILL SWEEP EASTWARD AND EVENTUALLY
REACH WESTERN SOUTHCENTRAL BY FRIDAY. AT THIS POINT WORDING WILL
REMAIN AS A CHANCE FOR PRECIPITATION ACROSS THE WESTERN HALF OF
SOUTHCENTRAL DUE TO SOME UNCERTAINTY ON HOW FAR EAST THE FRONT WILL
PUSH BEFORE SIGNIFICANTLY WEAKENING...THE MODELS KEEP STRONG HIGH
PRESSURE OVER THE EASTERN HALF OF THE STATE...WHICH WILL HELP TO KEEP
A SLOW EASTWARD PROGRESSION OF THE FRONT BEYOND THE BRISTOL BAY AREA.

.SOUTHWEST...
AN ACTIVE FORECAST CONTINUES. A STRONG SURFACE LOW HAS CROSSED THE
WESTERN ALEUTIANS AND WILL CONTINUE A NORTHEASTERLY TRACK. A COLD
FRONT EXTENDS FROM THE LOW DEEP INTO THE PACIFIC. STRONG SOUTHERLY
WINDS AHEAD OF THE FRONT WILL BRING AND KEEP TEMPERATURES UP ALONG
THE CENTRAL CHAIN AND AKPEN TODAY. THE STRONGEST WINDS WILL WRAP
ALONG THE BACK SIDE OF THE LOW IN THE WESTERN AND CENTRAL ALEUTIANS
THROUGH FRIDAY MORNING. THESE WINDS WILL COINCIDE WITH COLD AIR
ADVECTION AND ARE EXPECTED TO REACH HURRICANE FORCE SPEEDS.  AS
PREVIOUSLY MENTIONED...KEPT THE HIGH WIND WARNING INSTEAD OF A
BLIZZARD WARNING ACROSS THE CHAIN AS THE SNOW WILL BE RATHER WET IN
NATURE AND THE WINDS WILL HAVE MORE OF AN IMPACT THAN THE BLOWING
SNOW. WINDS AHEAD OF THE COLD FRONT SWEEPING ACROSS THE CHAIN WILL
BRING STRONG WINDS TO THE AKPEN AND SOUTHWEST MAINLAND TODAY. A
BLIZZARD WARNING HAS BEEN ISSUED FOR THE COASTAL KUSKOKWIM DELTA
STARTING MID MORNING. WINDS WILL DEFINITELY BE BEYOND CRITERIA AND
TEMPERATURES ARE STILL COLD ENOUGH ALONG THE COAST TO KEEP CONDITIONS
HAZARDOUS THROUGH LATE TONIGHT INTO TOMORROW MORNING.

.LONG TERM FORECAST...THE OVERALL PATTERN WILL CONTINUE TO BE QUITE
ACTIVE ACROSS THE DOMAIN THROUGH THE WEEKEND AND BEYOND...BUT
SPECIFICS REMAIN UNRESOLVED AS ALL GUIDANCE DIVERGES BEYOND
TUESDAY...AND MODEL RUNS CONTINUE TO FLIP-FLOP.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING...155
         HIGH WIND WARNING...187 191
MARINE...HURRICANE FORCE WIND WARNING...172
         STORM WARNING...170 175 176 185 411 412 413
         GALE WARNING...130 132 138 140 141 150 160 165
                        180 181 351 352 414
         HEAVY FREEZING SPRAY WARNING...414
FIRE WEATHER...NONE

SSS FEB 09