Blizzard in Alaska, November 19, 2008

AREA FORECAST DISCUSSION...CORRECTED
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKST WED NOV 19 2008

CORRECTED FOR WARNINGS.

.MODEL DISCUSSION...
MODELS ARE SLIGHTLY MORE CONSISTENT IN THE MID RANGE AND SHORT TERM
THAN THEY HAVE BEEN OVER THE PAST FEW DAYS...BUT STILL NOT EXCELLENT.
TREND IS TOWARD LITTLE CHANGE FROM THE CURRENT FORECAST IN THE SHORT
TERM WITH A 50/50 BLEND TOWARD THE 00Z GFS IN THE MID RANGE.
REASONING BEHIND THIS IS THAT THE GFS SOLUTION HAS BEEN FURTHER SOUTH
BUT OVER THE PAST COUPLE OF RUNS THE OTHER MODELS HAVE TRENDED TOWARD
THAT SOLUTION. PAST 84 HOURS THE 19/00Z ECMWF WAS CHOSEN AS THE MODEL
OF THE DAY FOR HOW IT HANDLED THE NEXT LOW PRESSURE SYSTEM MOVING IN
FROM THE WEST. THIS IS ALSO IN LINE WITH THE HPC SOLUTION WHICH
LEANED HEAVILY ON THE ECMWF.

.ANALYSIS AND UPPER LEVELS...
CURRENT UPPER LEVEL PATTERN SHOWS A CLOSED LOW CENTER OVER THE GULF
OF ALASKA WITH A RIDGE OVER THE BERING SEA. THE SURFACE ANALYSIS
SHOWS A SIMILAR PATTERN WITH A COMPLEX LOW SYSTEM ROTATING OVER THE
GULF OF ALASKA AND A BLOCKING SURFACE HIGH OVER THE EASTERN BERING.
AS THE LOW IN THE GULF CONTINUES TO MAINTAIN ITS POSITION SEVERAL
IMPULSES WILL MOVE SOUTHWARD INTO THE BASE OF THE TROUGH CONTINUING
TO PROVIDE UPPER LEVEL SUPPORT FOR THE SURFACE FEATURES.  BETWEEN THE
HIGH AND THE LOW A TIGHTENED GRADIENT AND A STRONG UPPER LEVEL JET
ARE CONTRIBUTING TO GUSTY NORTHERLY WINDS AT THE SURFACE AS WELL AS
CONTINUING TO STRENGTHEN THE LONG WAVE TROUGH.

.SHORT TERM FORECAST...
EAST OF THE ALASKA RANGE...THE LOW PRESSURE SYSTEM IN THE GULF OF
ALASKA IS BRINGING MOISTURE TO THE SOUTH CENTRAL REGION.  AS
MENTIONED PREVIOUSLY THE NORTHERLY FLOW AHEAD OF THIS FRONT COMBINED
WITH SOME COLD AIR DAMMING TO THE NORTH IS CAUSING GUSTY WINDS
THROUGH CHANNELED AREAS...PARTICULARLY IN NORTH-SOUTH ORIENTED PASSES
LIKE THOMPSON PASS.  THE PRESENCE OF A LOW LEVEL JET OVER THE KENAI
PENINSULA WILL BRING WIND SHEAR TO SOME AREAS AND GUSTY SURFACE WINDS
TO OTHERS. STORM FORCE WINDS WILL BE PRESENT ALL ACROSS THE MARINES
TODAY AS THE TEMPERATURE GRADIENTS AND CHANNELING ENHANCE THE LOCAL
WINDS. PRECIPITATION WILL BE CONFINED TO THE COASTAL AREAS...AND
TEMPERATURES WILL KEEP IT A MIX ALONG THE GULF COAST AND OVER KODIAK
TODAY.  THIS PATTERN WILL CONTINUE THROUGH FRIDAY AS THE LOW IN THE
GULF SHIFTS SLIGHTLY NORTHWARD AND CONTINUES TO PUSH FRONTAL BANDS
ONSHORE.

WEST OF THE ALASKA RANGE...THE NORTHERLY FLOW OVER THE WESTERN
MAINLAND WILL CAUSE GUSTY WINDS THROUGH CHANNELED AREAS ALONG THE AK
PEN TODAY...WITH SOME STRONGER LOW LEVEL WINDS ALONG THE KUSKOKWIM
DELTA.  STORM FORCE WINDS ARE EXPECTED IN THE MARINE ZONES ALONG THE
COAST AS THE GUSTY WINDS MOVE OFF THE MAINLAND.  OTHERWISE COLD TEMPS
AND NICE WEATHER WILL CONTINUE FOR THE MAINLAND THROUGH FRIDAY
MORNING.

IN THE ALEUTIANS...A STRONG LOW WILL MOVE INTO THE WESTERN ALEUTIANS
FROM THE SOUTH BEGINNING ON THURSDAY.  AS THIS LOW GAINS THE SUPPORT
OF THE COLD AIR ADVECTING IN FROM RUSSIA IT WILL CONTINUE TO
STRENGTHEN.  THIS WILL BRING UPPER GALE FORCE WINDS TO THE ALEUTIANS
ON FRIDAY.  HOWEVER AS THE FRONT ASSOCIATED WITH THIS SYSTEM
PROGRESSES EASTWARD IT WILL GRADUALLY WEAKEN. BY FRIDAY MORNING THE
SYSTEMS WILL BRING WIND AND RAIN TO THE CENTRAL ALEUTIANS.

.LONG TERM FORECAST...THE LOW IN THE ALEUTIANS ON FRIDAY WILL
CONTINUE TO PROGRESS EASTWARD AND GRADUALLY BECOME ABSORBED BY THE
LOW IN THE GULF.  THIS WILL CAUSE THE ENTIRE PATTERN TO RETROGRADE
AND BY SATURDAY MOST OF THE MAINLAND WILL SEE PRECIPITATION. CURRENT
TEMPERATURE FORECASTS INDICATE THIS WILL BE SNOW FOR THE MOST PART.
AFTER SATURDAY A RIDGE BUILDS INTO THE EASTERN BERING AGAIN BUT THIS
PATTERN LOOKS TO BE WEAKER THAN OUR CURRENT PATTERN SO IT WILL NOT
REMAIN NEARLY AS STAGNANT FOR NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...STORM 120 130 132 138 150
         GALE 125 140 141 155 160 165 172 175 176 180 185
         HEAVY FREEZING SPRAY 160 180
FIRE WEATHER...NONE

LEWF NOV 08