Gale Warning 395, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKDT THU APR 9 2009

.MODEL DISCUSSION...
IN THE SHORT TERM GFS WAS USED.  THERE WERE A FEW SLIGHT DIFFERENCES
BETWEEN THE GFS AND THE NAM IN THE WAY THEY HANDLED THE LOW THAT
MOVES INTO THE GULF OF ALASKA AT THE 48 HOUR TIME FRAME.  NAM HAD THE
FURTHER SOUTH SOLUTION...BUT GFS WAS PREFERRED DUE TO ITS CONSISTENCY
AND EXCELLENT INITIALIZATION. AFTER 60 HOURS MODELS BEGAN TO DIVERGE
ON THEIR SOLUTIONS.  GFS AND ECMWF BOTH PLACE A COMPLEX LOW SYSTEM IN
THE GULF OF ALASKA BUT TIMING AND PLACEMENT OF THE INDIVIDUAL LOW
CENTERS VARIED DRAMATICALLY.  THE SOLUTION AT THIS POINT WAS TO GO
WITH HPC GUIDANCE...WHICH HAS BEEN VERY CONSISTENT AND WAS MORE OF A
BLEND BETWEEN THE TWO SOLUTIONS.

.ANALYSIS AND UPPER LEVELS...
LONGWAVE TROUGH IS STATIONED OVER THE WESTERN PORTION OF THE
MAINLAND...VERTICALLY STACKED WITH A SURFACE LOW JUST SOUTH OF COLD
BAY.  IN SPITE OF THE FACT THAT IT IS VERTICALLY STACKED THIS SURFACE
LOW WILL MAINTAIN ITS STRENGTH AS IT MOVES INTO THE GULF OF ALASKA
THANKS TO THE COLD AIR POURING SOUTHWARD THROUGH THE BERING.
ALTHOUGH THE RIDGE OVER THE WESTERN BERING IS NOT EXTRAORDINARILY
STRONG IT WILL ENHANCE THE COLD AIR ADVECTION OVER THE BERING FOR THE
NEXT COUPLE OF DAYS. BY SUNDAY THE COLD AIR BEGINS TO TAPER OFF AND
THE LOW WILL SLOWLY FILL IN THE GULF OF AK.

.SHORT TERM FORECAST...
IN THE EAST...SOUTHEASTERLY FLOW IS CAUSING A RAIN SHADOW OVER THE
ANCHORAGE BOWL AND MOST OF THE WESTERN KENAI THIS MORNING.  ON THE
EASTERN KENAI TEMPERATURES ARE STILL COLD ENOUGH TO BRING BLIZZARD
CONDITIONS TO PORTAGE AND WHITTIER.  THE TEMPERATURES ARE NOT
EXPECTED TO WARM UP BEFORE THE WINDS TAPER OFF LATER THIS MORNING. AS
THE LOW FILLS IN THE GULF THE PRECIPITATION ACROSS THE REGION WILL
BECOME MORE SHOWERY AND SOME AREAS MAY EVEN SEE BREAKS IN THE CLOUDS
ON SATURDAY.

WEST OF THE ALASKA RANGE...THE MAINLAND WILL CONTINUE TO SEE SHOWERY
PRECIPITATION OVER THE NEXT COUPLE OF DAYS AS THE LOW MOVES OFF TO
THE EAST AND SLOWLY FILLS.  ALONG THE KUSKOKWIM DELTA GUSTY NORTHERLY
WINDS ARE EXPECTED ON THE BACKSIDE OF THE LOW BUT THE BLOWING SNOW
WILL REMAIN LOCALIZED ALONG THE COAST. BANDS OF SHOWERS WILL MOVE
THROUGH THE PRIBILOFS AND THE AK PEN TODAY BUT WILL RAPIDLY DECREASE
AS THE LOW MOVES EASTWARD AND THE SHORTWAVE RIDGE SETS IN. BY
SATURDAY AFTERNOON RELATIVELY BENIGN CONDITIONS ARE EXPECTED ACROSS
THE BERING WITH THE RIDGE OVERHEAD.

.LONG TERM FORECAST...
THE RIDGE THAT SETS UP OVER THE CENTRAL BERING OVER THE WEEKEND WILL
BECOME A CUT OFF HIGH BY THE BEGINNING OF NEXT WEEK.  THIS WILL KEEP
ANY LOW PRESSURE SYSTEMS TO THE SOUTH OF THE ALEUTIANS AND PRETTY FAR
SOUTH IN THE GULF OF AK AS WELL.  SUNNY CONDITIONS BUT COOL
TEMPERATURES CAN BE EXPECTED OUT WEST...WITH MORE SHOWERS MOVING IN
FOR THE EAST AS A NEW LOW MOVES UP ON THE EAST SIDE OF THE HIGH.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 125
MARINE...GALE 120 176
         HEAVY FREEZING SPRAY 165 179
FIRE WEATHER...NONE

LEWF APR 09