High Wind in Alaska, October 6, 2009

AREA FORECAST DISCUSSION...CORRECTION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKDT TUE OCT 6 2009

.ANALYSIS AND UPPER LEVELS...
A MAJOR LOW PRESSURE SYSTEM IS APPARENT ON SATELLITE THIS MORNING
JUST SOUTH OF THE ALEUTIAN CHAIN.  THIS SYSTEM HAS A SOUTHERLY JET
EXTENDING ALMOST ALL THE WAY TO HAWAII AND AS A RESULT IS ENTRAINING
PLENTY OF WARM AIR AND MOISTURE.  AS THE LOW CONTINUES TO MOVE
NORTHWARD IT WILL STRENGTHEN SLIGHTLY WITH COLDER TEMPERATURES
FEEDING IT FROM THE NORTHERN BERING.  THE COLD AIR TO THE NORTH IS
NOT EXTREMELY COLD HOWEVER SO THIS SYSTEM WILL PLATEAU ONCE IT
REACHES THE BERING.  HOWEVER BY THAT TIME A NEW LOW PRESSURE SYSTEM
WILL BE APPROACHING FROM THE SOUTH...ON A SIMILAR TRACK AND
STRENGTHENING PATTERN.  MEANWHILE OVER THE EAST A RIDGE IS SETTING UP
OVER THE GULF OF ALASKA AND WILL EXTEND INTO THE PANHANDLE AND
WESTERN CANADA.  THIS RIDGE WILL CONTINUE TO STRENGTHEN AS WARM AIR
IS PUMPED INTO IT BY THE SOUTHERLY JET...KEEPING THE LOW PRESSURE
SYSTEMS TO THE WEST OUT IN THE BERING.

.MODEL DISCUSSION...
MODEL CONSISTENCY AND AGREEMENT HAS IMPROVED OVER THE PAST SEVERAL
DAYS.  IN THE SHORT TERM THE MODELS WERE IN GOOD AGREEMENT ON THE LOW
JUST APPROACHING THE CENTRAL ALEUTIANS.  THERE ARE SOME SLIGHT
DIFFERENCES ON FRIDAYS LOW PRESSURE SYSTEM HOWEVER.  MODELS HAVE BEEN
TRENDING ON A SLOWER SOLUTION FOR THAT LOW OVER THE PAST SEVERAL DAYS
AND TODAY GFS WAS FAIRLY CONSISTENT WITH PREVIOUS RUNS BUT THE ECMWF
HAD SLOWED THE LOW DOWN AGAIN.  IN THE EAST THERE WERE ALSO SOME
DIFFERENCES WITH HOW THE MODELS HANDLED THE FRONT MOVING THROUGH THE
GULF.  THE ECMWF KEPT A STRONG FRONTAL BAND ALONG THE NORTH GULF
COAST WHILE THE GFS MOVED THE FRONT THROUGH RAPIDLY.  ALTHOUGH THE
GFS WAS CHOSEN AS THE MODEL OF THE DAY OUT WEST...THE ECMWF SOLUTION
WAS USED FOR THE EASTERN ZONES AFTER 84 HOURS TO KEEP THAT FRONTAL
BAND ALONG THE NORTH GULF COAST.  AS FOR THE SHORT TERM...FEW EDITS
WERE MADE BUT THE OVERALL PATTERN LEANED TOWARD THE GFS SOLUTION.

.SHORT TERM FORECAST...
IN THE EAST...A SHORT RESPITE TODAY FROM THE WEATHER AS THE RIDGE
MOVES OVERHEAD. HOWEVER BY TONIGHT THE WARM FRONT WILL MOVE UP INTO
THE GULF OF ALASKA AND RAPIDLY PROGRESS INTO SOUTHCENTRAL ALASKA.
THIS IS NOT EXPECTED TO BE A STRONG CHINOOK EVENT BUT SOME
SOUTHEASTERLY WINDS WILL MAKE IT INTO THE AREA.  RAIN WILL FALL
ACROSS THE SOUTHCENTRAL AREA TONIGHT AND INTO TOMORROW AS
SOUTHWESTERLY FLOW ALOFT BRINGS PLENTY OF UPPER LEVEL MOISTURE. NOT
MUCH OF A BREAK CAN BE EXPECTED BEFORE THE NEXT SYSTEM ARRIVES
WEDNESDAY NIGHT AND THURSDAY...WITH SIMILAR CONDITIONS EXPECTED.
THIS SYSTEM IS A BIT STRONGER AND FURTHER EAST...SO TURNAGAIN ARM
WINDS IN PARTICULAR MAY BE STRONGER ON THURSDAY.

OUT WEST...MOST OF THE ACTION IS HAPPENING OUT WEST WITH STORM AFTER
STORM HITTING THE EASTERN ALEUTIANS.  THE LOW MOVING UP TODAY IS
EXPECTED TO REACH 979 MB...WHICH SHOULD BRING GALES TO MOST OF THE
MARINES AND STORMS ALONG THE SOUTHERN SIDE OF THE AK PEN.  THE AK PEN
AND THE EASTERN ALEUTIANS CAN EXPECT STRONG WINDS AT THE SURFACE WITH
SOME WIND SHEAR ALOFT AS JET SUPPORT IS PRETTY WELL STACKED THROUGH
THE SYSTEM.  THIS SYSTEM MOVES INTO THE BERING AND WEAKENS ON
WEDNESDAY BUT ANOTHER LOW MOVES UP IN ITS PLACE WEDNESDAY NIGHT.  THE
SECOND LOW IS A BIT STRONGER BUT THE JET SUPPORT AT THE LOWER LEVELS
IS A BIT WEAKER SO WINDS MAY NOT BE QUITE AS STRONG.

.LONG TERM FORECAST...
THIS PATTERN OF STRONG LOWS HITTING THE CENTRAL ALEUTIANS WILL NOT
END IN THE LONG TERM EITHER.  ON FRIDAY A VERY STRONG LOW PRESSURE
SYSTEM IS EXPECTED TO MOVE INTO THE BRISTOL BAY REGION. THIS SHOULD
BRING VERY STRONG WINDS TO MOST OF THE MAINLAND AND SOUTHCENTRAL ON
FRIDAY NIGHT AND SATURDAY...AND BEARS WATCHING FOR THE ACTUAL
STRENGTH OF THE SYSTEM.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...STORMS 155 170 171
         GALES 120 130 150 160 165 180 172 185 179
FIRE WEATHER...NONE

LEWF OCT 09