High Wind Watch 10, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
520 AM AKDT THU OCT 8 2009

.ANALYSIS AND UPPER LEVELS...

A HIGHLY AMPLIFIED WAVE PATTERN CONTINUES OVER THE REGION...WITH A
STRONG BLOCKING RIDGE MAINTAINING STRENGTH FROM THE EASTERN GULF
EXTENDING NORTHWARD ACROSS THE CENTRAL PART OF THE STATE OF ALASKA.
STRONG STACKED MID-LEVEL AND SURFACE LOWS CONTINUE TO REMAIN JUST
SOUTH OF THE EASTERN ALEUTIANS...WITH A STRONG SOUTHERLY JET STREAK
TRANSPORTING LOTS OF MOISTURE FROM THE SUBTROPICS INTO SOUTHWESTERN
ALASKA. ANOTHER IN A SERIES OF FRONTS HAS MOVED NORTH FROM THE GULF
INTO THE PRINCE WILLIAM SOUND AREA...AND WILL CONTINUE TO WEAKEN
AGAINST THE HIGH TERRAIN ALONG THE COAST.

.MODEL DISCUSSION...

MODELS ARE IN GOOD AGREEMENT THROUGH THE WEEKEND ON ALL SIGNIFICANT
WEATHER FEATURES TO AFFECT THE REGION. THE GFS AND EUROPEAN HAVE COME
INTO MUCH BETTER AGREEMENT OVER THE LAST 24 HOURS CONCERNING THE
PROGRESSION OF A MODERATE LOW WHICH WILL MOVE ACROSS THE ALASKA
PENINSULA FRIDAY NIGHT. THIS SYSTEM WILL BRING HIGH WIND CRITERIA OF
75 MPH GUSTS TO PARTS OF THE BRISTOL BAY REGION...ESPECIALLY ALONG
CHANNELED TERRAIN OF THE ALEUTIAN RANGE FRIDAY NIGHT INTO SATURDAY
MORNING.

.SHORT TERM FORECAST...

SOUTH AND EAST OF THE ALASKA RANGE...

THE MAIN ISSUE OVER THE NEXT FEW DAYS IS DETERMINING HOW STRONG WINDS
WILL BLOW THROUGH THE WEST-EAST TERRAIN GAPS WITH TWO SEPARATE LOWS
SET TO TRACK INTO THE BERING SEA OVER THE NEXT 60 HOURS. STRONG HIGH
PRESSURE WILL CONTINUE TO STRENGTHEN ALONG THE COAST AS STRONG
SOUTHEAST FLOW PILES THE AIR AGAINST THE CHUGACH RANGE AND INCREASES
SURFACE PRESSURES IN PRINCE WILLIAM SOUND. AS LOW PRESSURE IN THE
NORTH PACIFIC MOVES NORTH ACROSS THE EASTERN ALEUTIANS INTO THE
CENTRAL BERING SEA...WE SHOULD SEE AT LEAST STORM FORCE WINDS THROUGH
TURNAGAIN ARM BEGINNING THIS EVENING THROUGH FRIDAY MORNING AS THE
PRESSURE GRADIENT STRENGTHENS. AS THE LOW WEAKENS IN THE BERING SEA
FRIDAY WINDS SHOULD GRADUALLY SUBSIDE...BUT WILL THEN STRENGTHEN ONCE
AGAIN AS ANOTHER STRONG LOW MOVES NORTHWARD FROM THE NORTH PACIFIC
INTO THE EASTERN AND THEN CENTRAL BERING SEA FRIDAY NIGHT INTO
SATURDAY MORNING. WITH A STRONG JET STREAK IN SOUTHEASTERLY FLOW...IT
IS POSSIBLE THAT WINDS GUSTING TO HURRICANE FORCE ARE POSSIBLE IN THE
COASTAL WATERS OF THE WESTERN GULF...WITH STORM FORCE WINDS A SURE
BET. STILL...GIVEN THAT HIGH WIND CRITERIA OF 75 MPH FOR AREAS THAT
MIGHT BE AFFECTED (SUCH AS KODIAK ISLAND AND SURROUNDING COASTAL
WATERS AS WELL AS TURNAGAIN ARM) WOULD OCCUR DURING THE FOURTH
PERIOD...DECIDED TO LEAVE THE DECISION FOR THE ISSUANCE OF A HIGH
WIND WATCH OR WARNING UP TO THE AFTERNOON CREW.

SOUTHWEST ALASKA...

THE MAJOR ISSUE HERE ONCE AGAIN IS WINDS ASSOCIATED WITH THE MODERATE

LOW THAT WILL MOVE ACROSS THE AKPEN FROM THE NORTH PACIFIC FRIDAY
NIGHT INTO SATURDAY. WITH STRONG SOUTHEASTERLY FLOW ALOFT AND A VERY
STRONG EAST-WEST PRESSURE GRADIENT...WINDS ARE NOW FORECASTED TO
REACH HIGH WIND CRITERIA WITH GUSTS TO 75 MPH FOR THE BRISTOL BAY
ZONE...PARTICULARLY THROUGH CHANNELED TERRAIN ALONG THE ALEUTIAN
RANGE. THUS...A HIGH WIND WATCH HAS BEEN ISSUED FOR THE BRISTOL BAY
ZONE. STRONG WINDS WILL ALSO AFFECT BRISTOL BAY WATERS WITH GUSTS
LIKELY REACHING AT LEAST HIGH-END STORM FORCE.

BERING SEA/ALEUTIANS/ALASKA PENINSULA...

THE EXTREMELY ACTIVE WEATHER PATTERN LOOKS TO CONTINUE WITH LITTLE
END IN SIGHT. A SERIES OF LOWS WILL MOVE FROM THE NORTH PACIFIC INTO
THE CENTRAL BERING SEA AND THEN DISSIPATE THROUGH SATURDAY AROUND
CYCLONIC FLOW ALOFT CENTERED NEAR THE CENTRAL AND EASTERN ALEUTIANS.

.LONG TERM FORECAST...

IT APPEARS MOST OF THE STATE MAY FINALLY CATCH A BREAK FROM THE
ACTIVE WEATHER BY EARLY NEXT WEEK...AS STRONG RIDGING ALOFT CONTINUES
TO BUILD OVER THE STATE AND THE LOW IN THE ALEUTIANS DIGS INTO THE
SOUTHERN GULF OR NORTHEAST PACIFIC OCEAN. THIS SHOULD EVENTUALLY LEAD
TO MOSTLY OFFSHORE FLOW LEADING TO MUCH DRIER WEATHER ACROSS SOUTHERN
ALASKA...AND A RETURN TO COOLER TEMPERATURES.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WATCH...161.
MARINE...GALE WARNING...120 140 141 155 160 165 170 171 176 179 185
         STORM WARNING...130 132 138 150
FIRE WEATHER...NONE.

CC OCT 09