High Wind Watch 10, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
400 PM AKDT WED OCT 8 2008

.ANALYSIS AND UPPER LEVELS...THE UPPER LEVEL TROUGH THAT HAS DRIVEN
THE WEATHER OVER THE SOUTHERN MAINLAND THE PAST WEEK IS NOW EXITING
OFF TO THE EAST. A FILLING LOW OVER THE NORTHEAST GULF IS PRODUCING
JUST A FEW SHOWERS ALONG THE NORTH GULF COAST. THERE IS ALSO A
REMNANT MID-LEVEL CLOUD DECK LINGERING ALONG THE MOUNTAINS OF
SOUTHCENTRAL ALONG WITH A FEW PATCHES OF FOG. OTHERWISE...CONDITIONS
HAVE CLEARED OUT ACROSS THE SOUTHERN MAINLAND.

OUT WEST THERE IS A LARGE VERTICALLY STACKED LOW OVER THE WESTERN
BERING. UPPER LEVEL JET ON THE BACK SIDE OF THIS TROUGH IS CAUSING
AMPLIFICATION. AT THE BOTTOM OF THE TROUGH IS A 165 KT SUBTROPICAL
JET. RIGHT AHEAD OF THE TROUGH IN THE LEFT EXIT REGION OF THE
SUBTROPICAL JET IS A RAPIDLY DEVELOPING LOW...WHICH WILL BE A
MAJOR WEATHER MAKER FOR THE FORECAST AREA OVER THE NEXT FEW DAYS.

.MODEL DISCUSSION...12Z MODEL SOLUTIONS ARE IN GOOD AGREEMENT
THROUGH THE FIRST FEW DAYS OF THE FORECAST. THERE IS A SLIGHT
CHANGE IN TRACK OF THE LOW AND SPEED OF THE FRONT AND THESE
CHANGES WILL BE INCORPORATED INTO THE FORECAST. OTHER REFINEMENTS
OF THE FORECAST WILL FOCUS ON THE FIRST FEW PERIODS OF THE FORECAST.

.SHORT TERM FORECAST...

SOUTHCENTRAL...CONDITIONS WILL QUICKLY HEAD DOWNHILL LATE TONIGHT
OVER KODIAK ISLAND AND THE ACROSS THE REST OF SOUTHCENTRAL DURING
THE DAY THURSDAY. THERE IS ENOUGH COLD AIR IN PLACE THAT
PRECIPITATION WILL INITIALLY BE IN THE FORM OF SNOW...BUT SIGNIFICANT
ADVECTION WILL QUICKLY CHANGE THE SNOW TO RAIN MOST LOCATIONS BEFORE
ANY SIGNIFICANT ACCUMULATION CAN OCCUR. THE EXCEPTIONS ARE HIGHER
ELEVATIONS SUCH AS THOMPSON PASS...THE NORTHERN SUSITNA VALLEY...AND
ALONG THE MOUNTAINS OF THE COPPER BASIN WHERE SNOW ACCUMULATION IS
LIKELY THURSDAY NIGHT BEFORE MIXING WITH OR CHANGING TO RAIN ON
FRIDAY. SNOW ACCUMULATION IS ALSO LIKELY IN THE SUSITNA VALLEY
WEST OF THE PARKS HIGHWAY THURSDAY NIGHT. TEMPERATURE MAY BE
SLIGHTLY ABOVE FREEZING SO IT WILL BE VERY WET SNOW. STRONG EASTERLY
WINDS WILL RESULT IN SOME DOWNSLOPING WHICH WILL MINIMIZE
PRECIPITATION IN THE USUAL PLACES...BUT FLOW ALOFT WILL BE OUT OF
THE (MORE FAVORABLE) SOUTH AND SYSTEM DYNAMICS ARE STRONG...SO EXPECT
EVEN DOWNSLOPE AREAS WILL SEE SOME LIGHT PRECIPITATION.

A VERY STRONG FRONT WILL PUSH ACROSS THE GULF THURSDAY AND THURSDAY
NIGHT SETTING UP A STORM FORCE BARRIER JET WITH HURRICANE FORCE GUSTS
THROUGH CHANNELED AREAS ALONG THE NORTH GULF COAST. STRONG SOUTHERLY
FLOW ALOFT WILL PUSH THIS FRONT INLAND...SO WINDS WILL SPREAD INTO
PRINCE WILLIAM SOUND...PASSAGE CANAL...AND BECOME GUSTY OVER INLAND
LOCATIONS AS THE FRONT MOVES THROUGH LATE THURSDAY NIGHT AND FRIDAY.

BASED VERY GOOD MODEL CONSISTENCY IN THE STRENGTH OF THIS FRONT AND
BETTER MODEL AGREEMENT ON TRIPLE POINT DEVELOPMENT NEAR BARREN
ISLANDS AND NORTHWARD TRACK OF WEAK TRIPLE POINT LOW...THE HIGH WIND
WATCHES FOR ZONE 101 AND 125 WILL BE UPGRADED TO A WARNING. ALSO...A
HIGH WIND WATCH WILL BE ISSUED FOR SOUTHEAST PRINCE WILLIAM SOUND.

SOUTHWEST ALASKA...SOUTHWEST ALASKA WILL SEE A LOT OF THE SAME
AFFECTS AS SOUTHCENTRAL. EXPECT RAIN AND STRONG WINDS TO OVERSPREAD
BRISTOL BAY LATE TONIGHT INTO THURSDAY. PRECIPITATION FARTHER NORTH
OVER THE KUSKOKWIM VALLEY AND DELTA WILL START AS SNOW THURSDAY NIGHT
BUT MIX WITH OR CHANGE TO RAIN BY FRIDAY MORNING.

BERING SEA/ALEUTIANS...EXPECT WIDESPREAD GALE TO STORM FORCE WINDS
ACROSS THE ENTIRE REGION BY THURSDAY. THE LOW LOOKS LIKE IT WILL
BOTTOM OUT AROUND 960 MB THURSDAY AFTERNOON. COLD ADVECTION ON THE
BACK SIDE OF THE LOW WILL HELP ENHANCE WINDS...SO THERE COULD BE
SOME HURRICANE FORCE GUSTS OVER THE CENTRAL BERING. THE LOW WILL
TRACK EASTWARD TOWARD THE GULF ON FRIDAY SETTING UP BROAD AND STRONG
NORTHWEST FLOW OVER THE EASTERN BERING REGION. THESE WINDS WILL
GRADUALLY DIMINISH FROM WEST TO EAST THROUGH THE WEEKEND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING 101 125. HIGH WIND WATCH 135.
MARINE...STORM WARNING 120 125 155 170 172 179 180 185.
         GALE WARNING 129 130 132 150 160 165 171 175 176.
FIRE WEATHER...NONE.

SEB OCT 08