High Wind in Alaska, November 5 to 6, 2013

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKST TUE NOV 5 2013

.ANALYSIS AND UPPER LEVELS...

A RAPIDLY INTENSIFYING AND EXPANDING EXTRATROPICAL CYCLONE CONTINUES
TO MOVE INTO OUR FAR WESTERN AREA OF RESPONSIBILITY THIS
MORNING...ALREADY BRINGING WIND GUSTS TO HURRICANE FORCE TO SHEMYA.
THIS LOW...AT AROUND 960 MB CURRENTLY...WILL BEGIN TO PEAK LATE
TONIGHT AND EARLY WEDNESDAY IN THE WEST-CENTRAL BERING AT 949 MB
BEFORE SLOWLY WEAKENING AS IT MOVES INLAND OVER FAR EASTERN RUSSIA.
THE ASSOCIATED POWERFUL WEATHER FRONT ASSOCIATED WITH THIS LOW WILL
MOVE EAST ACROSS THE BERING TODAY AND TONIGHT...AND THEN MOVE INLAND
DURING THE SECOND HALF OF WEDNESDAY WHILE SLOWLY WEAKENING.

MEANWHILE...RADAR AND SATELLITE IMAGERY CONTINUE TO SHOW A STACKED
LOW PRESSURE SYSTEM SPINNING IN THE NORTHERN GULF JUST WEST OF
MIDDLETON ISLAND. THIS LOW IS A BIT STRONGER THAN FIRST PREDICTED AND
WILL MOVE SOUTH AND EAST TOWARD THE EASTERN GULF TODAY A LITTLE
QUICKER THAN INITIALLY EXPECTED.

.MODEL DISCUSSION...

MODELS ARE HANDLING THE BOMBING LOW OUT WEST VERY WELL. THE GFS WAS
PREFERRED THROUGH WEDNESDAY MORNING...THEN THE EUROPEAN MODEL WAS
PREFERRED THEREAFTER WHEN WIDESPREAD STRONG WESTERLY FLOW MOVES
ACROSS THE BERING.

CLOSER TO SOUTHCENTRAL...MODELS APPEAR TO BE CATCHING ON TO THE
SLIGHTLY STRONGER STACKED LOW IN THE GULF TODAY. MODELS SUGGEST THAT
BECAUSE THE LOW IS A BIT STRONGER THAN INITIALLY THOUGHT IT WILL HELP
PULL DRIER OFFSHORE NORTHERLY FLOW ACROSS THE WESTERN SLOPES OF THE
CHUGACH AND KENAI MOUNTAIN RANGES...WHICH WOULD HELP KEEP ANCHORAGE
AND NEARBY AREAS FROM SEEING MUCH IN THE WAY OF ANY PRECIPITATION
TODAY INTO THIS EVENING.

OTHERWISE...THE ONLY OTHER NOTABLE MODEL DISAGREEMENT OCCURS THURSDAY
INTO THURSDAY NIGHT OVER THE NORTHERN GULF. AS THE WEAKENING FRONT
ASSOCIATED WITH THE POWERFUL LOW IN THE BERING MOVES ACROSS THE
AREA...A TRIPLE POINT LOW WILL DEVELOP IN THE GULF. THE GFS AND NAM
ARE IN AGREEMENT WITH THE TRIPLE POINT LOW DEVELOPING NEAR PRINCE
WILLIAM SOUND BUT DIFFER IN THE PLACEMENT OF THE LOW FROM THE
EUROPEAN AND CANADIAN MODELS...WHICH DEVELOP THE LOW OUT IN THE
CENTRAL GULF. THIS LOW PLACEMENT WILL PLAY A SIGNIFICANT ROLE IN
PRECIPITATION AMOUNTS ESPECIALLY TOWARD INLAND AREAS SUCH AS
ANCHORAGE AND PALMER THURSDAY INTO THURSDAY NIGHT. AT THIS TIME THE
FORECAST WILL LEAN SLIGHTLY MORE TOWARD THE GFS AND NAM.

.SHORT TERM FORECAST...

SOUTHCENTRAL...

AS MENTIONED ABOVE...IT APPEARS THAT LOW-LEVEL DRIER AIR WILL BE
ARRIVING A BIT SOONER THAN ORIGINALLY ADVERTISED FOR ANCHORAGE
TODAY...AND THIS SHOULD KEEP MOST OF THE COOK INLET REGION FAIRLY
DRY. THE EXCEPTION MIGHT BE RIGHT ALONG THE MOUNTAINS WHERE A FEW
FLAKES MAY FALL...BUT IT APPEARS AS THOUGH WE WILL BE TRENDING THE
SNOW FORECAST DOWNWARD THROUGH THE DAY TODAY AS CONFIDENCE INCREASES.
THE ONE PLACE THAT LOOKS MORE PROMISING FOR SOME SNOWFALL TODAY IS
THE COPPER RIVER BASIN WHERE A WEAK DEFORMATION ZONE SHOULD ALLOW FOR
A PERIOD OF LIGHT SNOW TO OCCUR THIS AFTERNOON INTO EARLY EVENING
BEFORE ENDING. OTHERWISE...PRECIPITATION SHOULD BE MAINLY CONFINED TO
THE PRINCE WILLIAM SOUND AND NORTH GULF COAST REGION AS THE LOW MOVES
AWAY FROM THE AREA OVER THE NEXT COUPLE OF DAYS.

HIGH PRESSURE BUILDS OVER THE AREA AND OFFSHORE FLOW DEVELOPS...WHICH
WILL BE GUSTY THROUGH THE USUAL AREAS SUCH AS WHITTIER...THOMPSON
PASS THROUGH VALDEZ...AND SEWARD...WITH THESE WINDS PEAKING TUESDAY
INTO WEDNESDAY BEFORE BEGINNING TO WIND DOWN AS THE HIGH MOVES EAST.
ATTENTION THEN TURNS TO THE WEAKENING FRONT MOVING ACROSS THE AREA
THURSDAY INTO THURSDAY NIGHT. THE GFS AND NAM ARE BOTH IN AGREEMENT
(BUT IN CONTRAST TO MOST OTHER MODELS) IN TUCKING A SURFACE LOW NEAR
OR IN PRINCE WILLIAM SOUND. IF THIS WERE TO OCCUR ANCHORAGE WOULD
PICK UP ITS FIRST OFFICIAL SNOWFALL OF THE YEAR THURSDAY NIGHT. WHILE
THE FORECAST IS BEGINNING TO LEAN IN THAT DIRECTION...CONFIDENCE
REMAINS FAIRLY LOW SO STAY TUNED.

SOUTHWEST MAINLAND...

NORTHWEST FLOW WITH A WEAK DISTURBANCE MOVING SOUTHEAST ACROSS THE
KUSKOKWIM DELTA WILL HELP KEEP CLOUDS AND ISOLATED FLURRIES ACROSS
THIS AREA THIS MORNING. OTHERWISE...SKIES SHOULD FOR THE MOST PART
DECREASE IN COVERAGE ACROSS BRISTOL BAY AND THE KUSKOKWIM VALLEY.

THE FRONT ASSOCIATED WITH THE POWERFUL LOW IN THE BERING WILL BEGIN
TO IMPACT THE AREA WEDNESDAY WITH STRONG WINDS ESPECIALLY ALONG THE
COAST FROM CAPE NEWENHAM NORTH...AND WILL PRESENT PRECIPITATION TYPE
CONCERNS AS THE WARMER AIR BEGINS TO OVERRIDE THE COLDER AIR NEAR THE
SURFACE. AT THIS TIME WE DO NOT EXPECT THE NEED FOR ANY WINTER
WEATHER ADVISORIES DUE TO THE RAPID MOVEMENT OF THE FRONT AND THE
EXPECTED WARMING WITH THE FRONT AFTER THE PRECIPITATION BEGINS.
HOWEVER...THIS WILL BEAR CLOSE WATCHING.

BEHIND THE FRONT...WIDESPREAD STRONG WESTERLY FLOW DEVELOPS ACROSS
THE BERING WEDNESDAY THROUGH FRIDAY. THE LARGE SWELL GENERATED BY THE
CYCLONE WILL BE REINFORCED BY THIS STRONG WESTERLY FLOW...AND WILL
LIKELY GENERATE A STORM SURGE ALONG THE SOUTHWEST MAINLAND FROM CAPE
NEWENHAM NORTH. FOR THAT REASON A COASTAL FLOOD WATCH HAS BEEN ISSUED
FOR THIS AREA. THE ONLY CHANGE WAS TO BEGIN THE WATCH TIME SOONER
(WEDNESDAY AFTERNOON INSTEAD OF WEDNESDAY NIGHT).

BERING SEA/ALEUTIANS/AKPEN...

HIGH WINDS TO HURRICANE FORCE WILL CONTINUE TO BATTER THE WESTERN
ALEUTIANS THROUGH EARLY WEDNESDAY...AND TO A SLIGHTLY LESSER EXTENT
THE CENTRAL ALEUTIANS LATER TODAY. PARTICULARLY CONCERNING WILL BE ON
THE BACK EDGE OF THE CYCLONE AS COLD AIR ALOFT RAPIDLY ADVANCES INTO
THE BACK OF THE LOW AND GENERATES EXTREMELY POWERFUL WINDS
APPROACHING 100 MPH IN GUSTS NEAR SHEMYA TONIGHT.

ADDITIONALLY...IT APPEARS THE WINDS ASSOCIATED WITH THIS CYCLONE WILL
REMAIN STRONG ENOUGH TO WARRANT A HIGH WIND WARNING ISSUANCE FOR THE
PRIBILOF ISLANDS FOR TONIGHT. MARINERS ARE URGED IN THIS AREA TO TAKE
PRECAUTIONS FOR POWERFUL WINDS AND WAVE HEIGHTS TO 40 FEET OR MORE
ACROSS THE BERING SEA.

.LONG TERM FORECAST...

A STRONGLY PROGRESSIVE PATTERN ESTABLISHES ITSELF BY LATE WEEK INTO
THE WEEKEND ACROSS THE BERING REGION BEHIND THE BERING SEA LOW.
MODELS SUGGEST A FULL-LATITUDE COLD FRONT MOVING RAPIDLY EAST FROM
THE BERING SEA ACROSS THE SOUTHERN MAINLAND THIS WEEKEND...WHICH
WOULD BRING THE NEXT SHOT FOR PRECIPITATION TO SOUTHCENTRAL. OUT
WEST...STRONG WESTERLY FLOW LATE WEEK INTO SATURDAY WILL KEEP STRONG
ONSHORE FLOW AND PLENTIFUL PRECIPITATION IN THE FORECAST.
MEANWHILE...AN UNUSUALLY STRONG HIGH PRESSURE AT THE SURFACE OVER THE
NORTH PACIFIC WILL KEEP THE ALEUTIANS FAIRLY DRY FOR THE WEEKEND
BEHIND COLD FRONTAL PASSAGE FRIDAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING...187 191 195
         COASTAL FLOOD WATCH...155 161
MARINE...GALES...120 127 130-132 136-138 150 155 160 165 171
         STORMS...170 172-177 179-181 185
         HURRICANE FORCE...178
FIRE WEATHER...NONE.

CC NOV 13