High Wind in Alaska, November 30, 2013

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
1250 PM AKST FRI NOV 29 2013

.ANALYSIS AND UPPER LEVELS...A HIGH AMPLITUDE PATTERN IS IN PLACE
WITH A CLOSED LOW/TROUGH OVER THE MAINLAND AND A RIDGE OVER THE
HEART OF THE BERING SEA. THE UPPER LOW IS SLOWLY MAKING ITS WAY
TOWARD THE YUKON WHILE A TROUGH AXIS EXTENDING SOUTHWESTWARD FROM
THE CENTER DROPS SOUTHWARD ACROSS SOUTHCENTRAL. GAP WINDS ALONG THE
GULF COAST HAVE DIMINISHED A BIT FROM YESTERDAY BUT PASSAGE OF THIS
TROUGH FOLLOWED BY AN INCREASE IN NORTHERLY FLOW BEHIND IT WILL HELP
KICK THINGS UP AGAIN. ASIDE FROM THE GAP WINDS THE WEATHER IS VERY
QUIET FROM THE CENTRAL BERING TO MAINLAND ALASKA. ON THE WEST SIDE
OF THE BERING RIDGE A TROUGH IS MOVING OUT OF ASIA WITH A SURFACE
COLD FRONT OVER THE WESTERN BERING PUSHING SLOWLY EASTWARD. A LONG
BUT NARROW FETCH OF MOISTURE IS STREAMING FROM THE TROPICS NORTHWARD
ACROSS THE FAR WESTERN ALEUTIANS INTO THE WESTERN BERING.

.MODEL DISCUSSION...12Z MODELS HAVE COME INTO MUCH BETTER AGREEMENT
WITH HANDLING OF UPPER LOW OVER MAINLAND ALASKA AND THE WAVES MOVING
AROUND IT. THIS LEADS TO INCREASED CONFIDENCE IN THE INTENSITY OF
GAP WINDS ACROSS SOUTHCENTRAL AND THE GULF COAST THE NEXT FEW DAYS.
ON THE OTHER HAND MODEL SPREAD REMAINS LARGE ON THE WEST SIDE OF THE
RIDGE WITH DIFFERENCES IN WHETHER UPPER SHORT-WAVES PHASE INTO A
SINGLE TROUGH AND LARGE DIFFERENCES IN THE STRENGTH AND MOVEMENT
OF THE ASSOCIATED SURFACE LOW. FOR NOW WILL STICK CLOSE TO INHERITED
FORECAST WHICH GIVES INDICATIONS OF A WEAK LOW MOVING THROUGH THE
AREA.

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...AS THE UPPER TROUGH MOVES SOUTH INTO THE GULF
THIS AFTERNOON AND EVENING SUBSIDENCE ASSOCIATED WITH ITS PASSAGE
COMBINED WITH STRENGTHENING NORTHERLY FLOW BEHIND IT WILL LEAD TO
AN INCREASE IN WINDS ACROSS THE REGION...ESPECIALLY THROUGH MOUNTAIN
PASSES AND AT HIGHER ELEVATIONS. WINDS IN LOWER OR PROTECTED VALLEYS
WILL REMAIN CALM OR LIGHT AND TEMPERATURES WILL REMAIN FRIGID.
ANOTHER UPPER WAVE WILL DROP DOWN FROM THE NORTH SATURDAY...SMALLER
AND MORE FOCUSED THAN THE TROUGH TODAY...WITH THE STRONGEST
SUBSIDENCE IN THE PRINCE WILLIAM SOUND REGION. AT THE SAME TIME THE
UPPER LOW WILL CONTINUE SOUTHEASTWARD AND THE UPPER RIDGE WILL BUILD
IN FROM THE WEST...WITH A STRONG UPPER JET MAKING ITS WAY INTO
SOUTHCENTRAL. LASTLY...SURFACE PRESSURE GRADIENTS WILL TIGHTEN AS
HIGH PRESSURE STRENGTHENS OVER INTERIOR ALASKA. ALL OF THIS POINTS
TO HIGH WINDS IN THE VALDEZ AREA AS WELL AS THROUGH THE COPPER RIVER
DELTA. WILL UPGRADE THE CURRENT WATCHES TO WARNINGS WITH THE
AFTERNOON PACKAGE. GAP WINDS WILL STRENGTHEN ACROSS THE REMAINDER
OF THE REGION SATURDAY...BUT REMAIN WELL BELOW WARNING LEVELS.
THE WIND EVENT WILL COME TO AN END SUNDAY NIGHT INTO MONDAY AS THE
UPPER RIDGE MOVES OVERHEAD. TEMPERATURES WILL THEN BEGIN TO SLOWLY
MODERATE EARLY NEXT WEEK AS WARMER AIR MOVES UP AND OVER THE RIDGE.

SOUTHWEST ALASKA...COLD AND DRY CONDITIONS WILL PERSIST ACROSS
SOUTHWEST ALASKA UNTIL THE RIDGE PASSES TO THE EAST EARLY NEXT WEEK.
ALTHOUGH THERE ARE SOME MODEL DIFFERENCES IN TIMING IT LOOKS LIKE
PRECIPITATION AND WARMER TEMPERATURES WILL RETURN TO THE SOUTHWEST
COAST MONDAY NIGHT OR TUESDAY. THERE LIKELY WILL BE SOME FROZEN
PRECIP TO START BUT WITH LOTS OF WARM AIR MOVING UP THE WEST SIDE
OF THE RIDGE EXPECT PRECIP TO CHANGE TO MOSTLY RAIN BY MID WEEK.

BERING SEA/ALEUTIANS...AS THE UPPER RIDGE SLIDES EASTWARD OVER THE
NEXT FEW DAYS WARM MOIST AIR WHICH IS CURRENTLY CONFINED TO THE
WESTERN BERING WILL OVERSPREAD THE REMAINDER OF THE REGION. AN
ACTIVE STORM TRACK WILL SET UP UNDERNEATH A BROAD UPPER TROUGH AS
WE HEAD THROUGH NEXT WEEK.

.LONG TERM FORECAST...THERE ARE DIFFERENCES IN PLACEMENT OF THE UPPER
RIDGE OVER MAINLAND ALASKA NEXT WEEK WHICH LEADS TO UNCERTAINTY IN
WHEN PRECIP MAY MAKE IT BACK INTO SOUTHCENTRAL. RIGHT NOW IT LOOKS
LIKE THE EARLIEST THAT WILL BE IS LATE NEXT WEEK. MEANWHILE...
TEMPERATURES WILL SLOWLY MODERATE THROUGH THE WEEK AS WARM AIR
MOVES UP AND OVER THE RIDGE. MEANWHILE THE STORM TRACK WILL SET UP
OUT WEST RESULTING IN ACTIVE WEATHER ACROSS MUCH OF THE BERING AND
ALEUTIANS AND INTO SOUTHWEST ALASKA. AN INITIALLY WARM AND MOIST
AIRMASS MEANS PRECIP WILL BE MAINLY IN THE FORM OF RAIN...ALTHOUGH
INDICATIONS ARE A LESS AMPLIFIED PATTERN LATE IN THE WEEK WILL ALLOW
COOLER AIR TO MOVE BACK IN FROM THE WEST.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WATCH...131 135.
         WIND CHILL ADVISORY...131.
MARINE...GALE WARNING...127 128 130 131 132 178 185.
         HEAVY FREEZING SPRAY WARNING...121 126 127 128 129 130 139.
FIRE WEATHER...NONE.

SEB NOV 13