Gale Warning 1, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
342 PM AKST WED DEC 31 2014

.SHORT TERM...WEAKENING OCCLUDED FRONT WILL STALL OVER THE AREA AS
LOW PRESSURE BEGINS TO DEVELOP OVER THE NE PAC TONIGHT. THE LOW
WILL INTENSIFY TO STORM FORCE AND MOVE ACROSS THE CENTRAL GULF TO
JUST S OF CAPE SPENCER BY LATE THU AFTERNOON. USED BLEND OF THE
12Z GEM AND ECMWF AS THEY HAD BEST HANDLE ON MAIN FEATURES.

MAIN FORECAST CONCERNS WILL BE POTENTIAL FOR HAZARDOUS WINTER
WEATHER OVER THE N...AND WINDS. A SHALLOW COLD AIRMASS REMAINS
OVER THE CHILKAT VALLEY AND WILL REMAIN THERE INTO THU AS LOW
LEVEL WNW FLOW MAINTAINS THE COLD AIR. WARMER AIR RIDING OVER THIS
COLD AIR AHEAD OF LOW MOVING IN WILL CAUSE SNOW AND FREEZING RAIN
TO FALL IN THE CHILKAT VALLEY LATE TONIGHT AND THU...WITH THE
FREEZING RAIN EXPECTED EAST OF THE CHILKAT RIVER BRIDGE. WEST OF
THE BRIDGE HEAVY SNOWFALL IS EXPECTED...WITH LIGHTER SNOWFALL BUT
UP TO A HALF INCH OF ICE EAST OF THE BRIDGE. HAVE ISSUED A WINTER
STORM WARNING FOR THE CHILKAT VALLEY STARTING AT 09Z TONIGHT. IN
THE SKAGWAY AREA...WHITE PASS SHOULD REMAIN COLD ENOUGH FOR SNOW.
THINK THEY WILL SEE A DECENT ACCUMULATION THERE...ENOUGH TO ISSUE
A WINTER WEATHER ADVY FOR WHITE PASS BEGINNING AT 15Z THU. THINK
MOST ACCUMULATING SNOW WILL BE ABOVE 1500 FEET. COULD GET 4 TO 6
INCHES OF SNOW IN THE PASS BY THU EVENING.

AS FOR WINDS...THEY WILL INCREASE AS LOW MOVES IN. THE STRONGEST
WINDS ARE EXPECTED ON THE S-W SIDE OF THE LOW THU AFTERNOON WITH
STORM FORCE W-NW WINDS OVER MARINE ZONE 310. GALE FORCE WINDS ARE
EXPECTED FOR MUCH OF THE GULF COASTAL WATERS THU...WITH SOME GALE
FORCE WINDS IN THE SRN AND CENTRAL INNER CHANNELS THU. REST OF THE
AREA WILL SEE AT LEAST SCA LEVEL WINDS THU. MAY NEED STRONG WIND
HEADLINES FOR THE CENTRAL AND SRN COASTAL AREAS ESPECIALLY THU
AFTERNOON.

OTHERWISE...PRECIP HAS DIMINISHED OVER THE FAR NWRN AREA. IT WILL
RETURN THERE LATE TONIGHT. PRECIP RATES WILL INCREASE ON THU OVER
MOST OF SE AK AS LOW MOVES IN. TEMPS WILL GENERALLY REMAIN NEARLY
STEADY OR RISE A BIT OVER MOST AREAS TONIGHT. NOT MUCH RISE ON THU
EITHER DUE TO PRECIP.

.LONG TERM...WINTER WEATHER ADVISORY/WARNING WILL STILL BE GOING
ON AT THE START OF THE EXTENDED RANGE FORECAST PERIOD, BUT THINGS
WILL BE WINDING DOWN. AS THE PRECIPITATION TAPERS OFF, FRIDAY'S
HIGH TEMPERATURES WILL OCCUR EARLY IN THE DAY, THEN FALL THROUGH
THE NEXT 24 HOURS. SOUTH OF HAINES AND SKAGWAY, AND APART FROM
HYDER, WHERE SIGNIFICANT ACCUMULATIONS ARE EXPECTED THURSDAY NIGHT
AND FRIDAY MORNING, PRECIP FROM THE DEPARTING FRONT SHOULD REMAIN
AS RAIN. SNOW TOTALS AT EAGLECREST NOW LOOKING MORE LIKE 8 INCHES
IN A RAIN SNOW MIX...SORRY.

THE MAIN EVENT IN THE EXTENDED RANGE FORECAST CONTINUES TO BE THE
STRONG ARCTIC OUTBREAK THAT WILL SET UP AFTER THE THURSDAY FRONT
CLEARS TO THE SOUTHEAST. MODELS ARE IN GOOD AGREEMENT AND ARE
STRONGER THAN YESTERDAY IN TERMS OF THE STRENGTH OF THE OUTFLOW
WINDS AND HOW MUCH COLD AIR WILL PENETRATE INTO THE INNER CHANNELS
FROM THE EAST. HAVE STRONG WINDS IN SKAGWAY AND HAINES, AND
BORDERLINE HIGH WINDS FOR JUNEAU FROM FRIDAY MORNING THROUGH
SATURDAY NIGHT. AT THAT POINT, THE NORTHEASTERLY PRESSURE GRADIENT
LOOKS LIKE IT WILL LET UP A LITTLE BIT, BUT THE VERY COLD
CONTINENTAL AIRMASS WILL REMAIN IN PLACE OVER ALL OF SOUTHEAST
ALASKA. TEMPERATURE ADJUSTMENTS WERE IN THE COLDER DIRECTION
ACROSS THE BOARD WITH THE NORTHERN INNER CHANNELS GETTING DOWN TO
THE SINGLE DIGITS BY FRIDAY NIGHT, THEN GOING BELOW ZERO ON
SATURDAY NIGHT. BELOW ZERO OVERNIGHT LOWS WILL EXTEND AT LEAST AS
FAR SOUTH AS HOONAH AND JUNEAU FOR SATURDAY AND SUNDAY NIGHT.
STRONG WINDS AND COLD TEMPERATURES WILL INCREASE THE RISK OF
FROSTBITE AND FREEZING SPRAY. HAVE NOT ISSUED ANYTHING WARNINGS OR
ADVISORIES WITH THE AFTERNOON FORECAST, BUT THE SITUATION WILL
NEED TO BE WATCHED CLOSELY OVER THE NEXT SEVERAL DAYS. AS
ANTICIPATED YESTERDAY, MODELS ARE KEEPING THE COLD SURFACE AIR IN
PLACE LONGER INTO THE FUTURE THAN WAS THE CASE YESTERDAY, SO THIS
COLD SNAP WILL BE WITH US THROUGH AT LEAST THE FIRST HALF OF NEXT
WEEK. WITH SO LITTLE SNOW PACK, THIS IS GOING TO BE VERY HARD ON
SOME OF THE FLORA AND FAUNA ACROSS SOUTHEAST ALASKA.

USED A BLEND OF NAM AND ECMWF FOR UPDATES TO PRESSURE AND WIND
THROUGH SATURDAY NIGHT. POP AND QPF FROM ECMWF AND GFS. TEMPS
ADJUSTED PER GFS AND ECMWF MOS. OVERALL FORECAST CONFIDENCE IS
TRENDING TOWARDS ABOVE AVERAGE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO MIDNIGHT AKST
     THURSDAY NIGHT FOR AKZ019.
         WINTER WEATHER ADVISORY FROM 6 AM THURSDAY TO MIDNIGHT AKST
     THURSDAY NIGHT FOR AKZ018.
MARINE...GALE WARNING FOR PKZ012-021-022-033>036-041>043-051>053.
         SMALL CRAFT ADVISORY FOR PKZ011-013-031-032.

&&

RWT/FRITSCH

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