Gale Warning 359, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
331 PM AKST SAT NOV 28 2015

.SHORT TERM...STALLED FRONT OVER THE CENTRAL PANHANDLE WILL
GRADUALLY LIFT NWWD AS A COUPLE OF LOW PRESSURE WAVES MOVE N ALONG
IT THRU SUN. STILL SOME MODEL DISAGREEMENT ON TIMING AND STRENGTH
OF WAVES...BUT GIVEN FLOW PATTERN ALOFT...THINK THEY WILL NOT BE
TOO STRONG. USED BLEND OF THE 12Z GFS AND ECMWF FOR TONIGHT AND
SUN.

MAIN FORECAST CONCERNS WILL BE PRECIP POTENTIAL/AMOUNTS...HOW
MUCH MORE SNOW WILL FALL NEAR WHITE PASS...AND WINDS. THE SRN EDGE
OF THE PRECIP APPEARS TO BE NEAR A PAKW-PAWG LINE. AS FLOW ALOFT
BACKS AND DRIER AIR MOVES IN FROM THE SE...THIS EDGE SHOULD SHIFT
NWWD AND REACH THE PAJN-PASI AREAS AROUND 15Z SUN...THEN CONTINUE
NW TO BE JUST SE OF A PAGS-PAGY LINE SUN AFTERNOON. THE RAINFALL
WILL BE LOCALLY HEAVY ABOUT 60+ MILES NW OF THE SERN PRECIP
EDGE. THE WRN EDGE OF THE MAIN PRECIP BAND IS AROUND ICY BAY AND
WILL LIKELY STAY IN THE GENERAL AREA THRU SUN. LOOKING LIKE
ANOTHER 1-3 INCHES OF RAIN BETWEEN THE PAYA AND PAJN AREAS FOR
TONIGHT AND SUN.

THE SNOW LEVEL NEAR PAGY IS ABOUT 2400 FEET BASED ON TEMP NEAR
MOORE CREEK OBSERVATION SITE. EXPECT THE SNOW LEVEL TO REMAIN
BELOW TOP OF WHITE PASS THRU SUN WITH SOME LOWERING DURING THE
AFTERNOON. LOOKS LIKE THE TOP OF WHITE PASS COULD GET UP TO 16
INCHES OF ADDITIONAL SNOW THRU SUN AFTERNOON. DECIDED TO EXTEND
THE WINTER STORM WARNING FOR WHITE PASS UNTIL 6 PM SUN.

STRONGEST WINDS WILL BE AHEAD OF FRONT. GALE FORCE S-SE WINDS ARE
LIKELY OVER THE FAR ERN GULF AND SOME INNER CHANNELS TONIGHT AND
SUN WITH LOW PRESSURE WAVES MAINTAINING A STRONG PRESSURE
GRADIENT AHEAD OF THE FRONT. MUCH OF THE REMAINING INNER CHANNELS
WILL SEE SCA LEVEL WINDS...ALTHOUGH NRN LYNN CANAL WILL NOT GET
BACK TO THAT LEVEL UNTIL SUN. GLACIER BAY SHOULD STAY BELOW SCA
LEVELS THRU SUN. WILL KEEP STRONG WIND HEADLINES GOING FOR PUBLIC
ZONES 23 AND 27 THRU SUN AS WELL.

OTHERWISE...SRN PANHANDLE WILL SEE CLOUDS DECREASE TONIGHT BUT
WITH SOME WIND EXPECTED TO PERSIST...NOT EXPECTING ANY FOG
ISSUES. IF ANY DECOUPLING DOES OCCUR AND WINDS BECOME LIGHT IN
SOME LOCAL AREAS HOWEVER...SOME FOG COULD DEVELOP LATER TONIGHT.

.LONG TERM...SNOW / POTENTIALLY HEAVY / WILL CONTINUE FOR THE
KLONDIKE HIGHWAY NEAR WHITE PASS AT THE START OF THE EXTENDED RANGE
FORECAST PERIOD. THE FRONT CURRENTLY PRODUCING HEAVY PRECIPITATION
WILL CONTINUE TO SHIFT EAST AND WEST AS EMBEDDED WAVES RIDE UP
ALONG THE FRONTAL BOUNDARY. TPW IMAGERY INDICATING A LONG SWATH OF
PRECIPITABLE WATER IN EXCESS OF ONE INCH, SO HEAVY PRECIPITATION
WILL CONTINUE THROUGH MONDAY NIGHT. LOOK FOR THIS CYCLE TO
FINALLY END ON TUESDAY AS ANOTHER FRONT APPROACHES FROM THE WEST
AND DISPLACED THE CURRENT FRONT. BY TUESDAY NIGHT, ANOTHER SHORT
WAVE WILL APPROACH THE OUTER COAST FROM THE SOUTHWEST...AND THEN
AGAIN ON WEDNESDAY NIGHT. ALL THE WHILE, SUFFICIENT WARM AIR IN
THE LOW LEVELS WILL BE ADVECTED UP FROM THE SOUTH TO KEEP SNOW
LEVELS HIGH ENOUGH TO RESULT IN RAIN RATHER THAN SNOW FOR FOR THE
LOWER ELEVATIONS. NOTABLE EXCEPTION IS WHITE PASS, WHERE
ACCUMULATING SNOW IS EXPECTED FOR MOST OF THE UPCOMING WEEK.

THE PRESENT FRONT WILL STILL BE GENERATING GALE FORCE WINDS OVER
THE CENTRAL OUTER COAST MARINE ZONES. THE NEXT FRONT ON TUESDAY
WILL ALSO FEATURE SOME HEAVY PRECIPITATION, BUT WINDS WILL BE
SIGNIFICANTLY LOWER - GENERALLY 20 TO 25 KTS. A WAVE APPROACHING
ON WEDNESDAY NIGHT WILL FEATURE A COMPACT CLOSED LOW AND THIS
SYSTEM MAY FEATURE GALE FORCE WINDS AND STRONG WIND GUSTS OVER
THE SOUTHERN OUTER COAST. SITUATION WILL REPEAT ITSELF AGAIN LATE
FRIDAY NIGHT AS THE NEXT WAVE MOVES NORTH OVER THE EASTERN GULF.

DETAILS AND TIMING OF THESE VARIOUS WAVES REPRESENTS THE GREATEST
UNCERTAINTY IN THE EXTENDED RANGE FORECAST, AS MODELS ARE IN VERY
POOR AGREEMENT. USED A BLEND OF GFS AND ECMWF FOR UPDATES TO
PRESSURE AND WINDS FOR SUNDAY NIGHT. NUDGED HEAVILY TO THE LATEST
WPC FORECAST FROM WEDNESDAY NIGHT ONWARD. REMAINDER OF THE
PREVIOUS WIND FORECAST UNCHANGED. MODEL AGREEMENT MUCH BETTER IN
TERMS OF POP AND QPF. USED A BLEND OF GFS AND CANADIAN NH THROUGH
TUESDAY NIGHT. OVERALL FORECAST CONFIDENCE IS ABOVE AVERAGE FOR
MORE HEAVY PRECIPITATION BUT BELOW AVERAGE ON THE TIMING OF THE
VARIOUS WAVES.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND THROUGH SUNDAY AFTERNOON FOR AKZ023-027.
         WINTER STORM WARNING UNTIL 6 PM AKST SUNDAY FOR AKZ018.
MARINE...GALE WARNING FOR PKZ031-034-036-041>043.
         SMALL CRAFT ADVISORY FOR PKZ012-013-021-022-032-033-035-051.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ052.

&&

RWT/FRITSCH

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