Gale Warning 192, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
607 AM AKDT TUE APR 9 2013

.SHORT TERM...JUDGING BY THE IR SATELLITE AND A CRUDE RECKONING
OF WHERE THE SURFACE LOW IS, THE MODELS ARE LATE, MAYBE BY THREE
HOURS OR SO. THE ECMWF HAS BEEN THE BEST AND MOST CONSISTENT, BUT
FRANKLY ITS LOCATION IS STILL BEHIND WHAT OUR VIEW IS. IN FACT,
THE PREVIOUS FORECAST HAD A BETTER POSITION ON THE LOW THAN
THESE, SO HAVE NOT CHANGED THE TRACK OF THE LOW OR ITS POSITION
THAT MUCH FROM PREVIOUS. HOWEVER, I HAVE DEEPENED IT TO 975 MB
FROM THE PREVIOUS SHIFT OF AROUND 980. WINDS HAVE COME UP EARLIER
ACROSS THE PANHANDLE INCLUDING YESTERDAY AFTERNOON WITH SOME OF
THE EASTERLY GRADIENT AT JUNEAU, WRANGELL, AND CLARENCE STRAIT
AMONG OTHERS. CLARENCE STRAIT GUSTS EXCEEDED HURRICANE FORCE LATE
MONDAY EVENING. EVEN PETERSBURG HAD EASTERLY GUSTS OVER 30 MPH
BEGIN YESTERDAY AND CONTINUE OVERNIGHT. AND FINALLY...PRINCE OF
WALES ISLAND HAS JUST RECENTLY SEEN INDICATIONS OF GUSTS TO
60 MPH AT WHAT APPEARS TO BE A FRONTAL PASSAGE AS EVEN KLAWOCK
HAS BEGUN GUSTING FROM THE SOUTH.

 WITH THE FAST MOVING SYSTEM AND WITHOUT A LOT OF GREAT MODEL
GUIDANCE, HAVE TRIED TO INCREASE STRENGTH OF WINDS. BY 10 AM THE
SYSTEM SHOULD BE JUMPING ONSHORE NEAR YAKUTAT AND THUS WINDS
SHOULD FLIP TO TO SOUTHWEST TOWARD NOON AND STRENGTHEN WINDS INTO
YAKUTAT BAY TO 20 KT. THE 975 MB SYSTEM HAS TWO FRONTS ASSOCIATED
WITH IT, ONE MOVING THROUGH THE PANHANDLE OVERNIGHT AND ANOTHER
DUE INTO THE EASTERN GULF LATE THIS MORNING MOVING INTO THE
PANHANDLE THIS AFTERNOON. GALES WILL FADE THIS MORNING FROM THE
SOUTHERN OUTSIDE WATERS AND CROSS SOUND AS THE LOW JUMPS INLAND.
IN ADDITION...STORM FORCE WINDS IN CLARENCE STRAIT SHOULD BEGIN
DIMINISHING TOWARD THE AFTERNOON. LATE GUSTS AT LINCOLN ROCK
SURPASS 80 KT!  BUT EVEN AS THE GRADIENT SLACKENS A LITTLE,
850 MB WINDS SHOULD PROP IT UP AT LEAST UNTIL THE AFTERNOON.
LIKEWISE, STRONG WIND HEADLINES WILL DISAPPEAR FROM THE COAST BY
MID MORNING BUT WILL CONTINUE FOR KETCHIKAN, WRANGELL, JUNEAU,
AND BEGIN TO GET GOING IN SKAGWAY, AS A LEESIDE LOW BUILDS ON THE
LEEWARD SIDE OF ST. ELIAS. JUNEAU SHOULD SEE GUSTS TO 40 MPH
SOMETIME AROUND MIDDAY AND EARLY AFTERNOON BEFORE FRONTAL PASSAGE
AND AS LEESIDE LOW DEVELOPS IN THE YUKON. NORTHERN LYNN CANAL
WILL ACCELERATE TO GALE BEGINNING LATE THIS MORNING INTO THE
AFTERNOON REACHING 40 KT LATE.

 PRECIPITATION...WILL BE MAINLY STRATIFORM EARLY, EVEN AS THE
MAIN RAIN BANDS...AND SNOW AT WHITE PASS...WILL MOVE NORTHEAST OF
THE PANHANDLE EARLY AHEAD OF THE WARM FRONT. TRUE CONVECTIVE
PRECIPITATION WILL NOT BEGIN UNTIL THE COLD FRONT REACHES THE
PANHANDLE...MAINLY IN THE AFTERNOON. WITH THAT COLD POOL
ALOFT...IMPRESSIVE VALUES OF -10 C OVER THE GULF WATERS, THERE
SHOULD BE JUST ENOUGH TO CHANGE YAKUTAT PRECIPITATION TO SNOW
THIS AFTERNOON AND TO MIX IN WITH THE RAIN SHOWERS AT PELICAN.
POPS WILL BE CATEGORICAL THROUGHOUT THE ENTIRE PANHANDLE. LASTLY,
CANCELLED THE WINTER WEATHER ADVISORY FOR WHITE PASS, AS THE MAIN
BAND OF PRECIPITATION WILL HEAD NORTH AND EAST SHORTLY...BUT
SINCE CONVECTIVE SHOWERS SHOULD MOVE IN THIS AFTERNOON, STILL
KEPT SNOW ACCUMULATIONS OF 2 TO 4 INCHES, EVEN WITH WARMER
TEMPERATURES...NOT AS CONFIDENT WITH TEMPERATURE, AND DID NOT
SPEND AS MUCH TIME AS NORMALLY, SINCE THE WINDS COMMANDED MUCH
MORE TIME. ADDED SOME BLOWING SNOW THIS AFTERNOON AS TEMPERATURES
LOWER INTO THE 20S LATE.

 NO BIG MODEL OF CHOICE, KIND OF ADJUSTED GRIDS WITH SATELLITE
AND ANTICIPATION OF MOVEMENT...COMBINING IT WITH PREVIOUS
FORECAST. CONFIDENCE IN PATTERN GOOD, BUT DETAILS SKETCHY.

.LONG TERM...MADE LOCALIZED ADJUSTMENTS FOR THE MOST PART. DUE
TO STORM IN THE AREA...TOOK TONIGHT FORECAST TO ALLOW SHORT
TERMER TO FOCUS ON THE STORM FOR TODAY. MAIN ADJUSTMENTS WERE TO
BOOST WINDS IN THE LYNN CANAL/SKAGWAY AREAS TONIGHT THRU WED
NIGHT...AND INCREASED WINDS IN CROSS SOUND AS CONDITIONS WILL BE
FAVORABLE FOR A TIP JET THERE TONIGHT AND WED. DID NUDGE POPS
UPWARD SOME ESPECIALLY OVER THE NW HALF OF THE AREA AS AIRMASS
COMING IN IS UNUSUALLY COLD AND WILL CAUSE FAIRLY WIDESPREAD
SHOWER ACTIVITY TO DEVELOP. ATTM DID NOT HEADLINE FOR SNOWFALL
WITH THESE SHOWERS AS THERE WAS NO OBVIOUS MECHANISM TO ORGANIZE
THEM ENOUGH TO ALLOW HEAVY SNOW TO FALL FOR LONG STRETCHES OF
TIME IN ANY ONE LOCATION. HOWEVER...PLACE TO WATCH OUT FOR IS THE
PAYA AREA ESPECIALLY IF ANY VORT FEATURES DEVELOP AND ORGANIZE
THE SHOWERS. TRANSITION FROM RAIN TO SNOW SHOWERS SHOULD OCCUR
OVER THE NRN AND CENTRAL AREA THIS EVENING...AND LOOKS LIKE AT
LEAST SOME SNOW MAY MIX IN OVER THE S LATE TONIGHT. THE FAR SE
AREA WILL HAVE LEAST AMOUNT OF SHOWERS AS INSTABILITY WILL BE
SHALLOWER THERE.

 LATER ON...AS UPPER LOW SHIFTS INTO S-CENTRAL AK WED...DEEPER
COLD AIR WILL SHIFT TOWARD THE SRN AREAS SO SHOWERS WILL
GRADUALLY INCREASE THERE WED INTO WED NIGHT. LOOKS LIKE A LOW
WILL TRY TO MOVE INTO THE SE GULF FOR LATE WEEK BUT MODELS DIFFER
ON THIS FEATURE SOMEWHAT. FELT IT BEST TO STAY WITH CURRENT
FORECAST AND ALLOW LATER SHIFTS TO MAKE ANY NEEDED CHANGES LATE
IN THE WEEK. ALL IN ALL...PATTERN SHOULD MAINTAIN COLDER THAN
AVERAGE TEMPS THRU THE PERIOD.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND UNTIL 1 PM AKDT THIS AFTERNOON FOR AKZ026.
         STRONG WIND UNTIL 10 AM AKDT THIS MORNING FOR AKZ023-027.
         STRONG WIND UNTIL 4 PM AKDT THIS AFTERNOON FOR AKZ025-028.
         STRONG WIND FROM 1 PM AKDT THIS AFTERNOON THROUGH LATE TONIGHT
     FOR AKZ019.
         STRONG WIND FROM 10 AM AKDT THIS MORNING THROUGH WEDNESDAY
     EVENING FOR AKZ018.
MARINE...STORM WARNING FOR PKZ036.
         GALE WARNING FOR PKZ012-013-022-033>035-041>043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ011-021-031-032.

&&

JWA/RWT