HAMweather.com Area Forecast Discussion for County Warning Area AJK

Thu, 16 Feb 2012 06:42:55 GMT
FXAK67 PAJK 152352
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
252 PM AKST WED FEB 15 2012

.SHORT TERM...EARLY AFTERNOON INFRA RED SATELLITE IMAGERY
REVEALS AN OCCLUDED FRONT ENTERING INTO THE EASTERN GULF WITH ITS
TRIPLE POINT FAR SOUTH...HEADING TOWARD PACIFIC NORTHWEST. WATER
VAPOR IMAGERY DEPICTS MAIN JET STREAM SPLITS OVER EASTERN
GULF...PUSHING A DEFORMATION ZONE TOWARD NORTHEAST GULF COAST AND
SOUTHERN PART OF DYNAMICS EAST ACROSS HAIDA GWAII TO BRITISH
COLUMBIA COAST. SNOW HAS BEEN FALLING OVER YAKUTAT AREA WITH UP
TO 2 INCHES OF ACCUMULATION EARLY THIS AFTERNOON. HAS ISSUED A
WINTER WEATHER ADVISORY FOR YAKUTAT ZONE WITH 4 TO 6 INCHES OF
ACCUMULATION THROUGH LATE TONIGHT BEFORE TAPERING OFF BY EARLY
THURSDAY MORNING. A FEW FLURRIES STARTED ACROSS THE NORTH CENTRAL
PANHANDLE EARLY THIS AFTERNOON...BUT SOUTH OF A LINE FROM ELFIN
COVE TO JUNEAU AIRPORT REMAINED SPRINKLES. 

 MODELS ARE IN GENERAL AGREEMENT FOR THE TRACK OF THE INCOMING
FRONTAL PASSAGE THROUGH THURSDAY. THE ECMWF WAS INITIALIZED BEST
AND HAS BEEN SHOWING A BETTER CONSISTENCY THAN THE NCEP MODELS.
FOR TONIGHT AND THURSDAY...THE ECMWF HANDLES THE UPPER DYNAMICS
SPLITTING OVER THE EASTERN GULF...BUT KEEPS THE SURFACE
REFLECTIONS WITH THE FRONTAL BOUNDARY MOVING ONSHORE OVER THE
PANHANDLE THIS EVENING INTO TONIGHT. REFRESHED THE INHERITED
FORECAST PACKAGE WITH THE 12Z RUN ECMWF FOR TONIGHT AND THURSDAY.

 CATEGORICAL POPS ARE MAINTAINED ACROSS THE PANHANDLE FOR TONIGHT
WITH THE INCOMING FRONT. SNOW WILL AFFECT THE NORTHERN ONE THIRD
OF THE PANHANDLE AND THE CENTRAL AND SOUTHERN AREAS WILL REMAIN
WITH RAIN. SNOW LEVEL ACROSS THE NORTHERN PANHANDLE WILL QUICKLY
INCREASE ON THURSDAY MORNING WITH TAPERING OFF PRECIPITATION
BEHIND THE FRONTAL PASSAGE. WITH RELATIVELY LIGHT WINDS NEAR
HYDER AREA...KEPT THE PRECIPITATION AS SNOW WITH ACCUMULATION UP
TO 3 INCHES OVERNIGHT. EXCEPT THE YAKUTAT AREA...WHERE ADVISORY
LEVEL SNOWFALL WILL CONTINUE THROUGH LATE TONIGHT...NORTHERN ONE
THIRD OF THE PANHANDLE WILL SEE UP TO 2 INCHES OF SNOW THROUGH
LATE TONIGHT.  

 AS THE FRONT MOVES ONSHORE OVER THE PANHANDLE...SMALL CRAFT
WINDS ACROSS THE OUTER COASTAL WATERS AND OCEAN ENTRANCES OF THE
INNER CHANNELS WILL DIMINISH LATE TONIGHT. AS THE FRONTAL PASSAGE
CONTINUES MOVING EAST ACROSS THE NORTHERN INNER CHANNELS...SMALL
CRAFT WINDS WILL PICK UP OVER NORTHERN LYNN CANAL LATE TONIGHT
INTO EARLY THURSDAY MORNING. 

  

 .LONG TERM...LONG RANGE MODELS ARE IN BETTER AGREEMENT TODAY
COMPARED TO YESTERDAY. UKMET IS NO LONGER A WILD OUTLIER AND NAM
HAS SOMEWHAT ABANDON THE STRONG LOW LINGERING IN THE CENTRAL GULF
FOR LATE THIS WEEK THAT IT WAS SHOWING YESTERDAY. THROUGH IT IS
STILL THE SCENARIO WITH THE SECONDARY LOW THE FARTHEST EAST EARLY
FRIDAY. UPPER LEVEL PATTERN HAS CHANGED VERY LITTLE OVERALL FROM
YESTERDAY WITH SW TO W FLOW STILL DOMINATE OVER THE PANHANDLE
THROUGH EARLY NEXT WEEK. BROAD UPPER TROUGH STILL ENTRENCHED IN
THE NORTHERN PACIFIC AND BERING SEA. THE INITIAL EMBEDDED UPPER
LOW OVER THE BERING WILL DISSIPATE SAT ONLY TO BE REPLACED BY
ANOTHER EASTWARD MOVING LOW EARLY SAT. SOME DEBATE ON THE
STRUCTURE OF THE REPLACEMENT LOW AS GFS HAS A MORE COMPLEX
STRUCTURE WHILE THE EC IS GOING FOR A MORE SIMPLISTIC AND FARTHER
WEST APPROACH. 

 OVERALL WEATHER FOR THE PANHANDLE WILL BE SOMEWHAT ACTIVE WITH
AT LEAST FOUR WEAK TO MODERATE SYSTEMS AFFECTING THE AREA THROUGH
MID WEEK NEXT WEEK. FIRST IS A WEAK FRONT FOR THURS NIGHT. NOT
MUCH SUPPORT WITH THIS FEATURE EXCEPT FOR A WEAKENING UPPER
TROUGH TO HELP IT ALONG. LATE FRI AFTERNOON INTO SAT HAS A LOW
TRACKING WELL TO THE SOUTH. THE EASTERLY FLOW NORTH OF IT AND THE
RIDGE BUILDING IN BEHIND IT MAY OPEN UP SOME BREAKS IN THE CLOUDS
FOR SAT. LATE SAT NIGHT THROUGH THE REST OF THE EXTENDED PERIOD
IS WET AS A FEW MORE SYSTEM COME IN OFF THE GULF. 

 FOR FORECAST UPDATES DECIDED TO GO WITH THE EC AS IT LOOKED TO
HAVE THE BEST CONSISTENCY COMPARED TO YESTERDAY. GFS WAS A CLOSE
SECOND. FARTHER OUT USED HPC DATA FOR IT USE OF ENSEMBLE MEANS TO
EVEN OUT THE DIFFERENCES THAT CROP UP IN THE LONG RANGE. FORECAST
CONFIDENCE IS A LITTLE ABOVE AVERAGE FOR THE MID RANGE AND ABOUT
AVERAGE TO BELOW AVERAGE IN THE EXTENDED. 

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...SMALL CRAFT ADVISORY UNTIL MIDNIGHT AKST TONIGHT FOR AKZ019.
         WINTER WEATHER ADVISORY UNTIL 5 AM AKST THURSDAY FOR AKZ017.
MARINE...GALE WARNING FOR PKZ042-043-051-052. 
         SMALL CRAFT ADVISORY FOR PKZ012-021-022-033>036-041-053.