Gale Warning 87, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
1252 PM AKST SUN FEB 1 2009

.SHORT TERM...LOW PRES WILL REMAIN OVER THE NRN GULF THROUGH MON.
A TROF WILL SWING NE ACROSS THE NRN PANHANDLE TONIGHT AND EARLY
MON. AN OCCLUDED FRONT WILL STALL JUST S OF THE PANHANDLE THIS
EVENING. A LOW WILL BEGIN TO DEVELOP OVER THE NE PAC TONIGHT AND
MOVE NNE TO ABOUT 200 NM W OF THE CHARLOTTES BY LATE MON AFTERNOON.

PTYPE WILL BE THE MAIN FORECAST DILEMMA FOR TONIGHT. THE BIGGEST
CONCERN WILL BE AROUND PAYA...WHERE THE HEAVIEST PRECIP WILL FALL
THROUGH TONIGHT. THE KEY WILL BE THE LOW LEVEL WINDS...WHICH ARE
CURRENTLY WEAK...AND THIS IS ALLOWING AN ISOTHERMAL LAYER TO SET
UP DOWN TO THE SFC...KEEPING PRECIP AS SNOW. MODELS TRY TO BRING
INCREASED SE WIND THERE BY LATE THIS AFTERNOON AND EVENING...BUT
THEY APPEAR TO BE HAVING PROBLEMS WITH THE REMNANT LOW CURRENTLY
OVER THE CENTRAL GULF...A BIT TO THE SE OF THE MODEL POSITION. AT
THIS POINT...AM GOING TO STAY WITH MAINLY SNOW FOR THEM TONIGHT
BUT INDICATE POTENTIAL MIX WITH RAIN AT TIMES. WILL KEEP THE WSW
GOING AS WELL THROUGH 09Z TONIGHT FOR ANOTHER 3 TO 6 INCHES OF
SNOW. ELSEWHERE...PRECIP SHOULD BE MAINLY RAIN...BUT SOME OF THE
HEAVIER PRECIP COULD MIX DOWN SOME SNOW TO SEA LEVEL DURING THE
NIGHT OVER THE N AND HYDER AREAS. SNOW LEVELS WILL NOT BE ALL THAT
HIGH THOUGH...ABOUT 600-800 FT...SO MOST OF THE KLONDIKE HIGHWAY
AND NW PART OF THE HAINES HIGHWAY WILL LIKELY REMAIN SNOW. NOT
EXPECTING HEAVY AMOUNTS THOUGH SO NO HEADLINES WILL BE ISSUED FOR
THEM.

THE PRECIP SHOULD DIMINISH OVER THE S THIS EVENING AS SHORTWAVE
RIDGING MOVES IN FROM THE W BEHIND THE OCCLUDED FRONT. WILL KEEP
POPS LOW THERE FOR TONIGHT. WILL KEEP POPS HIGH OVER THE N WITH
THE TROF MOVING THROUGH THAT AREA. FOR MON...THE PRECIP SHOULD
DIMINISH SLOWLY OVER THE N...BUT MORE PRECIP WILL MOVE IN TO THE S
AS THE DEVELOPING LOW OVER THE NE PAC MOVES CLOSER TO THEM BY LATE
MON AFTERNOON.

WINDS WILL BE DIMINISHING ACROSS MUCH OF THE AREA EARLY THIS
EVENING...BUT PICK UP OVER THE N LATER THIS EVENING AS THE TROF
MOVES IN. STILL...EXPECT WINDS TO REMAIN AT SCA LEVELS OR LESS
THROUGH TONIGHT. WILL STILL HAVE SOME FAIRLY HIGH SEAS OVER THE
GULF SO WILL KEEP SCA FOR SEAS OUT THERE AT LEAST.

.LONG TERM...MODELS IN FAIR AGREEMENT TO THE MID PART OF UPCOMING
WEEK LEADING TO BETTER THAN AVERAGE CONFIDENCE THROUGH THAT TIME
FRAME. MORE DIFFERENCES IN THE LATER PERIODS HAS LOWERED MY
CONFIDENCE TO BELOW AVERAGE FOR THE LATER PERIODS. USED THE 12Z
ECMWF MODEL RUN FOR MOST OF THE ADJUSTMENTS AS IT HAD A GOOD
HANDLE ON THE MONDAY NIGHT SYSTEM AND THE SYSTEM INTO WEDNESDAY
SEEM REASONABLE. GFS HAS A MORE AGGRESSIVE SYSTEM FOR MID WEEK AND
DECIDED AGAINST IT BECAUSE OF THAT. EARLY I DID USE A BIT OF THE
GFS AND NAM (MONDAY NIGHT TO TUESDAY).

IF THE TRACK OF THE MONDAY NIGHT LOW HOLDS (UP CHATHAM STRAIT ON
INTO BRITISH COLUMBIA JUST EAST OF JUNEAU OR SO) ... SEE THE
POTENTIAL FOR A SIGNIFICANT SNOW FALL FOR SOUTHERN PORTION OF
HAINES AND GUSTAVUS ZONES WITH HOONAH...ANGOON AND JUNEAU
INCLUDED. ALSO EXPECT COOLER AIR TO RE FILTER BACK INTO THE HYDER
AREA SO EXPECTING THEM TO GET SOLID ACCUMULATIONS TOO. WILL BE
ISSUING A WATCH FOR HEAVY SNOW. WILL HAVE TO WATCH AS THE
TEMPERATURE FORECAST IS TRICKY AND WILL LIKELY BE THE KEY TO
WHETHER THE WATCH PANS OUT OR NOT.

BRIEF BREAK FOR TUESDAY WITH A FRONTAL BAND MOVING ACROSS THE
GULF. MAIN PARENT LOW HOLDING OVER THE BERING SEA SO EXPECT TO SEE
THIS FEATURE WEAKENING AS IT MOVES TO THE EASTERN GULF...AND
PROBABLY WILL BE DISSIPATING AS REACHES THE COAST.

AFTER THIS A STRONG FLOW PATTERN GOES FROM ZONAL TO TROUGH WITH A
SHORT WAVED DIGGING SOUTH INTO THE PACIFIC... SOUTH OF THE
ALEUTIANS AND MOVING EAST. POTENTIALLY A SIGNIFICANT SYSTEM TO
IMPACT SOUTHEAST ALASKA NEXT WEEKEND.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER STORM WATCH FROM MONDAY EVENING THROUGH TUESDAY MORNING
     FOR AKZ019>021-024-025.
         WINTER STORM WARNING UNTIL MIDNIGHT AKST TONIGHT FOR AKZ017.
         WINTER STORM WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY MORNING
     FOR AKZ029.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-013-021-022-031-034-041>043-051-
     052.

&&

RWT/BEZENEK