FXAK67 PAJK 262144
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
1242 PM AKST THU NOV 26 2009

.SHORT TERM...SCATTERED TO ISOLATED RAIN SHOWERS CONTINUE TO
MOVE ACROSS THE PANHANDLE EARLY THIS AFTERNOON AS A MID LEVEL AND
SURFACE RIDGE ADVECTS FROM THE EASTERN GULF INTO WESTERN CANADA.
THE RIDGING IS SUPPRESSING THE SHOWER ACTIVITY AND ALLOWING
SEVERAL SUNNY BREAKS...ESPECIALLY ALONG THE OUTER COAST. A 980 MB
SURFACE LOW SOUTHWEST OF KODIAK WILL ADVECT NORTHWARD ACROSS THE
KENAI PENINSULA TONIGHT AND ITS ASSOCIATED WEATHER FRONT WILL
APPROACH THE PANHANDLE THIS EVENING AND SPREAD RAIN ACROSS THE
PANHANDLE TONIGHT. THE WINDS ASSOCIATED WITH THIS WEATHER FRONT
AND THE MID LEVEL TO SURFACE CAA MOVING ACROSS THE PANHANDLE
TOMORROW ARE THE MAIN FORECAST PROBLEMS THROUGH THE SHORT TERM.
USED A BLEND OF THE 12Z GFS/NAM THROUGH TOMORROW AFTERNOON AS THE
GFS INITIALIZED THE WEATHER FRONT BETTER THIS MORNING, BUT THE
BARRIER FLOW IN THE NORTHERN GULF AND SURFACE PRESSURE GRADIENT
NEAR PAGY WERE BETTER HANDLED BY THE 12Z NAM. CONFIDENCE REMAINS
HIGH IN THE AFTERNOON FORECAST PACKAGE. 

 FOR TONIGHT THE PRECIPITATION WILL BECOME MORE STRATIFORM AS A
WEATHER FRONT SPREADS RAIN NORTHWARD ACROSS THE PANHANDLE. THE
HIGHEST RAINFALL AMOUNTS WILL BE NEAR YAKUTAT TONIGHT AS THE BEST
MID LEVEL DYNAMICS REMAIN ALONG AND WEST OF 140W. LOCALLY WINDY
CONDITIONS THIS AFTERNOON AND EVENING NEAR PAGY WILL DIMINISH
INTO THE EVENING AS THE SURFACE PRESSURE GRADIENT ORIENTATION
BECOMES MORE EASTERLY. SMCR WINDS WILL BEGIN LATE TONIGHT IN
EAST-WEST ORIENTED CHANNELS WITH MIN GALES ALONG THE OUTER
COASTAL WATERS. THE 850 MB LLJ IS BELOW 50 KNOTS AND THEREFORE
DON'T EXPECT WIND ADVY GUSTS TONIGHT ALONG THE OUTER COAST AND
THE PARENT SURFACE LOW WILL REMAIN WEST OF 150W KEEPING ALL THE
STRONGEST WINDS WELL WEST OF THE PANHANDLE. SNOW LEVELS TONIGHT
WILL REMAIN ABOVE 1000 FEET AS 850 MB TEMPERATURES WILL BE AROUND
-3 C FOR THE PANHANDLE BUT COULD SEE SOME SNOW MIX WITH THE RAIN
ALONG THE HIGHWAYS TOWARD THE CANADIAN BORDER. 

 FOR TOMORROW THE FRONT AND ASSOCIATED MID LEVEL TROUGH WILL
ADVECT ACROSS THE PANHANDLE AND BY THE AFTERNOON CAA FROM 500 MB
TO SURFACE WILL ALLOW THE PRECIPITATION TO BECOME CONVECTIVE AND
COULD SEE SOME SMALL HAIL AND SNOW MIX WITH RAIN NEAR THE
STRONGER SHOWERS AND HIGHER TERRAIN. ELSEWHERE LOCALLY BREEZY
CONDITIONS ALONG THE INNER CHANNELS WILL DIMINISH THROUGH THE DAY
AS THE SURFACE PRESSURE GRADIENT RELAXES BUT WILL CONTINUE TO SEE
GUSTS TO 25 KNOTS NEAR THE STRONGER SHOWERS THROUGHOUT THE DAY.
LI VALUES DROP BELOW -1 AND CAPE VALUES WILL BE NEAR 200 J/KG
ALONG THE OUTER COASTAL WATERS TOMORROW AFTERNOON AND SO COULD
SEE SOME ISOLATED THUNDERSTORMS BUT THE MOST UNSTABLE AIR WILL
REMAIN IN THE NORTHERN GULF WITH THE BEST MID LEVEL CAA. 

&&

.LONG TERM...WEAK RIDGE OVER THE PANHANDLE MOVES EAST WITH A
SHORT WAVE TRACKING OVER THE N PANHANDLE AT THE START OF THE
WEEKEND. THIS IS QUICKLY FOLLOWED BY A DEVELOPING GALE FORCE LOW
TRACKING N ALONG THE W GULF TOWARD PAMD. ASSOCIATED OCCLUDED
FRONT WILL PASS OVER THE REGION KEEPING HIGH POPS THROUGH THE
WEEKEND. WINDS FROM THE WEEKEND LOW WILL ONLY BE 30 TO 40 KT
HOWEVER THE TRAPPED FETCH WAVES WILL REACH HEIGHTS UP TO 35 FT
SAT EVENING THROUGH SUN. AS THE LOW MAKES LANDFALL AND WEAKENS A
HIGH PRESSURE RIDGE WILL MOVE OVER THE W GULF AND CONTINUE TO
BUILD AS IT TRACKS EAST. ANOTHER LOW WILL DEVELOP OVER THE BERING
SEA BUT AT THIS TIME LOOKS TO REMAINED BLOCKED BY THE DEVELOPING
RIDGE. 

PRECIP OVER THE WEEKEND WILL BE MOSTLY RAIN FOR THE CENTRAL TO
SOUTHERN PANHANDLE WITH SNOW LVL ABOVE 2K FT. NORTHERN PANHANDLE
WILL HAVE A MIX OF PRECIP WITH LIMITED SNOW ACCUMULATION ALONG
THE HAINES AND KLONDIKE HIGHWAY BORDERS. QPF VALUES FORECAST FROM
0.25 TO 0.50 IN WITH GFS PREDICTING UP TO 1 IN. WINDS ALONG THE
OUTER COAST INCREASING TO GALE FORCE WITH UPPER LVL SMCR I ALONG
THE INNER CHANNELS FOR THE WEEKEND BEFORE DIMINISHING RAPIDLY.
COMBINED SEAS FOR THE WEEKEND WERE SIGNIFICANTLY HIGH AS THE
TRAPPED FETCH WAVES ARE CONTINUALLY ENHANCED BY THE GALE FORCE
WINDS. THUS WAVE HEIGHTS WERE HIGHER THAN WOULD NORMALLY BE SEEN
WITH 30 TO 40 KT WINDS.

MODELS INITIALIZED WELL WITH THE EC BEING A BIT MORE CONSISTENT
FROM RUN TO RUN THAN THE GFS...MINOR DIFFERENCE IN FINAL LOW
TRACK AND STRENGTH. USED A BLEND OF EC WITH INHERITED GRIDS OUT
TO 4 DAY THEN BLENDED HPC GUIDANCE FOR THE REMAINDER OF THE
PERIOD. MODELS BEGAN TO DIVERGE SIGNIFICANTLY WITH THE PATTERN
CHANGE. FORECAST CONFIDENCE WAS AVERAGE FOR THE START OF THE LONG
TERM THEN DROPPED WITH INCREASED UNCERTAINTY.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND ADVISORY UNTIL 6 PM AKST THIS EVENING FOR AKZ018.
MARINE...GALE WARNING FOR PKZ012-041>043-052. 
         SMALL CRAFT ADVISORY FOR PKZ011-013-021-022-031>036-051.

&&

$$

PSS/PRB