FXAK67 PAJK 272144
AFDAJK
SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
1243 PM AKST FRI NOV 27 2009
.SHORT TERM...AN IMPRESSIVE MID LEVEL SHORTWAVE CONTINUES TO
ADVECT NORTHWESTWARD FROM THE NORTHERN GULF INTO THE ALASKA RANGE
LATE THIS MORNING. BEHIND THIS SHORTWAVE SATELLITE SHOWS AN
EXTENSIVE AMOUNTS OF CAA ACROSS THE EASTERN GULF AND PANHANDLE AS
THE MID LEVEL FRONTAL BAND HAS MOVED INTO WESTERN CANADA. SEVERAL
LIGHTNING STRIKES HAVE OCCURRED NEAR YAKUTAT LATE THIS MORNING
EVEN WITH A PLANE BEING STRUCK ON LANDING AND SO HAVE EXPANDED TO
COVER AKZ017 AND POINTS SOUTHEASTWARD WITH ISOLATED THUNDERSTORMS
THROUGH THE EVENING HOURS. WITH THE STRONG CAA THROUGH 500 MB THE
VERTICAL ENVIRONMENT WILL REMAIN QUITE UNSTABLE INTO EARLY
TOMORROW MORNING AND SO COULD CONTINUE TO SEE SMALL HAIL AND SNOW
MIX WITH RAIN IN THE SOUTHERN PANHANDLE WITH SHOWERS REMAINING
ALL SNOW NORTH OF THE ICY STRAIT CORRIDOR. THIS CONVECTIVE
ACTIVITY WILL MAKE THE SHORT TERM FORECAST DIFFICULT THROUGH
TONIGHT WITH SNOW AMOUNTS ALONG AND NORTH OF ICY
STRAIT...ESPECIALLY IF THE SHOWERS BEGIN TRAINING OVER THE SAME
AREA. ANOTHER FORECAST PROBLEM THROUGH THE SHORT TERM PERIOD IS A
DEVELOPING GALE TO STORM FORCE LOW IN THE NORTHEASTERN PACIFIC
AND THE MOVEMENT OF ITS ASSOCIATED FRONTAL BOUNDARY THROUGH
TOMORROW AFTERNOON. ATTM...ALL THE 12Z MODELS ARE CONSISTENT ON
THE SURFACE LOW MOVING ALONG AND JUST WEST OF 140W THROUGH
TOMORROW AFTERNOON. DID PREFER THE 12Z NAM THROUGH MOST OF THE
SHORT TERM PERIOD BECAUSE ITS DEPICTION OF THE FRONTAL BOUNDARY
MOVING INTO THE EASTERN GULF TOMORROW WAS MORE REALISTIC WITH THE
STRONG WINDS OUT OF INTERIOR PASSES. BUT ALSO BLENDED SOME OF THE
12Z GFS IN NEAR HAND OFF KEEPING GALE FORCE WINDS IN THE OUTER
COASTAL WATERS WITH THE SECOND WRAP TOMORROW AFTERNOON. FORECAST
CONFIDENCE IS BELOW AVERAGE THROUGH THE SHORT TERM PERIOD
ESPECIALLY WITH THE POSSIBLE SNOW AMOUNTS IN THE NORTHERN
PANHANDLE. 
 FOR TONIGHT SHOWERS WILL CONTINUE TO MOVE ACROSS THE PANHANDLE
AND BECOME SCATTERED LATE AS MID LEVEL RIDGING WILL ADVECT ACROSS
THE PANHANDLE LATE TONIGHT SUPPRESSING THE SHOWER ACTIVITY. WITH
THE LARGE AMOUNTS OF CAA THROUGH 500 MB AND SURFACE WINDS
BECOMING NORTHERLY LATE TONIGHT WILL SEE THE MAJORITY OF THE AREA
NORTH OF THE ICY STRAIT CORRIDOR CHANGE OVER TO ALL SNOW. THE
STRUGGLE IS DETERMINING HOW MUCH SNOW WILL FALL WITH THE
SCATTERED SHOWERS...BUT ATTM WILL HAVE THE MAJORITY OF THE
NORTHERN PANHANDLE WITH 1 TO 3 INCHES OF SNOWFALL. WILL MONITOR
THE 18Z MODELS RUNS AND UPDATE SNOWFALL AMOUNTS AS NEEDED.
ISOLATED THUNDERSTORMS WILL CONTINUE ESPECIALLY ALONG THE OUTER
COAST DURING THE EVENING HOURS WHERE SURFACE CONVERGENCE ENHANCES
THE SHOWER ACTIVITY. LOCALLY BREEZY CONDITIONS AND SMALL HAIL
WILL BE POSSIBLE NEAR THE STRONGER SHOWERS. WINDS WILL REMAIN
BELOW 25 KNOTS EXCEPT NEAR EAST-WEST ORIENTED CHANNELS LATE AS
THE SURFACE PRESSURE GRADIENT INCREASES. 
 FOR TOMORROW WILL SEE THE GALE TO STORM FORCE LOW MOVE INTO THE
WESTERN GULF AND WINDS INCREASE TO GALE FORCE ALONG THE OUTER
COAST. WILL ALSO HAVE WIND ADVY GUSTS ALONG THE OUTER COAST...BUT
THE LLJ 850 MB WINDS ARE BELOW 55 KNOTS AND SO ONLY HAVE LOCALLY
WINDY CONDITIONS ACROSS THE INNER CHANNELS THROUGH THE DAY
TOMORROW...BUT WILL HAVE TO MONITOR THE WINDS IN THE 18Z AND 00Z
MODEL RUNS FOR POSSIBLE EXPANSION OF THE WIND ADVY GUSTS. WITH
THE CONSISTENT NORTH TO NORTHEAST TRACK OF THE SURFACE LOW
TOMORROW A LARGE SWELL WILL DEVELOP WITH WAVE HEIGHTS NEAR
30 FEET IN PKZ0310 BY THE AFTERNOON AND THIS SITUATION WILL HAVE
TO CONTINUE TO BE MONITORED AFTER HAND OFF. ELSEWHERE PRECIP WILL
BEGIN OVERRUNNING ACROSS THE PANHANDLE TOMORROW AND AM CONCERNED
FOR AT LEAST SNOW ADVY AMOUNTS ALONG THE ROADWAYS NEAR THE BORDER
TOMORROW AS THE COLD AIR WILL BE IN PLACE TOMORROW MORNING.
850 MB TEMPS ARE BORDERLINE FOR SNOWFALL ALONG THE ICY STRAIT
CORRIDOR TOMORROW MORNING BUT SINCE THE MODELS HAVE POORLY
INITIALIZED THE COLD AIR CURRENTLY OVER THE EASTERN GULF
DECREASED TEMPERATURES TOMORROW MORNING TO ACCOUNT FOR POSSIBLE
SNOWFALL. IF THE WINDS DO REMAIN SOUTHERLY THROUGH MOST OF THE
DAY THEN SNOW AMOUNTS WILL REMAIN BELOW ADVY IN THE NORTHERN
PANHANDLE. THIS GALE TO STORM FORCE LOW  BEARS WATCHING OVER THE
NEXT FEW DAYS. 
&&
.LONG TERM...GALE FORCE LOW IN THE W GULF AT THE START OF THE
LONG TERM WILL TRACK N TOWARD PAMD. THE WEAKENING LOW WILL MAKE
LANDFALL SUN EVENING AS A WEAK RIDGE BUILDS OVER THE E GULF.
SHORT WAVE WILL QUICKLY TRACK ACROSS THE N GULF AS A STRONGER
RIDGE BUILDS OVER THE PANHANDLE WITH DEVELOPING LOW TO THE WEST.
FRONT ASSOCIATED WITH THE DEVELOPING LOW OVER THE BERING SEA WILL
MOVE OVER THE PANHANDLE TUE INTO WED.
FOR THE WEEKEND EXPECTING UPPER LVL GALE FORCE WINDS ALONG THE
COASTAL WATERS WITH TRAPPED FETCH WAVES PRODUCING 30 TO 35 FT
SEAS. CONTINUING THE WIND ADVISORY IN ZONE 23 AND 27 THROUGH SAT
EVENING. GRADIENT ORIENTATION FOR THE NORTHERN COASTAL AREAS
SHOULD KEEP WINDS BELOW ADVISORY LVLS...HOWEVER FINAL TRACK OF
THE LOW WILL DETERMINE IF ADDITIONAL LOCATIONS NEED ADV ADDED.
INSIDE CHANNELS WILL SEE SMCR WINDS WITH STRONGEST WINDS IN E-W
ORIENTATED CHANNELS. WEEKEND PRECIP WILL BE MOSTLY RAIN OVER THE
CENTRAL AND SOUTHERN REGIONS WITH SNOW OVER PAHN AND PAGY WITH
HIGHEST ACCUMULATIONS AT HIGHER ELEVATIONS AND ALONG THE BORDER.
MODELS WERE IN GOOD AGREEMENT AT THE START OF THE LONG TERM.
STARTED WITH A BLEND OF NAM AND GFS AS A TRANSITION FROM THE
SHORT TERM. GFS HAD A BETTER HANDLE ON THE WIND FIELD FOR SAT
NIGHT. THEN TRANSITIONED MORE TO ECMWF AND HPC GUIDANCE AS THE
GFS TRENDED AS AN OUTLIER. ECMWF HAS BEEN A BIT MORE CONSISTENT
WITH THE GFS A BIT FASTER WITH THE WED FRONT. MODELS DIVERGE
SIGNIFICANTLY AS WEATHER PATTERNS SHIFT. FORECAST CONFIDENCE WAS
AVERAGE AT THE START OF THE LONG TERM...CONFIDENCE DROPS
SIGNIFICANTLY DAY 4 ONWARD.
.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND ADVISORY FROM 6 AM TO 9 PM AKST SATURDAY FOR
AKZ023-027.
MARINE...GALE WARNING FOR PKZ021-022-042-043-051-052. 
         SMALL CRAFT ADVISORY FOR PKZ012-013-031>036-041. 
&&
$$
PSS/PRB