Gale Warning 413, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
214 PM AKST WED DEC 3 2008

.SHORT TERM...MORNING SATELLITE LOOP SHOWS INCREASING MID TO
HIGH CLOUD SHIELD ACROSS THE PANHANDLE...SPREADING SOUTHEAST AND
FILTERING THE SUNSHINE. STRONG NORTH TO SOUTH BAROCLINIC ZONE IN
THE CENTRAL GULF IS PUSHING A GUST FRONT INTO THE EASTERN GULF
AND THE RIDGE ALOFT OVER THE LOCAL AREA IS RAPIDLY WEAKENING THIS
MORNING. MODELS ARE IN FAIR AGREEMENT WITH THE INCOMING FRONT
TONIGHT AND THURSDAY. WILL USE THE NAM TO MAINTAIN THE CONTINUITY
FROM THE PREVIOUS FORECAST.

THE GALE FORCE FRONT ASSOCIATED WITH A 964 MB LOW IN THE WESTERN
GULF WILL MOVE INTO THE NORTHEAST GULF TONIGHT AND START AFFECTING
YAKUTAT AREA WITH INCREASING BARRIER JET. WARMER AIR FROM THE SOUTH
WILL ENHANCE THE ISENTROPIC LIFTING ACROSS THE NORTHERN COASTAL
ZONES TONIGHT WITH A HEAVY SNOW SCENARIO. WILL UPGRADE THE SNOW
ADVISORY TO A HEAVY SNOW WARNING FOR YAKUTAT AND GUSTAVUS. THE
FRONTAL BOUNDARY WILL ARRIVE YAKUTAT AREA BY EARLY THIS EVENING AND
SPREAD TO GUSTAVUS AREA SLIGHTLY AFTER MIDNIGHT TONIGHT. EXPECT 6 TO
10 INCHES OF SNOW AT YAKUTAT ZONE...MAINLY ALONG THE COAST AND 4 TO
8 INCHES AT GUSTAVUS ZONE...MAINLY OVER GLACIER BAY. EXPECT PRETTY
WET SNOW AND BLOWING SNOW WOULD NOT BE A CONCERN. WILL CONTINUE THE
SNOW ADVISORY FOR HAINES AND JUNEAU ZONES ON THURSDAY WITH A BIT
DELAYING OF BEGINNING TIME. A WARMING TREND WILL CONTINUE ACROSS THE
LOCAL REGION ON THURSDAY.

PRESSURE GRADIENT WILL CONTINUE TO RELAX THIS AFTERNOON THROUGH THE
EVENING HOURS. HOWEVER...WITH THE INCOMING GALE FORCE FRONT...WINDS
WILL INCREASE AND SHIFT TO MORE SOUTHEAST AT THE SURFACE WITH SOUTH
TO SOUTHWEST FLOW AT THE BOUNDARY LAYER. STRONG BARRIER JET WILL
DEVELOP IN THE NORTH EASTERN GULF LATE TONIGHT AND SPREAD SOUTHEAST
ALONG THE PANHANDLE COAST THROUGH THURSDAY MORNING WITH ADVISORY
LEVEL WIND GUSTS. WILL ISSUE A WIND ADVISORY FOR ALL COASTAL ZONES
WITH BEGINNING TIME FOR YAKUTAT BY MIDNIGHT TONIGHT.

.LONG TERM...NOT MUCH CHANGE IN THE LONG TERM FORECAST AS THE
MODELS AREA IN GOOD AGREEMENT THROUGH THE WEEKEND BUT THEN THEY
DIVERGE IN SOLUTIONS. THE ENSEMBLES ARE ALSO NOT SHOWING MUCH
CONSENSUS WITH A LOW MOVING OUT OF THE NORTH PACIFIC AND INTO THE
GULF MON INTO TUE. THE GFS IS MOVING THE LOW INTO THE WESTERN
GULF WHERE AS THE EC IS MOVING THE LOW INTO THE EASTERN GULF. THE
GFS IS PUMPING UP A STRONG RIDGE AHEAD OF THE UPPER LEVEL LOW AS
THE THE EC HAS A MUCH FLATTER RIDGE. SO WITH THAT SAID THERE IS
GOOD FORECASTER CONFIDENCE THROUGH THE WEEKEND THEN POOR FOR NEXT
WEEK. USED A BLEND OF THE EC AND GFS FROM THURSDAY NIGHT THROUGH
THE WEEKEND AS THERE WAS VERY GOOD AGREEMENT BETWEEN THE MODELS
AND ENSEMBLES AFTER THAT DID NOT CHANGE THE FORECAST WITH THE
LARGE UNCERTAINTY IN THE MODELS.

THE UPPER LEVEL LOW OVER THE BEARING AND AK PEN WILL CONTINUE TO
ERODE THE UPPER RIDGE OVER THE EASTERN GULF. SHORTWAVES ROTATING
AROUND THE LOW WILL FLATTEN AND PUSH EAST THE RIDGE OVER OF THE
PANHANDLE THROUGH SAT. THE UPPER TROF WILL COVER THE ENTIRE GULF
AS A VERY HIGH AMPLITUDE HIGH BUILDS OVER THE BERING EXTENDING
FROM THE PACIFIC. THIS TROF WILL CONTINUE TO ROTATE SHORTWAVE
TROF OVER THE PANHANDLE ALOFT AND AT THE SURFACE. THIS WILL KEEP
PRECIPITATION CATEGORICAL TO LIKELY OVER MOST OF SE AK. P-TYPE WILL
BE TRICKY BUT WITH ONSHORE FLOW AND SOUTHWEST FLOW ALOFT THINK
MOST PREICP WILL FALL AS LIQUID. OVER THE FAR NORTHERN AREAS IT
WILL BE A MIXED OF RAIN AND SNOW BUT MAINLY SNOW AS THEY WILL KEEP
A WEAK NORTHERLY GRADIENT.

FOR THURSDAY NIGHT INTO FRIDAY THERE WILL BE A BREAK IN THE PRECIP
OVER THE NORTHERN AREAS WITH JUST A CHANCE OF RAIN AND SNOW AS MOST
OF THE UPPER LEVEL DYNAMICS FROM THE PASSING FRONT WILL HAVE MOVED
INTO CANADA. OVER THE SOUTHERN AREAS THE FRONT WILL BECOME STATIONARY
THROUGH FRIDAY AFTERNOON TO KEEP MODERATE TO HEAVY RAIN OVER THE
AREA.

WINDS THROUGH THE LONG TERM WILL BE FAIRLY LIGHT WITH NO REAL BIG
SYSTEMS MOVING OVER THE AREA.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND ADVISORY FROM 6 AM TO 12 PM AKST THURSDAY FOR AKZ027.
         WINTER WEATHER ADVISORY FROM 5 AM TO 6 PM AKST THURSDAY FOR
         AKZ019-025.
         WIND ADVISORY FROM MIDNIGHT TONIGHT TO 12 PM AKST THURSDAY
         FOR AKZ017-022.
         WIND ADVISORY FROM 3 AM TO 12 PM AKST THURSDAY FOR AKZ023.
         WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM AKST
         THURSDAY FOR AKZ020.
         WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM AKST
         THURSDAY FOR AKZ017.
MARINE...GALE WARNING FOR PKZ011-022-041>043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ013-021-031>036.

SJA/ABJ