Small Craft Advisory 826, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
252 PM AKST TUE DEC 13 2011

.SHORT TERM...ONE BAND OF SEMI ORGANIZED SHOWERS ASSOCIATED WITH
AN UPPER TROUGH MOVING ACROSS THE CENTRAL INNER CHANNELS TUESDAY
AFTERNOON. A SECOND CLUSTER OF SHOWERS OVER THE NORTHERN GULF ARE
ARE TRACKING NORTH/NORTHEAST TOWARDS THE NORTHEAST GULF COAST.

 HIGH PRESSURE RIDGE OVER THE REST OF THE SOUTHEAST PANHANDLE
AREA WILL BE GIVING WAY TO AN INCOMING FRONTAL BAND OVER WESTERN
AND CENTRAL PANHANDLE. THIS TROUGH WILL BE WEAKENING AS IT MOVE
TO THE EASTERN GULF ON WEDNESDAY. PRECIPITATION TYPE OF SNOW...
OR SNOW GIVING WAY TO RAIN DURING THE DAY FOR THE NORTHERN HALF
... AND LIQUID OVER THE SOUTHERN THIRD. JUST CHANCE LEVEL
PRECIPITATION FOR THE SOUTHERN/EASTERN PORTIONS.  SNOW
ACCUMULATIONS OVER THE NORTHERN PORTION OF THE PANHANDLE SHOULD
BE LIMITED TO JUST A COUPLE OF INCHES TONIGHT INTO WEDNESDAY.

 SMALL CRAFT LEVEL WINDS WILL LIKELY SPREAD INTO MUCH OF THE THE
COASTAL WATERS OVER THE NORTHEAST  SECTIONS ON
WEDNESDAY...OTHERWISE THE SMALL CRAFT LEVELS WILL BE DUE TO THE
HIGHER SEES PERSISTING THERE.  DO EXPECT A SMALL INCREASE TO
25 KT FOR THE CROSS SOUND AREA WEDNESDAY AFTERNOON.

.LONG TERM...MODELS IN GOOD AGREEMENT ON THE LARGE SCALE PATTERN
THRU EARLY NEXT WEEK. THEY SHOW A LONGWAVE TROF WILL GENERALLY
REMAIN OVER WRN AK AND BERING SEA AND ADJACENT NPAC
WATERS...WHILE LONGWAVE RIDGE REMAINS OVER THE FAR ERN PAC AND
ADJACENT FAR WRN CANADA/WRN LOWER 48. THEY DIFFER SOMEWHAT ON
TIMING INDIVIDUAL SHORTWAVES MOVING THRU THE AREA...MAKING FOR A
TRICKY SYSTEM TIMING FORECAST BUT OVERALL PATTERN IS FAVORING
MILD AND WET WEATHER ESPECIALLY OVER THE NW HALF OF THE AREA.
THERE ARE DIFFERENCES ON STRENGTH OF SOME OF THE SHORTWAVES AS
WELL...SO CONFIDENCE IN HOW MUCH WIND WILL OCCUR IS RATHER LOW
ESPECIALLY FROM THE WEEKEND ONWARD. DUE TO THE SIMILAR WAY THEY
HANDLE FEATURES THRU FRI...USED A 12Z GFS/ECMWF BLEND THRU 06Z
SAT...THEN WENT WITH LATEST HPC FROM 12Z SAT ON OUT.

 FOR WED NIGHT...WEAKENING FRONT WILL DISSIPATE ALONG THE OUTER
COAST...AND PRECIP SHOULD GRADUALLY DIMINISH ESPECIALLY ON THE
ERN SIDE OF THE PRECIP SHIELD.

 STRONGER FRONT WILL MOVE IN THU THRU FRI. SHOULD SEE MORE
WIDESPREAD PRECIP MOVE BACK IN ALONG WITH SOME WARMER AIR. WILL
ALSO SEE MORE WIND WITH THIS FRONT WITH GALES LIKELY OVER THE ERN
GULF AND CLARENCE STRAIT AREAS AHEAD OF IT. ONE ISSUE WITH THIS
FRONT IS HOW MUCH LOW PRESSURE WAVE ACTIVITY WILL DEVELOP AND
MOVE NE INTO THE AREA THU NIGHT AND FRI. OPERATIONAL MODELS AND
ENSEMBLE MEMBERS WERE ALL OVER THE PLACE ON THIS EXCEPT THE 12Z
ECMWF/GFS WERE FAIRLY CLOSE. THEY TAKE ONE WAVE INTO THE SE GULF
THU NIGHT THEN A SECOND WAVE INTO THE NE GULF FRI. THAT AGREEMENT
WAS DECIDING FACTOR IN CHOOSING THAT MODEL BLEND DURING THIS
TIME. ALREADY 18Z GFS IS GOING SOMEWHAT DIFFERENT AGAIN ON
THIS...SO CONFIDENCE IS LOW HERE.

 FOR WEEKEND ONWARD...ABOUT ONLY THING MODELS AGREE ON IS ANOTHER
FAIRLY STRONG BUT WEAKENING FRONT WILL MOVE INTO THE ERN GULF
SOMETIME DURING THE SUN/MON PERIOD.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ022-042-043-051-052.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ041.

&&

BEZENEK/RWT