Small Craft Advisory 655, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
200 PM AKDT MON OCT 24 2011

.SHORT TERM...A RAPIDLY DEVELOPING STORM S OF THE AKPEN WILL
MOVE TO THE FAR NW GULF BY TUE AFTERNOON. A STRONG OCCLUDED FRONT
WILL MOVE TO THE EASTERN GULF BY TUE AFTERNOON. USED A BLEND OF
THE 12Z UKMET AND GFS MAINLY FOR THE WAY THEY HANDLE THE FRONT
MOVING INTO THE AREA.

 MAIN CONCERN WILL BE WINDS AHEAD OF THE FRONT. STRENGTH OF
850 MB FLOW AHEAD OF THE FRONT SUGGESTS POTENTIAL FOR HIGH WINDS
DEVELOPING ALONG THE CENTRAL AND SRN COAST BY 00Z WED. FURTHER NW
THE ORIENTATION OF THE FRONT MAKES IT A BIT LESS FAVORABLE FOR
60+ MPH WINDS...BUT STRONG WIND HEADLINES ARE LIKELY NEEDED FOR
PAEL AND PAYA AREAS AS GUSTS TO 50 MPH ARE A GOOD BET.
ALSO...STRONG SLY WINDS UP LYNN CANAL SHOULD GET INTO PAGY AREA
SO WILL LIKELY NEED STRONG WIND HEADLINES FOR THEM STARTING
AROUND MIDDAY TUE. OTHER AREAS WILL BE CLOSE TO STRONG WIND
LEVELS BY 00Z WED. THIS WILL BE ONE OF THE STRONGEST WIND EVENTS
IN SOME TIME FOR THIS AREA...MAINLY JUST AFTER THE SHORT TERM
PERIOD.

 OTHER ISSUES OF CONCERN WILL BE HOW QUICKLY PRECIP ARRIVES WITH
FRONT...AND HOW MUCH SHOWER ACTIVITY WILL OCCUR WELL OUT AHEAD OF
THE FRONT. MODEL SOUNDINGS SUGGEST BOUNDARY LAYER WILL REMAIN
NEAR OR JUST GREATER THAN THE MOIST ADIABATIC LAPSE RATE THROUGH
MUCH OF TUE...SO WITH ANY UPSLOPE FLOW SHOWERS WOULD BE ABLE TO
FORM. THAT WILL BE PARTIALLY NEGATED BY SOME RIDGING BUILDING
OVER THE TOP OF THE MAIN PART OF THE PANHANDLE TONIGHT. BUT ON
TUE AS UPPER HEIGHTS FALL INCREASING LIFT WILL LIKELY INCREASE
SHOWERS WELL OUT AHEAD OF THE FRONT. FOR SIMPLICITY OF
TERMINOLOGY TUE WILL STICK WITH STRATIFORM WORDING AS THE MAIN
PRECIP AREA WITH THE FRONT SHOULD MOVE INTO THE ERN GULF TUE
MORNING...THEN SPREAD TO MOST OF THE PANHANDLE AREA TUE
AFTERNOON. THE RAIN WILL BECOME FAIRLY HEAVY AROUND THE PAYA AREA
BY 18Z TUE...THEN BY 21-00Z ALONG THE CENTRAL OUTER COAST. SNOW
LEVELS WILL BE AROUND THE 2500 TO 3000 FOOT LEVEL FOR MUCH OF THE
AREA. WHITE PASS SHOULD GET A COUPLE INCHES OF SNOW THROUGH LATE
TUE AFTERNOON.

.LONG TERM...FORECAST CHALLENGE CONTINUES TO BE STORM CENTER MOVING
TO SITKINAK ISLAND BY 12Z TUE THEN CENTER MOVING TO CAPE SUCKLING
12Z WED. SATELLITE IMAGERY SHOWS A VERY NICE FORMATION 250 NM S OF
PADU STARTING TO CURVE TRACK TOWARD KODIAK ISL AS OF 24/22Z. BEST
MODELS DAY 2 TO 3 WAS 24/12Z UKMET AND AK-GFS-40 AND USED.

ASSOCIATED FRONT WILL CAUSE STORM FORCE WIND BUT DILEMMA WAS TO
INCLUDE HIGH WIND WARNINGS FOR LAND AREAS GREATER THAN 60 MPH. GUT
FEELING WAS BORDERLINE BUT 24/12Z AK-GFS-40 850 MB WIND INSISTS
THAT STRONG GUSTS WOULD REMAIN OVER THE OUTSIDE WATERS THROUGH
26/00Z THEN BRUSH ZONE 23 BEFORE MOVING OVER 27 & 28. WE THOUGHT
ABOUT THIS LONG AND HARD BEFORE SHIFTING THE WATCH TO SOUTHERN
BARANOF THEN INTO THE USUAL WINDY SPOTS IN THE SOUTH. HEAVY RAIN
WITH THIS ONE INDICATED IN THE QPF. USED COMBO GFS AND HPC FOR THE
DAY 4 THROUGH 7. CONFIDENCE HIGH DAYS 2 & 3 AND MODERATE BEYOND.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WATCH TUESDAY AFTERNOON - LATE TUE NIGHT OR
AKZ023 AND 027-028.
STRONG WIND TUE AKZ022. AKZ018.
MARINE...STORM WARNING PKZ043-051-052.
         GALE WARNING PKZ012-022-033-036-041-042-053.
         SMALL CRAFT ADVISORY PKZ011-013-021-031-032-034-035.
&&

RWT/JC