Small Craft Advisory 718, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
231 PM AKST SAT NOV 12 2011

.SHORT TERM...WEAKENING LOW IS NOW MOVING ACROSS NRN SE AK AND
WILL BE E OF THE AREA BY 00Z. A WEAK LOW WILL FORM OVER THE FAR
NRN GULF THIS EVENING AND DRIFT SLOWLY EWD INTO THE FAR NE GULF
SUN. A TROF WILL MOVE E THRU THE PANHANDLE TONIGHT. USED THE 12Z
ECMWF FOR THE PRESSURE FIELD AS IT HAD GOOD HANDLE ON THE
SITUATION.

MAIN ISSUE WILL BE WINDS AND SEAS. ATTM STG WLY WINDS ARE OVER
MUCH OF THE CENTRAL AND ERN GULF AND THEY JUST RECENTLY REACHED
THE OUTER COAST. EXPECT THESE WINDS TO CONTINUE BUT BACK OFF
SLIGHTLY ALONG THE COAST THIS EVENING AS THE LOW OVER THE NRN AREA
PULLS AWAY. WILL KEEP HIGH WIND WARNING GOING UNTIL 03Z FOR ZONES
23 AND 27. THEY WILL LIKELY HAVE STRONG WIND HEADLINES FOR LATER
THIS EVENING THRU SUN AFTERNOON ONCE WARNING ENDS. WILL KEEP THE
STRONG WIND HEADLINES ELSEWHERE S OF A PAJN-PAEL LINE. DROPPED THE
STRONG WIND HEADLINES FOR THE FAR NRN AREAS DUE TO THE MAIN BELT
OF STRONGER WINDS AND PRESSURE GRADIENT REMAINING TO THEIR S.

WAVE HEIGHTS HAVE RISEN UP TO 32 FT OVER THE E-CENTRAL GULF. THEY
WILL REMAIN IN THE 26 TO 32 FT RANGE OVER MUCH OF THE ERN GULF
THRU SUN. THE FAR NRN GULF SEAS WILL BE SOMEWHAT LESS GIVEN THE
LARGE WLY SWELLS WILL BE DIRECTED TO THEIR S.

OTHERWISE...OTHER THAN THE FAR NRN AREA PRECIP HAS BECOME RAIN
SHOWERS. THE FAR N HAS A FEW FLURRIES AROUND. OTHER THAN THE
CHILKAT VALLEY EXPECT ENOUGH WARMING TO CAUSE PRECIP OVER THE N TO
GO LIQUID NEAR SEA LEVEL BUT IT WILL BE SPOTTY AT BEST. COLDER AIR
WILL FILTER IN FROM THE W AND BASED ON 850 MB TEMPS DROPPING TO
-8C OR COLDER...PRECIP SHOULD TRANSITION TO MOSTLY SNOW SHOWERS
FROM THE W SUN OVER ALL BUT THE FAR SERN AREA. NOT EXPECTING MUCH
SNOW ACCUMULATION NEAR SEA LEVEL THROUGH SUN WITH TEMPS LIKELY
REMAINING IN THE MID TO UPPER 30S. A DUSTING TO AN INCH OF SNOW IS
LIKELY.

.LONG TERM...A TWO STEP COOLING TREND WILL OCCUR WITH THE FIRST A
WEAK PRECIP MECHANISM FOR SUN NIGHT, AND A LARGE SCALE ARCTIC OUTBREAK
BEGINNING TUE NIGHT. PRIMARY CHANGES TO THE LONG RANGE PACKAGE HAVE
BEEN FOR STRONGER WINDS AND LOWER TEMPERATURES WITH THE ARCTIC OUTBREAK.
CONFIDENCE IS AVERAGE.

FIRST AN ARCTIC OUTBREAK FROM THE INTERIOR TO PRINCE WILLIAM SOUND
WILL BECOME MARINE MODIFIED AS IT TRACKS E TOWARD THE PANHANDLE.
THIS ARCTIC OUTFLOW OVER THE COMPARATIVELY WARM WATER IN THE GULF
RESULTS IN A SHALLOW UNSTABLE LAYER THAT RAPIDLY SENDS WATER VAPOR
AND WARMING INTO THE BOUNDARY LAYER. LIFTING OF THIS AIRMASS THEN
RESULTS IN LOW LEVEL CLOUDMASS, AS WELL AS PRECIP WITH AMOUNTS
LIMITED BY MOST OF THE PRECIPITABLE WATER BEING IN THE LOWEST
LEVELS.

00Z TO 12Z WED. AN UNMODIFIED ARCTIC OUTBREAK FM THE N WILL
FOLLOW WITH TUE NIGHT AND EARLY WED.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND THROUGH SUNDAY AFTERNOON FOR AKZ021-024>026-028-029.
         HIGH WIND WARNING UNTIL 6 PM AKST THIS EVENING FOR AKZ023-027.
         STRONG WIND FROM 6 PM AKST THIS EVENING THROUGH SUNDAY AFTERNOON
     FOR AKZ023-027.
         STRONG WIND THROUGH SUNDAY AFTERNOON FOR AKZ022.
MARINE...STORM WARNING FOR PKZ022-041>043-051.
         GALE WARNING FOR PKZ012-013-021-031>033-035-036-052.
         SMALL CRAFT ADVISORY FOR PKZ011-034-053.

&&

RWT/JBT

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
1050 PM AKST SAT NOV 12 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0900 PM     NON-TSTM WND GST 18 WNW EDNA BAY         56.01N 134.13W
11/12/2011  M100 MPH                            AK   C-MAN STATION

            CAPE DECISION LIGHTHOUSE HAS BEEN REPORTING GUSTS OVER
            HURRICANE FORCE FOR ABOUT 13 HOURS. FROM ABOUT 8 AM THIS
            MORNING TO 9 PM THIS EVENING. HIGHEST GUSTS DURING THIS
            PERIOD WAS 100 MPH ABOUT 1 PM.

&&

EAL