Area Forecast Discussion
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000
FXAK67 PAJK 271259
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
459 AM AKDT WED APR 27 2016

.SHORT TERM...WEATHER FRONT THAT CROSSED OVER THE PANHANDLE
OVERNIGHT IS NOW IN BRITISH COLUMBIA AS A WEAK RIDGE BUILT OVER
THE PANHANDLE. STEADY RAINFALL TRANSITIONED TO SHOWERS, WHICH THEN
BECOME MORE SPORADIC IN INTENSITY AND COVERAGE EARLY THIS MORNING.
A FEW BREAKS IN CLOUD COVER PRODUCED AREAS OF RADIATIONAL FOG
DEVELOPMENT ALONG THE COASTAL PANHANDLE. MODEL SOUNDINGS SHOWED A STABLE
AIR MASS OVER SHALLOW MOISTURE THROUGH 6 AM, WHEN THE FOG WILL
LIFT. AREAS OF FOG DID DROP DOWN BELOW 1 MILE FOR YAKUTAT AND
KLAWOCK, BUT THEN VISIBILITY QUICKLY IMPROVED. ANOTHER SHORT WAVE
IS MOVING INTO THE EASTERN GULF TODAY AND TRACKING NORTHEASTERLY.
IT WILL THEN CROSS INTO THE NORTHERN PANHANDLE THIS EVENING.
UNSTABLE AIRMASS ASSOCIATED WITH THIS WAVE PRODUCING CAPE VALUES
NEAR 200 J/KG AND LI NEARING -2C. PUT IN SLIGHT CHANCE OF
THUNDERSTORMS IN THE N GULF UNDER THIS WAVE. SHOWER ACTIVITY WILL
DIMINISH OVER THE SOUTHERN PANHANDLE THROUGH THE DAY BUT INCREASE
IN THE AFTERNOON OVER THE CENTRAL AND NORTHERN AREAS EARLY IN THE
EVENING UNDER THIS NEXT VORT LOBE. A MORE ORGANIZED FRONT
EXTENDING FROM A LOW NEAR THE ALEUTIANS MOVES IN RAPIDLY TONIGHT
WITH MORE STRATIFORM RAIN CROSSING INTO THE PANHANDLE AND GULF.

SOUTHERLY WINDS OVER THE AREA DROPPED THROUGH THE NIGHT WITH WIND
SPEEDS CURRENTLY 15 KT OR LESS. WINDS WILL PICK UP TO GALE FORCE
ALONG THE NORTHERN COASTAL WATERS THROUGH THE EVENING WITH
SOUTHERN COASTAL WATER AND INNER CHANNEL WINDS PICKING UP TO SMALL
CRAFT LATER TONIGHT. MAINLY E-W PARALLEL GRADIENT FOR THE CENTRAL
AND NORTHERN CHANNELS FOR N-S CHANNELS WINDS WILL BE WEAKER THAN
THE E-W CHANNELS.

MODELS STILL IN DECENT AGREEMENT AND WHILE THERE ARE SOME DETAILS
WITH TIMING OF FRONTS DIFFERING FROM INHERITED FORECAST THESE
DIFFERENCES WERE RATHER SMALL. LIKED THE 00Z NAM/EC OVERALL BUT
MADE FEW CHANGES TO GRIDS. FORECAST CONFIDENCE IS AVERAGE.

.LONG TERM...A GALE FORCE FRONT /WITH GALE STRENGTH SPEEDS OVER
GULF MARINE ZONES 51 AND 52/ IS FORECAST TO WEAKEN DURING THU AS
IT ENCOUNTERS THE PANHANDLE. THEREAFTER...MOIST ONSHORE SWLYS WILL
PROMOTE RAIN OVER THE REGION INTO SAT AFTERNOON. RAIN IS FORECAST
TO BECOME INCREASINGLY CONFINED TO THE NRN PANHANDLE SAT
NIGHT...WHILE A DRIER/SUBSIDENT ENVIRONMENT OVER THE SRN PANHANDLE
YIELDS A BRIEF RESPITE FROM WET WEATHER.

MEANWHILE...MODEL GUIDANCE IS IN GOOD AGREEMENT SHOWING A DEEP-
LAYER CYCLONE STRENGTHENING AS IT EJECTS FROM THE NCNTRL PAC
TOWARD THE SWRN GULF FRI AND SAT. A 100+ KT UPPER-LEVEL JET WILL
BE PRESENT ALONG THE ERN PERIPHERY OF THE CYCLONE...WITH THE JET
TAKING AIM AT THE PANHANDLE DURING THE WEEKEND. IN ADDITION...A
WARM AIRMASS AND SUBTROPICAL MOISTURE WILL SPREAD TOWARD THE
SRN/CNTRL PANHANDLE...SETTING THE STAGE FOR HEAVY RAIN SAT NIGHT
THROUGH MON.

UPDATES TO THE INHERITED FORECAST WERE MADE THROUGH SAT...WITH THE
BULK OF THE PREVIOUS FORECAST MAINTAINED THEREAFTER. ENSEMBLE
APPROACH WAS USED FOR CHANGES.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ043-051-052.
     SMALL CRAFT ADVISORY FOR PKZ022-033-036-041-042.
     SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ053.
&&

$$

PRB/GARNER

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