Area Forecast Discussion
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FXAK67 PAJK 261333
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
533 AM AKDT THU MAR 26 2015

.SHORT TERM...LACK OF MODERATE RAINFALL THUS FAR AS WELL AS WINDS
IN MOST AREAS A BIT PUZZLING BUT MAINLY DUE TO POOR MODEL
FORECASTS. THIS MORNING...OFFSHORE WINDS TO 35KT AT BUOY 46082 AND
G30KT AT CDE ARE REALLY THE ONLY LOCATIONS WITH ANY SIGNIFICANT
WIND AT THE MOMENT. OTHER OFFSHORE BUOYS ARE GUSTING 25-30. LOW IS
POSITIONED OVER THE WESTERN GULF ATTM AND BEGINNING TO RETROGRADE
TO THE NORTHWEST AS SHOWN IN CURRENT IR IMAGERY. STRONG SSWLY FLOW
EAST OF THE LOW ALOFT IS BRINGING UP A GOOD SLUG OF MOISTURE FROM
THE SOUTH BUT WITHOUT ORGANIZATION AND WITHOUT LARGE-SCALE LIFT.
THE LOW POSITION IS WELL TO THE WEST OF PREVIOUSLY FORECASTED
ONES...AND THIS IS THE PRIMARY CAUSE OF THE OVERFORECASTED RAIN
AMOUNTS AND WINDS. DYNAMIC UPLIFT IS MUCH WEAKER THAN PREVIOUS
SCENARIO AS STRONG DYNAMICS ARE WELL TO THE WEST AND HEADING
NORTHWARD. HOPEFULLY WITH THE LATEST MODEL RUNS WE HAVE CORRECTED
THIS TO A SUFFICIENT DEGREE IN THE FORECASTS. CURRENTLY HAVE SCAS
FOR ALL OF THE ADJACENT OFFSHORE MARINE ZONES AND FOR SOUTHERLY
WINDS LATER IN THE NORTHERN LYNN CANAL. HOWEVER BUOY 46084 IS ONLY
GUSTING TO 27KT NOW AND MAY NOT MAKE IT INTO SCA LEVEL WIND. ONLY
ABOUT HALF OF THE CURRENT METARS ARE SHOWING LIGHT RAIN
NOW...EXPECT SHOWERY CONDITIONS TO PREVAIL MOST OF THE DAY HOWEVER
WITH MOISTURE ADVECTING FROM SOUTH AND ONSHORE FLOW. MODERATE
RAINFALL DEVELOPMENT WILL LIKELY BE CONFINED TO OROGRAPHICALLY
FAVORED AREAS FOR SOUTHERLY FLOW. KETCHIKAN WAS DOWN TO A HALF
MILE OVERNIGHT WITH FOG BUT THIS HAS BEEN REPLACED WITH LIGHT
RAIN. FOG MAY BECOME A PROBLEM OVER THE SOUTH TONIGHT IF BREAKS IN
THE OVERCAST OCCUR OVER RAIN-FREE REGIONS BUT ELECTED TO NOT PUT
IT INTO THE FORECAST FOR NOW AS CLOUDY CONDITIONS SHOULD DOMINATE.
STRONGEST GRADIENT...WITH SOUTH WINDS...IS OFFSHORE AND REMAINS
OFFSHORE...AND THIS SHOULD BEGIN TO WEAKEN LATE THIS AFTERNOON. BY
FRIDAY MORNING ALL GRADIENTS OVER LAND ARE MUCH WEAKER AND WINDS
WILL DECREASE QUICKLY AS THIS CHANGE OCCURS. WINDS WILL BRIEFLY
SWITCH TO SOUTHERLY OVER THE MORE EXPOSED SITES IN THE PANHANDLE
AFTER THE FRONTAL PASSAGE TODAY...PRIOR TO WEAKENING. MADE GRID
UPDATES USING MOSTLY AN EC/NAM COMBO KEEPING IN MIND THAT THE NAM
QPF IS LIKELY OVERDONE. QPF VALUES ARE GREATER OVER THE NORTHERN
PANHANDLE WITH SOME LOCATIONS APPROACHING A HALF INCH TOTAL. NO
SEA-LEVEL AREAS IN PANHANDLE SHOULD SEE ANY THREAT OF MIXED PRECIP
TYPE THROUGH FRIDAY.

.LONG TERM...UPPER TROUGH EXTENDING SSE FROM THE ALEUTIANS INTO
THE NRN PAC THIS MORNING IS FORECAST TO EJECT NE TOWARD THE CNTRL
GULF BY MIDDAY FRI...AND THEN MOVE ACROSS THE PANHANDLE FRI NIGHT.
AS THIS TAKES PLACE...MOIST ONSHORE FLOW AND FORCING FOR ASCENT
ASSOCIATED WITH THE UPPER DISTURBANCE WILL AID IN SHOWER
DEVELOPMENT ACROSS MUCH OF THE REGION. IN ADDITION...COLD MIDLEVEL
TEMPERATURES...NEAR -36C AT 500 MB...AND ASSOCIATED STEEP LAPSE
RATES WILL SPREAD OVER THE GULF RESULTING IN THE DEVELOPMENT OF A
COUPLE HUNDRED J/KG OF SBCAPE. HOWEVER...BOUNDARY LAYER AND SEA
SURFACE TEMPERATURES ARE CURRENTLY EXPECTED TO BE TOO COOL FOR
THUNDERSTORM DEVELOPMENT.

MEANWHILE...SECOND SHORTWAVE TROUGH WILL ROTATE NWD OVER THE
WRN/CNTRL GULF GOING INTO SAT MORNING. ASSOCIATED SURFACE CYCLONE
WILL PROGRESS N WITH IT/S PARENT UPPER TROUGH...WHILE A GALE
STRENGTH FRONT MOVES INTO THE ERN GULF LATE SAT MORNING...AND THEN
ONSHORE OVER THE CNTRL/SRN PANHANDLE BY EARLY SAT AFTERNOON. AS
THE FRONT MOVES ONSHORE...STRONG WINDS /GUSTS NEAR 40 MPH/ WILL
BECOME INCREASINGLY PROBABLE FOR AKZ027 /HYDABURG/ AND AKZ028
/KETCHIKAN...METLAKATLA...AND ANNETTE/. WINDS WILL THEN GRADUALLY
WEAKEN BEHIND THE FRONT GOING INTO SAT EVENING. MODERATE RAIN
RATES WILL ALSO BE LIKELY AS PW VALUES FROM 0.4-0.6 INCH SPREAD
NWD ALONG/AHEAD OF THE FRONT. WET PATTERN PERSISTS THEREAFTER INTO
EARLY NEXT WEEK...WITH MODEL SPREAD AND FORECAST UNCERTAINTY
INCREASING BY MID WEEK.

BLENDED IN THE 00Z ECMWF AND GEM WITH INHERITED PRESSURE GRIDS
THROUGH 12Z SUN...THEN LEFT WPC GRIDS UNTOUCHED FOR THE REMAINDER
OF THE LONG TERM. POP AND QPF WERE REFRESHED WITH GFS/ECMWF
BLENDED IN WITH PREVIOUS FORECAST.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-041>043-051-052.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ053.

&&

$$

WESLEY/GARNER

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