Small Craft Advisory 45, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
341 PM AKST TUE JAN 12 2016

.SHORT TERM...A LARGE LOW PRESSURE SYSTEM WITH MULTIPLE FRONTAL
BANDS WRAPPING AROUND IT CAN BE SEEN ON SATELLITE THIS AFTERNOON
WEST OF HAIDA GWAII. RAIN SHOWERS ARE PROGRESSING NORTHWARD OVER
THE PANHANDLE UNDER THE FIRST FRONTAL BAND. GALE FORCE WINDS ARE
MOVING INTO THE SOUTHERN OUTSIDE WATERS THIS EVENING WITH THE
SECOND BAND. THIS TREND WILL CONTINUE THROUGH TOMORROW AS THE LOW
SLOWLY MOVES NORTH TO BE WEST OF SITKA BY THE LATE AFTERNOON.

OFFSHORE FLOW ON THE NORTH SIDE OF THE LOW HAS LIMITED PRECIP OVER
THE NORTHERN PANHANDLE ALL DAY AND SHOULD ALSO LIMIT QPF AMOUNTS
ONCE THE RAIN MOVES IN THIS EVENING. THIS WILL BE THE CASE
TOMORROW...BUT THE STRONGEST FRONTAL BANDS LOOK TO STAY OVER THE
SOUTH AND BE SCATTERED OVER THE NORTH. THESE STRONGER BANDS WILL
HAVE GUSTY WINDS WITH IT...ESPECIALLY ALONG THE SOUTHERN OUTER
COAST CLOSEST TO THE LOW CENTER TONIGHT. BARANOF ISLAND AND THE
KETCHIKAN AREA WILL SEE GUSTS OF AROUND 35 MPH TONIGHT WHILE
PRINCE OF WALES WILL BE UP TO 45 MPH. GUSTY WINDS CAN ALSO BE
EXPECTED OUT OF CROSS SOUND AND SOME OTHER INTERIOR PASSES.

MODELS WERE IN FAIR AGREEMENT WITH PLACEMENT OF THIS LOW AND GOOD
AGREEMENT ON STRENGTH. 12Z MODELS MOVED THE LOW SLIGHTLY CLOSER TO
BARANOF ISLAND AND WERE A COUPLE MILLIBARS DEEPER WITH IT. USED
AN ENSEMBLE APPROACH TO ACHIEVE THIS WITH AN EMPHASIS ON THE
GFS22.

.LONG TERM...THE LOW DISCUSSED ABOVE WILL WEAKEN OVER THE
NORTHEAST GULF EARLY ON IN THE EXTENDED RANGE FORECAST PERIOD WITH
SHOWERS ENDING FROM SOUTH TO NORTH THURSDAY NIGHT. FRIDAY IS STILL
LOOKING LIKE A DRY DAY WITH PARTLY CLOUDY TO MOSTLY SUNNY
CONDITIONS DEVELOPING THROUGH THE AFTERNOON. THE BREAK WILL BE
SHORT LIVED, AS THE NEXT FRONT ROTATES NORTH OVER THE EASTERN GULF
AND SOUTHEAST ALASKA FRIDAY NIGHT INTO SATURDAY. MODEL AGREEMENT
IS STILL POOR ON THE DEVELOPMENT AND MOVEMENT OF THIS NEXT FRONT
AND GRIDS REFLECT THIS WITH A BROAD AREA OF LIKELY POP SPREADING
NORTH LATE FRIDAY NIGHT THROUGH SATURDAY AFTERNOON. PRESSURE
GRADIENT ASSOCIATED WITH THIS FRONT IS FAIRLY STRONG AND HAVE
SOUTHEASTERLY GALES OVER THE EASTERN GULF FRIDAY NIGHT EASING TO
SMALL CRAFT INTENSITY ON SATURDAY MORNING. THESE SMALL CRAFT WINDS
ARE FORECAST TO LAST INTO EARLY NEXT WEEK. RESPONSE TO THIS
GRADIENT OVER THE INNER CHANNELS WILL BE TYPICAL WITH SMALL CRAFT
WINDS OVER ALL OF THE INNER CHANNELS AND GALES OVER NORTHERN LYNN
AND CROSS SOUND. AS ON THE OUTSIDE, THESE WINDS WILL LINGER
THROUGH THE WEEKEND BUT THE GALES OVER LYNN CANAL AND CROSS SOUND
SHOULD RELAX BY SATURDAY AFTERNOON.

TEMPERATURES ARE FORECAST TO GRADUALLY FALL THROUGH THURSDAY
NIGHT AND THEN LEVEL OFF. SOME WEAK DIURNAL VARIABILITY IS
EXPECTED FOR LATE THIS WEEK INTO THE WEEKEND, BUT TEMPERATURES ARE
NOT EXPECTED TO VARY MUCH MORE THAN 5 TO 7 DEGREES BETWEEN DAY AND
NIGHT. THE TAKE AWAY POINT HERE IS THAT THERE WILL LIKELY BE SOME
SNOW FOR THE NORTHERN INNER CHANNELS - TO INCLUDE JUNEAU - AS WELL
AS MISTY FJORDS FOR WEDNESDAY NIGHT. AS SNOW LEVELS FALL, SNOW FOR
A MUCH LARGER AREA BECOME MORE PROBABLE FROM SATURDAY ONWARD. AS
OF RIGHT NOW, NO ADVISORY OR WINTER STORM WARNING AMOUNTS ARE IN
THE FORECAST.

USED THE 00Z ECMWF FOR PRESSURE AND WIND FOR THE VERY EARLY
PORTION OF THE EXTENDED RANGE, THEN TRANSITIONED TO THE 12Z ECMWF
FOR UPDATES THROUGH FRIDAY NIGHT. POP AND QPF FROM A BLEND OF
GFS22 AND GEM. TEMPS ADJUSTED PRIMARILY USING GFS MOS. LATEST WPC
USED FOR PRESSURE, WIND, AND POP FROM SATURDAY ONWARD. OVERALL
FORECAST CONFIDENCE IS AVERAGE THROUGH FRIDAY NIGHT AND TRENDING
BELOW AVERAGE THEREAFTER.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND UNTIL 3 AM AKST WEDNESDAY FOR AKZ027.
MARINE...GALE WARNING FOR PKZ022-033-036-041-042.
         SMALL CRAFT ADVISORY FOR PKZ012-013-021-031-032-034-035-043.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ051-052.

&&

FERRIN/FRITSCH

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