Small Craft Advisory 50, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
323 PM AKST THU JAN 14 2016

.SHORT TERM...A LOW VERY NEAR CROSS SOUND AS OF THIS AFTERNOON
CONTINUES TO ROTATE BANDS OF SHOWERS OVER THE CENTRAL AND NORTHERN
PANHANDLE WITH LIMITED SHOWER ACTIVITY OVER AREAS TO THE SOUTH.
APART FROM SOME SNOW MIXED WITH RAIN IN THE HYDER AREA EARLIER
TODAY, ALL OF THE SHOWER ACTIVITY HAS BEEN IN THE FORM OF RAIN.
AS THE LOW DISSIPATES, THE WARMER LOW LEVEL AIRMASS WILL WEAKEN AS
WELL AND BOTH THE LOWS TONIGHT AND THE HIGHS TOMORROW ARE EXPECTED
TO BE A LITTLE BIT COOLER THAN LAST NIGHT OR TODAY. EXPECTATIONS
IT THAT THE SHOWERS WILL DRY UP BEFORE TEMPS FALL BELOW FREEZING
SO NO SIGNIFICANT SNOWFALL IS EXPECTED TONIGHT OR EARLY TOMORROW
MORNING. EXCEPTIONS WILL BE ALONG THE HIGHWAYS NEAR THE BORDER.

CLEARING SKIES ARE EXPECTED IN THE WAKE OF THE LOW AND THE
DIMINISHING POP WITH THE CLEARING PROGRESSING FROM SOUTH TO NORTH
THROUGH THE SHORT TERM FORECAST PERIOD. EVEN THOUGH THERE WILL BE
SOME SUNSHINE, TOMORROW'S HIGHS ARE EXPECTED TO MAX OUT BETWEEN
THE UPPER 30S TO LOWER 40S DUE TO A SLIGHTLY COOLER LOW LEVEL
AIRMASS AT 850MB.

WINDS OVER THE EASTERN GULF WILL BEGIN INCREASING OUT OF THE
SOUTHEAST TOMORROW IN ADVANCE OF THE NEXT FRONT THAT WILL ARRIVE
EARLY ON IN THE EXTENDED RANGE FORECAST PERIOD. SMALL CRAFT SEAS
WILL NEVER COMPLETELY ABATE TONIGHT BEFORE SMALL CRAFT WINDS
RETURN TO THE EASTERN GULF. BY TOMORROW AFTERNOON, GALE FORCE
WINDS WILL EXTEND FROM SOUTH OF CAPE EDGECUMBE WEST-NORTHWEST
ACROSS OFFSHORE ZONE 310.

MODEL AGREEMENT IN THE SHORT RANGE BETTER THAN AVERAGE. UPDATED
THE SHORT RANGE FORECAST USING A BLEND OF GFS22 AND NAM12 FOR
PRESSURE AND WIND DIRECTION. WIND SPEEDS OVER THE GULF ARE A
MODIFIED NAM FIELD. POP AND QPF FROM GFS22 AND GEM. TEMPS ADJUSTED
USING GFS MOS. OVERALL FORECAST CONFIDENCE IS AVERAGE.

.LONG TERM...UPPER TROUGH/LOW EXTENDING SSE FROM THE BERING SEA
ACROSS THE ALEUTIANS IS FORECAST TO BE MAINTAINED IN ONE SENSE OR
ANOTHER THROUGHOUT MOST OF THE LONG TERM PERIOD. MODEL GUIDANCE
SHOWS A SERIES OF UPPER DISTURBANCES ROTATING NWD AROUND THE ERN
PERIPHERY OF THE LARGER-SCALE TROUGH...THE FIRST TWO OF WHICH WILL
IMPACT THE PANHANDLE AND GULF THIS WEEKEND.

THE FIRST DISTURBANCE ASSOCIATED WITH A GALE FORCE FRONT WILL
ENTER THE REGION ON SAT...SPREADING A MIX OF RAIN/SNOW INLAND.
THEREAFTER...A COMPACT...POTENTIALLY POTENT...SURFACE CYCLONE IS
FORECAST TO MOVE TO THE SERN GULF SUN EVENING...AND THEN ROTATE
WNW ACROSS THE CNTRL GULF SUN NIGHT INTO MON. THE 18Z GFS DETACHES
THIS LOW FROM THE PRIMARY TROUGH TO THE W...WHICH CAUSES IT TO
PROGRESS MUCH SLOWER THAN THE NAM AND ECMWF SOLUTIONS. THUS...HAVE
DISCOUNTED THE GFS AS AN OUTLIER ATTM. WINDS WILL BE THE PRIMARY
IMPACT WITH THE LOW ON SUN...WITH STRONG OUTFLOW WINDS DEVELOPING
OVER THE CNTRL/NRN INNER CHANNELS...AND SELY GALES OVER THE FAR
SRN INNER CHANNELS. STRONG WIND GUSTS ALSO APPEAR PROBABLE FOR
AKZ018...AKZ027...AKZ028...AND POSSIBLY AKZ023 AND 025.

INHERITED PRESSURE GRIDS WERE NUDGED TO THE 12Z NAM/ECMWF THROUGH
SUN. THIS SLOWED DOWN THE PROGRESSION OF THE GALE FORCE FRONT ON
SAT...AND INTRODUCED PREVIOUSLY MENTIONED LOW ON SUN/MON. WPC WAS
THEN USED FOR PRESSURE GRID UPDATES AFTER THE WEEKEND. REMAINDER
OF THE LONG TERM FORECAST WAS UPDATED WITH AN ENSEMBLE
BLEND...WITH QPF VALUES DRASTICALLY TRUNCATED TOWARD THE END OF
THE FORECAST PACKAGE DUE TO LARGE MODEL SPREAD/FORECAST
UNCERTAINTY.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ041-042.
         SMALL CRAFT ADVISORY FOR PKZ022-033-034-036-043-051-052.

&&

FRITSCH/GARNER

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