Gale Warning 117, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
356 PM AKST THU FEB 11 2016

.SHORT TERM...THE LATEST SATELLITE IMAGERY SHOWS A GALE FORCE LOW
OVER THE NORTH PACIFIC AND ITS ASSOCIATED WEATHER FRONT OVER THE
SOUTHEAST GULF. THERE ARE SOME SHOWERS OVER THE NORTHEAST GULF
THAT ARE ROTATING TO THE NORTHWEST LATE THIS AFTERNOON. THE REST
OF THE FORECAST AREA IS MOSTLY DRY WITH WINDS RELATIVELY ON THE
LIGHT SIDE. AS THE FRONT MOVES NORTH THROUGH TONIGHT PRECIP WILL
SLOWLY SPREAD NORTHWARD WITH CAT RAIN OVER THE THE SOUTHERN TWO
THIRDS OF THE AREA BY LATE TONIGHT. THE FAR NORTHERN AREAS WILL
NOT SEE THAT MUCH PRECIP TONIGHT WITH A NORTH GRADIENT BUT THEY
WILL GET INTO THE PRECIP BY FRIDAY MORNING. MOST OF THE PRECIP
WILL BE IN THE LIQUID FORM WITH TEMPS VERY MILD. THERE WILL BE
SOME CAA OVER THE AREA TONIGHT SO THE TEMPS WILL SLOWLY FALL FROM
THE UPPER/MID 40S TO THE UPPER 30S/LOWER 40S. THE HIGHWAYS MAY SEE
SOME SNOW AS DEW POINTS WILL COOL WITH OFFSHORE FLOW TO THE LOWER
30S. THE FRONT WILL PUSH THROUGH THE FORECAST AREA BY FRIDAY
AFTERNOON WITH SHOWERS OVER THE NORTH AND SCATTERED OVER THE SOUTH
WITH LESS PVA. THERE IS A CHANCE THAT THERE WILL BE SOME ISO
THUNDERSTORMS OVER THE GULF WITH A STRONG UPPER LEVEL VORT, STEEP
LAPSE RATES FROM ABOVE NORMAL SST. AT THIS TIME THE ISO TS IS
CONFINED TO THE GULF BUT LATER SHIFTS MAY NEED TO BRING THEM INTO
THE COASTAL AREAS DUE LAND BASE CONVERGENCE ZONES.

WIND WISE...THE FRONT WILL PRODUCE SOLID 40 KT GALES TONIGHT WITH
CONTINUED LARGE SEA HEIGHTS. THE WINDS WILL PERSIST INTO FRIDAY
AS THE LOW TRACKS OVER THE CENTRAL GULF BUT THE SE GULF WILL SEE
THE WIND SPEEDS RELAX BY THE AFTERNOON. THE NORTH HALF OF THE INNER
CHANNELS ARE SEEING THE WINDS SWITCH AROUND TO THE NORTH AND THEY
WILL INCREASE AS THE FRONT APPROACHES THE PANHANDLE. SPEEDS WILL
RANGE FROM 20 TO 30 KT. THE MAIN PRESSURE GRADIENT IS FROM THE E/W
SO THOSE CHANNELS WILL INCREASE TO 20 TO 25 KT WITH LIGHTER WINDS
IN N/S CHANNELS. THE WINDS WILL SWITCH BACK TO THE SOUTH THROUGH
FRIDAY AS A WEAK SURFACE RIDGE BUILDS OVER THE INNER CHANNELS. THE
STRONGEST WINDS WILL BE NORTHERN LYNN WITH 20 KT.

OVERALL THERE IS ABOUT AVERAGE FORECASTER CONFIDENCE IN THE SHORT
TERM PERIOD. USED A MIX OF THE 18Z NAM AND GFS.

.LONG TERM...ACTIVE PATTERN WILL CONTINUE INTO EARLY NEXT WEEK AS
UPPER TROUGH OVER THE ALEUTIANS PERSISTS. MINOR PERTURBATIONS
EJECTING OUT OF THE PARENT LOW WILL RESULT IN QUICK MOVING FRONTAL
SYSTEMS MOVING ACROSS THE FORECAST AREA WITH AT LEAST 3 SYSTEMS
BETWEEN THIS WEEKEND INTO NEXT WEEK. THESE IMPULSES WILL ALSO
SLIGHTLY WEAKEN THE UPPER RIDGE OVER W NOAM RESULTING IN SLIGHTLY
COOLER TEMPS. MODEL SOLUTIONS DIVERGE TOWARDS THE MIDDLE OF NEXT
WEEK WITH BOTH EC AND GFS SHOWING AN UPPER LOW/OPEN WAVE
UNDERCUTTING THE RIDGE AND IMPACTING THE W COAST. AS THIS FEATURE
MOVES S...ANOTHER LOW WILL BECOME ESTABLISHED OVER THE CENTRAL
GULF MAINTAINING ACTIVE PATTERN THROUGH THE EXTENDED. SINCE
SENSIBLE WX WILL DEPEND GREATLY ON THE TIMING/TRACK OF EACH
IMPULSE...MAINLY MAINTAINED INHERITED FORECAST. BIGGEST CHANGE WAS
TO TEMPS EARLY NEXT WEEK...USED GFS MOS TO NUDGE TEMPS SLIGHTLY
DOWN AND INCREASE DIURNAL SPREAD. OVERALL FORECAST CONFIDENCE
REMAIN ABOUT AVERAGE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ041>043-051-052.
     SMALL CRAFT ADVISORY FOR PKZ012-013-022-031-035-036.
     SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ033-053.
&&

ABJ/BC

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