Gale Warning 253, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
203 PM AKDT FRI OCT 17 2008

.SHORT TERM...CURRENT SATELLITE IMAGERY SHOWS THE AREA UNDER
CLOUDY SKIES WITH A FEW SUNNY BREAKS OVER PORTIONS OF THE CENTRAL
AND SOUTHERN PANHANDLE. A WEAK MID LEVEL LOW AND ASSOCIATED TROUGH
OVER THE CENTRAL GULF ARE BRINGING SCATTERED TO NUMEROUS SHOWERS
OVER THE PANHANDLE THIS AFTERNOON. BIORKA RADAR HELPS TO CONFIRM
THIS AS IT SHOWS NUMEROUS SHOWERS ASSOCIATED WITH A 850 MB BAND OF
VORTICITY MOVING INLAND NEAR SITKA. A COUPLE MORE OF THESE BANDS
COMBINED WITH MOIST ONSHORE FLOW WILL CONTINUE TO BRING SHOWERS
ACROSS THE AREA TONIGHT BEFORE THE MID LEVEL LOW MOVES EASTWARD
ACROSS THE SOUTHERN PANHANDLE LATE TONIGHT.

A GALE FORCE LOW WILL MOVE INTO THE WESTERN GULF BY EARLY
SATURDAY MORNING. AN ASSOCIATED FRONT WILL MOVE ACROSS THE GULF
SATURDAY BRINGING STEADIER PRECIPITATION INTO THE SOUTHERN
PANHANDLE BY SATURDAY AFTERNOON. GALE FORCE WINDS ALONG THE FRONT
WILL MOVE ACROSS THE OUTER WATERS TO 40 KTS WHILE SMALL CRAFTS ARE
EXPECTED FOR THE INNER CHANNELS. WINDS COULD BE CLOSE TO ADVISORY
CRITERIA ALONG THE SOUTHERN OUTER COAST LATE BEGINNING LATE SAT
AFTERNOON. FELT IT WAS A LITTLE TOO EARLY TO PULL THE TRIGGER SO
WILL HOLD OFF ON ANY ISSUANCES WITH THIS PACKAGE.

MODELS WERE IN GOOD AGREEMENT THOUGH NO PARTICULAR MODEL WAS
DEEMED SUPERIOR. FOR PRESSURE...BLENDED THE 12Z UKMET WITH CURRENT
GRIDS THROUGH EARLY SAT MORNING. FROM THERE WENT WITH A 50/50
BLEND OF THE UKMET AND 12Z GFS GRADUALLY LEANING TOWARDS THE GFS
BY SAT AFTERNOON. OTHER GRIDS RECEIVED UPDATES AND TWEAKS USING
THE GFS.

&&

.LONG TERM...00Z RUN OF THE ECMWF AND GFS ARE IN GENERAL AGREEMENT
WITH A LOW MOVING INTO THE CENTRAL GULF OVER THE WEEKEND.
HOWEVER...THE 12Z RUN GFS SHOWS A SLOWER BUT STRONGER TREND WITH THE
LOW. BEGINNING ON MONDAY NIGHT...MODEL SOLUTIONS DIVERT GREATLY WITH
A DEVELOPING LOW IN THE NORTH PACIFIC. THE GENERAL TREND OF THIS LOW
IS NORTHEASTWARD TRACK ACROSS THE CENTRAL GULF WITH THE ECMWF FASTER
BUT WEAKER THAN THE GFS. HPC GUIDANCE BRINGS THE LOW TO THE NORTH
CENTRAL GULF BY WEDNESDAY MORNING THEN QUICKLY DISSIPATE TO A TROUGH
ALONG THE PANHANDLE COAST ON THURSDAY AND FRIDAY. WITH SLIGHTLY
BELOW THE AVERAGE FORECAST CONFIDENCE...WILL BLEND THE INHERITED
GRIDS WITH THE ECMWF AND GFS THROUGH LATE MONDAY THEN USE THE HPC
GUIDANCE AS A SMOOTHING TOOL THROUGH THE END OF LONG TERM PERIOD.

THE LOW IN THE NORTH CENTRAL GULF OVER THE WEEKEND WILL CONTINUALLY
PUSH FRONTAL BOUNDARY ACROSS THE SOUTHEAST ALASKA WITH WET AND BREEZY
TO WINDY CONDITIONS. THEN THE NEXT LOW IN THE NORTH PACIFIC ON
TUESDAY WILL QUICKLY TRACK NORTHEASTWARD ACROSS THE CENTRAL GULF AND
ARRIVE IN THE NORTHEASTERN GULF BY WEDNESDAY MORNING. BETWEEN THESE
TWO LOWS...THERE WILL BE A BRIEF BREAK OF WET PATTERN OVER NORTHERN
HALF OF THE PANHANDLE ON LATE MONDAY. THE NORTH PACIFIC LOW HAS A
GREAT POTENTIAL TO PRODUCE STRONG WINDS ACROSS THE OUTSIDE WATERS
TUESDAY AND WEDNESDAY...AND LONG FETCH AREA WILL GENERATE VERY ROUGH
SEAS ON WEDNESDAY AND THURSDAY. EXPECT ADVISORY LEVEL WINDS ALONG
THE PANHANDLE COAST ON TUESDAY AND WEDNESDAY. THE LOW WILL WEAKEN IN
THE NORTHERN GULF WEDNESDAY NIGHT INTO THURSDAY AND PUSH SEVERAL
WAVES TOWARDS THE SOUTHEAST ALASKA THROUGH FRIDAY. THIS WILL KEEP
THE FORECAST AREA WET WITH LIKELY TO CATEGORICAL POPS THROUGH THE
END OF LONG TERM FORECAST PERIOD. NEXT LOW SOUTH OF THE ALEUTIANS
WILL TRACK EAST AND MOVE INTO THE CENTRAL GULF BY SATURDAY.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ033-036-042-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ011-013-021-022-031-032-034-035-041.

MAM/RWT/SJA