High Wind in Alaska, October 20 to 21, 2012

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
400 PM AKDT SAT OCT 20 2012

.SHORT TERM...THE LATEST SATELLITE IMAGERY SHOWS CLOUDS MOVING
OVER THE AREA FROM THE EAST OVER THE NORTHERN THIRD, MOSTLY CLEAR
OVER THE CENTRAL AREAS AND SOME CUE FROM THE DEPARTING LOW OVER
THE SOUTHERN THIRD. THE HIGH PRESSURE OVER THE YUKON WILL
CONTINUE TO KEEP STRONG NORTH WINDS OVER THE NORTHERN MARINE
WATERS WITH HIGHER GUSTS FROM INTERIOR PASSES. THE HIGH WILL
CONTINUE TO BUILD DOWN INTO BC THROUGH TONIGHT TO INCREASE THE
WINDS FROM INTERIOR PASSES ALONG THE COAST MOUNTAINS. THESES
CONDITIONS WILL PERSIST INTO SUNDAY AFTERNOON WITH THE FORECAST
AREA FREE OF ANY PRECIP.

 GALE FORCE WINDS OVER NORTHERN LYNN, CROSS SOUND AND OVER THE
NORTHEAST GULF WILL PERSIST TROUGH TONIGHT BUT AS THE PRESSURE
GRADIENT WEAKENS SOME THROUGH SUNDAY THE WINDS WILL RELAX TO
SMALL CRAFT LEVEL. THE REST OF THE MARINE WATERS OVER THE
NORTHERN HALF WILL SEE SMALL CRAFT WINDS THROUGH SUNDAY MORNING
WITH A DIMINISHING TREND THROUGH THE AFTERNOON. THE WINDS OVER
THE SOUTHERN AREAS WILL SEE AN INCREASE THE NNE WINDS TO 20KT
WITH HIGHER GUSTS FROM INTERIOR PASSES BY THE SUNDAY AFTERNOON.
LAND AREAS OVER THE NORTHERN HALF WILL SEE LOCALLY GUSTY WINDS IN
EXPOSED AREAS BUT STRONGER GUSTS TO 35 MPH NEAR DOWNTOWN JUNEAU
AND NEAR SKAGWAY THROUGH SUNDAY AFTERNOON WITH CROSS BARRIER FLOW
OF 45 KT.

 CLOUD COVER WAS TRICKY AGAIN TODAY WITH MOISTURE MOVING IN FROM
THE EAST BUT THE THINKING IS THAT THE CENTRAL AREAS WILL SEE SOME
HIGH CLOUDS MOVE OVER THE AREA LATE THIS EVENING. THE NORTHERN
AREAS WILL SEE CLOUD MOVE OVER THE AREA THROUGH TONIGHT BUT THE
ENTIRE FORECAST AREA WILL SEE THE CLOUDS DIMINISH THROUGH SUNDAY
TO BE MOSTLY CLEAR BY THE AFTERNOON.

 TEMPS WILL FALL AGAIN INTO THE UPPER 20S TO LOWER 30S IN MOST
PLACES BUT WHERE THERE IS WIND TEMPS WILL REMAIN IN THE UPPER
30S. FOR SUNDAY THERE IS SOME COOL AIR MOVING OVER THE AREA THAT
HIGHS WILL BE A BIT LOWER THAN TODAY AND RANGING FROM THE MID 30S
TO LOWER 40S.

 THERE IS ABOUT AVERAGE FORECASTER CONFIDENCE IN THE NEXT 24HRS
AND USED A BLEND OF THE NAM/EC FOR THE SHORT TERM FORECAST.

&&

.LONG TERM...MODELS REMAIN FAIRLY PERSISTENT THROUGH THE MIDDLE OF
NEXT WEEK WITH AN UPPER LEVEL LOW NEARLY STATIONARY OVER THE FAR
SOUTHEASTERN GULF. STRONG UPPER HIGH CONTINUES TO BUILD OVER THE
ALASKAN INTERIOR AND YUKON. STRONG ARCTIC SURFACE HIGH CONTINUE TO
AFFECT ACROSS THE ALASKAN PANHANDLE. A WEAK INVERTED TROUGH OF
LOW PRESSURE ACROSS THE EASTERN GULF WILL CONTINUE TO ENHANCE THE
MODERATE TO STRONG OFFSHORE FLOW OVER THE FORECAST AREAS. REFRESHED
THE INHERITED FORECAST PACKAGE WITH THE NAM FOR ITS GOOD
INITIALIZATION AND HANDLING THE TIGHTENING NORTHERLY PRESSURE
GRADIENTS THROUGH TUESDAY.

 INCREASING OFFSHORE LOW TO MID LEVEL FLOW WILL KEEP FORECAST
AREAS COLD UNDER PARTLY CLOUDY TO MOSTLY CLEAR SKIES. THE
TIGHTENING NORTHERLY PRESSURE GRADIENT WILL MAINTAIN GALE FORCE
WINDS OVER THE NORTHERN INNER CHANNELS AND OUT OF INTERIOR PASSES.
IN ADDITION TO THE OVERNIGHT RADIATION COOLING...CONTINUED
ENTRAINMENT OF ARCTIC COLD AIR WILL KEEP THE PANHANDLE QUITE COLD
THROUGH MUCH OF NEXT WEEK.

 MODELS BEGIN DIVERTING BY MID WEEK AND LEANED OVER THE HPC
ENSEMBLE APPROACH OF GFS AND ECMWF FOR THE REMAINING PERIODS.
GENERALLY SPEAKING...DRY WEATHER WILL CONTINUE THROUGH MUCH OF THE
NEXT WEEK WITH A BIT TEMPERATURE MODIFICATIONS. MODEL CONSENSUS
STILL HINTS A DEVELOPING LOW IN THE NORTH PACIFIC MOVES NORTHEASTWARD
INTO THE SOUTH CENTRAL GULF BY SATURDAY. THIS INCOMING SYSTEM
WILL INCREASE CLOUDS OVER THE SOUTHERN PANHANDLE FROM THE SOUTHWEST
ON SATURDAY.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND UNTIL 7 PM AKDT THIS EVENING FOR AKZ018-025.
MARINE...GALE WARNING FOR PKZ012-022-043-051.
         SMALL CRAFT ADVISORY FOR PKZ011-013-021-031-032-035-042.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ041.

&&

ABJ/AHN