High Wind in Alaska, November 4, 2012

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
516 AM AKST SUN NOV 4 2012

.SHORT TERM...SATELLITE IMAGERY SHOWING WEAKENING LOW PRESSURE
SYSTEM IN THE NORTHERN GULF WITH ASSOCIATED FRONT EXITING THE
NORTHERN PANHANDLE AND MOVING INTO THE YUKON. PRECIPITATION FROM
THIS FRONT WILL DIMINISH THROUGH THE MORNING IN TIME FOR NEXT
BANDS OF PRECIP TO MOVE IN FROM THE SOUTH. THESE BANDS ARE
ASSOCIATED WITH A RAPIDLY DEVELOPING STORM FORCE LOW MOVING FROM
THE NORTHEAST PACIFIC INTO THE SOUTHEAST GULF. THIS LOW WILL
DEEPEN FROM CURRENT 970 MB CENTER TO AROUND 963 MB THIS
AFTERNOON. THE RAPID DEVELOPMENT IS DUE IN PART TO THE LOW CENTER
SITUATED UNDER LEFT EXIT REGION OF 130 KT 300 MB JET. AS THE LOW
MOVES OVER THE PANHANDLE JUST NORTH OF CAPE DECISION IT WILL
WEAKEN RAPIDLY THIS EVENING AS IT CONTINUES TO MOVE INTO BRITISH
COLUMBIA. LATE TONIGHT LOW PRESSURE REMNANTS IN THE NORTHERN GULF
WILL CONTINUE TO WEAKEN AS HIGH PRESSURE RIDGE BUILDS OVER THE
PANHANDLE.

AS THE LOW PUSHES INTO THE SOUTHEASTERN GULF WINDS WILL PICK UP
TO STORM FORCE ALONG THE SOUTHERN COASTAL WATERS AND CLARENCE
STRAIT WITH SUSTAINED WINDS OF 50 TO 60 KTS. FURTHER NORTH GALE
FORCE WINDS WILL DEVELOP OVER THE INNER CHANNELS AS THE LOW
PROGRESSES. HIGH WIND WARNING FOR ZONE 027 DIXON ENTRANCE TO CAPE
DECISION COASTAL AREA INCLUDING...CRAIG...KLAWOCK AND ZONE 28
SOUTHERN INNER CHANNELS- INCLUDING...KETCHIKAN...METLAKATLA
REMAINS IN EFFECT STARTING FROM NOON TODAY THROUGH MIDNIGHT
TONIGHT WITH GUSTS OF 60 TO 65 MPH EXPECTED. FOR AREAS JUST TO THE
EAST AND NORTH EXPECTING GUSTS TO INCREASE TO 40 TO 45 MPH. DUE TO
THE RAPID WEAKENING AS THE LOW MOVES NORTHWARD AT THIS TIME NOT
EXPECTING AS STRONG OF WINDS TO MATERIALIZE FOR AREAS NORTH OF
FREDERICK SOUND.

TEMPERATURES FOR MOST OF THE PANHANDLE WILL BE IN THE UPPER 40S
FOR THE SOUTHERN PANHANDLE AND LOW TO MID 40S FOR CENTRAL
PANHANDLE NORTHWARD. SNOW CURRENTLY FALLING IN SKAGWAY AND ALONG
THE HAINES HIGHWAY WILL DIMINISH THROUGH THE
MORNING...TRANSITIONING TO RAIN WITH THE WARMER AIR MASS BEING
PUSHED NORTHWARD. AS THE LOW EXITS THE REGION TONIGHT COLDER TEMPS
OVER THE NORTHERN PANHANDLE WILL RESULT IN A RAIN SNOW MIX...WITH
SNOW AT HIGHER ELEVATIONS. ONLY EXPECT 1 TO 2 INCHES OF
ACCUMULATION AS THE LOW PRESSURE SYSTEM AND FORCING MECHANISMS
WILL BE EXITING THE AREA. FOR THE SOUTHERN PANHANDLE RAIN WILL
BECOME HEAVY AT TIMES FROM MOISTURE FEED FROM THE NE PACIFIC.

MODELS FELL INTO LINE FOR THE 00Z RUNS WITH SOME DIFFERENCES IN
TIMING OF THE LOW MOVING OVER THE PANHANDLE THIS EVENING. LIKED
THE INITIALIZATION OF THE ECMWF 00Z RUN. NAM WAS IN LINE WITH THE
ECMWF REGARDING POSITION OF MANY FEATURES BUT THE NAM AND GFS WERE
MORE IN LINE WITH THE STRENGTH OF THE LOW PRESSURE SYSTEMS. USED A
BLEND OF 00Z ECMWF AND 00Z NAM TO UPDATE INHERITED GRIDS.
RESULTING CHANGES WERE MINOR. FORECAST CONFIDENCE IS ABOVE
AVERAGE.

&&

.LONG TERM...SOUTHERLY WINDS WILL INCREASE MONDAY AS THE REMNANT LOW
FROM SUNDAY DEPARTS TO THE NORTH AND A RIDGE OF HIGH PRESSURE
BUILDS IN FROM THE SOUTH. EXPECT SMALL CRAFT LEVEL WINDS FOR MOST
OF THE INSIDE WATERS DURING THEN DAY THEN DIMINISHING MONDAY NIGHT
AS THE RIDGE IS PUSHED OFF TO THE EAST BY A LOW IN THE NORTHERN
GULF. THIS LOW WILL CONTINUE THE PRECIP OVER THE REGION THROUGH
MONDAY. THE PRECIP IS EXPECTED TO FALL AS MAINLY RAIN WITH
EXCEPTION OF THE FAR NORTHERN BORDERS WHERE A FEW INCHES OF ADDITIONAL
ACCUMULATION IS EXPECTED THROUGH MONDAY.

THE GULF LOW WILL SHIFT SOUTHEASTWARD THROUGH TUESDAY TAKING THE
RAIN WITH IT. CHANCES OF PRECIP WILL DECREASE FROM NORTH TO SOUTH
THROUGH WEDNESDAY. HIGH PRESSURE BUILDING OVER THE YUKON ALONG
WITH THE LOW TO THE SOUTH WILL CAUSE WINDS TO SHIFT OUT OF THE
NORTH LATE MONDAY NIGHT AND INCREASE TO GALE FORCE THROUGH
NORTHERN LYNN CANAL TUESDAY THROUGH THURSDAY. THE NORTH WINDS WILL
BRING ANOTHER ROUND OF ARCTIC AIR TO THE AREA WITH HIGH
TEMPERATURES IN THE LOW 30S AND LOW TEMPERATURES IN THE 20S UNDER
MOSTLY CLEAR SKIES THROUGH FRIDAY. THE NEXT LOW PRESSURE SYSTEM
MOVES INTO THE GULF SATURDAY WITH CHANCES OF PRECIP RETURNING TO
THE FORECAST...HOWEVER THERE ARE GREATER DIFFERENCES BETWEEN
MODELS BY THAT TIME SO THERE IS LESS CERTAINTY THAN THE REST OF
THE PACKAGE.

THROUGH MUCH OF THE WEEK MODELS ARE IN GOOD AGREEMENT AND CHANGES
TO THE GOING FORECAST WERE RELATIVELY MINOR. USED AN ENSEMBLE
APPROACH OF MODELS WITH AN EMPHASIS ON THE 00Z ECMWF AS IT
INITIALIZED THE BEST.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WARNING FROM NOON TODAY TO MIDNIGHT AKST TONIGHT FOR
     AKZ027-028.
         STRONG WIND LATE TONIGHT FOR AKZ027.
         STRONG WIND FROM 9 AM AKST THIS MORNING THROUGH THIS AFTERNOON
     FOR AKZ023.
         STRONG WIND FROM 9 AM AKST THIS MORNING THROUGH THIS EVENING FOR
     AKZ029.
         WINTER WEATHER ADVISORY UNTIL 6 AM AKST EARLY THIS MORNING FOR
     AKZ018-019.
MARINE...STORM WARNING FOR PKZ036-041.
         GALE WARNING FOR PKZ031-033>035-042-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ011>013-021-022-032-053.

&&

PRB/HANNON