Heavy Snow in Alaska, March 9, 2008

SOUTHEAST ALASKA FORECAST DISCUSSION
630 AM ADT SUN MAR 9 2008

.SYNOPSIS...
.SHORT RANGE...OCCLUDED FRONT JUST OFFSHORE SE AK WILL MOVE E
THRU THE PANHANDLE BY EARLY AFTERNOON. UPPER TROF WILL SWING NE
ACROSS THE NW HALF OF THE AREA TONIGHT.

MAIN FORECAST ISSUES ARE HOW LONG PREFRONTAL ADVY LEVEL WINDS
WILL LAST...POTENTIAL FOR ADVY WINDS AROUND PAGY AFTER
FROPA...AND WHEN THE HEAVY SNOW FALLING ALONG THE HAINES HIGHWAY
WILL END OR CHANGE TO RAIN. AS FOR THE WIND AHEAD OF THE
FRONT...LOOKS LIKE THE ADVY LEVEL WINDS WILL BE ENDING AROUND
18Z. THIS WILL BE A LITTLE BEFORE THE FRONT MOVES THRU THE SRN
INNER CHANNELS...BUT GRADIENT AHEAD OF THE FRONT WILL BE
WEAKENING AS IT MOVES ONSHORE.

AS FOR THE POST-FRONTAL WINDS IN PAGY...35-45 KT 700 MB SWLY
CROSS MTN FLOW WILL ENHANCE LEE-SIDE TROF OVER SRN YUKON BY LATE
AFTERNOON AND LAST UNTIL LATE TONIGHT. THIS SHOULD ALLOW ADVY
LEVEL WINDS TO DEVELOP IN PAGY...AND ISSUED ONE FOR THE 3 PM
TODAY TO 3 AM TONIGHT PERIOD. TIMING ON BACK END WILL BE TRICKY
AS THAT WILL DEPEND ON HOW FAST THE CROSS MTN FLOW WEAKENS OR THE
WIND SHIFTS TO MORE S DIRECTION.

AS FAR AS THE SNOW ALONG THE HAINES HIGHWAY GOES...LOOKS LIKE IT
WILL CONTINUE BEFORE IT WILL CHANGE TO RAIN OR DIMINISH BY EARLY
AFTERNOON. HAINES CUSTOMS AT MILE 40 REPORTED 5.5 INCHES OF SNOW
SO FAR THRU 4 AM AND STILL SNOWING HEAVILY. DECIDED TO ISSUE
HEAVY SNOW WARNING N OF THE CHILKAT RIVER BRIDGE THRU NOON TODAY
FOR STORM TOTAL OF 8 TO 14 INCHES.

OTHERWISE...THE RAIN BECOME SHOWERS AFTER FROPA TODAY...AND THE
NW HALF OF THE AREA SHOULD STAY SHOWERY TONIGHT AS UPPER TROF
MOVES THRU THE AREA. MAY SEE SOME SNOW SHOWERS LATE TONIGHT AS
COLDEST AIR ALOFT MOVES IN...WITH ONLY MINOR SNOW ACCUMS AT MOST.
SRN AREA MAY HAVE SPOTTY SHOWERS THIS EVENING BUT THOSE SHOULD
DIMINISH OR END OVERNIGHT AS LOWER LEVEL FLOW BECOMES E-NE.

.LONG RANGE...BETTER THAN AVERAGE MODEL AGREEMENT THROUGH THE
LONG RANGE FORECAST PERIOD AND CONFIDENCE IS GOOD. A BLEND OF GFS
AND ECMWF WAS USED FOR GRIDS.

A QUITE WEEK IN STORE. NO MAJOR SYSTEMS ARE FORECAST TO MAKE
LANDFALL OVER THE PANHANDLE DURING THE EXTENDED RANGE FORECAST
PERIOD SO NO MAJOR WIND EVENTS ARE EXPECTED. BREEZY CONDITIONS
ARE EXPECTED ALONG THE SOUTHERN OUTER COAST MONDAY NIGHT INTO
TUESDAY AND AGAIN WEDNESDAY NIGHT ALONG THE CENTRAL AND NORTHERN
OUTER COAST.

THESE WINDS ASSOCIATED WITH A PAIR OF WEATHER FRONTS...THE FIRST
OF WHICH WILL TRACK NORTH OVER THE SOUTHERN PANHANDLE MONDAY
NIGHT...STALL OVER THE CENTRAL PANHANDLE AS IT RE-ORIENTS IN A
NORTH-SOUTH FASHION...AND THEN RETREATS EAST INTO BRITISH
COLUMBIA ON TUESDAY. THE NORTHERN HALF OF THE PANHANDLE SHOULD
REMAIN FAIRLY DRY UNTIL LATE IN THE WEEK WHEN THE SECOND FRONT
WILL APPROACH THE COAST FROM THE SOUTHWEST. PRECIPITATION IS
EXPECTED TO MAKE IT AS FAR NORTH AS ICY STRAIT WEDNESDAY NIGHT
BEFORE THE FRONT BEGINS TO DISSIPATE. ZONES 17...18...AND 19 MAY
REMAIN DRY FOR THE MOST PART WITH THIS SECOND FRONT. A THIRD
FRONT WILL BE APPROACHING THE PANHANDLE FROM THE WEST AT THE END
OF THE EXTENDED RANGE PERIOD SUNDAY NIGHT. THE LATEST MODEL RUN
HAS SPED UP THE PROGRESS OF THIS FRONT AND HAS MOST OF THE
PANHANDLE UNDER RAIN AS EARLY AS SUNDAY MORNING WHICH IS A FULL
24 HOURS FASTER THAN CURRENT GRIDS DEPICT. COASTAL GALES AND WIND
ADVISORIES FOR THE OUTER COAST POSSIBLE WITH THIS LAST FRONT.

TEMPERATURES TREND DOWN TO A FEW DEGREES BELOW NORMAL DURING THE
UPCOMING WEEK. AS A RESULT THERE IS STILL SOME SNOW IN THE
FORECAST ALTHOUGH ONLY HYDER AND POSSIBLY THE HIGHWAYS ARE
EXPECTED TO RECEIVE ANY SIGNIFICANT ACCUMULATION.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...HEAVY SNOW WARNING...ZONE 19 N CHILKAT RIVER BRIDGE
      ...WIND ADVYS...ZONES 17...18...22...23...27...28

MARINE...STORM...PKZ051-052
      ...GALE...PKZ022-036-041>043-053-310
      ...SCA...ALL REMAINING WATERS

RWT/FCF