Heavy Snow in Alaska, March 6 to 7, 2004

SOUTHEAST ALASKA FORECAST DISCUSSION
245 AM AST SAT MAR 6 2004

.SYNOPSIS...
.SHORT RANGE...LATEST GOES IR SATELLITE IMAGERY AND ANALYSIS
SHOWS MAJOR LOW ENTERING THE SOUTHEAST GULF OF ALASKA AS A
970 MB LOW. THIS LOW CONTINUES TO MOVE TOWARD THE NORTHEAST. ALL
MODELS HAVE FORECAST THE 12Z SATURDAY POSITION WELL. WARM FRONT
EXTENDS FROM THE TRIPLE POINT NORTHEAST OF THE LOW CENTER TO
THE QUEEN CHARLOTTE ISLANDS. RAIN HAS ALREADY SPREAD INTO
SOUTHERN SOUTHEAST ALASKA.

FARTHER NORTH...A WEAK LOW NEAR CAPE FAIRWEATHER HAS WEAKENED TO
A TROUGH...HOWEVER...NUMEROUS CONVECTIVE CELLS CONTINUE TO DOT
THE EASTERN GULF COAST AND NORTH HALF OF SOUTHEAST ALASKA
DELIVERING MAINLY SNOW SHOWERS TO THOSE AREAS THIS MORNING.
THIS TROUGH IS ALSO RESPONSIBLE FOR VERY GUSTY SOUTH WINDS
IN NORTHERN LYNN CANAL WHERE A WIND ADVISORY IS CURRENTLY IN
EFFECT. WINDS IN THIS AREA WILL BE DIMINISHING AROUND NOON
AS THE TROUGH WEAKENS AND PRESSURES TO THE SOUTH BEGIN TO FALL.

MODELS SHOW THE STRONG LOW DEEPENING FURTHER TO 965 MB AS IT
MOVES NORTHEAST OVER THE EASTERN GULF OF ALASKA TO TODAY
AND TONIGHT. THE LOW IS FORECAST TO ARRIVE OVER A POSITION JUST
SOUTH OF YAKUTAT BY MID SUNDAY MORNING. THE ASSOCIATED FRONTAL
BOUNDARY WILL MOVE NORTHEAST TO BE OVER SOUTHEAST ALASKA TONIGHT
AND THEN PROCEED EAST TO BE OVER OVER BRITISH COLUMBIA EARLY
SUNDAY MORNING. A BROAD BUT WEAK HIGH PRESSURE RIDGE WILL BEGIN
TO BUILD OVER THE REGION FROM THE SOUTH SUNDAY AFTERNOON.

RAIN WILL CONTINUE TO SPREAD OVER THE SOUTH HALF OF SOUTHEAST
ALASKA THIS MORNING INTO THIS AFTERNOON. SNOW OR MIXED RAIN AND
SNOW SHOWERS OVER THE NORTH HALF OF SOUTHEAST ALASKA WILL
INCREASE TO STEADY SNOW LATER THIS MORNING INTO THIS AFTERNOON
BEFORE CHANGING TO RAIN BY LATE AFTERNOON ALONG THE EASTERN
GULF AND CENTRAL SOUTHEAST ALASKA IN THE STRONG WARM ADVECTION
AHEAD OF THE LOW. OCCASIONAL SNOW OVER NORTHERN SOUTHEAST
ALASKA MAY TAKE UNTIL TONIGHT BEFORE THE CHANGE OVER RAIN TAKES
PLACE. RAIN WILL CONTINUE ON SUNDAY AS THE SECOND WRAP OF THE
OCCLUSION MOVES THROUGH THE REGION.

VERY STRONG GUSTY WINDS WILL BE POSSIBLE TONIGHT AND SUNDAY
MORNING OVER THE SOUTH HALF OF SOUTHEAST ALASKA AS WELL AS THE
OUTER COASTAL SECTIONS OF THE PANHANDLE TONIGHT AND SUNDAY
MORNING WHERE A HIGH WIND WATCH IS IN EFFECT.

.LONG RANGE...WEATHER FRONT OVER SOUTHEAST ALASKA CONTINUES TO
PUSH OFF INTO BRITISH COLUMBIA AND THE REMAIN OF THE SURFACE JOIN
THE LOW IT FORMED IN THE SOUTHERN YUKON AND JUMPS INLAND WITH THE
EXCEPTION OF A WEAK LOW PERSISTING BACK TOWARDS PRINCE WILLIAM
SOUND. A MINOR RIDGE BEING PUSHED THROUGH THE SOUTHERN HALF OF
THE PANHANDLE AS THE NEXT DEVELOPING WAVE MOVES NORTHEAST FROM
THE NORTH PACIFIC SUNDAY NIGHT AND OVER THE SOUTH CENTRAL
PANHANDLE REGION MONDAY MORNING. MODELS DEEPENING THIS WAVE TO
AROUND 989 MB.  WITH THE UPPER LEVEL LOW THROUGH THE WEEKEND OVER
THE KENAI PENINSULA IT IS PULLING SOME COLDER AIR ALOFT BACK OVER
THE NORTHERN GULF AND BACK TO THE SOUTHEAST ALASKA BY TUESDAY AS
WELL.

THE NEXT MAJOR WEATHER PLAYER IS THE OCCLUDED FRONT SWEEPING ITS
WAY ACROSS THE NORTH PACIFIC AND WESTERN GULF OF ALASKA. SUNDAY
AND MONDAY.  THE MAIN PARENT LOW IS STAYING WELL TO THE WEST SO
EXPECT TO SEE THE FRONT WEAKENING BY IT REACHES SOUTHEAST
ALASKA...BY THE TIME THE FRONT IS OVER THE CENTRAL GULF THE MAIN
PARENT LOW IS OVER THE CENTRAL ALEUTIANS.  IN ALL LIKELIHOOD...
WILL PROBABLY SEE NEXT MODEL RUN SLOW THE FRONT DOWN BASED ON THE
PATTERN. THE ONLY THING THAT MAY NOT BE AGREEING WITH THAT IS
120-140 KT JETSTREAM DRIVING THE ASSOCIATED SHORT WAVE ALONG.
TENTATIVELY THIS FRONT IMPACTS SOUTHEAST ALASKA TUE NIGHT AND A
DEVELOPING WAVE ON THE FRONT ROLLS UP INTO THE EASTERN GULF LATE
WEDNESDAY.

THE PARENT LOW CONTINUES TO DRIFT SLOWLY EAST AND LIFTS OUT OVER
THE NORTHERN GULF END OF THE WEEK... THE COLD AIR BEHIND THE OLD
PARENT LOW WILL HELP SPIN ANOTHER DEVELOPING WAVE UP INTO THE
GULF OF ALASKA FOR NEXT WEEKEND.

EXPECT WINDS TO DIE DOWN SUNDAY EVENING WITH EXITING OF THE FIRST
SYSTEM BUT SHOULD INCREASE OVER THE SOUTHERN PANHANDLE WITH THE
NEXT WAVE. NEAR SMALL CRAFT WINDS PERSIST OVER THE GULF  MONDAY
NIGHT AND WILL LIKELY INCREASE BACK TO GALES TUESDAY FOR THE
CENTRAL GULF AND COASTAL WATERS ARE. SOUTHWEST WINDS DIMINISH
BEHIND THE FRONT BUT THE DEVELOPING WAVE SHOULD BRING AT LEAST
GALE FORCE BACK TO THE EASTERN GULF WEDNESDAY NIGHT.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...HIGH WIND WATCH TONIGHT AND SUNDAY MORNING...
         ZONES 21..22..23..24..26..27..28..29
      ...WIND ADVISORY THIS MORNING...ZONE 18

MARINE...STORM...
           INSIDE WATERS...PKZ036
           OUTSIDE WATERS...PKZ041..052
      ...GALES...
           INSIDE WATERS...PKZ033..034..035
           OUTSIDE WATERS...PKZ042..043..051

DED - BMB