Heavy Snow in Alaska, March 10 to 11, 2007

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM AST SAT MAR 10 2007

.SYNOPSIS...
.SHORT RANGE...THE LATEST SATELLITE IMAGERY SHOWS A LOW PRESSURE
SYSTEM SPINNING NEAR CAPE SUCKLING AND ANOTHER LOW MOVING OUT OF
THE EASTERN PACIFIC WEST OF THE QUEEN CHARLOTTES. THE LOW IN THE
NORTHERN GULF IS PRODUCING GALE FORCE WINDS AND SOME ISOLATED
LIGHTNING BUT THE SYSTEM IS MOVING WEST AND WEAKENING SO THINK
THE GALES WILL DIMINISH THROUGH THE AFTERNOON ALONG WITH THE
THREAT OF LIGHTNING. THERE WILL SOME SNOW DEVELOPING NEAR PAYA
BUT THERE WILL BE STRONG DOWNSLOPING THAT MAY KEEP SNOW
ACCUMULATIONS AROUND 1 INCH BUT IF THEY GET INTO A STRONGER BAND
THEY COULD PICK UP A COUPLE OF INCHES REAL QUICK.

SOUTHEAST ALASKA IS CURRENTLY MOSTLY CLOUDY...THERE ARE SOME
BREAKS IN THE HIGH CIRRUS OVER THE NORTHERN AREAS AHEAD OF THE
WEATHER FRONT LIFTING NORTH OVER THE FAR SOUTHERN AREAS. THE LOW
PRESSURE SYSTEM ASSOCIATED WITH THE WEATHER FRONT WILL LIFT NORTH
OVER THE EASTERN GULF THEN WEAKEN AS IT LIFTS OVER THE NORTHERN
ZONES INTO CANADA THROUGH TONIGHT. LOW PRESSURE WILL REMAIN IN
THE NORTH GULF THROUGH SUNDAY AS THE UPPER LEVEL TROF REMAINS
OVER THE GULF.

THE SNOW IS CHANGING OVER TO RAIN OVER THE FAR SOUTHERN AREAS
EXCEPT FOR THE HYDER AREA BUT THINK WITH THE WAA THEY WILL ALSO
CHANGE TO RAIN THROUGH THE DAY. SO WITH THAT SAID DID CANCEL THE
SNOW ADVISORY FOR ZONES 27 AND 28. THIS PRECIP IS MOVING NORTH
AND THE CENTRAL AND NORTH CENTRAL AREAS WILL SEE THE CLOUDS
THICKEN UP AND SNOW BEGIN TO FALL THROUGH THE AFTERNOON. THE FAR
NORTHERN AREAS WILL NOT SEE THE PRECIP START UNTIL LATE
AFTERNOON/EARLY EVENING. PASI AREA WILL START OUT AS SNOW BUT AS
THE LOW LIFTS NORTH THINK THEY WILL CHANGE OVER TO AND MIX THIS
EVENING AND THEN OVER TO RAIN LATE. THE CENTRAL INNER CHANNELS
AREA IS A LITTLE BIT TRICKIER AS THEY WILL START OUT AS SNOW AND
BEGIN TO MIX WITH RAIN THROUGH THE EVENING HOURS AS THERE LOOKS
TO BE ENOUGH WARM AIR ALOFT THAT WILL GET MIXED DOWN WITH THE
WIND. THE WINDS NEAR PAPG USUALLY STAYS LIGHT SO DO NOT THINK
THAT THEY WILL CHANGE OVER FOR THAT LONG AND COULD PICK UP 2 TO 5
INCHES. ZONE 26 WILL NOT BE MIXED VERY LONG AS THE COLD FRONT
LIFTS OVER THEM LATE TONIGHT AND WILL CHANGE BACK OVER TO SNOW
SHOWERS.

AS FOR THE NORTHERN HALF OF THE PANHANDLE THERE IS A HEAVY SNOW
WARNING OUT FOR TONIGHT INTO EARLY SUN MORNING. ATTM EVERYTHING
LOOKS TO BE ON TRACK SO WILL NOT MAKE ANY BIG CHANGES TO THE
CURRENT PACKAGE. THE SNOW WILL BEGIN THIS AFTERNOON AND MOVE
NORTH INTO THE FAR NORTHERN ZONES THIS EVENING. THE HEAVIEST SNOW
WILL MOVE INTO THE AREA THIS EVENING WITH LOW CEILINGS AND POOR
VISIBILITIES AS THE STRONG MID-LEVEL DYNAMICS MOVES OVER THE
AREA. SNOW AMOUNTS WILL RANGE FROM 6 TO 12 INCHES WITH LOCALLY
HIGHER AMOUNTS.

THE PRECIP WILL CHANGE TO SHOWERS ACROSS THE ENTIRE FORECAST AREA
BY SUN MORNING AS THE UPPER LEVEL TROF ASSOCIATED WITH THE
SURFACE LOW LIFTS INTO THE YUKON AND PUSHES COLD AIR OVER THE
AREA. THERE IS VERY COLD AIR BEHIND THIS FRONT SO SOME OF THE
SHOWERS ON SUN MAY BE STRONG WITH GUSTY WINDS AND MODERATE SNOW.
AMOUNTS WILL VARY DEPENDING ON THE SHOWER BUT WILL RANGE FROM 1
TO 3 INCHES.

AS FOR WINDS...THERE WILL BE GALES ALONG THE COAST AREAS AS THE
LOW ROLLS UP THE COAST BUT AS IT WEAKENS AND MOVES INLAND THE
WINDS WILL COME AROUND TO THE SOUTHWEST AT 20 KT ON SUN. THE
INNER CHANNELS WILL SEE NORTH WINDS THROUGH TODAY AND INTO
TONIGHT BUT WILL SWITCH TO A LIGHT SOUTHERLY OVER NIGHT AS THE
MOVES INTO CANADA AND WEAKENS. THE STRONGEST WINDS WILL OVER THE
EAST/WEST CHANNELS WITH SMALL CRAFT ADVISORIES TONIGHT BUT THEN
DIMINISH THROUGH SUN.

.LONG RANGE...UPPER LEVEL TROUGH AND ASSOCIATED LOW DOMINATES THE
GULF OF ALASKA WITH A HIGHLY AMPLIFIED RIDGE IN THE BERING SEA AT
THE START. ANOTHER UPPER LOW SOUTH OF 40N NEAR THE DATELINE WILL
BE A FACTOR LATER ON. BY WEDNESDAY AFTERNOON THE WEAKENING TROUGH
OVER ALASKA AND THE GULF WILL RECEIVE SUPPORT FROM AN UPPER LEVEL
LOW DESCENDING FROM THE BEAUFORT SEA. AT THE SAME TIME...THE LOW
NEAR 40N MOVES EAST AND THEN NORTH AND MERGES WITH THE TROUGH
AXIS NEAR 160W. THESE EVENTS PLUS ANOTHER UPPER LOW MOVING INTO
THE PACIFIC OVER HOKKAIDO JAPAN ON FRIDAY WILL CUT OFF THE UPPER
HIGH OVER THE BEARING SEA.

AT THE SURFACE...A LARGE COMPLEX OF LOW PRESSURE IN THE GULF AND
A STRONG SURFACE HIGH OVER THE BERING SEA WILL SLOWLY INCREASE IN
PRESSURE AS THE TROUGH RIDGE AXIS MOVES EAST THROUGH WEDNESDAY.
AS THIS HAPPENS...A SERIES OF SURFACE LOWS AND SHORT WAVES WILL
TRACK OVER THE PANHANDLE PRODUCING MORE PRECIPITATION. THE FIRST
WILL IMPACT THE NORTHERN PANHANDLE ON SUNDAY NIGHT...FOLLOWED BY
ANOTHER OVER THE SOUTHERN PANHANDLE MONDAY NIGHT. FARTHER OUT TO
THE WEST...A 978MB SURFACE LOW VERTICALLY STACKED WITH THE PARENT
FEATURE NEAR 40N AND THE DATELINE WILL MOVE NORTHEAST AND PRODUCE
A TRIPLE POINT LOW WHICH WILL IMPACT THE CENTRAL AND SOUTHERN
PANHANDLE THURSDAY AFTERNOON THROUGH FRIDAY NIGHT.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...WSW...AKZ19-22...25...24
         WIND ADV AKZ17

MARINE...GALE...PKZ52 51 43
         SCA...PKZ...21 22 31 34 35 36 42 41