Gale Warning 116, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM AST FRI MAR 2 2007

.SYNOPSIS...
.SHORT RANGE...MARTIME AIRMASS WITH LOW LATITUDE SOURCE REGION
WILL CONTINUE TO OVER RUN A DEEP ARCTIC OUTBREAK WITH LITTLE
SYNOPTIC CHANGE THROUGH AT LEAST 12Z TONIGHT.  MORE ON THESE
LARGER SCALE FEATURES IN THE NEXT COUPLE OF PARAGRAPHS.
RAIN TO SNOW LINE THROUGH ZONES 23 AND 26...AND UNMIXED SNOW
NEAR THE COAST MOUNTAIN RANGE TO AT LEAST HYDER WILL ALSO
PERSIST. PRIMARY PRECIP FOOTPRINT WILL DRIFT SOUTH FROM 12Z
TONIGHT THROUGH 00Z TOMORROW WITH FREDERICK SOUND BECOMING
THE NORTHERN EDGE OF PRECIP.

LARGE SCALE COLD SOURCE...STRONG TROUGH ALOFT EXTENDING FROM
OVER GREAT BEAR LAKE IN NW TERRITORY CANADA TO OVER AN AREA
500 NM S OF KODIAK.  BY STRONG WE MEAN THIS TROUGH HAS
A HIGH AMPLITUDE AND IS COLD THROUGH A GREAT DEPTH.  THIS
TROUGH IS SLOWLY TILTING BUT FOR OUR PURPOSES IS SYNOPTICALLY
QUASISTATIONARY.

LARGE SCALE WARM MARITIME SOURCE...TO THE SOUTHEAST OF THE
TROUGH IS A BROAD RIDGE THAT IS ASSOCIATED WITH SOURCE REGION
IN SUBTROPICS NEAR 150W.  GOES VIS AND IR DEPICT MAJOR BREAK
IN CLOUD COVER FROM 45 TO 51 NORTH ON THIS WATER VAPOR STREAM
BUT THE HIGH PRECIPITABLE WATER VALUES WILL SHOW UP AS EXTENSIVE
AND DEEP CLOUD MASS BEFORE THE OVER RUN OF THE PANHADLE TONIGHT.

.LONG RANGE...FOR THE LONGTERM MODELS ARE STILL PRETTY VARIABLE
WITH THE SOLUTIONS.  IN THE SUNDAY AND MONDAY TIMEFRAME A WEAK
SHORTWAVE MOVING ONSHORE SEEMS TO BE BETTER DELINEATED USING THE
NAM 40...SO WENT WITH A NAM/GFS BLEND DURING THIS TIME PERIOD.
AFTER SUNDAY/MONDAY THE MODELS BEGIN TO VARY QUITE A BIT.
DECIDED TO DEVIATE FROM THE PREVIOUS SHIFTS CHOICE OF ECMWF
BECAUSE THE RESOLUTION OF MULTIPLE LOWS IN THE GULF WAS WAY TOO
BROAD.  AT THIS POINT AM LEANING TOWARD THE GFS SIMPLY BECAUSE IT
SEEMS TO PICK UP THE TRIPLE POINT LOWS A LITTLE
BETTER...PARTICULARLY AT 120 HRS.  HOWEVER WITH THE VARIANCE IN
THE MODELS CONFIDENCE REMAINS LOW.

IN TERMS OF ACTUAL WEATHER EXPECTED DURING THIS TIME PERIOD THE
LONGTERM FORECAST REMAINS ABOUT THE SAME. THE ARCTIC HIGH TO THE
NORTH WILL REMAIN IN PLACE AND STRONG NORTHERLY WINDS AND COLD
AIR WILL BE EXPECTED FOR THE NORTHERN PANHANDLE THROUGHOUT THE
EXTENDED PERIOD.  THE NEXT WAVE MOVING UP ON MONDAY MORNING
SHOULD BRING ENOUGH WARM AIR TO CAUSE THE PANHANDLE TO CHANGE
OVER TO RAIN SOUTH OF FREDERICK SOUND BUT THIS WILL BE SHORTLIVED
AS THE ARCTIC AIR MOVES BACK IN ON WEDNESDAY.  PREVIOUS
DISCUSSION WAS RIGHT ON TARGET WITH THE POTENTIAL FOR SIGNIFICANT
SNOW OVER THE NORTHERN PANHANDLE...BUT AGAIN WITH THE MODEL
VARIANCE CURRENT LOW TRACK MAY CHANGE SIGNIFICANTLY OVER THE NEXT
FEW DAYS.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...WINTER STORM WARNING ZONES...21 THROUGH 26...AND 29.
WIND ADVISORY 17...27 AND 28. WINTER WEATHER ADVISORY 18 AND 19.
MARINE...GALE...11 THROUGH 32...41...43 AND 51. SCA...33 THROUGH
36...42...52.

JT/LEWF