Gale Warning 381, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM AST MON DEC 24 2007

.SYNOPSIS...
.SHORT RANGE...SATELLITE IMAGERY THIS MORNING IS REVEALING A
FAIRLY DEEP LOW JUST SOUTH OF KODIAK ISLAND. ASSOCIATED OCCLUDED
FRONT IS NOW OVER THE CENTRAL GULF AND FRONTAL CLOUD SHIELD IS
JUST NOW COMING ASHORE ALONG THE OUTER COAST OF THE PANHANDLE.
OBSERVED WINDS IN ADVANCE OF THE FRONT ARE SOUTHEAST AT 45 KTS
SUSTAINED.  THERE ARE AT LEAST THREE EASILY IDENTIFIABLE SHORT
WAVE FEATURES ROTATING AROUND THE PARENT LOW AND NAM HAS DONE A
FINE JOB OF CAPTURING THESE DETAILS. A SURFACE RIDGE HAS PUSHED
THE LOW FROM LAST NIGHT WELL INTO BRITISH COLUMBIA AND IS ITSELF
NOW BEING PUSHED EAST AS THE ADVANCING FRONT BEGINS TO RIDE OVER
THE TOP. THERE IS A LITTLE PRECIPITATION GOING ON IN VARIOUS
PLACES BUT THIS IS ALL CLEARLY LEFTOVER SHOWER ACTIVITY FROM THE
LOW THAT CROSSED THE PANHANDLE LAST NIGHT.

MAINS ISSUES AFFECTING THE SHORT RANGE FORECAST PERIOD DEAL WITH
THE ONSET AND DURATION OF ADVISORY LEVEL WINDS ALONG THE OUTER
COAST AND SNOWFALL AMOUNTS. PREVIOUS THINKING HAS WIND ADVISORIES
BEGINNING AROUND 6 PM TONIGHT AND THAT TIMING SEEMS TO BE HOLDING
UP WELL WITH THE CURRENT MODEL RUN SO AM NOT ANTICIPATING MAJOR
CHANGES TO THE CURRENT WIND ADVISORIES.

MORE COMPLICATED IS THE TOTAL EXPECTED SNOWFALL AND JUST WHERE
THE RAIN-SNOW LINE WILL BE. HAVE NOT YET DECIDED ON ADVISORY
LEVEL OR HEAVY SNOW FOR ZONE 19. AM ALSO CONSIDERING ADVISORY FOR
ZONES 17 AND 25.

.LONG RANGE...
MODELS STILL INDICATE THAT A LONGWAVE RIDGE IN THE WESTERN
PACIFIC WILL BUILD AND BEGIN TO PUSH THE COLD UPPER LOW IN THE
BERING SEA EASTWARD BY THE END OF THE WEEK. THE LOW EVENTUALLY
SETTLES OVER THE NORTH GULF OF ALASKA BY NEXT MON AS THE RIDGE
MOVES EAST AND EXTENDS FROM THE PACIFIC INTO THE BERING. DURING
THIS TRANSITION A SERIES OF TROUGHS MOVE INTO THE GULF FROM THE
SOUTHWEST AND WEAKEN AS THEY GET STRETCHED BY THE STRONG JET TO
THE SOUTH.

THE GFS APPEARS TO BE TOO DEEP WITH THE LOW MOVING INTO THE NORTH
CENTRAL GULF OF AK AT THE END OF THE WEEK. THERE IS A LARGE
SPREAD IN THE ENSEMBLES WITH THIS SYSTEM AND THE OPERATIONAL GFS
IS ONE OF THE DEEPER SOLUTIONS. WITH THE JET FURTHER SOUTH A
BLEND GFS/ECMWF IS PREFERRED TO HELP TONE DOWN THE LOW IN THE
GULF A BIT AND PUT MORE EMPHASIS ON WAVE DEVELOPMENTS TO THE
SOUTH.

TEMPERATURES WILL BEGIN TO COOL DURING THE MIDDLE OF THE WEEK
FROM COLD AIR INFILTRATING THE GULF BEHIND THE CURRENT LOW. AS
FRONTAL WAVES DEVELOP AND MOVE SOUTH OF THE PANHANDLE LOW LEVEL
WINDS WILL BE PRIMARY OFFSHORE NORTHEASTERLY DRYING OUT NORTHERN
SE AK AND THE NE GULF COAST THU-FRI. PRECIPITATION OVER THE
WEEKEND WILL BE MAINLY SNOW.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...WIND ADVISORY AKZ017-022>023-027>028 WSW AKZ019
MARINE...SCA PKZ011-031-034 GALE
PKZ021>022-033-035>036-041>043-051 STORM PKZ052