Gale Warning 16, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
1140 AM AST WED JAN 3 2007

.SYNOPSIS...
.SHORT RANGE...POTENTIAL EXISTS FOR A POTENT WINTER WEATHER STORM
TO AFFECT PARTS OF SOUTHEAST ALASKA DURING THE AFTERNOON AND
EVENING HOURS THURSDAY AND INTO EARLY FRIDAY. ONE AREA OF LOW
PRESSURE THAT IS NOW OVER THE GULF WILL LIFT NORTHWARD ACROSS THE
NORTH CENTRAL GULF AND INTO THE PRINCE WILLIAM SOUND AREA LATER
TONIGHT. MEANWHILE...ANOTHER SYSTEM WILL TAKE SHAPE OVER THE
WESTERN END OF THE ALEUTIANS AND MOVE RAPIDLY EASTWARD INTO THE
GULF ON THURSDAY. THE SYSTEM ENTERING THE GULF WILL DEEPEN
SIGNIFICANTLY...AND WILL BRING AN INCREASINGLY TIGHT PRESSURE
GRADIENT TO THE REGION. IT WILL ALSO BRING THE POTENTIAL FOR
SIGNIFICANT SNOWFALL TO NORTHERN AND CENTRAL PORTIONS OF THE
PANHANDLE.

THE THURSDAY LOW IS EXPECTED TO MOVE TO THE NORTH CENTRAL PARTS
OF THE GULF BY THURSDAY AFTERNOON. MEANWHILE...A TRIPLE POINT LOW
IS FORECAST TO DEVELOP OVER THE NORTHERN OR CENTRAL PANHANDLE.
THE EXACT POSITION AND TRACK OF THE LOW WILL DETERMINE THE
PRECIPITATION TYPE. AS OF NOW...THE TRIPLE POINT LOW IS EXPECTED
TO MOVE FROM JUST NORTH OF SITKA TO JUST SOUTH OF JUNEAU. WARM
ADVECTION NORTH OF THE LOW SHOULD BRING SIGNIFICANT SNOWFALL
NORTH OF A LINE FROM SITKA TO FIVE FINGERS. THE PATH OF THE
TRIPLE POINT LOW IS NOT CERTAIN...SO WILL NOT UPGRADE THE WATCH
AT THIS TIME. HOWEVER...A HEAVY SNOW/WINTER STORM WARNING MAY
BECOME NECESSARY FOR PART OF THE AREA AS THE EVOLUTION OF THE
SYSTEM BECOMES MORE APPARENT.

TEMPERATURES WILL REMAIN AT OR SLIGHTLY BELOW FREEZING OVER THE
NORTHERN AND CENTRAL PANHANDLE WHILE THERE WILL BE SOME AREAS
OVER THE SOUTHERN PANHANDLE THAT RISE TO ABOVE FREEZING. LITTLE
CHANGE IN THE FORECAST IS EXPECTED WITH THE UPCOMING ZONES.

.LONG RANGE...NO CHG TO RECENT LONG TERM FCST TRENDS. SEVERAL
FRONTAL SYSTEMS BRINING A COMBINATION OF RAIN SNOW AND WIND
THROUGH SUN THEN DRIER COLDER AIR MASS DROPS IN FROM THE NORTH
NEXT WEEK. LARGE SCALE MODEL FCSTS ARE MORE SIMILAR THIS MORNING
THAN THEY WERE TUE MORNING.

BY EARLY FRI... THE SYSTEM CROSSING THROUGH 45N 170W TODAY WILL
BE AFFTECTING MUCH OF THE SE AK PANHANDLE. GFS AND ENSEMBLE
MEMBERS INDICATE EVOLVING DYNAMICS WITH LOW CENTERS BUT
CONFIDENCE IS HIGH THE ULTIMATE AFFECT ON FRI WILL BE A SFC
LOW...APPROX 975 MB... MOVING INLAND NORTH OF SITKA. JETSTREAM
DYNAMICS AND WSW FLOW PERPENDICULAR TO THE TOPOGRAPHY WILL MAKE
FOR A WIDESPREAD PRECIP EVENT FRI ALONG A NEG TILTED FRONT
EXTENDING SOUTH DOWN THE COAST. STG WINDS AND HI SEAS WILL
DEVELOP OVER THE SOUTHERN PANHANDLE ZONES AS WELL. 850MB TEMPS
SUPPORT SNOWY PRECIP FRI ALL THE WAY TO A SITKA-PETERSBURG LINE
AND MIXED RAIN AND SNOW SOUTH OF THERE.

RESIDUAL TROUGHING PERSISTS FRI NIGHT AND SAT AS THE TRAILING
OCCLUDED LOW IS FCST TO MOVE QUICKLY ACROSS GRAHAM ISLAND SOUTH
OF DIXON ENTRANCE AND INTO BC. THIS EVENT WILL ALSO LIKELY HAVE A
BRIEF PERIOD OF STIFF WIND AND PRECIP PARTICULARLY SOUTHERN
ZONES. GENERALLY UNSETTLED WET WEATHER AND SEASONABLY COOL TEMPS
PERSIST ACROSS THE FCST AREA THROUGH SUN NIGHT. BY MON THE
JETSTREAM SAGS FARTHER SOUTH CLOSER TO 50N AND A VERY COLD 1045
MB SFC HIGH DOMINATES INTERIOR AK. I BELIEVE THE MODELS ADVANCE
THE HIGH CENTER TOO FAR EAST TOO QUICKLY TUE-WED. IF IT STAYS
LONGER OVER ERN AK AND THE YUKON AS I SUSPECT THEN A NEW DOSE OF
COLD DRY OFFSHORE FLOW WILL PERSIST THROUGH LATE NEXT WEEK. TA

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...SNOW ADVISORY FOR TODAY AKZ019
         SNOW ADVISORY FOR TOMORROW AKZ023>024-026>028
         WINTER STORM WATCH TOMORROW AKZ017-019>022-025-029
         WIND ADVISORY TOMORROW AKZ023-024-026>029

MARINE...SCA PKZ011>013-021-022-031>033-035-036-041>043-051>053