Gale Warning 55, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM AST SAT JAN 20 2007

.SYNOPSIS...
.SHORT RANGE...LARGE UPPER LOW AND ACCOMPANYING SURFACE CYCLONE
WILL MOVE ONSHORE LATER TONIGHT ALONG THE NORTHERN GULF COAST...
LIKELY SOMEWHERE BETWEEN PRINCE WILLIAM SOUND AND YAKUTAT.
IMPRESSIVE CLOUD SHIELD CONTINUES TO SPREAD ACROSS THE
NORTHEASTERN GULF AND THE ADJACENT PORTIONS OF SOUTHEAST ALASKA.
MODELS APPEAR TO BE IN PRETTY CLOSE AGREEMENT WITH THE POSITION
AND MOVEMENT OF THIS SYSTEM IN THE SHORT RANGE...ALTHOUGH THERE
ARE SIGNIFICANT DIFFERENCES WITH THE DEPTH OF THE SYSTEM. THIS
FORECAST WILL LARGELY USE THE GFS-40.

PRESSURE GRADIENT WILL BECOME INCREASINGLY TIGHT LATER THIS
AFTERNOON AND CONTINUE THROUGH TONIGHT. WINDS SHOULD STEADILY
INCREASE THROUGH THE DAY AS THE LOW AND THE ACCOMPANYING
BAROCLINIC ZONE MOVE ACROSS THE EASTERN GULF AND SOUTHEAST
ALASKA. THE STRONGEST DYNAMICS WITH THE SYSTEM SHOULD MOVE THE
FRONT MOST RAPIDLY ACROSS THE NORTHERN AND CENTRAL PANHANDLE.
WINDS SHOULD DIMINISH FAIRLY RAPIDLY ONCE THE FRONT MOVES THROUGH
THE AREA.

THE HEAVIEST SNOW WITH THIS SYSTEM LIKELY TO BE CONFINED TO THE
NORTHERN AREAS AS WELL AS THE INTERIOR PORTIONS OF ZONE 29. COLD
AIR WILL BE SLOWER TO ERODE OVER INTERIOR PARTS OF ZONES 18 AND
19 SO SNOW WILL LAST LONGER THERE. THE YAKUTAT ZONE WILL LIKELY
SEE VERY HEAVY SNOW BEFORE THE STRONGEST WINDS DEVELOP AND BECOME
MORE SOUTHEAST AT WHICH TIME...SNOW SHOULD BECOME RAIN.

.LONG RANGE...MODELS AGAIN DIVERGING STARTING IN THE MID RANGE
FORECAST PACKAGE. ALL SEEM TO AGREE ALONG THE LINES OF A TRAILING
WAVE ON THE FRONTAL BOUNDARY SPREAD ACROSS SOMEWHERE GENERALLY
ALONG THE SOUTHERN HALF OF PANHANDLE REGION MONDAY...BUT LOCATION
AND TIMING ARE A LITTLE DIFFERENT. ALSO A SECOND DEVELOPING
SYSTEM TO THE SOUTHERN GULF BY TUESDAY AFTERNOON IS RIGHT NOW
BEING SHOWN WITH VARIOUS LOCATIONS AND DEPTHS.  AT THIS TIME
SINCE CURRENT GRIDS FALL WITHIN THE RANGE SOLUTIONS WILL MAKE
LITTLE IN WAY OF PATTERN CHANGES TO MID AND LONG RANGE SITUATION.

THERE FORE AM NOT EXPECTING TO SEE SIGNIFICANT CHANGES TO THE
LATER FORECAST PERIODS. HAVE WORKED ON SOME MINOR CHANGES TO
PRECIPITATION FIELD AND TEMPERATURES.

IN THE LONG RANGE AM NOT SEEING A MAJOR PATTERN SHIFT NEXT
WEEKEND AT THE EARLIEST AS THE ACTIVE WEATHER PATTERN PERSISTS
THROUGH THEN.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...HEAVY SNOW WARNING 3 PM TO MIDNIGHT AKZ017-019
         HEAVY SNOW WARNING 6 PM TO NOON SUN AKZ029
         SNOW ADVISORY 6 PM TO 3 AM SUN AKZ018
         WIND ADVISORY 3 PM TO 9 PM AKZ022
         WIND ADVISORY 3 PM TO MIDNIGHT AKZ023-027
         WIND ADVISORY 6 PM TO MIDNIGHT AKZ019>021-024>026
         WIND ADVISORY 6 PM TO 3 AM SUN AKZ028
         WIND ADVISORY 6 PM TO 6 AM SUN AKZ029
         WIND ADVISORY MIDNIGHT TO 9 AM SUN AKZ017

MARINE...STORM WARNING PKZ052
         GALE WARNING PKZ022-036-041>043-051
         SCA PKZ011>013-021-031>035-053

MLR - BMB