Gale Warning 149, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM ADT THU MAR 22 2007

.SYNOPSIS...
.SHORT RANGE...MORNING SATELLITE IMAGERY SHOWS A LARGE SCALE LOW
OVER THE CENTRAL GULF OF ALASKA MOVING TOWARD THE NORTHEAST. THE
MODELS HAVENT BEEN TOO BAD IN HANDLING THIS FEATURE...ALTHOUGH
THE NAM HAS BEEN A LITTLE TOO FAST IN THE PREVIOUS COUPLE OF
RUNS. NOT TOO CONFIDENT THAT THE NAM HAS SLOWED IT DOWN ENOUGH SO
THIS FORECAST WILL BE LARGELY BASED ON THE GFS40.

DEEP ONSHORE FLOW BEGINNING JUST OFF THE SURFACE HAS MAINTAINED
PLENTIFUL MOISTURE ACROSS ALL OF SOUTHEAST ALASKA.
ADDITIONALLY...WATER VAPOR IMAGERY INDICATES THE UPCOMING LOW
WILL BE BRINGING ABUNDANT MOISTURE WITH IT. THIS ALL SPELLS A
HIGH LIKELIHOOD OF WIDESPREAD RAIN AND/OR SNOW OVER THE
PANHANDLE. THE MAJORITY OF THE AREA WILL REMAIN WARM ENOUGH SUCH
THAT THE PRECIPITATION WILL FALL AS RAIN. HOWEVER...SOME OF THE
HIGHER ELEVATION AREAS WILL SEE MORE SNOW.

THE PRESSURE GRADIENT WILL BECOME INCREASINGLY TIGHT AS THE LOW
APPROACHES THE COAST. WE WILL LIKELY SEE WIDESPREAD GALE
CONDITIONS OVER THE WATERS...AND WILL LIKELY NEED TO MAINTAIN
WIND ADVISORIES...ESPECIALLY IN THE USUAL WINDY SPOTS.

.LONG RANGE...VERY GOOD UPPER LEVEL ENSEMBLE AGREEMENT THROUGH
DAY FOUR. DIFFERENCES GET LARGE AFTER THIS TIME BUT ARE WELL
SOUTH AND WEST OF THE FORECAST AREA AND PROPAGATE SW INTO CONUS.

DIGGING UPPER LEVEL TROUGH MOVES WEST INTO THE GULF EARLY ON 25
MAR AND BECOMES NEGATIVELY TILTED ON 26 MAR. UPPER LEVEL LOW CUTS
OFF ON 27 MAR BUT IS WELL SOUTH OF THE FORECAST AREA. A SECOND
UPPER LOW...HOWEVER...CUTS OFF AS IT MOVES OVER WATER VICINITY
KODIAK AND TRACKS SE TOWARDS QUEEN CHARLOTTE BEFORE RECONNECTING
WITH THE PARENT UPPER LEVEL TROUGH. THIS FEATURE WINDS UP LYING
OVER THE COAST FROM YAKUTAT CLEAR DOWN TO OREGON AS A STRONGLY
NEGATIVELY TILTED UPPER LEVEL TROUGH  BY THE END OF DAY SEVEN.

AT THE SURFACE...LONG RANGE PERIOD BEGINS WITH SURFACE LOW
TRACKING NORTHEAST INTO YUKON FROM VICINITY YAKUTAT. ANOTHER LOW
TRACKING EAST BUT TURNING NORTH ENTERS THE FORECAST AREA NEAR THE
DIXON ENTRANCE 24/00Z AND THERE IS SOME UNCERTAINTY ASSOCIATED
WITH THIS LOW. ENSEMBLE MEMBERS ARE STAMPING IT ANYWHERE FROM
WELL WEST OF OREGON TO VICINITY HYDER TO THE BRITISH COLUMBIA
ALBERTA BORDER. UKMET AND NAM ARE WITHIN 4MB OF EACH OTHER AND
PLACE THIS FEATURE WSW OF VANCOUVER ISLAND AND BRING IT ASHORE
SOUTH OF QUEEN CHARLOTTE ISLAND. EXPECTING RAIN...POSSIBLY MIXED
WITH SNOW IN THE SOUTHERN THIRD OF THE PANHANDLE. COLDER TEMPS
AND UNRELATED SHOWER ACTIVITY AT THE SAME TIME OVER NORTHERN
PORTIONS WILL LIKEY PRODUCE SNOW SHOWERS IN THE NORTHERN HALF
DURING THE SAME TIMEFRAME.

AMBIGUITY AT THE SURFACE IMPROVES UNTIL 26 MARCH WHEN SIGNIFICANT
ENSEMBLE DIFFERENCES AGAIN OCCUR THIS TIME IN THE NORTHEAST GULF
AS A RESULT OF THE TIMING AND INTENSITY OF A LOW TRACKING EAST
OVER THE BERING SEA INTO SOUTHWEST ALASKA. MEMBER DEVIATION ONCE
AGAIN IMPROVES AS THIS LOW TRACKS OFFSHORE NEAR THE KENAI
PENINSULA AROUND 27/12Z BUT THERE IS SOME DOUBT AS TO HOW FAST
THIS LOW WILL TRACK SOUTHEAST AND HOW CLOSE IT WILL COME TO THE
PANHANDLE. CURRENT GFS MODEL RUN IS INDICATING A VERY PRONOUNCED
THICKNESS RIDGE AND ASSOCIATED FRONTAL BOUNDARY THAT PUTS THE
ENTIRE PANHANDLE IN COLD AIR SO SNOW APPEARS LIKELY. 6 HR QPF
VALUES RANGE FROM 0.5 TO 0.8 LIQUID INCHES IN ZONES 17 AND 20 ON
MONDAY NIGHT. NORTHERN...CENTRAL...AND SOUTHERN PANHANDLE VALUES
RANGE FROM 0.3 TO 0.5 INCHES THROUGH THE DAY ON TUESDAY

BLENDED GFS WITH UKMET AT THE START OF THE LONG RANGE PERIOD TO
CAPTURE THE SLOWER AND MORE SOUTHERLY SOLUTION ASSOCIATED WITH
THE 24 MAR LOW.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...WIND ADVISORY AKZ018>028
         FLOOD ADVISORY AKZ017>022-024>026

MARINE...GALE WARNING PKZ012>013-021>022-031>036-041>043-051>053
         SCA PKZ011