Small Craft Advisory 121, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM AST MON FEB 26 2007

.SYNOPSIS...
.SHORT RANGE...AN UPPER LEVEL TROUGH WILL CONTINUE TO DIG SOUTH
OVER THE EASTERN GULF TODAY...THEN MOVE SLOWLY ACROSS THE
PANHANDLE THROUGH TUESDAY. A WEAK LOW IS STILL EXPECTED TO
DEVELOP OVER THE SOUTHEAST PANHANDLE TODAY...THEN WEAKEN AND MOVE
EAST TUESDAY. THE ARCTIC HIGH TO THE NORTH WILL WEAKEN SOME TODAY
BUT BUILD BACK IN THROUGH TUE AND BRING A REINFORCING SHOT OF
ARCTIC AIR INTO THE NORTHERN PANHANDLE IN ADDITION TO PERSISTENT
WINDY CONDITIONS.

THE CURRENT FORECAST IS LOOKING ON TRACK THROUGH TUE...SO NO
MAJOR CHANGES WILL BE MADE TO THE CURRENT FORECAST PACKAGE.
PRECIP FROM THE DEVELOPING WEAK LOW STILL LOOKS TO BE CONFINED TO
THE SOUTHEAST PANHANDLE AND POSSIBLY BRING A PERIOD OF STEADY
PRECIP TO THE SOUTHEAST PORTION OF ZONE 26. PRECIP TYPE WILL BE
MAINLY SNOW AS COLDER AIR WRAPS AROUND INTO THE SOUTHERN
PANHANDLE WITH HIGHEST QPF AMOUNTS IN ZONE 29. SNOW AMOUNTS ON
THE 12Z RUNS STILL INDICATE BELOW ADV AMOUNTS FOR THAT ZONE BUT
WILL WAIT AND EVALUATE THE EVOLUTION OF THIS LOW INTO THE
AFTERNOON AND THE 18Z RUNS BEFORE FINAL DECISION IS MADE.
ELSEWHERE...MOSTLY CLOUDY SKIES WILL CONTINUE THROUGH MUCH OF THE
NIGHT WITH FLURRIES CONTINUING OVER THE EASTERN PANHANDLE AS FAR
NORTH AS JUNEAU...HOWEVER PARTLY CLOUDY SKIES AND SOME CLEARING
AREAS WILL CONTINUE OVER THE NORTHEAST GULF COAST AND NORTHWEST
PANHANDLE.

DECREASING CLOUDS LOOKS GOOD FOR ALL BUT THE FAR EASTERN AREAS
TOMORROW AS NORTH TO NORTHWEST FLOW DEVELOPS AT ALL LEVELS. MID
CLOUDS AND A FEW FLURRIES MAY LINGER INTO THE EARLY AFTERNOON
OVER THE FAR EASTERN AREAS UNTIL THE UPPER TROUGH MOVES EAST.

WINDS...ONCE AGAIN WIND ADVISORIES FOR 17 18 AND 19 (AND WIND
CHILL FOR ZONE 18) WILL BE EXTENDED OUT THROUGH THE FIRST THREE
PERIODS OF THE FORECAST (UNTIL 6 AM WED) AS A TIGHT GRADIENT
PERSISTS OVER THE NORTHERN PANHANDLE. GALES TO SMALL CRAFT WINDS
AND FREEZING SPRAY WILL CONTINUE OVER THE CENTRAL TO NORTHERN
INNER CHANNELS WITH STRONG OUTFLOW WINDS OVER THE CENTRAL AND
NORTHERN OUTSIDE WATERS.

.LONG RANGE...THE MODELS ARE IN GOOD AGREEMENT THROUGH FRI SO
THERE IS GOOD FORECASTER CONFIDENCE. WILL USE THE GFS190 12Z RUN
AS IT HAS BEEN CONSISTENT FROM RUN TO RUN THE PAST COUPLE OF
DAYS.

THE PANHANDLE WILL CONTINUE TO STAY COLD AND WINDY THROUGH THE
WEEKEND. AS THE UPPER HIGH OVER THE BERING AND THE UPPER TROF
OVER THE OVER THE EASTERN PART OF THE STATE/YUKON WILL CONTINUE
TO SEND COLD AIR OVER THE FA FROM THE POLE TO KEEP SOUTHEAST
ALASKA WITH BELOW NORMAL TEMPS. THE STRONG NORTHERLY GRADIENT
WILL REMAIN TIGHT SO THERE WILL BE NO LET UP IN THE STRONG
NORTHERLY WINDS THROUGH THE LONG TERM PACKAGE. WITH THAT SAID
WILL KEEP THE FREEZING SPRAY AND GALES TO SMALL CRAFTS OVER
NORTH/SOUTH CHANNELS THROUGH MOST OF THE LONG TERM PERIOD.

TUE AFTERNOON THE UPPER TROF OVER THE FA WILL CONTINUE TO SLIDE
TO THE EAST INTO CANADA THROUGH WED MORNING AS ANOTHER STRONG
SHORTWAVE DROPS OUT OF THE WESTERN INTERIOR AND INTO THE WESTERN
GULF WED NIGHT. AS THIS HAPPENS A WEAK SURFACE LOW OVER THE
SOUTHERN CENTRAL GULF WILL BEGIN TO DEEPEN AND DEVELOP THROUGH
WED NIGHT. THE UPPER TROF WILL CONTINUE TO DRIFT EAST AND CUTOFF
FROM THE PARENT UPPER LOW OVER THE ARCTIC THROUGH THU NIGHT. THE
SURFACE LOW WILL CONTINUE TO DEEPEN INTO THE MID 990S AS IT
DRIFTS EAST TO BE OVER THE QUEEN CHARLOTTES BY THU EVENING AND
THEN INTO CANADA BY FRI MORNING. THE ASSOCIATED WEATHER FRONT
WILL AFFECT THE SOUTHERN THIRD OF SE AK THU. SINCE THE TRACK OF
THE LOW CENTER IS SOUTH OF THE AREA THINK MOST OF THE PRECIP THAT
WILL FALL WILL BE SNOW AS THERE WILL STILL BE CAA FROM THE UPPER
TROF. THE LOW WILL ENHANCE THE NORTHERLY (OFFSHORE) GRADIENT SO
THINK THERE WILL NOT BE THAT MUCH OF A CHANCE FOR PRECIP OVER THE
NORTHERN HALF.

ONCE THE SURFACE LOW MOVES INTO CANADA THERE IS NO REAL THREAT
FOR PRECIP FOR LATE IN THE WEEK INTO THE WEEKEND ACROSS THE
FA...AS MAJORITY OF THE UPPER LEVEL FLOW WILL BE FROM THE NORTH.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...WIND ADV 17 18 19
         WIND CHILL ADV 18

MARINE...GALES 11 12 13 52
         SCA 21 22 31 32 41-43 51
TAR/ABJ