Gale Warning 150, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM ADT MON MAR 26 2007

.SYNOPSIS...
.SHORT RANGE...CLOUDINESS AND SHOWERS FROM AN OLD LOW ARE BEING
LIFTED NORTHEAST OUT OF THE PANHANDLE AREA BY AN UPPER LEVEL
SHORTWAVE CROSSING THE COAST THIS MORNING. IMMEDIATELY BEHIND
THIS FEATURE IS A SHORT LIVED SURFACE RIDGE THAT IS PRODUCING
PARTIAL CLEARING OVER MUCH OF THE PANHANDLE. THE NOTABLE
EXCEPTION THIS MORNING IS YAKUTAT WHICH IS EXPERIENCING SOME
INTENSE SNOW SHOWER ACTIVITY WITH ACCUMULATION RATES OF 1 INCH IN
8 MINUTES IN HEAVIER SHOWERS. IN SPITE OF THIS IMPRESSIVE SHOWER
ACTIVITY...CONDITIONS IN YAKUTAT ARE EXPECTED TO IMPROVE EARLY
THIS AFTERNOON AND THE REGION WILL EXPERIENCE SOME PARTIAL
CLEARING AS WELL BEFORE EVENING.

THE BREAK IN THE CLOUDS AND PRECIPITATION WILL BE BRIEF AS A
DEVELOPING LOW OVER KODIAK THIS MORNING MOVES EAST ACROSS THE
NORTHERN GULF. IN ADVANCE OF THIS LOW...CLOUDS AND PRECIPITATION
ASSOCIATED WITH A WARM FRONT SHOULD REACH THE PANHANDLE COAST
TONIGHT. AT LEAST THREE SHORT WAVES ARE EXPECTED TO ROTATE AROUND
THE BASE OF THE PARENT LOW AND KEEP SOUTHEAST AK IN SHOWERS
BEYOND THE SHORT RANGE FORECAST PERIOD. AS A RESULT OF THE
THERMAL RIDGE AND UPPER LEVEL SUPPORT FEATURES...PRECIP MAXIMA
CONTINUES TO LOOK LIKE CENTRAL AND SOUTHERN OUTER COAST AND IS
STILL EXPECTED TO RESULT IN WARNING LEVEL SNOW FALL FOR ZONE 22
BUT ADVISORY LEVEL SNOW TO THE SOUTH DUE TO SNOW CHANGING TO
RAIN. A LARGE PORTION OF AVAILABLE PRECIP WILL FALL ON THE OUTER
COAST BUT ADVISORY LEVEL SNOWFALL IS STILL EXPECTED IN ZONES
21...24...AND 26. CURRENT MODEL RUN INDICATES THAT ZONE 20 MAY
HAVE TO BE ADDED TO THE SNOW ADVISORY. SOUTH OF SUMNER STRAIT
SNOW WILL CHANGE TO RAIN SOONEST AND ADVISORY LEVEL ACCUMULATIONS
STILL NOT ANTICIPATED.

MAJOR FEATURES OF THIS DEVELOPING SYSTEM ARE SIMILAR IN
GFS...UKMET...AND NAM. GFS IS SIGNIFICANTLY DEEPER ON CP THAN
OTHERS AND WAS DISCOUNTED. PREFERRED THE UPPER LEVEL PATTERN AND
THE SURFACE FIELD OF THE UKMET THOUGH DIFFERENCES BETWEEN UKMET
AND NAM95 AND THE END OF THE SHORT RANGE PERIOD WERE MINOR.

.LONG RANGE...MEDIUM RANGE MODELS CONTINUE TO BE IN GOOD
AGREEMENT WITH THE UPPER LEVEL FEATURES THROUGH EARLY NEXT
WEEKEND. AN UPPER LEVEL LOW THAT DROPS INTO THE GULF EARLY THIS
WEEK WILL MOVE EAST THROUGH EARLY NEXT WEEKEND AND TRACK SOUTH OF
THE PANHANDLE INTO BRITISH COLUMBIA. A RIDGE WILL THEN BUILD UP
INTO INTERIOR ALASKA. SOME DIFFERENCES DO EXIST WITH THE SURFACE
FEATURES. A DEVELOPING LOW WILL MOVE NORTH OVER THE EASTERN GULF
TUE NIGHT AND ROTATE NORTHWEST AROUND THE LOW MENTIONED IN THE
SHORT TERM INTO WED...WHILE ANOTHER LOW MAY DEVELOP ON THE FRONT
WED OVER THE SOUTHEAST GULF AND ROTATE AROUND THE LOWS INTO THU
AS THE LOW COMPLEX MOVES SOUTHEAST TO NEAR THE QUEEN CHARLOTTES.
THE NAM WILL BE USED TO HANDLE THESE SURFACE FEATURES AS THE GFS
RESOLUTION JUST CREATES ONE DEEP LOW CENTER ON THE LATEST RUN.

THE DEVELOPING LOW TUE NIGHT WILL SPREAD PRECIPITATION MAINLY
OVER THE SOUTHERN HALF OF THE PANHANDLE WITH WARMER AIR SPREADING
NORTH AND CHANGING THE PRECIP TO MAINLY RAIN. AS THE LOW CURVES
NORTHWEST...OFFSHORE FLOW WILL DEVELOP OVER THE NORTHERN HALF
WITH THE POTENTIAL FOR LIGHT SNOW TO DEVELOP ONLY AS FAR NORTH AS
JUNEAU-ICY STRAIT. OFFSHORE FLOW INCREASES MORE INTO WED OVER THE
NORTHERN HALF AS THE LOW COMPLEX DRIFTS FURTHER SOUTH WHICH
BRINGS THE CHANCE OF PRECIPITATION EVEN LOWER OF THE NORTHERN
HALF. MAINLY RAIN OVER THE SOUTHERN HALF WILL CONTINUE WITH THE
FRONT AS THE NEXT WEAK LOW DEVELOPS ALONG IT. COLDER AIR WRAPPING
AROUND MAY ALLOW SOME AREAS TO MIX WITH OR CHANGE TO SNOW LATE
WED AFTERNOON INTO WED NIGHT. GALE FORCE TO SMALL CRAFT WINDS
WILL OCCUR OVER THE EASTERN GULF AND INNER CHANNELS WITH THE LOWS
WITH WINDY CONDITIONS GUSTING TO ADVISORY LEVEL AT
TIMES...ESPECIALLY OVER THE SOUTHERN HALF.

AS THE LOW COMPLEX DRIFTS SOUTH OF THE PANHANDLE THU EXPECT
DECREASING CLOUDS AND PRECIPITATION FROM NORTH TO SOUTH. DRIER
NORTHWEST TO NORTHEAST FLOW WILL CONTINUE FRI THROUGH THE WEEKEND
WITH PARTLY CLOUDY SKIES AND TEMPS AROUND NORMAL (COOL NIGHTS
(20S) AND MILD DAYS (40S)) STILL LOOKING GOOD.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...WINTER STORM WATCH...ZONE 22 LATE TONIGHT AND TUE
      ...SNOW ADVY...ZONE 17 THROUGH TODAY-ZONES 21..23..24..26
         LATE TONIGHT AND TUE

MARINE...SCA...ALL AREAS EXCEPT PKZ033