Gale Warning 172, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
112 PM AKDT SAT MAR 28 2009

.SHORT TERM...WEAK TROUGHS ALOFT EMBEDDED IN WEAK ZONAL FLOW
TODAY, WITH A RIDGE ALOFT OVER THE CENTRAL GULF MOVG E AND OVER
THE PNHDL TONIGHT PROVIDING ENOUGH SUPPRESSION TO END THE SHOWERS
S OF FREDERICK SOUND. PTCHY FOG SPCLY IN SRN HLF OF PNHDL LATE
TONIGHT. COLDER LOWS TONIGHT SPCLY IN NRN PNHDL. THIS COOLING IS
DUE TO THE BREAKS IN CLOUD COVER LATE TONIGHT WHEN COMBINED WITH
RADIATIVE COOLING ENHANCED BY AN EXTENSIVE SNOW PACK.

 NAM USED AS PRIMARY GUIDANCE TODAY BUT SEEMS TO KEEP  SHOWERS
RUNNING TOO LATE TONIGHT. HAS SHUTOFFS ABT 6 HRS  EARLIER AND IF
PREFERRED FOR LATE TONIGHT. OTHERWISE THE FIELDS ARE USING THE
NAM WITH LITTLE OR NO ADJUSTMENT.

 &&

 .LONG TERM...LARGE SCALE PATTERN REMAINS MOSTLY UNCHANGED
THROUGH THE LONG TERM PERIOD. MOSTLY ZONAL FLOW WITH A FEW SHORT
WAVE TROUGHS MOVING THROUGH ARE THE MAIN HIGHLIGHTS IN THE UPPER
LEVELS. MODELS ARE FAIRLY CONSISTENT THROUGH TUESDAY WHERE THEY
START TO SPLIT UP INTO TWO DISTINCT GROUPS ON HOW THEY HANDLE THE
SYSTEM COMING ON WEDNESDAY. THE FIRST GROUP CONSISTING OF THE EC,
THE HPC, AND THE LONG RANGE UKMET HAVE A FAST MOVING LOW AT ABOUT
1000MB MOVING SOUTH OF THE AREA. THE SECOND GROUP CONSISTING OF
THE GFS, THE GFS ENSEMBLE MEAN, AND THE AK-DGEX HAVE A STRONGER
SYSTEM, ABOUT 995 MB, SLOWER FORWARD SPEED AND A SLIGHTLY MORE
NORTHERLY TRACK. IN THIS CASE, LIKED THE SOLUTION PRESENTED BY
GROUP 2 AS I FELT GROUP ONE WAS TOO FAST WITH THE LOW. FORECAST
WAS UPDATED WITH THE GFS.

 LONG TERM PERIOD STARTS OUT WITH THE FRONT THAT IS JUST MOVING
ONSHORE SUNDAY NIGHT. PRECIP WILL BE A MIX IN MOST PLACES WITH
THE SOUTHERN ZONES SEEING ALL RAIN AND THE FAR NORTHERN ZONES
SEEING ALL SNOW. EXPECTING ONLY A FEW INCHES OF NEW SNOW
ACCUMULATION IN MOST PLACES. ALSO WINDY CONDITIONS WILL BE
PRESENT ALONG THE CENTRAL AND SOUTHERN COAST. EXPECTING THE WINDS
TO CALM DOWN LATE MONDAY NIGHT AS THE FRONT PUSHES PAST.

 BEHIND THIS SYSTEM SHOWER ACTIVITY WILL RESUME OVER THE AREA AND
SOUTHWESTERLY FETCH IN THE OFFSHORE WILL PUSH WAVE HEIGHTS TO
ABOUT 20 FEET ON MONDAY. NEXT SYSTEM COMES WEDNESDAY IN THE FORM
OF A WEAK LOW THAT WILL MOVE ACROSS THE NORTHERN PACIFIC AND GIVE
THE SOUTHERN ZONES A GLANCING BLOW OF HEAVIER PRECIP WEDNESDAY.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND ADVISORY FROM 3 PM TO 9 PM AKDT SUNDAY FOR AKZ023-027.
MARINE...GALE WARNING FOR PKZ041>043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ021-022-033>036.

&&

JBT/EAL