Gale Warning 200, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
1235 PM AKDT MON AUG 25 2008

.SHORT TERM...A WEAKENING LOW IN THE EASTERN GULF IS PUSHING A
SURFACE TROUGH NORTHEASTWARD ACROSS THE PANHANDLE. MORNING
SATELLITE LOOP SHOWS SCATTERED RAIN BAND CONSOLIDATING ALONG THE
PANHANDLE COAST WITH A BIT MORE MOISTURE ORGANIZING JUST WEST OF
DIXON ENTRANCE. THIS TROUGH HAS GENERATED LOCALLY BREEZY
CONDITIONS ACROSS MOST OF THE FORECAST AREAS WITH PERIODS OF
RAIN...MOMENTARILY MODERATE ESPECIALLY ACROSS THE CENTRAL
PANHANDLE. PERIODS OF RAIN AND DRIZZLE WILL CONTINUE ACROSS THE
REGION THIS AFTERNOON BUT THE WINDS SHOULD DECREASE GRADUALLY AS
THE TROUGH DISSIPATES. A WEAK UPPER LEVEL TROUGH ACROSS THE YUKON
TERRITORY SLOWLY PUSHES MID LEVEL DYNAMICS SOUTHWARD ACROSS
YAKUTAT ARES AND SLIGHTLY EXPANDS SOUTHEAST INTO NORTHERN ONE
THIRD OF THE PANHANDLE.

 MODELS ARE IN GENERAL AGREEMENT TO YIELD ABOVE AVERAGE FORECAST
CONFIDENCE FOR TONIGHT AND TUESDAY. PREFER TO LEAN OVER THE
LATEST NAM SOLUTIONS TO MAINTAIN CONTINUITY. THE GFS HAS SHOWN A
RELATIVELY POOR TREND ON HANDLING THE LOW IN THE YUKON OVER THE
PAST FEW DAYS. BASED ON THE NAM OUTPUTS...THE MID TO UPPER LEVEL
TROUGH ASSOCIATED WITH THE UPPER LOW IN THE SOUTHERN YUKON WILL
SLOWLY FILL AND MOVE SLOWLY TO THE EAST THROUGH TUESDAY EVENING.
THIS WILL CHANGE THE FLOW PATTERN ACROSS THE REGION FROM
MERIDIONAL TO MORE ZONAL LATE TONIGHT INTO EARLY TUESDAY MORNING.
A WEAK SURFACE RIDGE ACROSS THE PANHANDLE WILL DISSIPATE BY
MIDDAY TUESDAY AS THE NEXT VERTICALLY STACKED LOW IN THE WESTERN
GULF RAPIDLY MOVES EAST INTO THE EASTERN GULF EARLY TUESDAY
AFTERNOON.

 CONTINUING ONSHORE FLOW ACROSS THE SOUTHEAST ALASKA WILL
MAINTAIN LIKELY TO CATEGORICAL POPS TONIGHT AND TUESDAY. AHEAD OF
THE NEXT SYSTEM...A LEADING EDGE OF THE FRONTAL BOUNDARY WILL
START AFFECTING THE SOUTHERN MOST ZONES TONIGHT AND CONTINUE
THROUGH TUESDAY WITH SMALL CRAFT WINDS AND SEAS FOR SOUTHERN
OUTSIDE WATERS WITH A BIT STRONGER WINDS FOR SOUTHERN MOST INSIDE
WATERS. AS THE SOUTHERN BOUNDARY OF THE FRONT SWEEPS ACROSS THE
SOUTHERN PANHANDLE...CLARENCE STRAIT IS EXPECTED TO MEET GALE
FORCE WINDS AS WELL AS SMALL CRAFT WINDS EXPANDING TO THE NORTH
TO INCLUDE SUMMER AND SOUTHERN CHATHAM BY LATE TUESDAY AFTERNOON.
WILL GO WITH NO WIND ADVISORIES FOR SOUTHERN ZONES BUT WILL
MENTION BREEZY TO LOCALLY WINDY CONDITIONS FOR TUESDAY WITH THE
AFTERNOON PACKAGE. NEED TO KEEP AN EYE ON FOR ANY POSSIBLE
DEVELOPMENT AS TIME GOES.

.LONG TERM...POLAR FRONT ZONE WAVE, CURRENTLY ABT 300 S OF
DUTCH HARBOR, WILL DVLP TO 992 MB 400 NM S OF YAKUTAT 00Z WED.
LOW INTENSIFYING TO ABT 995 MB AS IT MAKES LANDFALL NEAR
CAPE DECISION ABT 18Z WED, BUT ONLY AS A SCA.  THESE VALUES
COME FROM THE IMPROVED CONSENSUS BETWEEN THE GFS AND ECMWF.

SOME PREFERENCE FOR THE GFS THIS MORNING DUE TO THE SLOWER TRACK
AND STRONGER CYCLOGENESIS OF THE SYSTEM APPROACHING THE PANHANDLE
FM THE SW THU NIGHT.  THE GOES IR LOOP SHOWS THE FRONTAL WAVES S
OF THE AK PEN LOSING SOME ACCESS TO COLD AIR THAT WILL CAUSE
LATER WAVES TO BE BETTER CANDIDATES FOR CYCLOGENESIS.  USING THE
LOOP OF GOES IR AND WV, THE ECMWF COULD STILL BE A VIABLE SOLN
AS THE LOOPS INDICATE FAST MOVING WAVES.  AT THIS TIME THE
GFS SEEMS TO BE THE BETTER SOLN BUT ECMWF WILL CONT TO BE
MONITORED.

A FAMILY OF FRONTAL WAVES WILL FOLLOW ONSHORE THU AND FRI,
BUT THE MODEL CONSENSUS IS POOR.  THE GFS SOLN HAS SFC WINDS
ABT 30 KT STGR THAN THE ECMWF FOR FRI.  THE GFS SOLN SEEMS
TO BE DETECTING CYCLOGENETIC WAVES THAT CLIMATOLOGICALLY
FIT THE STRONGER SYSTEMS THIS TIME OF YEAR.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ036.
         SMALL CRAFT ADVISORY FOR PKZ033-035-041>043.

SJA  MAM/JBT