Small Craft Advisory 66, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM AST THU JAN 25 2007

.SYNOPSIS...
.SHORT RANGE...TRANSITION TO EXTREMELY STABLE AIR MASS UNDERWAY
TODAY. STRONG RIDGING AND DRY WX CONTINUES TO BE THE MAIN MESSAGE
FOR OUR FCST AREA. SUBSIDENCE WILL FLATTEN MARINE LAYER AND
EVENTUALLY DISSIPATE LOW CLOUDS...ESPECIALLY SRN ZONES TODAY.
BEST CHC FOR PRECIP AT TIMES IN SHORT RANGE WILL BE ZONE 17
YAKUTAT WHICH IS CLOSER TO STATIONARY FRONT IN CENTRAL GULF.

HEMISPHERIC LONG WAVES EVOLVING TO A WINTER BLOCKY PATTERN. LONG
WAVE RIDGE BUILDING ALONG WEST COAST N AMERICA AND COLD CYCLONES
GETTING ANCHORED IN N PAC NR TIP OF ALEUTIANS AND HUDSON
BAY/GREAT LAKES. VARIOUS SATELLITE IMAGES USED TO CONFIRM
ANALYZED POSITIONS OF MAJOR FEATURES. ALOFT... DEEP SFC CYCLONE
CENTERED S OF COLD BAY NR 51N 163W AND IS REASONABLY WELL
POSITIONED BY NAM.  SFC HIGH CENTER IS OFF BC COAST NR 53N 135W.
170KT WEST JET BETWEEN 35-40N SPLITS APART EAST OF 160W DUE TO
BUILDING RIDGE.

MODELS AGREE RIDGING SFC/ALF WILL BE STRONG ENOUGH TO KEEP FRONT
WITH HUGE PLUME OF TROPICAL MOISTURE TO OUR WEST THROUGH THE
SHORT RANGE PERIOD AND BEYOND. AS MENTIONED ABOVE...THE
EXCEPTION IS OUR WESTERN MOST ZONE 17 WHICH WILL HAVE INCREASING
CLOUDS TONIGHT AND STRONG OMEGA (LIFT) FRI W OF YAK BAY. MARINE
WX...GALES N COASTAL ZONES LIMITED TO RIGHT ALONG FRONT. FARTHER
DOWN COAST SCA MAINLY FOR SEAS OVER 10FT. AVN WX...SUBSIDING
MARINE STRATUS LAYER WILL PERSIST LONGER OVER NRN COASTAL AREAS
AND DISSIPATE QUICKEST OVER INNER CHANNELS. VERY SHALLOW
CONVECTION UNDER LOWERING INVERSION CAUSING A FEW FLURRIES N AND
W OF JNU BUT THATS IT. FOG MAY BE PROBLEM FOR TAFS FRI MORNING.

.LONG RANGE...UKMET AND ECMWF NOT PICKING UP ON AMPLIFIED TROUGH
IN WESTERN GULF AS WELL AS NAM AND GFS. HOWEVER BOTH EUROPEAN
MODELS DO A GOOD JOB AT DEPICTING AN INITIAL PIECE OF SHORTWAVE
ENERGY BREAKING OFF FROM THE MAIN TROUGH AND UNDER CUTTING THE
UPPER LEVEL RIDGE WEST OF OREGON AS DO NAM AND GFS. ENSEMBLE
MEMBERS ARE SHOWING A SECOND PERIOD OF UNDER CUTTING BEGINNING ON
2700Z WHICH THE EUROPEANS DO NOT. CONSISTENT THEME IS THE HIGHLY
AMPLIFIED UPPER LEVEL TROUGH IN THE CENTRAL GULF THAT MOVES VERY
SLOWLY TO THE EAST WITH A DRYING AND CLEARING TREND OVER MOST OF
THE PANHANDLE BUT NOT ZONE 17 UNTIL 30 JAN. GOOD ENSEMBLE MEMBER
AGREEMENT FOR THE EASTERN GULF AND PANHANDLE THROUGH 0200Z. AFTER
WHICH...MODEL CONFIDENCE IS VERY LOW. UNCERTAINTY IS GREATER AND
OCCURS EARLIER IN SURFACE PRESSURE PATTERNS...BY 3112Z.

GOOD AGREEMENT EARLY ON PROMPTED BLENDING NAM AND GFS THROUGH
SATURDAY WITH WEIGHTING SLIGHTLY IN FAVOR OF NAM. STABILITY
BETWEEN RUNS LEAD TO A BLEND BETWEEN PREVIOUS GRIDS AND GFS UP TO
0212Z. SURFACE LOWS NOW SHOWING UP IN EASTERN GULF AT THE END OF
THE CURRENT LONG RANGE MODELS IS A FAIRLY LARGE DEPARTURE FROM 12
HOURS AGO AND THEREFORE HAVE OPTED TO KEEP LAST NIGHTS FORECAST
IN PLACE FOR THE LAST 18-24 HOUR PERIOD.

WIDESPREAD FOG SEEMINGLY MORE AND MORE LIKELY DUE TO SURFACE HIGH
PRESSURE BUILDING IN OVER THE PANHANDLE AROUND 29 JAN BUT STILL
TOO FAR INTO THE FUTURE TO ADD TO THE PUBLIC FORECAST YET.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...NONE
MARINE...SCA OUTER COAST MAINLY FOR SEAS...GALE TONIGHT MAINLY
         WEST OF ICY BAY.