Gale Warning 23, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
353 PM AKST FRI JAN 4 2013

.SHORT TERM...SATELLITE IMAGERY THIS AFTERNOON SHOWING A WEATHER
FRONT ASSOCIATED WITH A 992 MB LOW IN THE NORTH PACIFIC TRACKING
TO THE NORTH. THE FRONT WILL REACH THE SOUTHERN PANHANDLE THIS
EVENING THEN MOVE OVER THE ENTIRE PANHANDLE BY SATURDAY. THE LOW
WILL TRACK TO THE EAST NEARING HAIDA GWAII SATURDAY AFTERNOON AS
IT WEAKENS TO AN OPEN WAVE TROUGH. THERE IS DISAGREEMENT AMONG
THE MODELS REGARDING THE DEVELOPMENT OF A SHORTWAVE ALONG THE
FRONT IN THE SE GULF LATE TONIGHT. EARLIER RUNS OF THE UKMET AND
ECMWF SHOWED A MORE PRONOUNCED TROUGH WHILE THE GFS/NAM DID NOT.
NEW RUNS OF THE NAM NOW SHOW A MORE PRONOUNCED FEATURE IN TH SE
GULF WHILE THE ECMWF DOES NOT. WITH THIS KIND OF SPREAD THIS
EARLY IN THE FORECAST KEPT WITH AN ENSEMBLE BLEND NOTING THAT IF
THE TROUGH DOES DEVELOP THERE WILL BE MARKED CHANGES TO THE
FORECAST.

WINDS ALONG THE SOUTHERN COASTAL WATERS WILL INCREASE TO GALE
FORCE THIS EVENING WITH THE APPROACHING FRONT THEN DISSIPATE LATE
TONIGHT. THE SOUTHERN PANHANDLE WINDS WILL ALSO INCREASE THROUGH
THE EVENING WITH SOUTHERLY SMALL CRAFT WINDS DEVELOPING. KEEPING
WIND GUSTS FOR THE SOUTHERN PANHANDLE BELOW STRONG WIND HEADLINE
LEVELS. WHILE 850 MB WINDS FOR THIS REGION PICK UP TO 50 KTS THE
MAIN LOW WILL STILL BE SOUTH OF THE AREA THEREFORE THINK THE FRONT
WILL DISSIPATE ENOUGH TO LIMIT WIND GUSTS. FOR THE NORTHERN
REGIONS AS THE LOW MOVES TO THE SOUTH WITH HIGH PRESSURE OVER THE
YUKON WINDS WILL CONTINUE TO SHIFT TO THE NORTH AND INCREASE TO
NEAR SMALL CRAFT TONIGHT. AS WITH THE SOUTHERN AREAS WINDS WILL
SUBSIDE THROUGH SATURDAY WITH THE WEAKENING FRONT AND LOW.

TEMPERATURES WILL DROP IN THE EARLY EVENING OR REMAIN STEADY THEN
SLOWLY RISE OVERNIGHT INTO IN THE EARLY MORNING WITH THE PASSING
FRONT. FOR THE NORTHERN PANHANDLE THE NORTHERLY WINDS MAY KEEP
TEMPS LOWER OVERNIGHT BEFORE INCREASING THROUGH THE DAY SATURDAY.

THE CLEAR BREAKS THAT DEVELOPED OVER THE PANHANDLE THIS AFTERNOON
WILL DIMINISH AS CLOUD COVER AND PRECIPITATION MOVES INTO THE
SOUTHERN PANHANDLE THIS EVENING AND THEN MOVES NORTHWARD AS THE
FRONT TRACKS OVER THE PANHANDLE. PRECIPITATION FOR AREAS SOUTH OF
FREDERICK SOUND AND ALONG THE PANHANDLE COAST WILL START AS ALL
RAIN WITH THE WARM AIR MOVING IN. REGIONS BETWEEN FREDERICK SOUND
AND ICY STRAIT WILL BEGIN AS A SNOW RAIN MIX DUE TO THE COLDER AIR
CURRENTLY IN PLACE BUT TRANSITION TO ALL RAIN AS PRECIP INCREASES
WITH THE ADVANCING FRONT. EXPECTING SNOW AMOUNTS ONLY AROUND 1
INCH FOR THIS REGION. NORTH OF ICY STRATI TEMPERATURES SHOULD
REMAIN COLD ENOUGH THROUGH THE MORNING TO KEEP PRECIP MAINLY AS
SNOW...BEFORE MIXING IN WITH RAIN IN THE AFTERNOON. AS PRECIP WILL
START LATER TONIGHT ONLY EXPECTING SNOWFALL AMOUNTS OF 1 TO 3
INCHES. IF THE FRONT WEAKENS DUE TO LIMITED SUPPORT FROM THE
PARENT LOW SNOW AMOUNTS COULD BE LESS...HOWEVER IF THE WAVE DOES
DEVELOP ALONG THE FRONT IN THE SE GULF LOOKING AT SOME HIGHER QPF
AMOUNTS.

KEPT WITH AN ENSEMBLE BLEND FOR PRESSURE AND WINDS WITH A BIT
MORE GFS BLENDED IN FOR THE COASTAL WATERS. FOR POP USED THE SREF
AS ECMWF WAS A BIT TOO FAST MOVING IN PRECIP AND NAM WAS BIT TOO
SLOW. AS CONFIDENCE IN LATEST MODELS IS LOW DID NOT MAKE MUCH
CHANGE TO PREVIOUS FORECAST. WHILE GENERAL SYNOPTIC PATTERN
AGREEMENT IS GOOD THE DEVELOPING WAVE MAY CAUSE SOME ISSUES. OTHER
QUESTION IS ADVANCING WARM AIR AND RESULTING HIGHER SNOW LEVEL FOR
AREAS NORTH OF ICY STRATI. THE NORTHERLY WIND THERE MAY KEEP TEMPS
LOW ENOUGH RESULTING IN MORE SNOW.

.LONG TERM...THE WINDS WILL BE LESS THAN USUAL FOR OUR WINTER
FRONTAL SYSTEMS, AND FORECAST TEMPERATURES ARE TYPICALLY ABOVE
CLIMATE WITH RAIN OFTEN AT LEAST MIXED IN.

AFTER THE LAND FALLING GALE FORCE SYSTEM DISCUSSED IN THE SHORT
RANGE SECTION ABOVE, THERE ARE NO SUSTAINED WINDS GIVEN ABOVE 30
KT IN ANY OF THE MARINE FORECASTS. THE MODELS HAVE A WIDER VARIETY
OF SOLUTIONS FOR POLAR FRONT ZONE WAVES SO EARLY IN THE FORECASTS,
BUT THIS IS DUE TO THESE SYSTEMS BEING TOO CLOSE COUPLED WITH ONE
ANOTHER TO DEVELOP STRONGER WINDS THROUGH DAYTIME SUNDAY. ABOUT
06Z MON A FRONTAL BOUNDARY WILL MOVE ONSHORE ALONG THE WHOLE GULF
COAST FROM YAKUTAT TO HYDABURG, YET WITHOUT SUSTAINED WINDS OF 30
KT OR LESS.

TEMPERATURES WILL REMAIN ABOVE CLIMATE DUE TO THE COMBINATION OF
ONSHORE FLOW AND THE LACK OF ANY ARCTIC AIR MASS TO BE OVER RUN.
ONE RESULT IS THAT SNOW AMOUNTS NEAR SEA LEVEL ARE TYPICALLY 2
INCHES OR LESS PER PERIOD.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ022-041-042.
         SMALL CRAFT ADVISORY FOR PKZ012-021-031>036-043-051-052.

&&

PRB/JBT