Small Craft Advisory 110, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
213 PM AKST THU FEB 3 2011

.SHORT TERM...EARLY AFTERNOON SATELLITE LOOP SHOWS A DEVELOPING
LOW ENTERING THE FAR SOUTHEASTERN GULF. THE ASSOCIATED OCCLUDED
FRONT STRETCHES EASTWARD FROM THE LOW TO DIXON ENTRANCE AND
SOUTHERN TIP OF THE PANHANDLE WITH ITS TRIP POINT APPROACHING
WEST OF QUEEN CHARLOTTES. A WEAKENING LOW NEAR COOK INLET IS
NEARLY STATIONARY...WRAPPING PRECIPITATION BAND ACROSS KODIAK. AS
THE DEVELOPING LOW TRACK NORTHEAST...SOUTHERLY PRESSURE GRADIENT
HAS BEEN RELAXING ACROSS THE PANHANDLE...LETTING THE WIND
ADVISORY EXPIRED FOR SKAGWAY.

 MODELS ARE IN FAIR AGREEMENT FOR TONIGHT AND FRIDAY WITH THE
DEVELOPING LOW APPROACHES JUST W OF CAPE DECISION THIS AFTERNOON
THEN WEAKENS AS IT TRACKS NORTH ACROSS THE PANHANDLE
TONIGHT...THEN INTO NORTHWESTERN CANADA BY FRIDAY MORNING. THE
WEAKENING LOW NEAR COOK INLET WILL DRIFT EASTWARD ACROSS THE
NORTHERN GULF THROUGH FRIDAY. THE ECMWF HAS SHOWN A BETTER
CONSISTENCY AND WAS OPTED TO REFRESH THE INHERITED GRIDS FOR
TONIGHT AND FRIDAY.

 THE APPROACHING LOW FROM THE SOUTHWEST WILL DEEPEN TO 998 MB
JUST WEST OF CAPE DECISION THIS AFTERNOON. THIS SYSTEM WILL
GENERATE GALE FORCE WINDS ACROSS THE SOUTHERN OUTSIDE WATERS AND
CLARENCE STRAIT...AS WELL AS ADVISORY LEVEL WIND GUSTS FOR ZONES
27 AND 28 THROUGH LATE TONIGHT INTO EARLY FRIDAY MORNING. WILL
KEEP THE WIND ADVISORIES AS THEY ARE. PRESSURE GRADIENT WILL
BECOME NORTHERLY THIS EVENING BUT FAIRLY WEAK PRIOR TO SHIFTING
TO SOUTH. THE LOW WILL BE ONSHORE THE PANHANDLE LATE TONIGHT
BEFORE FURTHER WEAKENING AND MOVING INTO NORTHWESTERN CANADA BY
FRIDAY MORNING.

 THE INCOMING FRONT FROM THE SOUTHWEST WILL BRING LIKELY TO
CATEGORICAL POPS FOR RAIN ACROSS THE FORECAST DOMAIN TONIGHT
EXCEPT THE NORTHERN MOST AREAS WHERE CHANCE POPS ARE EXPECTED.
THE FRONT WILL WEAKEN AND CONTINUE TO MOVE NORTHEAST ON
FRIDAY...AND THE WEAKENING LOW TRACKING EAST ACROSS THE NORTHERN
GULF WILL PUSH A COLDER AIR MASS OVER THE PANHANDLE. EXPECT SNOW
SHOWERS ACROSS NORTH OF A LINE FROM ELFIN COVE TO JUNEAU WITH
RAIN SHOWERS OVER THE SOUTHERN AREAS.

&&

.LONG TERM...ACTIVE YET UNCERTAIN WEATHER PATTERN IN STORE FOR THE
LONG RANGE FORECAST. HIGH PRESSURE RIDGE BUILDS OVER THE AK GULF
AND TRACKS EAST MOVING OVER THE AK PANHANDLE THIS WEEKEND.
EXPECTING A DRY PERIOD WITH OFFSHORE FLOW AND PARTLY CLOUDY
SKIES. FOR THE START OF NEXT WEEK A SHORT WAVE MOVES OVER THE
RIDGE WITH AN OCCLUDED FRONTAL BAND BRINGING PRECIP TO THE
PANHANDLE. LOCATION OF THE LOW CENTER AND NORTHERLY EXTENT OF THE
PRECIP BAND A BIT UNCERTAIN RIGHT NOW. WITH THE PASSAGE OF THIS
SHORT WAVES EXPECT ANOTHER BRIEF DRY PERIOD WITH THE HIGH PRESSURE
RIDGE REBUILDING. THIS DRY SPELL WILL BE SHORT LIVED AS FRONTAL
BAND ASSOCIATED WITH THE NEXT LOW MOVING UP THE WESTERN EDGE OF THE
RIDGE MOVES ACROSS THE AK GULF AND OVER THE PANHANDLE WED. BY THE
END OF THE WEAK AS UPPER LEVEL HIGH BREAKS DOWN THIS LOW WILL
TRACK INTO THE AK GULF, WHERE IT WILL GO ISN'T EXACTLY CLEAR.
WEEKEND TEMPERATURES WILL DROP AS COLDER AIR FLOWS IN FROM THE
NORTH AND LOOKS TO REMAIN IN PLACE FOR MOST OF THE WEEK...WITH THE
EXCEPTION OF THE SOUTHERN THIRD OF THE PANHANDLE WED INTO THU.

GFS AND EC MODELS INITIALIZED FAIRLY WELL WITH THE NAM BEING A BIT
OF AN OUTLIER. MODELS WERE IN FAIR AGREEMENT UP UNTIL 00Z SAT WHERE
ANALYSIS OF LOW MOVING UP INTO THE AK GULF. EC AND UK MET SHOW A
MORE NORTHERLY TRACK COMPARED TO A WEAKER AND MORE SOUTHERLY GFS.
EC ALSO KEEPS THE LOW QUASI STATIONARY THROUGH 00Z MON AND
DEEPENING TO ABOUT 994 MB. MODELS FALL BACK MORE IN LINE WITH THE
HIGH MOVING BACK OVER THE PANHANDLE THEN AGAIN SEE QUITE A SPREAD
FOR THE NEXT LOW PRESSURE SYSTEM MOVING INTO THE WESTERN GULF AT
THE END OF THE WEEK. IN ADDITION TO DIFFERENCES BETWEEN EACH MODEL
SAW SOME INCONSISTENCIES RUN TO RUN. WHILE THE EC WAS PRECIOUSLY
FAIRLY CONSISTENT RUN TO RUN DID SEE SOME DIFFERENCES BETWEEN THE
02/02 12Z, 02/03 00Z AND 02/03 12Z. HOWEVER THE 12Z RUNS DID SEEM
TO FALL BACK MORE IN LINE WITH EACH OTHER. OPERATIONAL MODELS
WERE ALSO SHOWING DIFFERENCES WITH ENSEMBLE RUNS SO LEANED MORE
TOWARD THE MORE CONSISTENT ENSEMBLE SOLUTIONS.

UPDATED GRIDS WITH 12Z EC THROUGH DAY 4 THEN WITH 12Z HPC GUID,
WHICH WAS A BLEND OF EC AND GFS ENSEMBLES WITH MORE EMPHASIS ON
THE EC. OVERALL WITH SOME FAIR UNCERTAINTY IN THE CURRENT LONG
RANGE FORECAST LIMITED ANY CHANGES. FORECAST CONFIDENCE IS BELOW
AVERAGE.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND ADVISORY UNTIL 4 AM AKST FRIDAY FOR AKZ027.
         WIND ADVISORY FROM 9 PM THIS EVENING TO 4 AM AKST FRIDAY FOR
     AKZ028.
MARINE...GALE WARNING FOR PKZ036-041.
         SMALL CRAFT ADVISORY FOR PKZ013-022-033-035-042-043.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ051-052.

&&

AHN/PRB