Gale Warning 3, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
542 AM AKST TUE JAN 8 2013

.SHORT TERM...EARLY MORNING SATELLITE IMAGES SHOW A 993 MB LOW
TREKKING SOUTHEASTWARD ACROSS THE GULF OF ALASKA. AHEAD OF THIS
WEAKENING LOW...SOUTHWESTERLY ONSHORE FLOW CONTINUES TO TRANSPORT
MOISTURE INTO THE AREA. SNOW AND RAIN SHOWERS SHOULD LINGER FOR
THE REST OF THE DAY. NORTHERN AND CENTRAL PANHANDLE WILL SEE UP
TO 1 INCH OF NEW SNOW ACCUMULATION. THE COLD AIR ALOFT ASSOCIATED
WITH THIS LOW PRESSURE SYSTEM WILL CONTINUE TO CREATE INSTABILITY
ACROSS THE AREA. ISOLATED THUNDERSTORMS ARE EXPECTED FROM CROSS
SOUND TO CAPE DECISION.

 AS THIS LOW CONTINUES TO MOVE SOUTHEASTWARD...WINDS WILL SHIFT
TO THE EAST AND NORTHEAST LATER THIS AFTERNOON. THIS WILL CUT OFF
THE MOISTURE PLUME. AS A RESULT...SHOWERS WILL BECOME
INCREASINGLY SCATTERED. THE THREAT FOR THUNDERSTORMS ALONG THE
CENTRAL PORTION OF THE OUTER COAST SHOULD END LATER THIS
AFTERNOON.

 IN ADDITION...AN AREA OF HIGH PRESSURE OVER YUKON WILL START TO
BUILD INTO THE PANHANDLE...ALLOWING THE WINDS ACROSS THE
PANHANDLE TO SHIFT TO THE NORTH. WINDS IN THE OFFSHORE WATERS
WILL SHIFT TO THE NORTH TONIGHT. THE NORTHERLY WIND WILL ALSO
USHER IN COOLER AIR INTO THE REGION BY TONIGHT.

 FORECAST CONFIDENCE IS ABOVE AVERAGE. MODEL OF CHOICE IS A
COMBINATION OF NAM AND ECMWF.

 &&

 .LONG TERM...MODEL AGREEMENT CONTINUES TO BE HIT OR MISS ONCE WE
GET PAST THE RIDGE IN THE GULF MID WEEK. EACH INDIVIDUAL MODEL
SEEMS TO HAVE THERE OWN LITTLE SCENARIO IN MIND FOR THE FIRST
WAVE TO MAKE IT OVER THE RIDGE ON THURS MOSTLY VARYING IN
STRENGTH AND THE AMOUNT OF PRECIP EXPECTED FROM IT. THE ECMWF HAS
THE MOST WIDE SPREAD PRECIP OUT OF THE VARIOUS MODELS WHILE THE
OTHER MODELS ARE DRYER DUE TO THE WAVE FIGHTING THE RIDGE AS IT
MAKES ITS WAY EAST. DECIDED TO GO A BIT MORE TOWARD THE NAM AND
GFS FOR THE FIRST SYSTEM AS THE DRYER SCENARIO SEEMED TO MAKE
MORE SINCE GIVEN THE STRENGTH OF THE RIDGE IN PLACE OVER THE
GULF.

 PRECIP WILL EVENTUALLY MAKE IT TO THE PANHANDLE ON THURS NIGHT
AND WITH THE COLDER AIR THAT HAS LEAKED INTO THE PANHANDLE,
DURING THE BRIEF COOL SPELL MID WEEK, IT WILL MOSTLY FALL AS SNOW
INITIALLY. SNOW AMOUNTS WILL NOT BE THAT GREAT HOWEVER AS THIS
FIRST WAVE DOES NOT HAVE A TROPICAL CONNECTION AND IT IS FIGHTING
THROUGH THE RIDGE ON TOP OF THAT. WIND WILL NOT BE MUCH OF A
PROBLEM EITHER AS THE TROUGH IS RATHER WEAK.

 BEHIND THE FIRST WAVE, MODEL AGREEMENT DOES NOT IMPROVE VERY
MUCH IF AT ALL. THE MAIN BRIGHT SPOT IS THAT THE ECMWF SEEMS TO
BE CONSISTENT RUN TO RUN FOR THE WEEKEND AND BEYOND BUT IT STILL
DIFFERS FROM OTHER MODEL GUIDANCE. GENERAL TREND FOR THE WEEKEND
AND BEYOND INVOLVES WESTERLY FLOW IN THE UPPER LEVELS CONTINUING
TO SUPPORT ALTERNATING WEAK SHOTS OF WARM AIR FOLLOWED BY COLD
AIR WITH A FEW SOMEWHAT WEAK WAVES DRIFTING ACROSS THE GULF.
PRECIP TYPE WILL VARY THROUGH OUT THE EXTENDED PERIOD BUT WILL
TEND TOWARD SNOW FOR THE NORTHERN HALF OF THE PANHANDLE AND RAIN
AND SNOW FOR THE SOUTHERN HALF. UPPER LEVEL AND SURFACE FLOW
BECOMES MORE SW BY THE END OF THE WEEKEND AS A RIDGE BUILDS UP
OVER THE PANHANDLE DRIVING A MORE AGGRESSIVE WARM PUSH FOR EARLY
NEXT WEEK. WITH THE MODEL DIFFERENCES APPARENT THIS FAR OUT
DECIDED TO MAINLY STICK WITH THE HPC FOR ANY NEEDED CHANGES.
FORECAST CONFIDENCE IS ABOUT AVERAGE FOR THE PERIOD.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ041>043-051-052.

&&

RCL/EAL