Area Forecast Discussion
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FXAK67 PAJK 221540
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
640 AM AKST MON DEC 22 2014

.SHORT TERM...PRESSURE HAS BEEN RISING STEADILY OVERNIGHT AFTER A
TROUGH PASSED TO THE EAST INTO CANADA AND A BROAD RIDGE OF HIGH
PRESSURE HAS FORMED OVER THE INNER CHANNELS. THIS HAS CAUSED SOUTHERLY
WINDS TO INCREASE THROUGH THE INSIDE WATERS WITH NORTHERN LYNN
CANAL REACHING SMALL CRAFT LEVEL. SW ONSHORE FLOW ACROSS THE GULF
CAN BE SEEN ON THE VAD WIND PROFILE FROM THE RADAR EXTENDING ALOFT
AT ALL LEVELS.

SHOWERS ACROSS THE AREA THIS MORNING ARE ASSOC WITH A TROUGH
EXTENDING FROM A LOW NEAR PRINCE WILLIAM SOUND AND A BAND OF UPPER
LEVEL VORTICITY. THIS WILL SHIFT NORTH THROUGH THE DAY AND ALLOW
FOR SHOWERS TO BECOME MORE SCATTERED OR ISOLATED WITH BREAKS IN
THE CLOUDS. LOOKING AT THE LATEST SATELLITE IMAGERY...THE
SOUTHERN OUTER COAST WILL PROBABLY HAVE A GOOD AMOUNT OF SUNSHINE
THIS MORNING. THIS WONT LAST TOO LONG HOWEVER AS THE NEXT SYSTEM
TO AFFECT THE AREA CAN ALSO BE SEEN ON THE SATELLITE APPROACHING
FROM THE SOUTH.

THE APPROACHING GALE FORCE LOW SOUTH WILL BRING RAIN TO THE
SOUTHERN PANHANDLE LATE TONIGHT. EXPECT PORTIONS OF POW ISLAND SEE
GUSTS OF 40MPH LATE TONIGHT AND INCREASING GUSTS OUT OF INTERIOR
PASSES AS WELL. FLOW WILL BECOME OFFSHORE ON THE NORTH SIDE OF THE
LOW AND CAUSE SHOWERS AND CLOUDS TO DIMINISH. SURFACE WINDS WILL
FLIP BACK TO THE NORTH THIS EVENING THROUGH THE INNER CHANNELS AND
INCREASE AS THE LOW DRAWS NEAR.

AS EXPECTED...TEMPERATURES SPIKED UP WITH THE WIND SHIFT TO THE
SOUTH IN SKAGWAY...JUMPING UP TO 41F EARLY THIS MORNING. THE
HAINES AIRPORT IS STILL REPORTING A NW WIND DIRECTION...BUT
SHOWERS OVERNIGHT HAVE MOSTLY BEEN LIQUID AND DOWNTOWN HAINES MOST
CERTAINLY HAS A SOUTH WIND NOW AND A BIT WARMER. THESE SOUTHERLY
WINDS WILL KEEP TEMPERATURES MILD AS WILL THE SUNNY
BREAKS...HOWEVER TEMPERATURES ALOFT ARE COOLING SOME AND THE
AMOUNT OF DAYLIGHT IS SHORT. SO NOT EXPECTING TEMPS TO WARM MUCH
DURING THE DAY. GOING INTO TONIGHT IS ANOTHER STORY. 850MB
TEMPERATURES DROP TO ABOUT -6C OVER THE NORTHERN PANHANDLE AS
SURFACE WINDS SHIFT BACK TO THE NORTH. SHOWERS WILL BE DIMINISHING
WITH INCREASING OFFSHORE FLOW...BUT SOME OF THE SCATTERED SHOWERS
COULD HAVE SNOW MIXED IN THE EVENING. AFTER THAT THE DECREASING CLOUDS
OVERNIGHT WILL MAKE FOR A COLDER MORNING ON TUESDAY.

DID NOT MAKE MANY CHANGES TO THE INHERITED FORECAST...MAINLY FOR
LOCAL EFFECTS. THE NAM INITIALIZED WELL AND WAS CLOSE TO THE GOING
FORECAST SO THAT WAS BLENDED INTO SOME FIELDS. FORECAST CONFIDENCE
IS ABOVE AVERAGE.

.LONG TERM...MOST ADJUSTMENTS TO THE FORECAST WERE MADE FOR THE
TUE AND TUE NIGHT PERIODS. WHILE THE FORECAST STILL LOOKED GOOD AS
FAR AS LOW TRACK ACROSS THE SRN AREA TUE...MODELS WERE SUGGESTING
PRECIP WOULD GET A LITTLE FURTHER N THAN PREVIOUSLY THOUGHT.
RAISED POPS ALONG THE CENTRAL PANHANDLE AROUND FREDERICK SOUND AND
ADJACENT OUTER COAST FOR TUE. SLOWED THE DEPARTURE OF THE PRECIP
TO THE SE TUE NIGHT SOME. WINDS AND TEMPS LOOKED GOOD FOR THE MOST
PART...ALTHOUGH MAX TEMPS AROUND PAYA WERE BOOSTED A BIT FOR TUE
WITH OFFSHORE FLOW AND PLENTY OF SUNSHINE EXPECTED. WILL BE
BORDERLINE FOR WIND HEADLINES OVER THE SRN AREA DUE TO GRADIENT
ORIENTATION...BUT IF LOW TRACKS ONLY A LITTLE TO THE N OF CURRENT
FORECAST...MORE WIND WILL HIT THE SRN AREA TUE INTO TUE EVENING.

STILL A TRICKY FORECAST FOR WED-THU. MODELS SEEM TO BE COMING
CLOSER TOGETHER ON SHORTWAVE ENERGY RIDING THRU RIDGE TOP AND INTO
SE AK DURING WED NIGHT AND THU. THE TEMPS REMAIN SOMEWHAT TRICKY
THOUGH AS THEY WILL DEPEND ON HOW MUCH COLDER AIR CAN MOVE INTO
THE AREA FROM THE N TUE NIGHT AND WED. IF THE COLDER AIR CAN
BECOME ESTABLISHED BEFORE PRECIP WITH SHORTWAVE MOVES IN...WILL
SEE MAINLY SNOW OVER THE NRN AND FAR ERN AREAS. THE NAM SHOWS THE
MOST COLD AIR COMING IN...AND HAS BEEN CONSISTENT ON THIS THE PAST
FEW RUNS. THE ECMWF HAS THE LEAST COLD AIR...WITH GFS AND GEM IN
THE MIDDLE. DECIDED TO LEAVE TEMPS AS IS FOR WED-THU BUT LATER
SHIFTS MIGHT NEED TO LOWER SOME TEMPS...MAINLY OVER THE N...WED
INTO THU. LOOKING LIKE AN INCREASING CHANCE FOR A WHITE CHRISTMAS
FOR THE NRN AREAS THAT DO NOT HAVE SNOW ON THE GROUND ATTM.

FOR LATE WEEK INTO EARLY NEXT WEEK...UPPER RIDGE SHOULD BUILD OVER
THE GENERAL AREA...BUT SOME MODEL DIFFERENCES ON EXACTLY WHERE IT
BUILDS REMAIN...AND THESE ARE BIG AS FAR AS BOTH PRECIP POTENTIAL
AND PTYPE ARE CONCERNED. DECIDED TO NOT CHANGE THIS PERIOD AS IT
WAS BASED ON LATEST WPC...WHICH LOOKS OK AT THIS POINT.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND LATE TONIGHT FOR AKZ027.
MARINE...GALE WARNING FOR PKZ036-041>043.
         SMALL CRAFT ADVISORY FOR PKZ011>013-021-022-031>035.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ051-052.

&&

$$

FERRIN/RWT

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