Area Forecast Discussion
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FXAK67 PAJK 020006
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
306 PM AKST SUN MAR 1 2015

.SHORT TERM...UPPER RIDGE WILL DOMINATE THE AREA THRU MON. THE
RIDGE AXIS WILL BE OVER THE CENTRAL AND ERN GULF TONIGHT...THEN
DRIFT SLOWLY TO THE OUTER COAST OF SE AK MON. HIGH PRESSURE WILL
BUILD OVER THE YUKON TONIGHT..THEN DRIFT SLOWLY E MON. INVERTED
SFC TROF WILL REMAIN ALONG THE OUTER COAST OF SE PUBLIC...BUT WEAKEN
SOME MON. A WEAKENING OCCLUDED FRONT WILL MOVE NE INTO THE CENTRAL
GULF BY LATE MON AFTERNOON. MODELS WERE FAIRLY CLOSE ON THESE
FEATURES...AND CLOSE TO PREVIOUS FORECAST...SO CHANGES WERE
MINIMAL TO THIS FORECAST FOR THE MOST PART.

MAIN FORECAST CONCERNS WILL BE WINDS...TEMPS...AND FOG POTENTIAL.
RIGHT NOW...HAVE 20-25 KT NLY WINDS OVER THE NRN INNER CHANNELS
WITH JUST A BIT LESS OVER THE S. THINK WINDS WILL INCREASE SOME
OVER THE N...BUT SHOULD NOT GET ABOVE SCA LEVELS. MAY SEE
INCREASING WINDS FOR DOWNTOWN JUNEAU AND DOUGLAS AS WELL
TONIGHT...WITH GUSTS TO 35 MPH POSSIBLE AS A WEAK MTN WAVE EVENT
IS LIKELY. THESE WINDS SHOULD WEAKEN SOME MON AFTERNOON. ELSEWHERE
FOR TONIGHT...WINDS SHOULD GENERALLY BE 15 KT OR LESS. ON
MON...THE N-S CHANNEL WINDS SHOULD START TO WEAKEN SOME BUT THE
E-W CHANNEL WINDS WILL PICK UP AS PRESSURE GRADIENT ORIENTATION
BECOMES MORE FAVORABLE TO ELY FLOW. ALSO...WILL SEE INCREASING
SELY FLOW OVER THE WRN PART OF THE GULF MARINE AREA...WITH 20 KT
LIKELY BY MON AFTERNOON AS OCCLUDED FRONT MOVES CLOSER TO THE AREA.

AS FOR TEMPS...WILL SEE SOME LARGE SPREAD TONIGHT. TEMPS FOR WIND
SHELTERED AREAS WILL LIKELY PLUNGE WELL INTO THE 20S MOST
PLACES...WITH LOCALLY MID TO UPPER TEENS POSSIBLE IN THE
MENDENHALL VALLEY. WHERE WINDS STAY UP...TEMPS MAY END UP ONLY
FALLING TO THE LOWER TO MID 30S. ON MON...WITH STILL A LOT OF
SUNSHINE FOR MOST AREAS AND AN OFFSHORE FLOW...TEMPS SHOULD
RECOVER WELL INTO THE 40S. WOULD NOT BE SURPRISED IF A COUPLE
SPOTS HIT 50...ESPECIALLY OVER THE S.

AS FOR THE FOG POTENTIAL...THINK ANY FOG WILL BE PATCHY AND
LOCALIZED TO WIND SHELTERED AREAS...AND THIS WILL BE MOSTLY OVER
THE S. DECIDED TO KEEP FOG MENTION OUT FOR THE N DUE TO BETTER
DRYING DURING THE DAY TODAY AND A BIT MORE WIND AROUND IN GENERAL.
CANNOT RULE OUT A SMALL PATCH OF FOG FOR THE LEMON CREEK AREA
THOUGH FOR TONIGHT AND EARLY MON MORNING.

.LONG TERM...COLLAPSING UPPER RIDGE MID TO LATE WEEK
TRANSITIONING TO MORE ZONAL FLOW BY THE WEEKEND IS WHAT IS MAINLY
RESPONSIBLE FOR THE WETTER TREND IN THE FORECAST THROUGH EARLY
NEXT WEEK. SEVERAL SHORT WAVES WILL BE HELPING THE TRANSITION
ALONG AS THEY MOVE THROUGH THE OVERALL PATTERN.

THE FIRST SHORT WAVE THROUGH COMES THROUGH ON TUE. MODELS SEEM TO
HAVE A GOOD HANDLE ON THIS FEATURE AS THERE HAS NOT BEEN MUCH
ADJUSTMENT BY THE MODELS OVER THE LAST 24 HOURS. MAIN EFFECTS WILL
BE INCREASED CLOUD COVER OVER MUCH OF THE PANHANDLE ON TUE AND
RAIN FOR THE YAKUTAT AREA (WITH SOME POSSIBLE SNOW EARLY TUE).
AREAS FARTHER EAST ARE MORE PROTECTED FROM PRECIP BY THE STILL
STRONG UPPER RIDGE THAT THIS SHORT WAVE IS FIGHTING AGAINST. KEPT
POPS AT CHANCE HOWEVER FOR THE NORTHERN PANHANDLE (YAKUTAT HAS
CATEGORICAL) AS THE DYNAMICS OF THE TROUGH COULD STILL BE ENOUGH
TO OVERCOME THE EFFECTS OF THE RIDGE OVER THE NORTHERN PANHANDLE.

A SECOND TROUGH COMES ON THE HEELS OF THE FIRST ON WED AND WILL BE
THE ONE THAT DESTROYS THE RIDGE. IT WILL ALSO BE THE NEXT SYSTEM
TO TO BRING PRECIP TO THE PANHANDLE. LONG RANGE MODELS ARE HAVING
SOME TROUBLE REPRESENTING THIS SYSTEM AS THEY TRY AND DEAL WITH
THE PATTERN CHANGE TAKING PLACE IN THE UPPER LEVELS. GFS SEEMS TO
BE AN OUTLIER AS ITS 12Z RUN BROUGHT A 1005 MB LOW ACROSS THE
CENTRAL GULF ON WED. MOST OF THE REST OF THE MODELS WENT WITH A
WEAKER AREA OF LOW PRESSURE TRACKING NEAR KODIAK AND UP TO THE
NORTHERN GULF COAST INSTEAD. DECIDED ON USING THIS SCENARIO FOR
THE FORECAST WHICH STILL RESULTS IN A WET WED NIGHT INTO THU FOR
MOST OF THE PANHANDLE.

INTO THE WEEKEND THE GENERAL TREND REMAINS WET AS PIECES OF ENERGY
FIRST FROM THE SOUTH ON FRI NIGHT AND THEN FROM THE WEST LATER IN
THE WEEKEND. MOST MODELS GENERALLY AGREE ON THIS BUT THE DETAILS
ARE STILL IN DEPUTE. GENERALLY USED MAINLY GEM AND ECMWF FOR LATE
WEEK THEN TRANSITIONED TO SOME WPC DATA WHERE POSSIBLE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-013-031.

&&

$$

RWT/EAL

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