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468
FXAK67 PAJK 201319
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
519 AM AKDT SUN APR 20 2014

.SHORT TERM...OUR GALE FORCE LOW THAT BROUGHT STRONG WINDS TO
PRINCE OF WALES...BARANOF AND THE SOUTHERN INNER CHANNELS IS
SLOWLY RETREATING WESTWARD FROM THE CENTRAL GULF. MEANWHILE AN
ASSOCIATED WEATHER FRONT IS PUSHING NORTHWESTWARD INTO THE
NORTHERN PANHANDLE AND IS LOSING ENERGY AS IT DOES SO. WHILE
WINDS AREN`T STRONG...DIRECTIONS HAVE SHIFTED SOUTH AND A SHORT
BURST OF 20 KT IS OCCURRING OVER LYNN CANAL AND GLACIER BAY. TO
THE SOUTH...THE SOUTHERLY BURST WAS MUCH STRONGER. WITH THIS
FRONT PERIODS OF RAIN WILL OCCUR THIS MORNING, BUT DIMINISH AS
THE FRONT LOSES STEAM AND PUSHES WESTWARD. IN FACT, GRADIENTS
WILL BEGIN TO TURN NORTH LATE THIS AFTERNOON AS WEAK RIDGING
DEVELOPS BEHIND THIS FRONT. THE RIDGING WILL HELP END MUCH OF THE
PRECIPITATION OVER THE NORTH, BUT A TRIPLE POINT FEATURE MOVING
NORTHWARD...CURRENTLY SOUTHWEST OF HAIDA GWAII WILL PUSH MORE
RAIN INTO THE SOUTHERN ZONES LATER TODAY. THIS FEATURE WILL SKIRT
PRINCE OF WALES AND BARANOF OFFSHORE, BUT GRADIENT ORIENTATION
AND AN LOWER LEVEL JET AT 850 MB SHOULD HELP ONCE AGAIN
ACCELERATE WINDS THROUGH CLARENCE STRAIT AND THE SOUTHERN INSIDE
CHANNELS THIS EVENING BEFORE DIMINISHING ONCE AGAIN LATE TONIGHT.

 NATURE OF PRECIPITATION WAS A TOUGH CALL. THE STABILITY SEEMS
NEUTRAL...AT TIMES AND IN LAYERS A LITTLE MORE CONVECTIVE...BUT
THERE WAS QUITE A BIT OF OMEGA VALUES WITH EACH WAVE. TO MAKE
THINGS SIMPLER ELECTED TO REPRESENT CATEGORICAL AREAS AS PERIODS
OF RAIN...AND EXPRESSING CHANCE/LIKELY AREAS WITH THE
ADJECTIVE--LIGHT.

 SOME SLIGHTLY COOLER AIR BEHIND THE FRONT SO TEMPERATURES WON`T
BE AS WARM AS YESTERDAY, IN PART OWING TO MORE CLOUD COVER, BUT
POTENTIALLY WITH SOME SUN BREAKING OUT IN NORTHERN AREAS BEHIND
THIS FIRST WAVE...THINGS WILL LIKELY TURN PLEASANT THIS
AFTERNOON...ESPECIALLY OVER THE NORTHERN INTERIOR PANHANDLE.

 NEW ECMWF USED AS A FORECAST BACKBONE. FORECAST CONFIDENCE A
LITTLE ABOVE AVERAGE.

.LONG TERM...WEAKENING LOW WILL MOVE WWD ACROSS THE GULF MON.
WEAK HIGH PRESSURE WILL BUILD OVER THE ERN GULF AND NRN SE AK MON
NIGHT. INVERTED TROF WILL SLOWLY DEVELOP NW INTO THE PANHANDLE
TUE. AFTER THAT...GENERALLY WEAK FLOW ALOFT WILL BE THE RULE THRU
LATE WEEK...AND MODELS ARE STRUGGLING WITH SYSTEMS IN THIS FLOW.
ENDED UP BLENDING IN THE 00Z ECMWF FOR MON-WED MORNING...THEN
MAINLY WENT WITH WPC FOR WED AFTERNOON ON OUT.

 PRECIP WITH THE MON LOW WILL BE MOVING WWD AND MOSTLY OFFSHORE
BY LATE MON AFTERNOON. THINK THE CENTRAL COASTAL AREA WILL HAVE
BEST OVERALL THREAT FOR PRECIP ON MON. WINDS WILL ALSO DECREASE
MON AS LOW MOVES AWAY AND WEAKENS.

 AS SFC HIGH BUILDS OVER THE AREA...LOOKS LIKE ENOUGH OFFSHORE
FLOW TO SCATTER OUT CLOUDS OVER THE NRN AREA MON EVENING...AND
THIS CLEARING TREND SHOULD REACH MUCH OF THE REMAINDER OF THE
PANHANDLE LATER MON NIGHT. DID NOT BRING IN FOG FOR MON NIGHT AS
MOST PLACES WILL HAVE DRIED OUT SOMEWHAT...BUT PATCHY FOG IS
POSSIBLE. TUE IS LOOKING FAIRLY NICE FOR THE AREA ALTHOUGH MORE
CLOUDS AND A FEW SHOWERS MAY GET INTO THE SERN CORNER OF THE AREA
AS INVERTED TROF DEVELOPS AND WEAK SHORTWAVE ALOFT MOVES INTO
THAT AREA.

 FOR TUE NIGHT AND WED...MODELS DIFFER SOMEWHAT ON A SHORTWAVE
THAT WILL BE NEARBY THE AREA. THE ECMWF BRINGS THIS SYSTEM WWD
INTO THE NRN PANHANDLE WED AS AN ELY WAVE. OTHER MODELS KEEP IT
FURTHER E. OUT OF RESPECT TO THE ECMWF...DID BRING IN A BAND OF
HIGHER CHANCE POPS TO THE NRN AREA WED. IF ECMWF IS RIGHT...POPS
WILL NEED TO BE RAISED MORE.

 WITH WPC USED FURTHER OUT...BASICALLY BROUGHT IN CHANCE POPS
FROM THE S AND ENDED UP GOING MOSTLY CLOUDY FOR THE ENTIRE AREA
FOR WED NIGHT INTO THE WEEKEND. FORECAST CONFIDENCE IS RATHER LOW
AFTER WED FOR THIS REASON.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND FROM THIS EVENING THROUGH LATE TONIGHT FOR AKZ028.
MARINE...GALE WARNING FOR PKZ036-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ021-022-033>035-041-042.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ053.

&&

$$

JWA/RWT






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