Area Forecast Discussion
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FXAK67 PAJK 171708
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
908 AM AKDT WED SEP 17 2014

.SHORT TERM...FOG IS THE MAJOR ISSUE THIS MORNING AS IT PERSISTS
OVER SOME AREAS LIKE PETERSBURG HOONAH AND SITKA AND IS ON AND OFF
IN OTHERS...LIKE SKAGWAY. SEVERAL AREAS IN THE SOUTH HAVE
MAINTAINED VERY LOW CIGS. SKAGWAY HAS MAINTAINED CIGS AT ONLY A FEW
HUNDRED FEET BUT HAS NOT REPORTED FOG FOR A FEW HOURS. SPORT
MODIS-VIIRS HAS BEEN USEFUL TONIGHT IN DIAGNOSING REGIONS. HOONAH
AND HAINES AREA HAVE BEEN ADDED TO THE DENSE FOG ADVISORY THROUGH
10AM...WAS ORIGINALLY FOR THE MAJORITY OF THE SOUTHERN PANHANDLE.
AFTER DISSIPATING LATER THIS MORNING OVER WHAT WE ANTICIPATE TO BE
ALL OF THE AREAS, TONIGHT SHOULD BE MOSTLY FOG-FREE FOR A CHANGE AS
PRE-STORM CLOUDS MINIMIZE RADIATIONAL COOLING AND WINDS BEGIN TO
PICK UP AHEAD OF THE NEW SYSTEM.

AT THE MOMENT 120KT+ JET STREAK IS ENTERING THE SOUTHWESTERN GULF
ALONG WITH A STRENGTHENING UPPER WAVE AND THE BEGINNINGS OF WHAT IS
LIKELY TO BE A 975ISH LOW THURS OVER THE GULF ALONG WITH A STRONG
OCCLUSION. MODELS SAG THE JET STREAK SOUTHEASTWARD THROUGH THE
NIGHT TONIGHT AND THE DYNAMIC LIFT WILL TAKE AIM ON MUCH OF THE
PANHANDLE LATER. THE DETAILS ON THIS SYSTEM ARE THE CHALLENGE BUT
MODELS GENERALLY AGREE THROUGH THURSDAY MORNING AND ONLY A FEW
MINOR CHANGES WERE MADE TO GRIDS THROUGH THURS AM WITH COORDINATION
WITH AFC. DEEP UPPER CLOUD SHIELD HAS ALREADY REACHED THE CENTRAL
GULF OUT AHEAD OF THE SHARPENING UPPER TROUGH. SOME SUBTROPICAL
MOISTURE ALREADY BEGINNING TO BE DRAWN UP INTO THE SYSTEM FROM THE
SOUTH AND WEST. RAIN ONSET LIKELY BY TONIGHT OVER NORTHWEST
PORTIONS AND LATER IN THE NIGHT TOWARDS MORNING OVER MOST OF THE
PANHANDLE. WIND AFFECTS WILL BEGIN LATER TODAY. WE BROUGHT THE
STRONGER SURGE OF WIND+WAVES INTO YAKUTAT AND PORTIONS OF THE
NORTHERN COAST BY THURS AM. VARIOUS GALES ARE LIKELY BEGINNING
TODAY OFFSHORE AND THEN ADVISORY CONDITIONS AND SOME GALES BEGIN
THURSDAY MORNING OVER THE INNER CHANNELS. SEAS FORECAST TO BE WELL
ON THEIR WAY TOWARDS MID TEENS IN FEET BY THURSDAY MORNING FOR
OFFSHORE AND 4-8 FEET FOR VARIOUS INNER CHANNELS...WORST AT THAT
TIME OVER THE SOUTH IN GENERAL. FORECAST CONFIDENCE IS AVERAGE FOR
THIS PERIOD.

.LONG TERM...FIRST FALL WIND EVENT ON THU & THU NIGHT WILL BE DUE TO A
STRONG UPPER DISTURBANCE MOVING RAPIDLY OUT OF THE SW INTO THE CENTRAL
GULF. THIS WILL CERTAINLY SUPPORT A GALE FORCE LOW PRES SYSTEM WITH AT
LEAST ONE CENTER NEAR 54N 149W AT 12Z ON THU. THE UNCERTAIN PART IS
THE CONFIGURATION OF THE ASSOCIATED FRONT AND IF A SECONDARY LOW WILL
DEVELOP CLOSER TO OUR COAST. 17/00Z & 17/06Z OPS MODELS WIDELY
DISAGREE ON A WAVE OR TRIPLE POINT SOMEWHERE ALONG 140W THU AFTERNOON
AKDT. SO INCREASED WIND IN THE FORECASTS FOR THU INTO FRI. AS WE GET
CLOSER TO THE EVENT MAY HAVE TO UP THE WIND SOME MORE. IT LOOKS WET
FOR A WEEK DUE TO SW FLOW ALOFT. KEPT AMOUNTS UP TO MODERATE SO WILL
KEEP AN EYE ON HYDRO AS USUAL. FOR DAYS 4-8 STAYED WITH DAY SHIFTS USE
OF WPC GUIDANCE. CONFIDENCE HIGH ON GENERAL PATTERN AND WIND ON THU-
FRI BUT AGAIN UNCERTAIN ON FRONTAL WAVE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...DENSE FOG ADVISORY UNTIL 10 AM AKDT THIS MORNING FOR AKZ019-021-
     023-026-028.
MARINE...GALE WARNING FOR PKZ041>043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ033-053.

&&

$$

WESLEY/JC

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