Area Forecast Discussion
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FXAK67 PAJK 301444
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
644 AM AKDT SUN AUG 30 2015

.SHORT TERM...ANOTHER COMPLICATED FORECAST TODAY WITH TWO LOWS
AFFECTING THE AREA WITH HEAVY RAIN SHOWERS, STRONG WIND AND
POSSIBLE THUNDERSTORMS.

THE FIRST WEAKER LOW IS CURRENTLY OFF THE COAST OF YAKUTAT AND
HAS BEEN CAUSING MODERATE SHOWERS OVERNIGHT. WINDS OFFSHORE AND
NEAR THE MOUTH OF YAKUTAT BAY ARE EXPECTED TO BE AROUND 25KT WITH
THIS LOW. LIGHTNING STRIKES HAVE BEEN DETECTED IN THE FAIRWEATHER
GROUNDS OVERNIGHT AS WELL. HAVE CONTINUED WITH A SLIGHT CHANCE OF
THUNDER OVER THE NORTHERN GULF WATERS THROUGH TONIGHT...ALTHOUGH
THE LOW IS PROGGED TO WEAKEN SOME THIS AFTERNOON.

UPPER LEVEL JET DYNAMICS AT THE BASE OF A TROUGH DIGGING INTO THE
GULF WILL CAUSE THE DEVELOPMENT OF A NEW SURFACE LOW EARLY SUNDAY
MORNING OVER THE FAR SE GULF. THIS LOW WILL INTENSIFY AS IT
APPROACHES THE SOUTHERN TIP OF BARANOF ISLAND. STRONG VORTICITY
ADVECTION (PVA) WILL HELP TO STRENGTHEN THE LOW AS WELL...INCREASING
THE POSSIBILITY OF MORE THUNDERSTORMS NEAR THIS LOW CENTER.

WINDS WILL INCREASE QUICKLY OVER THE SOUTHERN PANHANDLE THIS
MORNING...MAINLY SOUTH OF SITKA. HAVE REDUCED THE HIGH WIND WATCH
TO A STRONG WIND HEADLINE AS WINDS GUSTS ARE NOT EXPECTED TO QUITE
REACH THE 60MPH CRITERIA OVER LAND. NEAR LINCOLN ISLAND AND CAPE
DECISION WILL SEE THE STRONGEST WINDS FOR THE MARINE AREAS OF
50KT...SO A STORM WARNING IS IN EFFECT FOR CLARENCE STRAIT. THE
HEAVY RAIN AND GUSTY WINDS POSE A THREAT FOR MUDSLIDES...SO HAVE
ISSUED A SPECIAL WEATHER STATEMENT HIGHLIGHTING THAT INFORMATION.
THINK THE BIGGEST THREAT AREA FOR THAT WOULD BE PRINCE OF WALES
ISLAND.

THE UPPER LEVEL JET ENERGY SHIFTS SOUTH OF THE AREA BY LATE
AFTERNOON AND THE SURFACE LOW LOSES SUPPORT CAUSING IT TO WEAKEN
QUICKLY AFTER IT MOVES INLAND. THE SOUTHERN PANHANDLE WILL SEE
WINDS SHIFTING TO THE WEST BEHIND THE LOW. THE NORTHERN HALF OF
THE REGION WILL SEE NORTHERLY WINDS AS THE LOW MOVES THROUGH THEN
BECOME GENERALLY LIGHT AND VARIABLE OVERNIGHT.

THE NAM12 PICKED UP ON THE SECOND STRONGER LOW SEVERAL MODEL RUNS
AGO AND NOW THE CANADIAN REGIONAL MODELS LOOKS VERY SIMILAR. BOTH
HAVE A HIGHER TEMPORAL RESOLUTION WHICH HELPED WITH THIS FAST
MOVING SYSTEM. FORECAST CONFIDENCE IS ABOVE NORMAL FOR THE BASIC
WET/WINDY DAY FOR THE SOUTH...BUT LOWER ON DETAILS OF JUST HOW
STRONG THE WINDS WILL GET. ALSO LOWER CONFIDENCE ON HOW MUCH RAIN
THE NORTHERN PANHANDLE WILL RECEIVE AS THE LOW TO THE SOUTH COULD
CAUSE SHADOWING...BUT THE 1ST LOW OVER THE NORTHERN GULF HAS KEPT
POPS UP.

.LONG TERM...NOT MUCH CHANGE FROM PREVIOUS FORECAST THINKING.
UPPER TROF OVER THE AREA WILL SHIFT SLOWLY E THRU MIDWEEK. UPPER
RIDGE WILL MOVE INTO THE WRN GULF AROUND MIDWEEK. SHORTWAVE TROFS
WILL MOVE ACROSS THE AREA FROM THE NW EARLY IN THE WEEK...THEN
COME IN MORE FROM THE N FOR MIDWEEK. FOR LATE WEEK ONWARD...MODELS
DIFFER ON POTENTIAL SYSTEM THAT MIGHT AFFECT THE AREA AS THEY
DIFFER ON HOW FAST UPPER TROF WILL MOVE TOWARD THE AREA...AND HOW
FAR W IT WILL BE BEFORE DIVING SE. ONE CONCERN LATER ON (OVER NEXT
COUPLE OF WEEKS) IS WHETHER ONE OF THE MYRIAD OF HURRICANES OVER
THE CENTRAL PACIFIC WILL GET PULLED N INTO THE WESTERLIES AT SOME
POINT. THIS WILL NEED TO BE MONITORED DURING THE FIRST HALF OF
SEPTEMBER.

FOR MON...SHORTWAVE WILL MOVE ESE INTO THE ERN GULF AND BRING WEAK
SFC LOW WITH IT. THIS SHORTWAVE LOOKS STRONG ENOUGH TO MAINTAIN
SHOWERS OVER MUCH OF THE AREA...AND EVEN SOME TSTMS OVER THE SRN
GULF INTO SRN SE AK.

FOR MON NIGHT AND TUE...ANOTHER SHORTWAVE WILL DROP SEWD INTO THE
GULF...BUT MOST OF THE ENERGY WILL BE FURTHER OFFSHORE AS IT
PASSES BY THE AREA. INCREASING LOW LEVEL OFFSHORE FLOW WILL
DIMINISH THE SHOWER THREAT LATER MON NIGHT INTO TUE. THERE MAY BE
A FEW TSTMS IN THE FAR SERN GULF AND SRN PANHANDLE MON NIGHT. MAY
SEE MORE SUNSHINE OVER THE NRN AREA TUE THAN CURRENTLY FORECASTED
GIVEN THE INCREASING OFFSHORE FLOW...ALTHOUGH BANDS OF MIDLEVEL
CLOUDS COULD AFFECT THE AREA FROM THE SHORTWAVE.

FOR TUE NIGHT INTO AT LEAST THU...PRECIP THREAT LOOKS MINIMAL WITH
NORTHERLY FLOW ALTHOUGH WEAK SHORTWAVES WILL LIKELY DROP SWD THRU
THE AREA. WOULD EXPECT MOST OF THESE TO HAVE MAINLY HIGH LEVEL
CLOUDS AT MOST AS LOWER LEVELS WILL BE FAIRLY DRY IN THE OFFSHORE
FLOW.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND FROM 10 AM THIS MORNING TO 4 PM AKDT THIS AFTERNOON
     FOR AKZ023-026>028.
MARINE...STORM WARNING FOR PKZ036.
         GALE WARNING FOR PKZ033>035-041-042.
         SMALL CRAFT ADVISORY FOR PKZ031-032-043-051>053.

&&

$$

FERRIN/RWT

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