Area Forecast Discussion
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FXAK67 PAJK 032133 COR
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION...CORRECTION
NATIONAL WEATHER SERVICE JUNEAU AK
636 AM AKDT THU SEP 3 2015

.SHORT TERM...UPPER TROF JUST E OF SE AK WILL DIG SE TOWARD THE
PAC NW STATES THRU TONIGHT. AN ELONGATED SHORTWAVE TROF WILL DIVE
SWD THRU THE SRN PANHANDLE THIS AFTERNOON. A COMPLEX FRONTAL
SYSTEM OVER THE ERN AKPEN WILL MOVE E TO THE CENTRAL GULF BY LATE
TONIGHT. MODELS WERE IN FAIRLY GOOD AGREEMENT ON THESE
FEATURES...AND ENDED UP USING A BLEND OF THE 00Z GFS22 AND NAM12.

MAIN FORECAST CONCERNS WILL BE PRECIP POTENTIAL AND WINDS. AS
SHORTWAVE MOVES THRU SRN AREA THIS AFTERNOON...SOME SHOWERS MAY
DEVELOP NEAR HYDER. ONCE SHORTWAVE GOES PAST THEM THIS
EVENING...ANY
SHOWERS NEAR HYDER SHOULD DIMINISH. PRECIP WITH THE COMPLEX
FRONTAL SYSTEM SHOULD BE MOVING SLOWLY E INTO THE CENTRAL AND PART
OF THE ERN GULF TONIGHT. THINK THIS PRECIP WILL MAKE IT TO THE
PAYA AREA AROUND MIDNIGHT TONIGHT. THE MODELS DID DIFFER A BIT ON
THE TIMING...AND THE MIDNIGHT TIMING INTO PAYA IS A MIDDLE GROUND
COMPROMISE. SOME SPRINKLES COULD REACH THE FAR NRN AREA LATE
TONIGHT...SO WENT WITH A LOW POP THERE TO COVER THAT.

WIND WISE...STRONGEST WINDS ARE GENERALLY OVER THE NRN INNER
CHANNELS ATTM. 20-25 KT NLY WINDS ARE OCCURRING IN LYNN
CANAL...BUT WITH A RAPIDLY WEAKENING NLY PRESSURE GRADIENT THIS
MORNING...THEY SHOULD DROP OFF INTO THE 10-15 KT RANGE BY LATE
MORNING. THE GRADIENT WILL LIKELY FLIP TO SLY THIS AFTERNOON AS
SWLY FLOW ALOFT LOWERS PRESSURES OVER THE YUKON AND FAR NRN
PANHANDLE. DO NOT SEE MORE THAN 15 KT S WINDS FROM THIS. FURTHER
S...N-NW WINDS OF 10-15 KT ARE COMMON OVER THE CENTRAL INNER
CHANNELS...WITH GENERALLY LESS THAN 10 KT OVER THE SRN AREA. THESE
WINDS WILL LIKELY DIMINISH THIS AFTERNOON. AS COMPLEX FRONTAL
SYSTEM MOVES CLOSER TO THE AREA TONIGHT...SOME INCREASE IN E-SE
WINDS WILL OCCUR...BUT MOST PLACES WILL BE 15 KT OR LESS. MAY BE A
SMALL AREA OF 20 KT E WINDS NEAR SCULL ISLAND TONIGHT AS ELY
PRESSURE GRADIENT WILL BE LOCALLY ENHANCED BY THE NEARBY TERRAIN
THERE. OVER THE GULF...E-SE WINDS WILL PICK UP OVER THE NRN GULF
TONIGHT...WITH AREAS W OF ICY BAY INCREASING TO SCA LEVELS AS WEAK
BARRIER JET DEVELOPS AHEAD OF THE FRONTAL SYSTEM.

.LONG TERM...AT THE START OF THE LONG TERM PERIOD A LOW WILL BE
OVER THE NORTHERN GULF WITH AN ASSOCIATED COMPLEX WEATHER FRONT
EXTENDING EAST TOWARDS YAKUTAT. THIS FRONT WILL PRODUCE A BARRIER
JET TO MIN GALES OVER THE NORTHERN GULF AND THEN 25 TO 35 KT ALONG
THE FRONT ON FRIDAY. THE E/W Gradient WILL ALSO INCREASE AS THE
FRONT Approaches SO INCREASED THE WINDS TO 25 KT OVER CROSS SOUND
AND 20 KT OVER ICY STRAIT. THE WINDS OVER THE INNER CHANNELS WILL
INCREASE SOME FRIDAY FROM THE SOUTH AS THE SURFACE RIDGE OVER THE
AREA SHARPENS UP AS IT FEELS THE AFFECTS OF THE FRONT. SMALL
CRAFT WINDS WILL DEVELOP OVER NORTHERN LYNN AND 20 KT OVER
SOUTHERN LYNN THE REST OF THE INNER CHANNELS WILL SEE SOUTH WINDS
LESS THAN 15 KT THROUGH FRIDAY. THE RIDGE WILL PUSH TO THE EAST AS
THE FRONT MOVES INTO THE EASTERN GULF AND THE SOUTH WINDS OVER N/S
CHANNELS WILL DIMINISH. LAND WINDS WITH THIS FRONT WILL BE THE
STRONGEST OVER THE GULF COAST WITH 15 TO 25 MPH AND THEN SPREADS
INLAND WITH THE FRONT LATE FRIDAY INTO SATURDAY MORNING BUT IT
WILL BE WEAKENING SO WINDS WILL BE MORE LIKE 10 TO 20 MPH WITH
SOME HIGHER GUSTS.

THE FRONT HAS SOME TROPICAL CONNECTION AS SEEN ON SATELLITE
IMAGERY AND AS IT MOVES OVER THE FORECAST AREA IT WILL PRODUCE
SOME HEAVY RAIN. THE RAIN WILL SPREAD FROM THE NORTHERN GULF
FRIDAY MORNING AND OVER THE NORTHERN HALF THROUGH FRIDAY
AFTERNOON THEN OVER THE SOUTHERN HALF BY FRIDAY NIGHT. AT THIS
TIME THE HEAVY RAIN WILL BE ALONG THE COASTAL AREAS WITH THE
GUSTAVUS AND HOONAH AREAS ALSO SEEING SOME SIGNIFICANT RAIN
AMOUNTS. RAIN TOTAL ACROSS THE AREA WILL RANGE FROM 1 TO 2 INCHES
FROM FRIDAY MORNING THROUGH SATURDAY MORNING. THE LOW WILL SLOWLY
WEAKEN THROUGH SATURDAY AND SHOWERS WILL PERSIST OVER MOST OF THE
AREA. THE SHOWERS WILL BECOME MORE SCATTERED THROUGH SATURDAY
NIGHT.

THERE REMAINS A LOT OF MODEL DISAGREEMENT FROM SUNDAY INTO NEXT
WEEK. THE GEM AND EC WANT TO KEEP THE PANHANDLE ON THE DRIER SIDE
ON SUNDAY WHILE THE GFS KEEPS MORE SHOWERS OVER THE AREA. TO
COMPLICATE THE SITUATION EVEN MORE HURRICANE IGNACIO IS FORECASTED
TO MOVE NORTH OUT OF THE CENTRAL PACIFIC AND INTO THE NORTH
PACIFIC EARLY NEXT WEEK. THE MODELS ARE HAVING A DIFFICULT TIME
TRYING TO GET A HANDLE ON WHERE THIS EXTRA-TROPICAL SYSTEM WILL GO.
THE EC AND GEM KEEPS THIS SYSTEM SOUTH OF OUR AREA WHILE THE GFS
LIFTS THE SYSTEM RIGHT OVER SEAK ON TUESDAY MORNING.
THERE IS SO MUCH UNCERTAINTY AT THIS TIME THAT EVEN BEFORE
IGNACIO MOVES INTO THE GULF THERE ARE ISSUES WITH A LEADING WAVE
AHEAD OF THE SYSTEM THAT THE MODELS ARE NOT HANDLING WELL. THE
EC DEVELOPS THIS WAVE MOVING OUT OF THE NORTH PACIFIC AND INTO THE
EASTERN GULF SUNDAY INTO MONDAY. THE GEM DEVELOPS A WAVE MOVING
OUT OF THE BRISTOL BAY AREA AND INTO THE GULF ON MONDAY.

SO WITH THAT SAID THERE IS VERY LOW FORECASTER CONFIDENCE FROM
SUNDAY INTO NEXT WEEK. THE MAIN POINT IS THAT SOMETHING WILL MOVE
INTO THE GULF FROM THE TROPICS BUT WHERE IT WILL GO AND WHEN IS
STILL YET TO BE SEEN.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-051-052.

&&

$$

RWT/ABJ

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