Area Forecast Discussion
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FXAK67 PAJK 021443
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
643 AM AKDT WED SEP 2 2015

.SHORT TERM...UPPER TROF AXIS WILL BE E OF THE AREA WITH UPPER
RIDGE AXIS OVER THE CENTRAL GULF THRU TONIGHT. A SHORTWAVE TROF
OVER FAR NW BC WILL MOVE S ACROSS SRN SE AK THIS AFTERNOON AND
EVENING. A HIGH PRESSURE RIDGE WILL REMAIN OVER THE SRN YUKON
THRU TONIGHT. SFC TROF OVER THE SRN PANHANDLE WILL WEAKEN
GRADUALLY TONIGHT. PREFERRED BLEND OF THE GFS20/ECMWF/NAM FOR
PRESSURES/WINDS...BUT OTHER THAN SOME TWEAKS TO WINDS OVER MAINLY
THE INNER CHANNELS DID NOT CHANGE PRESSURES OR WINDS AS THEY
LOOKED GOOD COMPARED TO THAT MODEL BLEND.

MAIN FORECAST CONCERNS WILL BE WIND...TEMPS...AND PRECIP
POTENTIAL. RIGHT NOW STRONGEST WINDS ARE OVER THE NRN HALF OF THE
INNER CHANNELS WITH SCA LEVEL NLY WINDS. MODELS SUGGEST THERE MAY
BE A BIT OF A DECREASE IN WIND THIS AFTERNOON DUE TO DIURNALLY
DRIVEN LOCAL EFFECTS BUT STILL EXPECT SCA LEVEL WINDS TO REMAIN IN
MUCH OF LYNN CANAL AND PARTS OF THE CENTRAL INNER CHANNELS. WINDS
SHOULD COME BACK UP A BIT TONIGHT OVER THE NRN AND CENTRAL AREAS.
GUSTINESS WILL INCREASE DURING THE DAY AS BOUNDARY LAYER BECOMES
WILL MIXED AND SOME WIND MIXES DOWN FROM ALOFT. THIS SHOULD
DIMINISH TONIGHT AS LOWER LEVELS COOL.

WITH THE WELL MIXED ENVIRONMENT AND DECENT AMOUNT OF SUNSHINE FOR
MOST AREAS THIS AFTERNOON...TEMPS SHOULD BE ABLE TO GET INTO THE
60S IN MOST PLACES. THE FAR SERN AREA WILL HAVE MORE CLOUDS THOUGH
AND SOME PRECIP IS POSSIBLE THERE...SO THEY MAY END UP DROPPING
BACK INTO THE 50S AFTER ANY SHOWERS DO DEVELOP.

AS FOR PRECIP POTENTIAL...THE SERN AREA AROUND HYDER WILL HAVE
BEST THREAT AS SHORTWAVE DROPS SWD INTO THE SRN PANHANDLE THIS
AFTERNOON. MODELS SUGGEST ENOUGH INSTABILITY FOR SOME TSTMS TO
DEVELOP AROUND THE HYDER AREA THIS AFTERNOON AND CONTINUE INTO THE
EVENING...BEFORE COMBINATION OF DIURNAL COOLING AND SHORTWAVE
MOVING OUT OF THE AREA DIMINISHES THE TSTM THREAT. WENT WITH
SCATTERED SHOWER COVERAGE FOR THE HYDER AREA THIS AFTERNOON AND
EVENING...DIMINISHING TO ISOLATED OVERNIGHT AS SHORTWAVE MOVES
OUT. THERE MAY BE A FEW SHOWERS AROUND WHITE PASS EARLY THIS
MORNING AS TAIL END OF SHORTWAVE BRUSHES PAST THEM.

.LONG TERM...THERE IS STILL A LOT OF MODEL DISAGREEMENT FROM
FRIDAY THROUGH THE WEEKEND INTO NEXT WEEK. A PIECE OF ENERGY WILL
MOVE OUT OF THE BERING AND INTO THE GULF OF ALASKA BY FRIDAY. THIS
FEATURE WILL TAP INTO SOME SUBTROPICAL MOISTURE AND SEND A FRONT
OVER THE GULF AND PANHANDLE FROM FRIDAY THROUGH SATURDAY. THE
EC/GEM STRENGTHENS A SOUTHERN STREAM AND DEVELOPS A LOW OVER THE
SE GULF FRIDAY NIGHT INTO SATURDAY. THE GFS/NAM DEVELOP A LOW BUT
IT IS FURTHER NORTH IN THE GULF AND A BIT FASTER...MOVING OVER THE
FORECAST AREA FRIDAY AFTERNOON THROUGH SATURDAY MORNING.

SO WITH THAT SAID A FRONT WILL MOVE INTO THE EASTERN GULF BUT THE
DETAILS ARE FUZZY AT THIS TIME. INCREASED THE WINDS OVER THE
NORTH AND EAST GULF TO MIN SMALL CRAFT FOR THE FRONT BUT DID NOT
CHANGE MUCH OVER THE INNER CHANNELS DUE TO THE ISSUES WITH THE LOW
PLACEMENT/DEVELOPMENT. INCREASED POPS AND CLOUD COVER FOR THURSDAY
NIGHT OVER THE NORTHERN GULF AND THEN OVER THE INNER CHANNELS ON
FRIDAY. THERE IS POTENTIAL FOR HEAVY RAIN WITH THE FRONT TAPPING
INTO SUBTROPICAL MOISTURE SO RIVERS WILL BE NEEDED TO KEEP AN EYE
ON.

BEFORE THIS FRONT MOVES ACROSS THE GULF THE NORTHWEST OFFSHORE FLOW
ALOFT WILL KEEP THE AREA DRY AND SUNNY. CLOUDS WILL BE INCREASING
FROM THE WEST THROUGH THE DAY AS THE FLOW BECOMES MORE ONSHORE. THE
NORTHERN GULF COAST AREA WILL BE OVERCAST BY THURSDAY AFTERNOON
WITH THE CLOUDS MOVING OVER THE REST OF THE PANHANDLE THURSDAY
NIGHT. WINDS WILL BE ON THE LIGHT SIDE AS THE NORTHERLY PRESSURE
GRADIENT WILL BE WEAKENING AND THE COMING AROUND TO THE SOUTH. THE
AREAS THAT WILL SEE THE MOST WIND AS THIS FRONT/LOW MOVES INTO THE
GULF WILL BE E/W CHANNELS AS THE N/S CHANNELS WILL BE NOT THAT
STRONG DUE TO PARALLEL PRESSURE GRADIENT TO THE CHANNELS.

THERE MIGHT BE A BREAK IN THE RAIN ON SATURDAY WITH THE LOW
SLIDING SE THROUGH THE DAY AND THE CHANCES OF SHOWERS MAY DECREASE
FROM NORTH TO SOUTH. THE NORTHERN AREAS WILL HAVE THE BEST CHANCE
TO SEE DRIER CONDITIONS BUT THE SOUTHERN AREAS LOOK TO STAY WET
WITH CLOSER PROXIMITY TO THE LOW MOVING SOUTH. THE LARGE
DIFFERENCES BEGIN TO POP UP AGAIN ON SUNDAY INTO EARLY NEXT WEEK.
THE LONG TERM MODELS AND ENSEMBLES ARE INDICATING THAT A HURRICANE
NOW NEAR HAWAII WILL GET PICKED UP THE WESTERLY FLOW AND MOVE INTO
THE GULF TUESDAY. IF THIS TROPICAL MOISTURE DOES GET WRAPPED UP
AND MOVES INTO THE GULF THIS WILL PRODUCE HEAVY RAIN WITH POSSIBLE
HYDRO ISSUES.

THERE IS A LOT OF TROPICAL CYCLONE ACTIVITY IN THE CENTRAL
PACIFIC RIGHT NOW WHICH COULD BE THE REASON FOR THE MODEL ISSUES.
SO AT THIS TIME THERE IS LOW FORECASTER CONFIDENCE IN THE FORECAST
FROM FRIDAY INTO NEXT WEEK.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-013-031-051.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ041.

&&

$$

RWT/ABJ

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