Area Forecast Discussion
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FXAK67 PAJK 302315
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
315 PM AKDT TUE SEP 30 2014

.SHORT TERM...THIS MORNINGS UPPER LEVEL LOW FROM THE NORTHEAST
GULF OF ALASKA CONTINUES TO JUMP MOST OF THE ENERGY IN TO
NORTHWEST BRITISH COLUMBIA. THERE REMAINS SOME ACTIVE HEAVIER
SHOWERS MOVING ACROSS THE NORTHERN PANHANDLE AND TOWARD BRITISH
COLUMBIA. SOME OF THESE HEAVIER SHOWERS THROUGH THE LATE AFTERNOON
HAVE BEEN SPARKING A FEW STRIKES OF LIGHTNING. DO NOT THINK THAT
THEY WILL CONTINUE MUCH MORE INTO THE EVENING.  SOUTHERN PANHANDLE
GETTING SOME ISOLATED SHOWERS THIS EVENING BUT MAJORITY AREA WAS
COVERED WITH LOWER CLOUD LEVELS.

THE REMAINS OF THE LOW WILL BE A TROUGH LYING ACROSS THE PANHANDLE
JUST SOUTH OF ICY STRAIT THIS EVENING THAT WILL BE MOVING SLOWLY
SOUTHWARD ACROSS THE PANHANDLE AND IS EXPECTED TO DISSIPATE NEAR
DIXON ENTRANCE WEDNESDAY. HIGH PRESSURE IS BUILDING OVER THE
ALASKAN INTERIOR AND YUKON TERRITORY. THIS IS EXPECTED TO INCREASE
THE NORTH GRADIENT AND OUTFLOW TONIGHT AND WEDNESDAY ACROSS THE
NORTH. THE COOLER AND DRIER HAS BEEN TRYING TO FILTER IN ALL DAY
ACROSS THE NORTH AND AS THE SHOWERS TAPER OFF AND END OVERNIGHT
LOOK FOR CLEARING TO START AND MOVE SOUTH AS WELL.

GALES FOR THE OFFSHORE WATERS AND TWO OF THE COASTAL ZONES TO
TAPER OFF TONIGHT WITH SMALL CRAFT WINDS AND SEAS FOR THE OUTER
WATER THROUGH MUCH OF WEDNESDAY. LYNN CANAL TO BE SMALL CRAFT FOR
WINDS TONIGHT AND WEDNESDAY FOR THE NORTH WINDS.

.LONG TERM...START OF THE LONG TERM WILL FEATURE A DRY CONTINENTAL
AIRMASS OVER SERN AK SUPPORTIVE OF A LARGE DIURNAL TEMPERATURE
SWING AS WED NIGHT TEMPERATURES IN THE 30S /POSSIBLY MID 20S INVOF
YAKUTAT/ WARM INTO THE UPPER 40S TO LOW 50S BY THU AFTERNOON.
ATTENTION QUICKLY TURNS TO AN UPPER TROUGH AND ASSOCIATED SURFACE
CYCLONE ENTERING THE GULF THU AFTERNOON AND NIGHT. A FRONTAL
BOUNDARY IS FORECAST TO ENTER THE SERN GULF AND FAR SRN PORTIONS
OF THE PANHANDLE THU NIGHT. STRONG WAA AND ISENTROPIC UPGLIDE WILL
DEVELOP ALONG AND N OF THE FRONT RESULTING IN THE DEVELOPMENT OF
RAIN QUICKLY SPREADING FROM SRN AREAS INTO CNTRL/NRN AREAS BY 12Z
FRI. BEST COMBINATION OF MOISTURE INFLUX AS WELL AS SYNOPTIC AND
OROGRAPHIC LIFT IS CURRENTLY FORECAST TO BE LOCATED OVER THE SRN
PANHANDLE...AND THUS WILL BE THE MOST PROBABLE LOCATION FOR HEAVY
RAINFALL.

DETERMINISTIC MODEL SOLUTIONS CONTINUE TO SHOW SUBSTANTIAL
VARIABILITY WITH THE EVOLUTION OF THE LOW OVER THE GULF. THE
ECMWF PRODUCES MULTIPLE LOW CENTERS...WHILE THE GFS AND GEM ARE
MORE CONSOLIDATED. THE GEM APPEARED TO BE A GOOD MIDDLE
GROUND...THUS USED THAT MODEL FOR A REFRESH OF PRESSURE FRI INTO
SAT MORNING BEFORE TRANSITIONING TO WPC GUIDANCE. DESPITE
DIFFERENCES IN SMALLER SCALE EVOLUTIONARY DETAILS...ALL GUIDANCE
IS IN AGREEMENT WITH THE DEVELOPMENT OF WIDESPREAD SMALL CRAFT AND
GALE FORCE WINDS FOR BOTH THE INNER CHANNELS AND OUTSIDE WATERS
THU THROUGH FRI. BORDERLINE STORM FORCE WINDS WILL BE POSSIBLE
OVER MARINE ZONES 41...42...43...AND 310 AS A 50-70 KT ELY LOW-
LEVEL JET LIFTS N THU AFTERNOON/NIGHT IMMEDIATELY AHEAD OF THE
FRONT. HIGH END GALE FORCE WINDS ALSO APPEAR PROBABLE OVER CROSS
SOUND.

ELSEWHERE...HIGHER RESOLUTION 12 KM NAM SHOWS 25-35 KT OF CROSS
BARRIER FLOW OVER SALISBURY RIDGE. THIS FLOW COMBINED WITH A LOW-
LEVEL INVERSION AND WIND REVERSAL ALOFT WILL FAVOR GUSTY NELY
WINDS IN DOWNTOWN JUNEAU AND S DOUGLAS THU AFTERNOON AND
NIGHT...WITH WINDS REMAINING ELEVATED AS SYNOPTIC SLYS SPREAD N
INTO THE AREA FRI MORNING. FARTHER S...PREVIOUSLY MENTIONED LLJ
TIED TO THE ADVANCING FRONTAL BOUNDARY WILL POSSIBLY YIELD GUSTS
UP TO 45 MPH OVER LAND ZONE 27 /CRAIG AND KLAWOCK AREA/.

UPPER TROUGH IS FORECAST TO PERSIST OVER THE GULF THROUGH THE
WEEKEND AND INTO EARLY/POSSIBLY MIDDLE OF NEXT WEEK. THIS WILL
LIKELY SUPPORT A PROLONGED PERIOD OF RAINY WEATHER. HOWEVER...DID
NOT ATTEMPT TO ADD A SUBSTANTIAL AMOUNT OF DETAIL TO THE FORECAST
DURING THESE LATER TIME PERIODS DUE TO INDIVIDUAL EPISODES OF RAIN
BEING TIED TO SMALL-SCALE/LOW PREDICTABILITY WAVES MOVING THROUGH
THE LARGE-SCALE TROUGH.

FORECAST CONFIDENCE IS ABOVE AVERAGE WITH REGARD TO WIDESPREAD
MARINE WIND HAZARDS THROUGH FRI. CONFIDENCE IN ONSET AND LOCATION
OF HEAVIEST PRECIPITATION IS AROUND AVERAGE. CONFIDENCE THEN FALLS
BELOW AVERAGE BY THE WEEKEND AND BEYOND.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ042-043-052.
         SMALL CRAFT ADVISORY FOR PKZ012-013-031>033-041-051.

&&

$$

BEZENEK/GARNER

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