Area Forecast Discussion
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FXAK67 PAJK 032322
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
322 PM AKDT THU SEP 3 2015

.SHORT TERM...EARLY AFTERNOON SATELLITE IMAGERY SHOWS MOSTLY CLEAR
SKIES OVER MOST OF THE PANHANDLE WITH INCREASING HIGH CLOUDS
BEGINNING TO STREAM INTO THE NORTHEAST GULF COASTAL AREA.
MEANWHILE...SURFACE FRONTAL SYSTEM STARTING TO TAKE SHAPE OVER THE
WESTERN GULF IN RESPONSE TO AN AREA OF ASCENT ASSOCIATED WITH AN
UPPER VORT LOBE NEAR KODIAK IS. THIS PIECE OF ENERGY IS FORECAST
TO BEGIN TO FLATTEN OUT THE UPPER RIDGE OVER THE CENTRAL AND
EASTERN GULF THIS EVENING AND ALLOW THE NW FLOW THAT HAS GIVEN SE
AK THE NICE WEATHER OVER THE PAST TWO DAYS TO TAKE MORE OF A
WESTERLY ZONAL COMPONENT.

AT THE SURFACE...A RIDGE OF HIGH PRESSURE OVER THE EASTERN GULF
WILL WEAKEN AND SLIDE EASTWARD INTO BC TONIGHT AS THE FRONTAL
SYSTEM BEGINS TO IMPINGE ON THE COASTAL WATERS FRIDAY MORNING. AS
THIS FRONT PUSHES EASTWARD...MODELS ARE SHOWING A DECENT BARRIER
JET DEVELOPING ALONG THE NE GULF COAST WITH THE NAM AND HIRES
MODELS INDICATING GALES DEVELOPING BY FRIDAY AFTERNOON. THIS WAS
WELL DEPICTED BY THE PREVIOUS SHIFT SO DID NOT MAKE ANY CHANGES TO
THE WINDS ON THE COASTAL WATERS FOR FRIDAY. MAIN CHANGES WERE TO
ADJUST THE WINDS OVER THE NORTHERN AND CENTRAL INNER CHANNELS TO
MORE OF A SELY COMPONENT AND TO INCREASE THE ELY WINDS FRIDAY
AFTERNOON IN ICY STRAIT IN RESPONSE TO THE APPROACHING FRONT AND
TIGHTENING GRADIENT.

12Z MODELS SEEMED TO SLIGHTLY SLOW DOWN THE ADVANCE OF RAIN INLAND
ON FRIDAY AFTERNOON BUT THE FLOW AT 700MB REMAINS OUT OF THE SW
WHICH IS A GOOD INDICATOR OF INCREASING ONSHORE FLOW AND LENDS
CREDENCE TO KEEPING LIKELY POPS FRIDAY AFTERNOON FOR NORTHERN
ZONES WITH CATEGORICAL POPS ALONG THE GULF COAST NORTH OF SITKA.

MADE MINOR ADJUSTMENTS TO TEMPERATURES OVER THE NORTHERN AND
CENTRAL AREAS TO RAISE OVER NIGHT LOWS IN PLACES WITH MORE CLOUD
COVER EXPECTED TONIGHT. ALSO ADDED PATCHY FOG TO THE
KLAWOCK...KETCHIKAN AND HYDER AREAS AS GOOD RADIATIONAL COOLING
EXPECTED AGAIN TONIGHT SIMILAR TO THIS MORNING WHEN THERE WAS SOME
LOCALLY DENSE FOG ON THE WEBCAMS IN THESE AREAS. DEBATED ABOUT
ADDING FOG TO PETERSBURG AND WRANGELL TONIGHT BUT THEY WILL BE ON
THE EDGE OF THE HIGH CLOUD COVER LATER TONIGHT AND NO FOG WAS
REPORTED THIS MORNING.

.LONG TERM...LONG TERM PERIOD REMAINS WET FOR THE WEEKEND AND
BEYOND AS UPPER LEVEL PATTERN STAYS MOSTLY WITH A FLAT, EAST TO
WEST FLOW. EMBEDDED IN THIS WESTERLY FLOW ARE A FEW SHORT WAVES
AS WELL AS THE REMAINS OF FORMER TYPHOON IGNACIO.

FIRST RATHER VIGOROUS SHORT WAVE CROSSES THE PANHANDLE ON SAT
BRINGING MORE RAIN AND SOME WIND TO THE AREA. THERE IS SOME
TROPICAL MOISTURE THAT HAS BEEN ABSORBED BY THE SYSTEM SO SOME
HEAVY RAIN IS EXPECTED AS THE FRONT MOVES THROUGH. AS THE FRONT
WILL NOT BE STICKING AROUND FOR ANY SIGNIFICANT LENGTH OF TIME
TOTAL RAINFALL AMOUNTS WILL ONLY BE AROUND HALF AN INCH TO 1 INCH.
WINDS WILL ALSO NOT BE THAT BAD WITH MOSTLY SMALL CRAFT WINDS IN
THE INNER CHANNELS AND GULF EXPECTED ON SAT.

ONE MORE WEAKER SHORT WAVE IS EXPECTED ON MON INTO TUE WITH MORE
RAIN EXPECTED. AFTER THAT IS THE REMAINS OF FORMER TYPHOON
IGNACIO. LONG RANGE MODELS CONTINUE TO HAVE TROUBLE DECIDING ON
WHERE EXACTLY IT WILL GO RESULTING IN A LOW CONFIDENCE FORECAST.
PREVIOUS RUNS HAVE HAD IT GO UP AS FAR AS THE NORTHERN GULF.
CURRENT RUNS ARE SHOWING MUCH LESS OF A SCATTER EFFECT ON
POSITION AND HAVE MOVED THE SYSTEM MUCH FURTHER SOUTH. THE CURRENT
FORECAST HAS THE REMAINS MOVING ACROSS THE EXTREME SE GULF AND
INTO THE SOUTHERN PANHANDLE OR HAIDA GWAII TUE EVENING.
CONSEQUENTLY THE WIND FORECAST FOR TUE INTO WED HAS CHANGED
PARTICULARLY IN THE GULF WITH SOME PLACES HAVING THE WIND FORECAST
LOWER AND DIRECTION CHANGE BY AROUND 180 DEGREES. THIS ALSO
RESULTS IN A POSSIBLY DRIER FORECAST FOR THE NORTHERN PANHANDLE
DUE TO MORE OFFSHORE FLOW DRYING THE AREA OUT AS MOST OF THE
FORECAST PRECIP IS AIMED AT THE SOUTHERN PANHANDLE. SO POPS HAVE
BEEN LOWERED TO CHANCE FOR THE NORTHERN PANHANDLE FOR THAT TIME
PERIOD.

FORECAST CONFIDENCE REMAINS LOW INTO MID TO LATE NEXT WEEK AS MORE
SHORT WAVES MOVE INTO THE PANHANDLE FROM THE WEST BUT TIMING AND
TRACK ARE STILL UP FOR DEBATE. THE ONLY THING THAT I CAN SAY WITH
SOME CERTAINTY IS THAT NEXT WEEK WILL BE DAMP. DECIDED TO LEAN
MOSTLY ON THE WPC DATA FOR THE EXTENDED RANGE FOR IT`S USE OF
MORE ENSEMBLE DATA IN THE FORECAST.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ051-052.
         SMALL CRAFT ADVISORY FOR PKZ012-022-042-043.

&&

$$

DEL/JWA/EAL

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