Area Forecast Discussion
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FXAK67 PAJK 251322
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
522 AM AKDT SAT APR 25 2015

.SHORT TERM...ONE MORE DAY OF NICE SPRING WEATHER...AND THEN THE
RAIN RETURNS. THE INVERTED TROUGH THAT HAS BEEN SITUATED OVER THE
PANHANDLE FOR THE PAST FEW DAYS IS NOW GONE. SIMILARLY, THE
SURFACE RIDGE THAT WAS LOCATED OVER THE CENTRAL GULF HAS SHIFTED
TO THE SOUTHEAST AND WEAKENED. HIGH PRESSURE OVER THE NORTHWEST
TERRITORIES REMAINS AND A SURFACE RIDGE EXTENDS SOUTHWEST ACROSS
NORTHERN BRITISH COLUMBIA. THIS WILL PROVIDE US WITH ONE LAST DAY
OF MOSTLY SUNNY AND WARM WEATHER FOR WEEKEND OUTDOOR ACTIVITIES.

TO OUR WEST, A LOW IS LOCATED OVER THE WESTERN END OF THE ALASKAN
PENINSULA AS OF EARLY THIS MORNING AND A TRIPLE POINT LOW HAS
FORMED ALONG THE FRONTAL BOUNDARY NEAR 50N/148W. AS THE PARENT LOW
WEAKENS, THE TRIPLE POINT FEATURE WILL ROTATE INTO THE CENTRAL AND
BE LOCATED OVER THE CENTRAL GULF BY SUNDAY MORNING. WIND AND RAIN
ASSOCIATED WITH THE FRONT WILL BEGIN TO AFFECT THE OUTER COAST
LATE SATURDAY NIGHT.

WINDS HAVE ALREADY RE-ORIENTED OUT OF THE SOUTHEAST OVER OFFSHORE
MARINE ZONE 310 AND WILL STEADILY INCREASE THROUGH THE DAY,
REACHING GALE FORCE OVER THE FAR SOUTHERN PORTION BY LATE THIS
AFTERNOON. BY THAT TIME, SOUTHEASTERLIES AT 20 KTS OR SO WILL
EXTEND FROM THE DIXON ENTRANCE ALL THE WAY TO CAPE SUCKLING. SMALL
CRAFT WINDS WILL SPREAD EAST OVER THE COASTAL MARINE ZONES EARLY
THIS EVENING, THEN SPREAD TO CROSS SOUND, ICY STRAIT, SOUTHERN
CHATHAM STRAIT, SUMNER STRAIT, AND CLARENCE STRAIT BY MIDNIGHT. BY
LATE SUNDAY NIGHT, SMALL CRAFT CONDITIONS WILL EXIST OVER ALL THE
INNER CHANNELS EXCEPT NORTH AND SOUTH LYNN CANAL. IN ADDITION, AM
EXPECTING STRONG WINDS ALONG THE SOUTHERN OUTER COAST. THIS SHOULD
BE A SHORT LIVED EVENT, WITH GUST DROPPING DOWN BELOW 40 MPH BY
EARLY SUNDAY MORNING.

MODELS IN VERY GOOD AGREEMENT ON THE TRACK AND INTENSITY OF THE
APPROACHING LOW AND ARE SLIGHTLY SLOWER THAN THE PREVIOUS FORECAST
AT MOVING THE RAIN OVER LAND. OTHERWISE, VERY FEW CHANGES TO THE
INHERITED GRID WITH NO SIGNIFICANT CHANGES TO THE FORECAST.
OVERALL FORECAST CONFIDENCE IS AVERAGE.

.LONG TERM...A STRONG BUT WEAKENING LOW WILL MEANDER OVER THE
S-CENTRAL GULF THRU MON NIGHT...THEN LIFT NE ACROSS THE PANHANDLE
DURING MIDWEEK. OCCLUDED FRONT WILL MOVE N THRU THE AREA SUN.
THERE MAY BE A LOW PRESSURE WAVE THAT DEVELOPS AND MOVES N INTO
THE AREA EARLY IN THE WEEK...BUT MODELS DIFFER ON THIS SOMEWHAT.
MODEL DIFFERENCES GET LARGER AFTER MIDWEEK SO LITTLE CHANGE WAS
MADE TO THE FORECAST FROM THAT TIME ONWARD. MOST OF THE
ADJUSTMENTS TO THE FORECAST WERE TO WINDS OVER THE INNER CHANNELS
SUN-TUE...MAINLY TO WIND DIRECTIONS.

FOR SUN...OCCLUDED FRONT WILL BRING RAIN TO MUCH OF THE AREA. THE
RAIN BAND WILL LIKELY GET NARROWER AS FRONT MOVES NWD THRU THE
AREA BUT EXPECT MOST PLACES TO GET WET. STRONGEST WINDS WITH THE
FRONT WILL BE OVER THE GULF...WITH GALES EXPECTED. MUCH OF THE
INNER CHANNELS WILL SEE 20-30 KT WINDS AS WELL...ALTHOUGH AREAS
WHERE WIND IS NLY WILL BE WEAKER. FRONT WILL LIKELY GO ALOFT AS IT
CROSSES THE NRN AREA LATE IN THE DAY...WHICH WILL RESULT IN A
WEAKER THAN USUAL SLY PUSH BEHIND THE FRONT DUE TO LACK OF STRONG
LOW LEVEL RIDGING BEHIND IT.

FOR SUN NIGHT AND MON...BANDS OF PRECIP WILL CONTINUE TO MOVE NWD
ACROSS THE AREA AS SEVERAL WEAK TROFS MOVE THRU THE AREA. THINK
THAT THE SRN AREA WILL GET THE MOST PRECIP DURING THIS TIME. ONE
CONCERN HERE IS THE LOW PRESSURE WAVE POTENTIAL. THE MODELS THAT
SHOW THE STRONGEST WAVE HAVE MUCH MORE ORGANIZED PRECIP AREA
SPREADING NWD INTO THE PANHANDLE. THE WEAKER MODELS KEEP THIS
FEATURE MORE TO THE S AND MAINTAIN THE BANDS OF PRECIP MOVING IN
WITH THE TROFS. LOW CONFIDENCE ON THIS RIGHT NOW. LATER SHIFTS CAN
ADJUST IF NEEDED IF THE WAVE DEVELOPMENT BECOMES BETTER RESOLVED BY
THE MODELS.

LATER IN THE WEEK...AS LOW SLOWLY WEAKENS AND LIFTS NE ACROSS THE
AREA...WILL SEE MORE PRECIP ESPECIALLY OVER THE SRN 2/3RDS OF THE
AREA. LOOKS LIKE THE SYSTEM WILL MOVE E OF THE AREA BY WED NIGHT
ALTHOUGH MODELS DISAGREE ON THE SPEED OF THIS SOME. FORECAST
CONFIDENCE LOWERS SIGNIFICANTLY FOR LATE WEEK DUE TO MODEL
DIFFERENCES ON THE LARGER SCALE FLOW PATTERN.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND LATE TONIGHT FOR AKZ027.
MARINE...GALE WARNING FOR PKZ041>043.
SMALL CRAFT ADVISORY FOR PKZ011-021-022-031-033>036-051-052.

&&

$$

FRITSCH/RWT

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