Area Forecast Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
000
FXAK67 PAJK 292339
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
339 PM AKDT MON JUN 29 2015

.SHORT TERM...THE LIGHT RAIN THAT WE CALLED FOR YESTERDAY
AFTERNOON WAS BOTH HEAVIER AND MORE EXPANSIVE THAN WE THOUGHT. FOR
THE QPF WHICH TURNED OUT TO BE THE SURPRISE OF THE DAY, THE GFS
BEAT THE ECWMF, THE NAM, AND NAM`S HIGH RES CHILDREN, NMM AND ARW
WHO CALLED FOR MUCH LESS RAINFALL. THE GFS ALSO BEAT THE GEM, WHO
CALLED FOR A LITTLE TOO MUCH. AS THE GFS SEVERAL DAYS AGO TOOK THE
LEAD WITH THE CURRENT SHORTWAVE OVER THE PANHANDLE BY CALLING OUR
ATTENTION TO IT WHEN ALL OTHER MODELS WERE INDICATING A MERE KINK
IN THE FLOW OVER THE NORTH PACIFIC...IT DESERVES PRAISE. RAINFALL
AMOUNTS ORIGINALLY PREDICTED TO BE LIMITED TO A HALF-INCH OR LESS
AROUND THE PANHANDLE REACHED NEARLY 1 INCH FOR JUNEAU WITH
ANYWHERE BETWEEN A QUARTER TO A HALF-INCH FOR
SITKA...PETERSBURG...WRANGELL...AND KLAWOCK WITH MUCH LIGHTER
AMOUNTS OVER LYNN CANAL, GUSTAVUS, AND KETCHIKAN.

THE SHORTWAVE ALOFT BROUGHT IN SOME TERRIFICALLY MOIST AIR OVER
SOUTHEAST. DEWPOINTS THIS AFTERNOON OVER THE SOUTHERN PANHANDLE
HAVE SURPASSED 60 DEGREES AND ARE VERY NEAR 55 FOR THE NORTH
CONTRIBUTING TO A VERY MUGGY FEELING. THIS LOW LEVEL MOISTURE MAY
BRIEFLY RIPEN INSTABILITY LATE THIS AFTERNOON AND THIS EVENING,
BUT AS A RIDGE BUILDS FROM THE EAST THIS MOISTURE WILL BE
INCREASINGLY CAPPED SO WE ARE NOT TOO CONCERNED.

AS ONE WAVE EXITS THIS AFTERNOON INTO CANADA...RAIN WILL QUICKLY
DIMINISH FOR COMMUNITIES AGAINST THE COAST MOUNTAINS WHERE THE
RAIN IS MAINLY FALLING CURRENTLY. A WEAK FRONT WILL APPROACH THE
NORTHEAST GULF THROUGH TUESDAY AND WILL BRING A GREATER
LIKELIHOOD OF RAIN FOR YAKUTAT STARTING TUESDAY MORNING. FOR THE
NORTHERN PANHANDLE RAIN CHANCES WILL DECREASE OVERNIGHT BUT WILL
ONCE AGAIN RISE TOWARD AFTERNOON AS THE WEAK FRONT APPROACHES FROM
THE SOUTHWEST. THE SOUTHERN PANHANDLE MEANWHILE WILL RECEIVE LESS
EFFECTS FROM THE WEAK SYSTEM PASSING ONSHORE TO THE NORTHWEST,
THUS MORE CONFIDENT THE WEATHER WILL BE DRIER FROM SUMNER STRAIT
SOUTH FOR TUESDAY.

WHEREAS WE ARE CALLING SKIES MOSTLY CLOUDY TONIGHT, THERE COULD BE
SUFFICIENT BREAKS IN THE CLOUDS ASSOCIATED WITH WEAK RIDGING ALOFT
THAT WILL ALLOW PATCHY FOG TO DEVELOP LATE TONIGHT OVER THE
PANHANDLE, ESPECIALLY GIVEN THE RAIN THAT FELL TODAY. SOME OF IT
COULD BE LOCALLY DENSE, BUT WITH SHORT NIGHTTIME HOURS, CONFIDENCE
NEVER GREAT THIS TIME OF YEAR.

EVEN AS THERE SHOULD BE SLIGHTLY COOLER TEMPERATURES ALOFT
TOMORROW...GIVEN LESS RAIN THAN TODAY...TEMPERATURES SHOULD BE
VERY SIMILAR IF NOT SLIGHTLY WARMER THAN TODAY.

USED ELEMENTS OF GFS, ECMWF, ARW, NMM, AND SREF FOR UPDATES.
CONFIDENCE GENERALLY GOOD.

.LONG TERM...THE RIDGE OF HIGH PRESSURE ALONG SOUTHEAST ALASKA
CURVING BACK ALONG THE COAST TO CENTRAL GULF COAST WILL HOLD INTO
EARLY WEDNESDAY HOWEVER DEVELOPING LOW MOVING NORTHEAST OUT OF THE
CENTRAL PACIFIC AND IS EXPECTED TO MOVE INLAND JUST SOUTH OF CAPE
FAIRWEATHER THURSDAY MORNING. AS THE LOW APPROACHES THE COAST
EXPECT TO SEE SMALL CRAFT WINDS OF 25 TO 30 KT IMPACTING THE
COASTAL MARINE ZONES AND MAY ALSO BRING SEVERAL OF THE INNER
CHANNEL UP TO TO CLOSE TO SMALL CRAFT LEVEL SPEEDS FOR THE MARINE
FORECASTS. RAIN WILL SPREAD INLAND WEDNESDAY NIGHT AND TAPER OFF
THROUGH FRIDAY NIGHT INTO VERY EARLY SATURDAY. THE SURFACE RIDGE
WILL BE REBUILDING OVER THE GULF BEHIND THAT LOW MOVING THROUGH
AND STRAIGHTENING TO THE WEEKEND.

THE GENERAL IDEA IN THE LONGER RANGE OF THE MODEL SOLUTIONS
SUGGEST THE RIDGE WILL WILL PERSIST OVER THE EASTERN GULF AND
SOUTHEAST ALASKA. A WEAK TROUGH EXTENDING NORTH FROM SOUTHWEST
BRITISH COLUMBIA TO LIE ALONG THE PANHANDLE OUTER COAST EARLY NEXT
WEEK HAS A POTENTIAL IN THE LONG RANGE THINKING. OVERALL THE
EXTENDED FORECAST SHOULD BE DRY WITH EXCEPTION OF AFTERNOON
SHOWERS FROM SOLAR HEATING DEVELOPING.

THE EARLY PORTION OF THE FORECAST HAD REASONABLE AGREEMENT BETWEEN
THE MODEL RUNS AND USED A BLEND OF EC AND NAM FOR THE WIND FIELD
AND THE RAIN AREAS. AM EXPECTING 1 TO 2 INCHES OF RAIN ACROSS THE
NORTHERN PANHANDLE WITH LOW PASSAGE..WITH SOME HIGHER AMOUNTS IN
THE HIGHER TERRAIN QUITE POSSIBLE. WILL MONITOR THE SITUATION
HOWEVER EXPECT THE STREAMS ACROSS THE REGION TO BE ABLE TO HANDLE
THE INFLUX OF RUNOFF WITH OUT ISSUE.


&&

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

&&

$$

JWA/BEZENEK

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.