Area Forecast Discussion
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FXAK67 PAJK 031314
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
514 AM AKDT SUN MAY 3 2015

.SHORT TERM...ONCE AGAIN FOG IS A PROBLEM IN JUST A FEW LOCATIONS
OVERNIGHT...LESS CLOUDINESS IN PLACE HAS FAVORED THIS SCENARIO
BUT A DRIER BOUNDARY LAYER HAS WON OUT IN MOST LOCATIONS. ONLY
ANGOON, YAKUTAT, AND PETERSBURG HAVE EXPERIENCED ANY REPORTABLE
FOG DESPITE MOST AREAS COOLING DOWN TO THE 30-35 DEGREE RANGE WITH
NO WIND TO SPEAK OF. MOST OF THESE REPORTS HAVE BEEN VCFG AND NOT
BELOW MINIMUMS. DO NOT ANTICIPATE ANY MAJOR CHANGE THIS MORNING.

MAIN CHALLENGES FOR LATER TODAY/TONIGHT ARE THE EAST-MOVING BIG
LOW SPINNING WELL SOUTHWEST OF THE AREA...PRIMARY IMPACT WILL BE
INCREASING UPPER CLOUDS OVER THE FAR SOUTH ALONG WITH SOME ROUGH
SEAS OVER ZONES 41/42. EVEN BUOYS 46085 AND 46184 ARE ONLY GUSTING
TO 20KT OUT OF THE EAST CURRENTLY AS MAIN ENERGY WITH THE LOW IS
WAY SOUTH. NOW APPEARS PRECIP WILL BE ALL SOUTH OF THE FORECAST
AREA. AS THE LOW MOVES SLOWLY EASTWARD A CONTINENTAL AIR MASS
SPREADS INTO THE NORTHERN HALF OF THE PANHANDLE TONIGHT WITH SOME
INCREASE IN NORTHEASTERLY OFFSHORE WINDS. THIS WILL INDUCE FURTHER
DRYING IN THE NORTH AND THUS ONLY RETAINED PATCHY FOG OVER THE
CENTRAL PANHANDLE. MEANWHILE SOUTHERN SECTIONS SHOULD SEE SOME EAST WINDS
AND MORE CLOUD COVER THAN TONIGHT IN THE FRINGE AREA OF THE UPPER
LOW. SEA BREEZES WILL BE PRESENT AND STRONGER FOR A FEW HOURS
LATER TODAY IN THE FAVORED LOCATIONS OVER THE NORTH AS SURFACE
HEATING WILL WARM TEMPS INTO THE MIDDLE/UPPER 50S. CROSS SOUND
SHOULD SEE A LARGER INCREASE IN DIURNAL NORTHWESTERLY FLOW TO 20KT
FROM ABOUT 21Z THROUGH 03Z BUT OPTED TO KEEP IT UNDER SCA- LEVEL
WINDS. VERY LITTLE THREAT (IF ANY) OF CONVECTIVE SHOWERS THROUGHOUT THE
PANHANDLE IS PRESENT TODAY AS ATMOSPHERE HAS STABILIZED AND DRYING
TREND IS IN FULL FORCE ALONG WITH SUBSIDENCE NORTH OF THE
DEFORMATION ZONE ALOFT OVER THE SOUTHERN PANHANDLE ASSOCIATED
WITH THE CLOSED LOW TO THE SOUTH. ALSO WITH THE HIGH MOVING IN
FROM THE NORTH, LOW- LEVEL PRESSURE GRADIENT FROM SKAGWAY TO
JUNEAU INCREASES ON THE MODELS TO MORE THAN 4MB BY LATE TONIGHT
AND THUS HAVE INCREASED WINDS TO 25KT IN NORTHERN LYNN CANAL AND
BACK UP TO 20KT AT CROSS SOUND WITH THE CHANGE IN DIRECTION TO
NORTHEASTERLY AS THE NIGHT PROGRESSES.

REFRESHED GRIDS WITH EC/NAM/INHERITED COMBO THROUGH THE PERIOD WITH JUST
A FEW TWEAKS REQUIRED.

.LONG TERM...EXTENDED RANGE FORECAST BEGINS WITH THE LOW DISCUSSED
ABOVE UNDERCUTTING THE PANHANDLE AND AN INVERTED TROUGH SETTING UP
ALONG THE OUTER COAST. SCATTERED SHOWER ACTIVITY WILL WRAP AROUND
THE LOW AND APPROACH THE SOUTHERN PANHANDLE FROM THE EAST ON
MONDAY, BUT WILL CLEAR OUT BY TUESDAY MORNING. WEAK OFFSHORE FLOW
WILL REMAIN COURTESY OF THE INVERTED TROUGH AND MOSTLY SUNNY SKIES
THAT WILL PREVAIL OVER THE NORTHERN HALF OF THE PANHANDLE ON
MONDAY WILL EXTEND TO THE SOUTHERN HALF BY TUESDAY. A HIGH
AMPLITUDE SURFACE RIDGE OVER THE CENTRAL GULF WILL BEGIN TO SHIFT
TO THE EAST ON TUESDAY AND DISPLACE THE INVERTED TROUGH. NORTHWEST
SURFACE FLOW WILL ALLOW CLOUD COVER TO BUILD BACK IN OVER THE
EASTERN GULF AND PANHANDLE ON WEDNESDAY, BUT DAYTIME HIGHS ARE
EXPECTED TO REMAIN SIMILAR TO THOSE ON TUESDAY DUE TO WARMER THAN
NORMAL H850 TEMPS. OVERNIGHT LOWS BEGINNING TUESDAY NIGHT WILL BE
ON THE RISE, HOWEVER, DUE TO THE INCREASING CLOUD COVER AND
NOCTURNAL BACK RADIATION. DAYTIME HIGH FOR THE SECOND HALF OF THE
WEEK WILL BE A FEW DEGREES COOLER, THOUGH.

THE NEXT FRONT PROJECTED TO IMPACT SOUTHEAST ALASKA IS NOT
EXPECTED UNTIL LATE THURSDAY NIGHT OR FRIDAY. MODELS STILL NOT IN
VERY GOOD AGREEMENT ON THIS AND POP GRIDS REFLECT THIS. THERE IS,
HOWEVER, FAIRLY GOOD AGREEMENT ON SOME SIGNIFICANT LOW LEVEL WARM
AIR ADVECTION ASSOCIATED WITH THIS SYSTEM AND TEMPERATURES LOOK
LIKE THEY WILL BE ON THE RISE AGAIN NEXT WEEKEND, EVEN THOUGH WET
WEATHER IS BECOMING MORE LIKELY.

PREVIOUS LONG RANGE FORECAST REMAINS ON TRACK, SO LITTLE IN THE
WAY OF CHANGES TONIGHT. OVERALL FORECAST CONFIDENCE IS AVERAGE TO
ABOVE AVERAGE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ041-042.

&&

$$

WESLEY/FRITSCH

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






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