National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXAK67 PAJK 212355
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
355 PM AKDT TUE MAY 21 2013

.SHORT TERM...MOSTLY QUIET DAY ACROSS THE AREA AS WE ARE STILL
UNDER THE INFLUENCE OF AN INVERTED TROUGH OVER THE PANHANDLE WITH
A RIDGE OVER THE CENTRAL GULF. THE RESULT IS CLEAR SKIES AND DRY
CONDITIONS FOR MOST AREAS. THE EXCEPTION IS THE HYDER AREA WHICH
IS RECEIVING SOME CLOUDS FROM A UPPER LEVEL LOW THAT IS SLOWLY
PULLING NORTH THROUGH BRITISH COLUMBIA. WINDS ARE THE MAIN
CONCERN TODAY WITH NE TO NW SMALL CRAFTS IN LYNN CANAL, STEPHENS
PASSAGE, THE SOUTHERN OUTSIDE WATERS AND CROSS SOUND.

 FOR TONIGHT INTO TOMORROW, DRY AND MOSTLY CLEAR CONDITIONS WILL
CONTINUE WITH SOME HIGH TO MID LEVEL CLOUDS TRYING TO FORCE THEIR
WAY OVER THE COAST MOUNTAINS. THEY WILL NOT GET FAR AS DOWN
SLOPPING WINDS ON THE WEST SIDE OF THE MOUNTAINS WILL RAPIDLY
CAUSE THE CLOUDS TO DIMINISH.

 DUE TO THE CLEAR SKIES TEMPERATURES ONCE AGAIN WILL DROP
TONIGHT. OVERNIGHT LOWS ARE NOT EXPECTED TO GET AS LOW AS THE
PAST FEW NIGHTS WITH THE COLD UPPER TROUGH THAT HAS BEEN
SUSTAINING IT MOVING OFF TO THE EAST. STILL I THINK TEMPERATURES
WILL GET COLD ENOUGH IN YAKUTAT AND HOONAH TO WARRANT FROST
ADVISORIES FOR THOSE AREAS LATE TONIGHT. TEMPERATURES TOMORROW
WILL REBOUND INTO THE 50S AND 60S FOR DAY TIME HIGHS.

 WINDS WILL CONTINUE TO BLOW ACROSS THE AREA INTO TONIGHT AS THE
NORTHERLY PRESSURE GRADIENT STAYS STRONG. THROUGH THE GRADIENT
WILL BE SOMEWHAT WEAKER THEN IT WAS TODAY. STILL EXPECT SMALL
CRAFT WINDS IN LYNN CANAL TONIGHT AND EARLY TOMORROW. IN THE
EASTERN GULF THE WINDS FROM THE INTERACTION BETWEEN THE INVERTED
TROUGH AND THE GULF HIGH WILL CONTINUE TO PRODUCE 25 KT NW WINDS
INTO TOMORROW.

 FIRE WEATHER. A CALL WAS RECEIVED FROM THE SKAGWAY FIRE
DEPARTMENT STATING THAT THE BURNABLE FUELS IN THE AREA WERE
RATHER DRY. THIS COMBINED WITH THE 20 TO 30 PERCENT HUMIDITY AND
STRONG NE WINDS BLOWING AT SKAGWAY PROMPTED THE ISSUANCE OF A RED
FLAG WARNING FOR THE SKAGWAY FIRE ZONE FOR THIS AFTERNOON AND
EVENING. THE FIRE DANGER WILL LESSEN OVERNIGHT AS WINDS DIE OFF
AND THE HUMIDITY RISES INTO THE 40 TO 50 PERCENT RANGE. THE
HUMIDITY IS EXPECTED TO CREEP BACK DOWN TOMORROW AFTERNOON AS AIR
TEMPERATURES RISE AND THE WINDS ARE FORECAST TO COME BACK UP
THROUGH NOT AS STRONG AS TODAY. FIRE WEATHER CONDITIONS WILL
CONTINUE TO BE MONITORED CLOSELY.

 SHORT RANGE MODELS WERE IN DECENT AGREEMENT TODAY BUT A FEW
DIFFERENCES WERE THERE. THOUGH THAT THE GFS HAD THE AXIS OF THE
INVERTED TROUGH TOO FAR OFFSHORE. DECIDED ON THE NAM FOR UPDATES
TO THE SHORT RANGE FORECAST TODAY. FORECAST CONFIDENCE IS ABOUT
AVERAGE.

.LONG TERM...DRY CONDITIONS AND ABOVE-NORMAL HIGH TEMPERATURES
WILL CONTINUE THROUGH THE START OF THE WEEKEND. CLOUDS AND
PRECIPITATION MAY CREEP BACK INTO THE PANHANDLE BY THE END OF THE
WEEKEND INTO EARLY NEXT WEEK.

 DRY AND CLEAR SKIES WILL CONTINUE INTO THE LONG RANGE FORECAST
PERIOD. AN AREA OF HIGH PRESSURE WILL REMAIN OVER THE GULF OF
ALASKA, WHILE AN INVERTED TROUGH REMAINS ALONG THE COAST MOUNTAIN.
THE COMBINATION OF THESE WEATHER SYSTEMS WILL CONTINUE TO DRIVE
NORTHERLY OFFSHORE FLOW OVER THE PANHANDLE. THROUGH THE END OF THE
WORKWEEK, WIND SPEED SHOULD BE LESS THAN 15 MPH ACROSS THE INSIDE
WATERS AND ADJACENT LAND AREAS.

 WITH CLEAR SKIES AND RELATIVE LIGHT WINDS, DIURNAL TEMPERATURE
RANGE WILL BE LARGE (UP TO 30 DEGREES IN SOME CASES) FOR THE NEXT
FEW DAYS. AS THE UNDERLYING CONTINENTAL POLAR AIRMASS CONTINUE TO
MODERATE, SOUTHEAST ALASKA WILL BE WARMING UP. THE THREAT OF
MORNING FROST SHOULD BE GOING AWAY. THE FORECASTED LOW
TEMPERATURES FOR WEDNESDAY AND THURSDAY NIGHT RANGE FROM 35 TO 45
DEGREES, WITH THE COLDEST CONDITIONS EXPECTED FROM YAKUTAT INTO
HOONAH AND GUSTAVUS AREAS. DAYTIME HIGH TEMPERATURES WILL RISE
INTO THE MID 60S STARTING THURSDAY. THE WARMEST LOCATIONS WILL BE
IN NORTH CENTRAL PANHANDLE, WITH SOME ISOLATED INLAND LOCATIONS SEEING
TEMPERATURES REACHING THE 70 DEGREE MARK. IN AREAS UNDER CLOUD
COVER OR INFLUENCED BY SEA BREEZES, HIGH TEMPERATURES MAY STRUGGLE
TO RISE INTO THE 60S. AFTERNOON SEA BREEZES AROUND 10 MPH ARE
EXPECTED ALONG COASTAL AREAS.

 AREAS ALONG THE COAST AND NEAR THE COAST MOUNTAIN MAY NOT SEE AS
MUCH SUN AS OTHER AREAS ACROSS THE PANHANDLE IN THIS STRETCH OF
DRY WEATHER. MARINE STRATUS ARE EXPECTED TO MOVE TOWARDS THE
COASTAL AREA IN THE LATTER PART OF THIS WEEK. RIGHT NOW, NOT TOO
SURE ABOUT THE AERIAL EXTEND OF THE MARINE STRATUS. CLOUDS AND
SCATTERED RAIN SHOWERS WILL BE CREEPING INTO THE SOUTHEASTERN
PART OF THE PANHANDLE STARTING FRIDAY. THERE ARE ALSO
UNCERTAINTIES ON THE EXTEND OF THE CLOUD COVER AND PRECIPITATION.
THE NORTHERN AND CENTRAL PANHANDLE SHOULD REMAIN MOSTLY CLOUD FREE
THROUGH THE START OF THE WEEKEND. CLOUDS AND PRECIPITATION ARE
EXPECTED RETURN TO SOUTHEAST ALASKA BY THE END OF THE WEEKEND AND
EARLY NEXT WEEK AS ONSHORE FLOW RESUMES.

 AS DISCUSSED IN THE SHORT TERM DISCUSSION ABOVE, FIRE WEATHER
CONDITIONS IN SKAGWAY ARE OF CONCERNED. HIGH TEMPERATURES THERE
ARE EXPECTED TO BE IN THE LOW TO MID 60S THROUGH EARLY NEXT WEEK.
AFTERNOON RH VALUE WILL BE AS LOW AS 40 PERCENT OR LOWER. WITH
AFTERNOON SEA BREEZES DEVELOPING, THE WIND SPEED MAY BE AS HIGH AS
15 TO 20 MPH IN THE AFTERNOON. NO PRECIPITATION IS EXPECTED, SO
FUEL CONDITIONS WILL CONTINUE TO BECOME DRIER. COMBINING THE
FACTORS OF LOW RH, WIND SPEED TO 20 MPH, AND DRY FUEL CONDITIONS,
FIRE DANGER WILL BE ELEVATED.

 FORECAST CONFIDENCE IS ABOVE AVERAGE THROUGH SATURDAY, THEN
DECREASES TO AVERAGE AFTERWARDS. FAIRLY CONFIDENT ON THE DRY
CONDITIONS OVER MOST OF THE PANHANDLE THIS WEEK. THERE ARE
UNCERTAINTIES IN HOW MUCH CLOUDS AND PRECIPITATION WILL SPILL OVER
FROM THE EASTERN SIDE OF THE COAST MOUNTAIN INTO HYDER AND
KETCHIKAN AREA IN THE LATTER PART OF THE WORK WEEK. ALSO UNCERTAIN
ON HOW WIDESPREAD THE MARINE LAYER WILL SPREAD INTO THE COASTAL
AREAS. UTILIZES NUMERICAL GUIDANCE FROM ECMWF AND WPC TO REFRESH
THE PREVIOUS FORECAST PACKAGE.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...FROST ADVISORY FROM 1 AM TO 7 AM AKDT WEDNESDAY FOR AKZ017-021.
         RED FLAG WARNING UNTIL MIDNIGHT AKDT TONIGHT FOR AKZ018.
MARINE...GALE WARNING FOR PKZ012.
         SMALL CRAFT ADVISORY FOR PKZ011-013-021-022-031>034-041>043.

&&

$$

EAL/RCL