Area Forecast Discussion
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FXAK67 PAJK 101513
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
613 AM AKST WED FEB 10 2016

.SHORT TERM...THE COMPLICATED PATTERN CONTINUES. ONE FRONT LIES
STRETCHED ACROSS SOUTHEAST ALASKA FROM THE FAR NORTHERN GULF
SOUTHEAST TO KETCHIKAN. RAIN BANDS HAVE BEEN MODERATE TO HEAVY AT
TIMES FOR THE SOUTHERN INNER CHANNELS BUT AS THE RAIN SPREADS
FARTHER NORTH OFFSHORE FLOW INHIBITS AMOUNTS. DRAINAGE WINDS OUT
OF THE CHILKAT VALLEY HAVE FORMED A COLD AIR WEDGE TO THE NORTH
THAT IS KEEPING PRECIPITATION SNOW IN HAINES. BUT WARMING THIS
AFTERNOON SHOULD HELP ERODE THIS LOCAL COLD AIR DOME THIS
AFTERNOON TO ALLOW A CHANGEOVER TO RAIN NEAR LYNN CANAL. THE
HIGHWAY THOUGH COULD RECEIVE AN INCH TODAY WITH THE POSSIBILITY OF
1 TO 3 INCHES TONIGHT. THE SIMPLE FORECAST OF RAIN TODAY BELIES
SOME COMPLEXITY WHICH WE WILL ATTEMPT TO EXPLAIN. THE FIRST FRONT
WILL LIFT NORTH OF SOUTHEAST ALASKA THIS MORNING. BUT A SECOND
FRONT FOLLOWS QUICKLY ON ITS HEALS TO BRING MORE RAIN FOR THE
SOUTHERN PANHANDLE THIS AFTERNOON AND SPREADING NORTHWARD QUICKLY
INTO THE CENTRAL PANHANDLE BY LATE THIS AFTERNOON. THUS...FOR THE
NORTH WE EXPRESS THE RAIN AS DIMINISHING THIS MORNING...WHILE
PORTIONS OF THE SOUTH LIKE PRINCE OF WALES WE HAVE RAIN
ENDING...THEN REDEVELOPING IN THE AFTERNOON. SO FOR THOSE IN THE
SOUTH, WE EXPECT A BRIEF BREAK IN THE RAIN THIS MORNING WITH MORE
ON THE WAY IN THE AFTERNOON. AND FOR THE NORTH...WE EXPECT A BREAK
AROUND LATE MORNING THROUGH MID-DAY WITH RAIN POSSIBLY
REDEVELOPING IN THE LATE AFTERNOON...WHICH IS WHY WE DID NOT WANT
TO REMOVE IT ENTIRELY DURING THE AFTERNOON.

THE SECOND FRONT WILL HERALD AT LEAST SOME WEAK COOLING ALOFT AND
WILL SUPPORT A CHANGE IN CHARACTER OF THE RAINFALL TO SHOWERS.
MEANWHILE A THIRD DISTURBANCE OR FRONT MAY ACTUALLY SUPPORT A
SLIGHT RISK OF THUNDERSTORMS FOR THE OFFSHORE WATERS AND INCREASE
WINDS TO GALE ALONG THE CENTRAL PANHANDLE COASTLINE LATE TONIGHT.

WIND FORECAST FOR THE INSIDE HAS ESSENTIALLY NOT CHANGED MUCH. WE
INCREASED SOME SOUTHERLIES OVER THE NORTHERN PANHANDLE THIS
AFTERNOON BEHIND THE SECOND FRONT AND SPREAD GALES ALONG THE
OFFSHORE WATERS FARTHER NORTH IN LINE WITH THE GFS/GEM OVER THE
SLOWER NAM/GEM SOLUTION FROM YESTERDAY.

TEMPERATURE ONCE AGAIN PROVIDED SOME HEADACHES. METLAKATLA REACHED
61 DEGREES YESTERDAY. OOPS...WE WERE 9 DEGREES OFF IN YESTERDAY`S
FORECAST. SITKA AND KLAWOCK LOOK TO HAVE BROKEN DAILY RECORDS. WE
DID NOT DEVIATE TEMPERATURES TOO MUCH FROM FORECAST AS THE RAPID
WARM AIR ADVECTION APPEARS TO BE BEHIND US...ALTHOUGH TEMPERATURES
WILL STILL REMAIN VERY MILD TODAY. TEMPERATURES WILL SLOWLY DROP
TONIGHT, ALTHOUGH OTHER THAN THE HIGHWAYS, WE DO NOT EXPECT
TEMPERATURES TO FALL BELOW FREEZING.

USED GFS/GEM FOR GUIDANCE TODAY. FORECAST CONFIDENCE AVERAGE.

.LONG TERM...A VERY LARGE AND NEGATIVELY TILTED UPPER LEVEL TROUGH
SITUATED OVER THE WESTERN GULF WILL DOMINATE THE WEATHER OVER
SOUTHEAST ALASKA AND KEEP THE PANHANDLE WET FOR THE REMAINDER OF
THIS WEEK. THE UPPER LOW WILL BREAK DOWN BY EARLY THIS
WEEKEND...ONLY TO BE REPLACED BY ANOTHER SUCH FEATURE THAT WILL
MOVE IN FROM SOUTH OF THE ALEUTIANS ON SUNDAY. A VIGOROUS SHORT
WAVE IN ADVANCE OF THE SECOND UPPER LEVEL LOW WILL SUPPORT THE
DEVELOPMENT OF A FRONT THAT WILL BEGIN TO AFFECT SOUTHEAST ALASKA
SATURDAY EVENING. MODELS ARE IN FAIRLY GOOD AGREEMENT ON THIS
FRONT BUT THEN DIVERGE ON THE POTENTIAL FOR ANOTHER SHORT WAVE AND
FRONT TO MOVE IN FROM THE GULF ON SUNDAY.

LOW LEVEL TEMPERATURES CONTINUE TO BE WELL ABOVE NORMAL FOR THIS
TIME OF THE YEAR AND THE EXTENDED RANGE FORECAST FEATURES DAYTIME
HIGHS RANGING FROM THE MID 40S TO LOWER 50S THROUGH AT LEAST
SATURDAY. SNOW LEVELS CORRESPONDINGLY HIGH. OVERNIGHT LOWS FOR
SATURDAY NIGHT MAY SUPPORT ACCUMULATING SNOW SATURDAY NIGHT.
OTHERWISE, SNOW WILL BE LIMITED PRIMARILY TO THE FAR NORTHERN
INNER CHANNELS AND THE HYDER AREA OF MISTY FJORDS.

FREQUENT FRONTAL PASSAGES WILL RESULT IN GALES OVER THE COASTAL
MARINE ZONES FOR MUCH OF THE UPCOMING WEEK. ALSO HAVE SOME GALES
FOR PORTIONS OF THE INNER CHANNELS...PARTICULARLY FOR THURSDAY
NIGHT.

USED BLENDS OF NAM, GFS22, THE CANADIAN NH AND ECMWF FOR UPDATES
TO PRESSURE, POP, QPF AND WIND THROUGH SATURDAY NIGHT. TEMPS
UPDATED PRIMARILY WITH GFS MOS. OVERALL FORECAST CONFIDENCE IS
AVERAGE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ041>043-051.
     SMALL CRAFT ADVISORY FOR PKZ012-021-022-033-036-052-053.
&&

$$

JWA/FRITSCH

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