Area Forecast Discussion
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FXAK67 PAJK 011331
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
525 AM AKDT TUE SEP 1 2015

.SHORT TERM...LOW PRESSURE NEAR DIXON ENTRANCE IS STILL CAUSING
SHOWERS OVER THE SOUTHERN PANHANDLE THIS MORNING...BUT THEY ARE
DIMINISHING A LITTLE SOONER THAN EXPECTED FOR THE REST OF THE
AREA. FLOW HAS TURNED OFFSHORE ON THE BACKSIDE OF THE LOW...HELPING
TO DECREASE SHOWERS AND CLOUDS DUE TO DOWNSLOPING/SHADOWING
EFFECTS. CONVECTION IS STILL A POSSIBILITY NEAR THE LOW CENTER
THIS MORNING...BUT THE FEW LIGHTNING STRIKES DETECTED OVERNIGHT WERE
SOUTH OF OUR AREA. SOME OF THE SHOWERS WILL STILL BE HEAVY AT TIMES
EARLY ON.

THE PRESSURE GRADIENT BETWEEN HIGH PRESSURE IN THE YUKON AND THE
LOW TO THE SOUTH INCREASED OVERNIGHT AND NORTH WINDS AT ELDRED
ROCK SPIKED UP TO +30KT. N-NW INTERIOR PASSES/CHANNELS WILL SEE
THE STRONGEST WINDS TODAY WITH MANY MARINE AREAS REACHING SMALL
CRAFT LEVEL. HOWEVER NELY PASSES ARE A LITTLE LIGHTER THIS
MORNING...FOR EXAMPLE LYNN CANAL WINDS ARE BLOWING OUT OF THE
CHILKAT VALLEY INSTEAD OF TAIYA INLET/SKAGWAY. A FEW PLACES OVER
THE CENTRAL PANHANDLE HAVE HAD SOME FOG THIS MORNING...BUT THE
NORTH WINDS ARE BRINGING IN DRYER AIR AND SHOULD HELP TO SCOUR
OUT ANY REMAINING SHOWERS/FOG FAIRLY EARLY ON.

MODELS WERE IN GOOD AGREEMENT WITH THE NORTHERLY PRESSURE GRADIENT
AND DIMINISHING POPS. USED MAINLY THE ECMWF AND GEM TO INCREASE
THE PRESSURE GRADIENT SLIGHTLY THEN ADJUSTED SPEEDS UPWARD A BIT
MORE THROUGH N-S INNER CHANNELS. INCREASED THE DIURNAL TEMPERATURE
RANGE BETWEEN MAX/MIN FOR EXPECTED FEWER CLOUDS...WITH SEVERAL
LOCATIONS FALLING BELOW 40F EARLY WEDNESDAY MORNING. FORECAST
CONFIDENCE IS ABOVE AVERAGE.

.LONG TERM...UPPER TROF WILL DRIFT E AWAY FROM THE AREA FOR WED-
THU. UPPER RIDGE WILL DRIFT EWD ACROSS THE GULF BUT SLOWLY FLATTEN
WED-THU. A SHORTWAVE TROF WILL DROP SWD ACROSS THE SRN PANHANDLE
WED-WED NIGHT. A COMPLEX SYSTEM WILL MOVE INTO THE GULF FOR LATE
THU INTO THE WEEKEND. USED A BLEND OF THE 00Z GFS20 WITH ECMWF FOR
WED-WED NIGHT...THEN BLENDED ECMWF WITH PREVIOUS FORECAST FOR THU.
REST OF THE PERIOD WAS MOSTLY LEFT AS IS EXCEPT DID CONTINUE
UPWARD TREND IN POPS FOR THE WEEKEND.

FOR WED-THU...MOST OF THE AREA WILL SEE PLENTY OF SUNSHINE UNDER A
DEEP LAYER NLY FLOW. THE SRN AREA WILL LIKELY SEE MORE CLOUDS WED
AFTERNOON AND NIGHT AS SHORTWAVE MOVES THRU THAT AREA...AND SOME
SHOWERS ARE POSSIBLE ESPECIALLY IN THE HYDER AREA. WITH MOST AREAS
SEEING DECENT AMOUNT OF SUNSHINE/CLEAR CONDITIONS...HAVE INCREASED
DIURNAL TEMP RANGES A BIT FOR MOST OF THE AREA...WITH MAX TEMPS
BOOSTED A FEW DEGREES IN MANY AREAS...WHILE THE NORMALLY COLDER
AREAS HAD MIN TEMPS LOWERED SOME FOR WED NIGHT. LIMITING FACTOR IN
THE NIGHTTIME TEMPS WILL BE WIND...WITH MAINLY THE NRN AND CENTRAL
AREAS SEEING DECENT NLY FLOW. STRONGEST WINDS WILL BE AROUND LYNN
CANAL WITH SCA LEVEL WINDS EXPECTED WED AND WED NIGHT...BUT THOSE
WILL DIMINISH THU.

FOR FRI INTO THE WEEKEND...LOOKING MORE LIKELY THAT RAIN WILL
MOVE BACK INTO THE AREA. MODELS STILL DIFFER ON DETAILS OF SYSTEMS
MOVING INTO THE AREA...BUT GENERALLY AGREE THAT PRECIP WILL MOVE
INTO THE AREA SOMETIME FRI-SAT. HAVE BOOSTED POPS TO LIKELY FOR
MAINLY THE WEEKEND TIME FRAME...AND IF LATEST MODEL TRENDS
HOLD...FRI MAY NEED HIGHER POPS AS WELL.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-013-022-031-032-041-042.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ043.

&&

$$

FERRIN/RWT

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