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
000
FXAK67 PAJK 211344
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
544 AM AKDT MON APR 21 2014

.SHORT TERM...DEJA VU WITH ANOTHER TROUGH AND ITS ASSOCIATED
BOUNDARY OR FRONT MOVING NORTHWARD FROM THE SOUTHERN INTO THE
CENTRAL AND POSSIBLY THE NORTHERN PANHANDLE. BOUNDARY LAYER WINDS
SEEM TO BE WEAKER WITH THIS ONE BUT THIS DOES NOT MEAN IT DID NOT
STRIKE WITH A PUNCH. LINCOLN ROCK GUSTED TO NEAR HURRICANE FORCE
IN CLARENCE STRAIT, AND THE STRONG WINDS FOR THE SOUTHERN INSIDE
CHANNELS DID VERIFY. HYDABURG SHOWED SOME STRONG WINDS, AS WELL.
SITKA MAY SEE SOME HIGHER GUSTS THIS MORNING AS WELL, BUT THE
TROUGH IS WEAKENING AS IT LIFTS NORTHWEST BACK OUT INTO THE GULF.
SO WE HAVE NO STRONG WIND HEADLINES THIS MORNING...EVEN IN THE
FRONT`S PATH SUCH AS BARANOF ISLAND. NEITHER DID WE EXTEND THE
SOUTHERLIES FARTHER NORTH THAN GLACIER BAY/NORTHERN
CHATHAM/STEPHENS PASSAGE. WE DO NOT THINK THEY WILL BE NEARLY AS
STRONG AS YESTERDAY EITHER.

POP FIELDS WERE DIFFICULT TO READ. I WOULD EXPECT A DIMINISHING
TREND IN THE AFTERNOON AS THE SYSTEM PULLS AWAY FROM THE COAST,
BUT SOME DIVERGENCE IN MID-LEVEL FLOW THIS AFTERNOON WITH EC GOING
A BIT MORE SOUTHEAST THAN GFS/NAM. ALSO...AM CONCERNED ABOUT A
COLD POOL OF AIR MOVING NORTHWARD INTO THE PANHANDLE BEHIND THE
TROUGH. A THUNDERSTORM STRIKE WAS DETECTED IN SOME OF THE
CONVECTION MOVING UP FROM THE SOUTH. WE PLACED A SLIGHT CHANCE OF
THUNDERSTORMS FOR MARINE ZONES 41 AND 42 FOR THIS AFTERNOON AS
THIS AREA LIFTS NORTHWARD. BUT ALSO, KEPT THINGS MOSTLY CLOUDY FOR
MUCH OF THE PANHANDLE...AS ONCE THIS CONVECTION HITS THE
PANHANDLE...THERE MAY BE SOME STRATIFICATION. WHAT DOES THIS MEAN?
I AM SUGGESTING THE POSSIBILITY THAT WE WILL SEE MORE SUN IN THE
MORNING THAN THE AFTERNOON.

THINGS BECOME MORE DIVERGENT TONIGHT. DECIDED ON A DRYING TREND
BUT INTERESTINGLY ECMWF SHOWING AN EASTERLY WAVE PUSHING THROUGH
THE NORTHERN PANHANDLE LATE TONIGHT. GRAND COALITIONS OF MODEL POP
FIELDS DID NOT YIELD A SATISFACTORY RESULT, SO ERRED ON THE SIDE
OF DRYING SINCE EASTERLY WAVES ARE SOMETHING MODELS TYPICALLY
STRUGGLE WITH. BASED ON TEMPERATURES THIS MORNING AND THE
POSSIBILITY OF CLEARER SKIES TONIGHT, FORECASTED TEMPERATURES MAY
BE A LITTLE TOO WARM.

CONFIDENCE IN FORECAST A LITTLE GREY TODAY. WE SHOULD SEE SUN,
BUT PROBABLY NOT MANY SHOWERS, BUT THERE WILL BE SOME. SKY COVER
SHOULD BE FUN TO WATCH. USED A VARIETY OF DIFFERENT MODELS. ECMWF
FOR OVERALL PRESS/WIND. NAM, GFS, GEM, AND ECMWF FOR POP/QPF.

&&

.LONG TERM...THE 00Z/21 SUITE OF MODEL GUIDANCE SHOWED QUITE A BIT
OF VARIABILITY WITH THE EVOLUTION OF A SMALL-SCALE MIDLEVEL SHORTWAVE
TROUGH ADVANCING NNWWD ALONG THE COAST OF SERN AK DURING MIDWEEK.
FOR EXAMPLE...THE 00Z GFS AND UKMET WERE FASTER WITH THE
PROGRESSION OF THIS FEATURE...WHILE THE 00Z ECMWF...GEM...AND NAM
WERE SLOWER. GIVEN THIS VARIABILITY...DID NOT MAKE SUBSTANTIAL
CHANGES TO WINDS...BUT DID BUMP UP POPS AND CLOUDS SLIGHTLY FOR
THE NRN CWA WED AFTERNOON AND NIGHT.

AFTER THIS FEATURE EXITS N OF THE REGION ON FRI...THE LARGE-
SCALE PATTERN WILL BE DOMINATED BY A PROGRESSIVE SERIES OF UPPER
WAVES WITH EMBEDDED IMPULSES. WEAK SURFACE HIGH PRESSURE DURING
MIDWEEK WILL BE REPLACED WITH A SRN GULF CYCLONE BY THE WEEKEND.
SSELY LOW-LEVEL FLOW WILL STRENGTHEN AHEAD OF THIS NEXT AREA OF
LOW PRESSURE...AND FAVOR SEASONABLE TEMPERATURES OVER SE AK.
OTHERWISE...STRONGEST FORCING FOR ASCENT SAT-MON EITHER REMAINS S
OF THE CWA...OR ROTATES NWD OVER THE GULF. THUS...LOW
PRECIPITATION CHANCES WILL MAINLY BE ASSOCIATED WITH MINOR
DISTURBANCES TRAVERSING THE AREA. PREDICTABILITY IS NOT HIGH WITH
THESE FEATURES ATTM...THUS MAINTAINED WPC POP GUIDANCE.

TEMPERATURES/DEWPOINTS/RH WERE REFRESHED WITH A MULTI-MOS
BLEND...CHANGES WERE MINOR. FORECAST CONFIDENCE IS BELOW AVERAGE
FOR POPS/WIND...AND AROUND OR SLIGHTLY ABOVE AVERAGE FOR
TEMPERATURES.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ036.
         SMALL CRAFT ADVISORY FOR PKZ022-033>035-041>043-051-052.

&&

$$

JWA/GARNER





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