Small Craft Advisory 486, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
551 AM AKDT WED AUG 24 2011

.SHORT TERM...SATELLITE IMAGERY IS SHOWING THE REMNANTS OF A LOW
THAT CAME ASHORE LAST NIGHT OVER THE SOUTHERN PANHANDLE NOW WELL
INLAND OVER BRITISH COLUMBIA. STRATIFORM PRECIPITATION NOW GIVING
WAY TO TO MORE INTENSE CONVECTIVE SHOWER ACTIVITY AND RADAR HAS
BEEN PAINTING REFLECTIVITIES OF UP TO 58 DBZ AS OF THE EARLY
MORNING HOURS. VARIOUS LAND AND MARINE OBSERVATIONS HAVE ALSO
REPORTED MODERATE TO HEAVY PRECIPITATION AT TIMES. WIDE SPREAD
SHOWER ACTIVITY IS EXPECTED TO LAST ALL MORNING THEN BEGIN TO
DIMINISH IN AREAL EXTENT THIS AFTERNOON AND THROUGH THE NIGHT.

 WITH LANDFALL AND WEAKENING OF THE LOW, A SOUTHERLY PRESSURE
GRADIENT HAS RE-ESTABLISHED OVER SOUTHEAST ALASKA AND HIGH
PRESSURE WILL BUILD IN OVER THE EASTERN GULF AS WELL AS THE
PANHANDLE THROUGH THE SHORT TERM FORECAST PERIOD. NOT A LOT OF
WIND IN THE FORECAST, BUT DO HAVE A SMALL CRAFT ADVISORY FOR
SOUTHERLY WINDS OVER NORTHERN LYNN CANAL LATER TODAY AND LASTING
INTO THE NIGHT. ELSEWHERE AND OTHERWISE, MARINE WINDS 20 KTS OR
LESS.

 CLOUDY TO MOSTLY CLOUDY CONDITIONS WILL PREVAIL OVER MOST
LOCATIONS TODAY AND TONIGHT, BUT DO EXPECT TO SEE A SOME
SIGNIFICANT CLEARING ALONG THE OUTER COAST THIS AFTERNOON AND
OVERNIGHT.

 USED A BLEND OF UKMET AND ECMWF FOR PRESSURE AND WINDS. BLENDED
GFS, NAM, AND GEM FOR POP. FORECAST CONFIDENCE ABOVE AVERAGE.

.LONG TERM...THE GULF OF ALASKA WILL REMAIN TO BE ACTIVE THROUGH
THE LONG TERM PERIOD WITH THURSDAY BEING THE DRIEST DAY THROUGH
THE FORECAST PERIOD. THE FORECAST MODELS ARE IN GOOD AGREEMENT
WITH JUST SOME MINOR TIMING ISSUES THROUGH OF INDIVIDUAL WEATHER
SYSTEMS THROUGH THE WEEKEND. DID NOT CHANGE THE FORECAST MUCH FROM
THE PREVIOUS PACKAGE DUE TO GOOD MODEL AGREEMENT USED A BLEND OF
THE NAM/EC THROUGH SAT AFTERNOON THEN KEPT THE FORECAST THE SAME
INTO EARLY NEXT WEEK. FORECASTER CONFIDENCE IS ABOUT AVERAGE TO
ABOVE AVERAGE THROUGH SATURDAY.

AT THE START OF THE LONG TERM PERIOD A LOW PRESSURE SYSTEM LIFTING
OUT OF THE NORTH PACIFIC WILL DRIFT NE AND BE OVER THE NORTHERN
GULF BY THURSDAY NIGHT. THIS LOW WILL SEND A WEATHER FRONT ACROSS
THE GULF AND OVER THE PANHANDLE THURSDAY AFTERNOON/NIGHT. THE
RAIN WILL SPREAD OVER THE PAYA AREA BY THURSDAY AFTERNOON THEN
OVER THE REST OF THE PANHANDLE FROM NORTH TO SOUTH THROUGH
THURSDAY NIGHT. BEFORE THAT THE PANHANDLE WILL SEE A DRY DAY
THROUGH THURSDAY AFTERNOON BEFORE THE THREAT OF RAIN INCREASES.
THE WINDS OVER THE NORTHERN GULF WILL INCREASE TO GALES AS THE
FRONT/LOW LIFTS INTO THE NORTHERN GULF WHILE THE REST OF THE GULF
WILL SEE MAX SMALL CRAFT WINDS. THE INNER CHANNELS WILL SEE
LIGHTER WINDS THROUGH THURSDAY BUT AS THE FRONT MOVES OVER THE
AREA WINDS WILL VEER AROUND FROM THE NORTH TO SOUTH AND RANGE FROM
10 TO 25 KT WITH THE STRONGEST WINDS IN THE E/W CHANNELS.

THE UPPER LEVEL TROF ASSOCIATED WITH THE SURFACE LOW OVER THE
NORTHERN GULF WILL WEAKEN AS MOST ENERGY DRIFTS INTO THE INTERIOR
THROUGH FRIDAY. RAIN WILL CONTINUE TO BE LIKELY TO CAT THROUGH
FRIDAY OVER THE NORTHERN AREAS BUT THE SOUTHERN HALF OF THE
FORECAST AREA WILL SEE JUST A CHANCE WILL A BIT MORE ANTI-CYCLONIC
ROTATION. ANOTHER STRONG UPPER LEVEL TROF WILL DIG INTO THE GULF AND
DEVELOP A LOW/WEATHER FRONT OVER THE GULF SAT. THERE IS SOME
TIMING ISSUES WITH WHEN THE FRONT WILL MOVE OVER THE GULF BUT FOR
THE MOST PART THE STEADY RAIN WILL MOVE OVER THE FORECAST AREA
SAT AFTERNOON OVER THE NORTHERN GULF AND THEN OVER THE REST OF SE
AK SAT NIGHT. WINDS OVER THE GULF WILL AGAIN INCREASE TO GALES/MAX
SMALL CRAFT WITH SEAS BUILDING TO 10 FT OR MORE.

FOR THE REST OF THE WEEKEND INTO NEXT WEEK THERE SEEMS TO BE A
TREND OF MORE ZONAL FLOW AND BREAK IN THE VERY ACTIVE WEATHER
PATTERN FOR THE GULF. SO WITH THAT SAID A CHANCE OF RAIN LOOKS
GOOD FOR NEXT WEEK WITH POSSIBLE A FEW DRY DAYS.

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

&&

FRITSCH/ABJ