Small Craft Advisory 234, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
355 PM AKDT THU MAR 29 2012

.SHORT TERM...THE LATEST SATELLITE IMAGERY SHOW A LOW PRESSURE
SYSTEM LIFTING NORTH OUT OF THE NORTH PACIFIC. THIS LOW WILL
CONTINUE ON ITS NNW TRACK TO BE OVER THE CENTRAL GULF BY FRIDAY
AFTERNOON. THERE IS A FRONTAL BAND LIFTING NORTH THROUGH THE
PANHANDLE ATTM THAT IS PRODUCING SOME VERY STRONG GUSTY WINDS.
THEY DO NOT LAST LONG BUT THEY ARE VERY INTENSIVE. THE BAND IS
MOVING THROUGH THE FAR NORTHERN AREAS AND THE PAHN AND PAGY AREA
WILL SEE GUSTS FROM 35 TO 45 MPH LATE THIS AFTERNOON/EARLY
EVENING FROM THE SOUTH. THE WINDS WILL SLOWLY DIMINISH AND BACK
AROUND TO THE NORTH OR JUST GO LIGHT. THE MARINE WINDS OVER LYNN
CANAL HAVE INCREASED TO MIN GALE/MAX SMALL CRAFT BUT THEY WILL
SLOWLY DECREASE SO WILL START THEM OUT WITH SMALL CRAFTS THIS
EVENING FROM THE SOUTH BEFORE THEY DECREASE AND BACK TO THE
NORTH. THE REST OF THE PANHANDLE ARE SEEING SOUTH WINDS GENERALLY
LESS THAN 20 KT BUT THE SOUTHERN AREAS WILL CONTINUE TO SEE
STRONGER WINDS AS THE BASE OF THE UPPER TROF AND SURFACE LOW
MOVES OVER THEM. GUSTS TO 35MPH AND GALES OVER CLARANCE WILL
PERSIST THIS EVENING BUT AS THE LOW AND PRESSURE GRADIENT WEAKENS
THE WINDS WILL RELAX.

 FOR THE MOST PART THE PANHANDLE IS ON THE DRY SIDE BUT THERE
AREA SHOWERS ROTATING AROUND THE LOW AND OVER THE SOUTHERN HALF
WITH SOME SCATTERED SHOWERS MOVING OVER THE NORTHERN HALF. THESE
SHOWERS WILL PERSIST THROUGH TONIGHT AND MAY SPREAD NORTHWARD AS
THE ENTIRE TROF FEATURE AND UPPER LEVEL DYNAMICS MOVES THROUGH
THE FORECAST AREA. THIS WILL REMAIN TRUE FOR FRIDAY WITH CAT
SHOWERS OVER THE SOUTHERN AREAS AND SCATTERED SHOWERS OVER THE
NORTH WITH SE FLOW A LOFT AND MOST UPPER LEVEL SUPPORT OFFSHORE.

 THE WINDS OVER THE INNER CHANNELS THROUGH FRIDAY WILL INCREASE
FROM THE SOUTH AS A RIDGE OF HIGH PRESSURE BUILDS OVER THE
PANHANDLE. THE WINDS WINDS WILL NOT BE THAT STRONG BUT WILL RANGE
FROM 15 TO 20 KT.

&&

.LONG TERM...SEMI PERMANENT BROAD AREA OF UPPER LEVEL LOW PRESSURE
REMAINS OVER THE GULF THROUGH MUCH OF THE EXTENDED RANGE FORECAST
PERIOD. NUMEROUS SMALL BUT DEEP SURFACE CIRCULATIONS WILL BE DRAWN
INTO THIS AREA AND REPRESENT THE GREATEST UNCERTAINTY IN THE LONG
RANGE FORECAST. SYN OPTICALLY, MODELS IN GOOD AGREEMENT ON THESE
SMALLER SCALE FEATURES BUT DIFFER ON THE DETAILS AND, BECAUSE THEY
ARE NOT TRIVIAL IN TERMS OF THEIR ASSOCIATED WINDS OR
PRECIPITATION FIELDS, MODEL SPREAD ON THESE FEATURES IS GREAT.

BIGGEST DEPARTURE FROM PREVIOUS FORECAST HAS TO DO WITH A LOW AND
ASSOCIATED WINDS EARLY NEXT WEEK. HAVE EAST TO SOUTHEAST GALES IN
THE SOUTHERN COASTAL MARINE ZONES AS WELL AS THE DIXON ENTRANCE
AND SOUTHERN PORTIONS OF CLARENCE STRAIT FOR NEXT MONDAY.
RESULTANT NORTHERLY PRESSURE GRADIENT WILL PRODUCE SMALL CRAFT
NORTHERLY/EASTERLY WINDS OVER MUCH OF THE REMAINING INNER
CHANNELS.

NO BIG CHANGES TO POP WITH THE AFTERNOON FORECAST. MOSTLY CLOUDY
TO CLOUDY WITH A CHANCE OF SHOWERS THROUGH SATURDAY NIGHT. THE
NORTHERN PANHANDLE MAY SEE A BREAK WITH SOME PARTIAL CLEARING ON
SUNDAY, THEN MOSTLY CLOUDY TO CLOUDY WITH A CHANCE OF RAIN BY DAY
AND A CHANCE OF SNOW BY NIGHT.

USED BLENDS OF GFS AND ECMWF THROUGH THE MID PERIOD, TRENDING MORE
TOWARDS HPC FARTHER OUT. FORECAST CONFIDENCE IS AVERAGE.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND FROM 7 PM THIS EVENING TO 1 AM AKDT FRIDAY FOR
     AKZ018.
MARINE...GALE WARNING FOR PKZ036.
         SMALL CRAFT ADVISORY FOR PKZ012-021-022-033>035-041>043-051-052.

&&

ABJ/FRITSCH