Small Craft Advisory 425, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
549 AM AKDT SUN JUL 22 2012

.SHORT TERM...1008 MB LOW NEAR KODIAK IS THE PARENT FEATURE FOR
AN OCCLUDED FRONT THAT EXTENDS S FROM THE VICINITY OF CORDOVA  AT
THIS TIME. THIS OCCLUDED FRONT IS PRECEDED BY AN ASSOCIATED BROAD
WARM SECTOR RIDGE THAT EXTENDS FROM THE EAST GULF OF ALASKA TO
OVER A SITKA TO JUNEAU LINE. THIS BROAD RIDGE IN TURN IS THE
SUPPORT FOR SEA STRATUS THAT COVERS MOST OF THE EASTERN GULF. THE
500H RIDGE ALOFT ALSO EXTENDS NE FROM OVER THE EASTERN GULF TO
OVER A SITKA TO JUNEAU LINE. THIS RIDGE ALOFT IS AIDING THE
DISSIPATION OF A WEAK FRONTAL BOUNDARY ALOFT OVER SOUTHERN
SOUTHEAST ALASKA.

 THE STRONGEST WINDS ARE TO BE IN NORTHERN LYNN CANAL THIS
AFTERNOON AND EVENING. CLEAR TO PARTLY CLOUDY CONDITIONS IN
SOUTHERN YUKON TERRITORY WILL PERMIT THERMAL PRESSURE FALLS THIS
AFTERNOON. THIS PRESSURE FALL, WHEN COMBINED WITH THE SURFACE AND
BOUNDARY LAYER RIDGE TO THE SOUTH, WILL RESULT IN A STRONG ENOUGH
PRESSURE GRADIENT TO SUPPORT GALE FORCE WINDS IN NORTHERN LYNN
CANAL THIS AFTERNOON AND EVENING.

.LONG TERM...MODELS SEEM TO BE SLOWLY CONVERGING ON A SOLUTION
FOR THE MIDWEEK TIME FRAME. ECMWF HAS SPED UP THE EASTWARD
MOVEMENT OF THE UPPER TROF ACROSS THE GULF...CLOSER TO THE
GFS/UKMET IDEA ON IT. THAT BEING SAID...ENDED UP LEAVING THE
MIDWEEK PERIOD AS IS IN GRIDS AS FAR AS POPS AND WINDS GO AFTER
COORD WITH WFO PAFC. WANT TO ALLOW MODELS TO CONTINUE TO CLOSE THE
DIFFERENCES ON THIS AND ALLOW LATER SHIFTS MAKE THE ADJUSTMENTS
FOR THIS.

 WHAT WAS ADJUSTED WAS CLOUD COVER AND TEMPS FOR MON-THU. GIVEN
THE SYNOPTIC ENVIRONMENT OF A LOW LEVEL RIDGE OVER THE GULF AND A
VERY STABLE LOWER LEVEL AIRMASS...WANTED TO PUT IN MORE CLOUDS
FOR THE GULF AND A GOOD PART OF THE INNER CHANNELS DUE TO MARINE
LAYER INFLUENCE. LOOKS LIKE THE SERN INNER CHANNELS WILL HAVE THE
LEAST AMOUNT OF CLOUD COVER ESPECIALLY LATER TUE INTO THU WITH
DECENT NW FLOW. THE PAYA AREA MAY SEE A DECENT BREAK WED INTO THU
AS LOWER LEVEL FLOW TURNS MORE NWLY THERE. MAX TEMPS WERE LOWERED
SOME IN AREAS WHERE CLOUD COVER WAS INCREASED ESPECIALLY TUE-THU.
OVERALL...FORECAST CONFIDENCE IS ABOUT AVERAGE EXCEPT FOR PRECIP
POTENTIAL...WHERE CONFIDENCE IS BELOW AVERAGE.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND FOR AKZ018.
MARINE...GALE WARNING FOR PKZ012.

&&

JBT/RWT