Small Craft Advisory 201, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
324 PM AKST SUN FEB 28 2016

.SHORT TERM...BROAD ZONE OF UPPER TROUGHING RESIDES FROM THE
NCNTRL PAC/ALEUTIANS REGION EWD ACROSS THE GULF OF AK AND NERN
PAC SUN AFTERNOON. WEAK UPPER WAVES ARE EMBEDDED WITHIN THIS FLOW
REGIME...ONE OF WHICH IS CURRENTLY MOVING ACROSS THE NERN/ERN GULF
COAST...WITH A SECOND FOLLOWING A SIMILAR PROGRESSION BY MON
MORNING. THESE WAVES WILL AUGMENT SHOWER DEVELOPMENT DURING THE
SHORT TERM PERIOD /BECOMING ISOLATED BY LATE MON AFTERNOON/...AND
THOUGH MARGINAL CAPE VALUES WILL EXIST OVER THE GULF...PROBABILITY
FOR THUNDERSTORM DEVELOPMENT APPEARS TO BE LOW ENOUGH ATTM /DUE TO
MODEST FORCING FOR ASCENT/ TO LEAVE OUT OF THE FORECAST.

AT THE SURFACE...WEAK RIDGE OF HIGH PRESSURE IS FORECAST TO BUILD
OVER THE CNTRL/SRN PANHANDLE TONIGHT INTO MON. THIS WILL INITIALLY
PROMOTE LIGHT WLYS /POSSIBLY BRIEFLY ENHANCED TO 20 KT OVER CROSS
SOUND THIS EVENING/ THAT WILL TRANSITION TO ELY/NLY MON AFTERNOON
AS THE RIDGE SHIFTS E INTO BC AND TAKES ON MORE OF A SE-NW
ORIENTATION.

SIGNIFICANT CHANGES TO THE INHERITED FORECAST WERE NOT
NECESSARY...MODEST UPDATES WERE MADE USING A COARSE/HI-RES
ENSEMBLE BLEND.

.LONG TERM...MODEL AGREEMENT IS ON THE POOR SIDE MON NIGHT AND TUE
HANDLING WEAKENING FRONT MOVING TOWARD THE AREA. THE UPPER FLOW
LOOKS LIKE IT WILL SPLIT TO THE SOUTH OF THE AREA...WHICH WILL
TEND TO KEEP ANY SYSTEM APPROACHING THE AREA WEAK AND MORE TO THE
SOUTH. THE CANADIAN AND NAM WERE FURTHEST NORTH WITH ANY
PRECIP...AND BASED ON FLOW ALOFT LOOKED TOO AGGRESSIVE BRINGING
IT TO THE NORTH. DID TWEAK SOME POPS DOWNWARD A BIT OVER THE
CENTRAL AREA BASED ON THE SPLIT FLOW EXPECTED TO OUR SOUTH.
OTHERWISE OTHER THAN SOME WIND DIRECTION TWEAKS...BASICALLY KEPT
MON NIGHT AND TUE FORECAST AS IS.

FURTHER OUT...LEANED TOWARD THE DRIER ECMWF AND CANADIAN FOR TUE
NIGHT AND WED WITH FLOW ALOFT STILL SOMEWHAT SPLIT OVER THE AREA.
CHOPPED BACK SOME OF THE LOW POPS OVER THE NORTH TUE NIGHT FOR
THIS REASON...ALTHOUGH POPS GENERALLY REMAIN BELOW CHANCE LEVELS
ANYWAY. SEVERAL SYSTEMS WILL TRY TO MOVE INTO THE AREA TOWARD LATE
WEEK...BUT THERE IS SOME DISAGREEMENT ON THE MODELS WITH THESE.
USED LATEST WPC FOR WED NIGHT ONWARD FOR THE MOST PART. DID LOWER
SOME MIN TEMPS TUE NIGHT-THU NIGHT THOUGH ESPECIALLY OVER THE N
WHERE BETTER CHANCE FOR BREAKS IN CLOUDS WILL OCCUR.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ036-041>043-051-052.
&&

GARNER/RWT

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