Small Craft Advisory 69, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
405 PM AKST FRI JAN 21 2011

.SHORT TERM... AT 2000 UTC THE SMALL 990 MB SURFACE LOW THAT HAD
MOVED TO CENTRAL SOUTHEAST ALASKA WAS IN THE PROCESS OF
REDEVELOPING TO THE EAST ON THE OTHER SIDE OF THE COAST MOUNTAINS
IN CANADA. ONLY A TROUGH REMAINED ACROSS THE CENTRAL PANHANDLE.
THE LOW HAD CAUSED WINDS TO SHIFT TO THE NORTHEAST IN NORTHERN
SECTIONS BUT THE RISING PRESSURES BEHIND THE TROUGH HAS PRODUCED
STRONG SOUTHWESTERLY GALES ALONG THE OUTER COAST SOUTH OF SITKA.
ADVISORIES LEVEL WINDS ARE EXPECTED IN ZONES 27 AND 28 WITH THESE
STRONG SOUTHWESTERLIES. THE TROUGH SHOULD CONTINUE NORTHWARD
SHIFTING WINDS TO THE SOUTH ALL THE WAY UP LYNN CANAL BY LATE
TODAY. THIS WILL ALSO HELP TO RELAX THE GRADIENT IN THE SOUTH AND
DIMINISH THE WINDS THERE.

 THE PRECIPITATION TYPE IS PRIMARY RAIN HOWEVER SNOW SHOULD
CONTINUE IN THE EXTREME NORTH UNTIL THE SURFACE TROUGH MOVES
NORTH OF THE AREA LATE TODAY. THE SWITCH TO THE SOUTHERLY
DIRECTION WILL HELP SCOUR OUT THE REMIANING COLD POCKETS.

 ANOTHER SYSTEM DEVELOPING IN THE PACIFIC WILL BE MOVING INTO THE
AREA TONIGHT. RAIN AND WIND SHOULD INCREASE OVERNIGHT AS A LOW
AND ASSOCIATED FRONT MOVES TO THE NORTHEAST GULF. HEAVIER
PRECIPITATION AMOUNTS ARE EXPECTED IN THE CENTRAL PORTION OF THE
PANHANDLE WITH THIS SYSTEM. WINDS WILL BE STRONGER IN SOUTHERN
SECTIONS EARLY SATURDAY BUT WILL BE INCREASING IN NORTHWARD
CHANNELS AS THE LOW MOVES CLOSE THE THE NORTHEAST GULF COAST AND
THEN REDEVELOPS INLAND.

 &&

.LONG TERM...DUE TO PERSONNEL CONSIDERATIONS THE LONG TERM
DISCUSSION WAS NOT UPDATED THIS AFTERNOON. A SLIGHTLY EDITED MORNING
DISCUSSION FOLLOWS.

.PREV DISCUSSION... /ISSUED 610 AM AKST FRI JAN 21 2011/

WE ARE TO REMAIN WET AND UNSEASONABLY WARM.

OUR GENERAL PATTERN IS TO CHANGE LITTLE WELL INTO NEXT WEEK: ONE FRONTAL
ZONE WAVE AFTER ANOTHER MOVING NE ACROSS THE GULF AND INTO SE AK. CONFIDENCE
IS ABOVE AVERAGE, WITH THE ONLY SGFNT ISSUES BEING ASSOCIATED WITH
TIMING OF EACH FRONTAL WAVE. MODEL CHOICES FOR THIS ARE DISCUSSED
BELOW.

LONG WAVE 500 MB TROUGH WILL CONTINUE TO EXTEND S FROM OVER THE
CHUKCHI SEA TO OVR ADAK. A BROAD LONG WAVE RIDGE ALOFT WILL
PERSIST JUST TO OUR EAST FROM SEATTLE TO AT LEAST BANKS ISLAND.
THE STRONGER FRONTAL WAVES WILL TEND TO REMAIN WEST OF OUR
FORECAST AREA AND THE LARGE SCALE ANTICYCLONIC FLOW OVER US
SUPPRESSES CYCLOGENEIS. ALSO THE RIDGE PLACEMENT TO OUR EAST WILL
BLOCK ANY RETURN OF ARCTIC AIR THROUGH THE FORECAST PERIOD.

MODELS: THE NAM AND ECMWF HAVE A GOOD CONSENSUS AND HAVE
INITIALIZED WELL. THE FORECASTS FOLLOW THIS GUIDANCE CLOSELY
THROUGH 12Z MON. THE GENERAL CONSENSUS OVER A WIDER RANGE OF
MODELS IS USED THEREAFTER, WITH THE NE TRACK OF FRONTAL ZONE WAVES
INTO THE PANHANDLE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ034-036-041>043.
         SMALL CRAFT ADVISORY FOR PKZ012-013-021-022-031>033-035-051-052.

&&

CFD/ABJ