Small Craft Advisory 7, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
218 PM AKST SUN JAN 2 2011

.SHORT TERM...THE CURRENT SATELLITE IMAGERY SHOWS A WEAKENING
WEATHER FRONT OVER THE EASTERN GULF WITH ANOTHER BUT STRONG FRONT
ENTERING THE CENTRAL GULF. MOST STATIONS ACROSS THE FORECAST
AREAS ARE REPORTING LIGHT RAIN AND DRIZZLE WITH RELATIVE WINDS
LESS THAN 15 MPH. THE STRONGEST WINDS THIS AFTERNOON ARE NEAR
PAGY WITH SOUTH WINDS 20 TO 30 MPH. ALONG WITH THE STRONG WINDS
NEAR PAGY THE MODERATE PRESSURE GRADIENT BETWEEN THE YUKON AND SE
AK IS PRODUCING SMALL CRAFT WINDS OVER NORTHERN LYNN. WINDS OVER
THE GULF THIS AFTERNOON RANGE FROM 25 KN IN THE NORTHERN GULF TO
ABOUT 15 KT OVER THE FAR SE GULF.

A WEAK UPPER LEVEL TROF ASSOCIATED WITH THE WEAKENING SURFACE
FRONT WILL MOVE THROUGH THE UPPER RIDGE OVER THE PANHANDLE THIS
EVENING. A UPPER LOW/TROF NEAR KODIAK WILL DRIFT NNE THROUGH EARLY
MONDAY MORNING AND THEN WEAKEN AS IT LIFTS INLAND OVER PAYA. THIS
UPPER FEATURE WILL SEND A FRONT ACROSS THE GULF TO BE OVER THE
EASTERN GULF BY MON AFTERNOON. THIS FRONT WILL PRODUCE GALES FORCE
WINDS OVER THE GULF THROUGH MON WITH WINDIER CONDITIONS ALONG
COASTAL LOCATIONS WITH SMALL CRAFT WINDS DEVELOPING IN THE
AFTERNOON OVER E/W CHANNELS. THE LIGHT RAIN/DRIZZLE AND FOG WILL
PERSIST THROUGH THE SHORT TERM PERIOD AS THE ATMOSPHERE WILL
REMAIN STABLE WITH A CONSTANT ONSHORE FLOW FROM THE WEST.

.LONG TERM...SUPPORT CONTINUES TO GROW FOR A PATTERN SHIFT ACROSS
THE PANHANDLE BACK TO DRIER AND COLDER WEATHER BY THE END OF NEXT
WEEK...BUT UNTIL THAT TIME WILL REMAIN UNDER MID LEVEL
SOUTHWESTERLY ONSHORE FLOW AND ABOVE NORMAL TEMPERATURES AND
PRECIPITATION. THE LONGWAVE TROUGH NOW IN THE BERING ADVECTS
EASTWARD OVER THE NEXT FOUR DAYS IN THE PROGRESSIVE MID LEVEL
PATTERN SENDING SEVERAL GALE FORCE FRONTS INTO THE GULF. THEN A
LARGE AMPLITUDE RIDGE BUILDS NORTHWARD FROM THE WESTERN GULF TO
POLE LATE NEXT WEEK AND THIS WILL ALLOW COOLER TEMPERATURES AND
DRIER CONDITIONS ACROSS THE PANHANDLE. THE OPERATIONAL ECMWF MODEL
CONTINUED TO BE THE MOST CONSISTENT MODEL WITH THE PLACEMENT OF
THE DEVELOPING RIDGE LATE NEXT WEEK AND ALSO THE ECMWF DIDN'T
OVER AMPLIFY ANY OF THE GALE FORCE FRONTS EARLY THIS WEEK LIKE THE
06/12Z OPERATIONAL GFS DID. FOR THIS REASON PREFERRED THE 12Z
ECMWF FOR DAYS 2 THROUGH 4 THEN A BLEND TOWARD HPC WAS PREFERRED
GIVEN MOST OF ITS SOLUTION CONSISTED OF THE 00Z ECMWF OPERATIONAL
AND ENSEMBLE RUNS. INHERITED SOLUTION DAY 4 ONWARD WAS VERY CLOSE
TO THE HPC SOLUTION SO IN THE EXTENDED CONTINUED THE TREND OF
DECREASING TEMPERATURES AND SKY COVER OVER THE ENTIRE PANHANDLE.

AFTER HAND OFF WITH SHORT TERM WILL SEE A GALE FORCE FRONT MOVE
ACROSS THE PANHANDLE WITH A 850 MB LLJ NEAR 55 KNOTS. THIS WILL
BRING LOCALLY WINDY CONDITIONS TO THE OUTER COAST BUT ATTM
CONTINUE TO EXPECT THE GUSTS TO REMAIN BELOW ADVY LEVEL. WITH THE
STRONG FRONT MOVING INTO YAKUTAT MONDAY NIGHT WILL ALSO SEE
INCREASED VERTICAL MOTION DUE TO UPPER LEVEL JET SUPPORT AND SO
BELIEVE RAIN WILL BE HEAVY AT TIMES DURING THE EVENING HOURS. THIS
HEAVIER RAIN WILL ALSO MOVE ACROSS THE CENTRAL AND SOUTHERN
PANHANDLE ON TUESDAY AS THE UPPER LEVEL JET SUPPORT INCREASES OVER
THE AREA. WHILE THE SURFACE PRESSURE GRADIENT ORIENTATION ISN'T AS
FAVORABLE FOR STRONG WINDS ACROSS THE INNER CHANNEL WATERS COULD
SEE SMCR LEVEL WINDS/GUSTS TUESDAY AND INTO TUESDAY NIGHT AS SOME
OF THE STRONGER 850 MB LLJ WINDS MIX DOWNWARD TO THE SURFACE.
ANOTHER GALE FORCE FRONT MOVES ACROSS THE PANHANDLE WEDNESDAY
THROUGH EARLY THURSDAY MORNING AND THIS WILL AGAIN BRING LOCALLY
WINDY CONDITIONS TO THE OUTER COAST AND LOCALLY HEAVY RAINFALL.
AFTER THIS FRONT PASSES THROUGH THE AREA WILL HAVE CAA AT 850 MB
ADVECTING EASTWARD ACROSS THE PANHANDLE AND THIS WILL ALLOW THE
VERTICAL ENVIRONMENT TO BECOME MORE CONVECTIVE AND COOL 850 MB
TEMPERATURES TO -4 TO -7 C. DUE TO THIS CAA WILL SEE SNOW MIX TO
THE SURFACE NEAR THE STRONGER SHOWERS ACROSS THE CENTRAL AND
NORTHERN PANHANDLE...WITH THE HIGHEST SNOW ACCUMULATIONS
REMAINING ALONG THE COLDER NORTHERN ROADWAYS.

THURSDAY AND FRIDAY WILL BE TRANSITION DAYS TO THE COOLER DRIER
PATTERN AS THE HIGH AMPLITUDE RIDGE BUILDS ACROSS THE WESTERN GULF
AND ALASKAN PENINSULA AND THIS WILL LEAD TO DECREASING PRECIP FROM
NORTH TO SOUTH ACROSS THE PANHANDLE UNDER CLEARING SKIES. ANY SNOW
ACCUMULATIONS DURING THESE TWO DAYS WILL BE LIMITED AS THERE IS NO
LARGE SCALE ORGANIZING MECHANISM FOR THE SNOW SHOWER ACTIVITY.

FORECAST CONFIDENCE IS ABOVE AVERAGE IN THE LARGE SCALE PATTERN
DEVELOPMENT OVER THE COMING WEEK WITH ABOVE NORMAL TEMPS AND
PRECIP ACROSS THE PANHANDLE THROUGH WEDNESDAY...THEN BELOW NORMAL
PRECIP AND TEMPERATURES INTO NEXT WEEKEND. WILL HAVE TO MONITOR
STEEP HILLSIDES OVER THE COMING DAYS FOR POSSIBLE
MUDSLIDE/AVALANCHE CONDITIONS AS THE GALE FORCE FRONTS WILL BE THE
FIRST STRONG FRONTS MOVING ACROSS THE AREA WITH AN INCREASINGLY
WET AND DESTABILIZING SNOW PACK.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ022-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ012-021-033-035-036-041-042.

&&

ABJ/PSS