Small Craft Advisory 701, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
317 PM AKST TUE NOV 8 2011

.SHORT TERM...THE LATEST SATELLITE IMAGERY SHOWS A LOW PRESSURE
SYSTEM IN THE NORTHERN GULF THAT WILL DISSIPATE IN PLACE THROUGH
TONIGHT. ANOTHER LOW IS LIFTING OUT OF THE NORTH PACIFIC AND WILL
BE OVER HECATE STRAIT BY WED AFTERNOON. WINDS ARE THE STRONGEST
OVER THE NORTHEAST GULF AND E/W CHANNELS TO 35 KT BUT AS THE LOW
WEAKENS THE WINDS WILL DIMINISH THROUGH THE EVENING HOURS. THE
WINDS OVER THE INNER CHANNELS ARE IN THE PROCESS OF BACKING
AROUND TO THE NORTH AND WILL INCREASE TO 20 KT WITH MIN SMALL
CRAFT NEAR NORTHERN LYNN. THERE IS SOME RAIN SHOWERS MOVING OVER
THE SOUTHERN AND THE COASTAL AREAS ALONG WITH THE CENTRAL INNER
CHANNELS. THESE SHOWERS ASSOCIATED FROM THE WEAK WEATHER FRONT
OVER THE EASTERN GULF WILL SLOWLY DIMINISH THROUGH THE EVENING
HOURS WITH JUST SOME SCATTERED TO ISOLATED SHOWERS LATE TONIGHT.

 AS THE LOW LIFTS NORTH INTO HECATE STRAIT THE LOW LEVEL FLOW
WILL TURN TO THE NORTH AND A WEAKENING UPPER LEVEL TROF WILL BE
MOVING OVER THE NORTHERN AREAS. THE TROF WILL PRODUCE SOME
ISOLATED SHOWERS OVER THE NORTHERN TWO THIRDS OF THE PANHANDLE
BUT AS THE TROF DRIFT TO THE EAST AND THE FLOW BACKS OFFSHORE THE
SHOWERS WILL DIMINISH WED MORNING. THERE WILL BE SOME BREAKS IN
THE CLOUD COVER OVER THE CENTRAL INNER CHANNELS AND SOME AREAS OF
FOG MAY FORM LATE TONIGHT. A WEATHER FRONT ASSOCIATED WITH THE
LOW WILL MOVES OVER THE FAR SOUTHERN AREAS AND MISTY FJORDS
THROUGH THE MORNING BEFORE THE FRONT DRIFTS EAST. THE WINDS OVER
THE INNER CHANNELS BE 15 TO 20 KT FROM THE NORTHERN IN THE
MORNING WITH SOME HIGHER GUSTS FROM INTERIOR PASSES BUT AS THE
LOW SOUTH OF THE AREA WEAKENS THE NORTHERLY WINDS WILL DECREASE
TO BE LESS THAN 15 KT.

&&

.LONG TERM...LOW PRESSURE SYSTEM WILL DEVELOP IN THE NORTHWESTERN
AK GULF WED EVENING THEN WILL TRACK EAST MOVING TOWARD YAKUTAT BAY
BY THURSDAY EVENING. THE FRONTAL BAND ASSOCIATED WITH THE LOW WILL
MOVE INTO THE NORTHWESTERN PANHANDLE WEDNESDAY EVENING AND TRACK
SOUTHEAST OVER THE PANHANDLE THURSDAY THEN EXITING THE REGION BY
FRIDAY. PRECIP ASSOCIATED WITH THE FRONT WILL BE A MIX OF RAIN AND
SNOW FOR THE NORTHERN AREAS. COLD AIR BEING PUSHED SE BEHIND THE
FRONT WILL DROP TEMPERATURES BUT AS MOST PRECIP WILL BE IN THE WARM
SECTOR AHEAD OF THE FRONT AND COLD AIR IS CURRENTLY NOT IN PLACE
ALONG WITH WIND SHIFT FROM NORTH TO SOUTH NOT EXPECTING ANY
SIGNIFICANT SNOW ACCUMULATION. ONLY TWO AREAS THAT MAY SEE
ACCUMULATION ARE ALONG THE HAINES AND KLONDIKE HIGHWAYS.
HIGH PRESSURE OVER THE YUKON WILL MOVE SOUTH FRIDAY AFTERNOON AS
ANOTHER LOW MOVES INTO THE AK GULF SAT. MODELS HAVE BEEN CHANGING
WITH RESPECT TO THIS LOW SO THERE IS STILL SOME UNCERTAINTY AT
THIS TIME. LOW SHOULD PROGRESS ON A NORTHERLY TRACK WITH FRONT
MOVING OVER THE REGION SAT INTO SUN. AGAIN PRECIP TYPE WILL BE A
MIX WITH THE WARM PUSH AHEAD OF THE FRONT AND ARCTIC AIR DROPPING
SOUTH BEHIND THE FRONT WITH COLDER TEMPS ON MONDAY.

MODELS BEGAN IN FAIR AGREEMENT FOR THE START OF THE
LONG TERM THEN BEGIN TO DIVERGE BY FRIDAY. SHIFT IN THE MODELS
FOR MID RANGE FORECAST. NEW ECMWF AND GFS RUNS HAVE MOVED THE LOW
MOVING INTO THE AK GULF 12Z SAT FURTHER NORTH WITH THE ECMWF THE
DEEPER SOLUTION. HOWEVER THE 18Z GFS STARTED TO FALL IN LINE MORE
WITH THE 12Z ECMWF. THERE WERE SOME SIGNIFICANT SHIFTS RUN TO RUN
WITH THE ECMWF WITH THE 08 00Z RUN DROPPING THE SAT LOW CENTER DOWN
TO 958 MB THEN THE 12Z RUN LOW CENTER AT 973 MB. THAT SAID DECIDED
TO USED A BLEND OF THE 12Z NAM AND 12Z GFS TO UPDATE GRIDS OUT TO
DAY 4 THEN TRANSITIONED TO A BLEND OF HPC GUID AND 12Z GFS. WHILE
THE NEW HPC WAS A SUPER BLEND IT STILL WAS CLOSER TO THE ECMWF
SOLUTION WITH THE LOCATION OF THE SAT LOW, HENCE USED SOME GFS TO
ADJUST POSITION A BIT FURTHER SOUTH AND LOWER STRENGTH. FORECAST
CONFIDENCE IS ABOUT AVERAGE THROUGH THE END OF THE WEEK THEN DROPS
BY SAT.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ043-051.
         SMALL CRAFT ADVISORY FOR PKZ012-021-022-036-041-042-052-053.

&&

ABJ/PRB