Storm Warning 54, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
535 AM AKST FRI DEC 18 2009

.SHORT TERM...WEATHER FRONT MOVING NORTHEAST THROUGH PANHANDLE
FRIDAY MORNING. STRONG WINDS OVER THE SOUTHERN HALF WILL BE
TAPERING OFF THROUGH THIS MORNING. LOOK FOR FEW HOUR BURST OF
STRONG WINDS AS HIGH PRESSURE RAPIDLY BUILDS IN BEHIND THE FRONT
AND WORKS ITS WAY NORTH THROUGH THE INNER CHANNELS. THESE GUSTY
WINDS SHOULD BE FINISHED BY AFTERNOON. WIND ADVISORIES SHOULD BE
ENDING THIS MORNING AS WELL.

 COLD AIR IS WORKING ITS WAY INTO SOUTHEAST ALASKA TODAY. HIGH
TEMPERATURES WILL BE THIS MORNING AS TEMPERATURES WILL HOLD
STEADY OR FALL THROUGH THE DAY. CONTINUED COOLING YET FOR TONIGHT
AS THE POOL OF COLDER AIR MOVES ACROSS THE REGION THROUGH
TONIGHT.

 SNOW WARNING AND ADVISORY FOR THE NORTHERN LYNN CANAL REGION WAS
ALLOWED TO EXPIRE THIS MORNING AS ADDITIONAL SIGNIFICANT (MORE
THAN 3 INCHES) ACCUMULATIONS WERE NOT EXPECTED TO FALL. FLOW
PATTERN SHIFTING TO A MORE WESTERLY COMPONENT IS NOT AS FAVORABLE
FOR THERE DUE TO TERRAIN BLOCKING THE FLOW.

 SNOW SHOWERS ALREADY STARTING TO MAKE APPEARANCES ON THE COASTAL
SITES THIS MORNING SO EXPECT UNMIXED PRECIPITATION UNTIL NOON AT
THE LATEST FOR THE PANHANDLE AS SNOW MOVES IN.

 FORECAST GRID UPDATES WERE DONE USING THE NAM SOLUTION THIS
MORNING DUE THE FINER GRID RESOLUTION THROUGH THE MORNING...THE
MODELS WERE FAIRLY CLOSE THIS MORNING.

&&

 .LONG TERM...BEGINS AS SFC HIGH PRESSURE CENTERED JUST WEST OF
QUEEN CHARLOTTE ISLAND CONTINUES TO BRING WEAK ONSHORE FLOW INTO
THE PANHANDLE FROM THE WEST THROUGH SUNDAY. EXPECT SNOW SHOWERS
IN THE NORTHERN ZONES AND RAIN AND SNOW SHOWERS IN THE SOUTHERN
ZONES SATURDAY AND DIMINISHING THROUGH THE DAY SUNDAY AS THE HIGH
CONTINUES TO MOVE TO THE NORTH.

 THE HIGH PRESSURE RIDGE DEVELOPS TWO CENTERS WITH ONE OVER THE
YUKON AND THE OTHER SITUATED IN WESTERN BC FROM SUNDAY THROUGH
TUESDAY OF NEXT WEEK. POPS AT CHANCE OR LOWER ACROSS MOST OF THE
PANHANDLE THROUGH MONDAY AND TUESDAY WITH THE EXCEPTION OF
WESTERN PORTION OF PKZ 17 WHICH WILL REMAIN IN WEAK ONSHORE FLOW
TO THE WEST OF THE HIGH PRESSURE RIDGE. GAP WINDS WILL BRING SCA
AND GALES AND IN ADDITION LOWER TEMPS THROUGH THE INNER CHANNELS.

 BY MID WEEK THE RIDGE BEGINS TO BREAK DOWN AS A SERIES OF WEAK
FRONTAL SYSTEMS ERODE THE RIDGE THROUGH FRIDAY. BY LATE WEEK A
965 MB LOW PRESSURE SYSTEM MOVES OUT OF THE NORTHERN PACIFIC
TOWARD COLD BAY. VERY LARGE CIRCULATION AROUND THIS LOW
ENCOMPASSES THE ENTIRE GULF OF ALASKA...MOST OF THE BERING SEA
AND PORTIONS OF THE NORTHERN PACIFIC WITH THIS SYSTEM.

 MODELS ARE IN GOOD AGREEMENT ON THE RIDGE THROUGH MIDDLE OF NEXT
WEEK BUT BEGIN TO DIFFER ON TIMING OF RIDGE BREAK DOWN AND
POSITION AND STRENGTH OF LARGE LOW TOWARD THE END OF NEXT WEEK.
MADE ONLY MINOR CHANGES TO INHERITED GRIDS THROUGH DAY 4 WITH
LATEST GFS AS IT CONTINUES TO HANDLE CURRENT SYSTEM IN THE GULF
VERY WELL. NUDGED HPC BASED GRIDS FROM DAY 5 TO THE END OF THE
PERIOD WITH LATEST ECMWF AS IT CONTINUES TO HAVE THE BEST RUN TO
RUN CONTINUITY IN THE LONG RANGE IS ALSO MORE CONSISTENT WITH HPC
TRENDS ON LATE WEEK LOW PRESSURE SYSTEM TRACK. NUDGING TO ECMWF
CAPTURED THE TRACK AND TREND OF HPC GRIDS BUT IN ADDITION IT
INCREASED ATTENDING WIND AND WAVES IN THE LONG RANGE GRIDS WITH
APPROACHING LARGE SCALE LOW PRESSURE SYSTEM. FORECAST IS ABOVE
AVERAGE THROUGH TUESDAY AND DROPS TO BELOW AVERAGE FROM WEDNESDAY
THROUGH THE END OF THE LONG TERM.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND ADVISORY UNTIL 8 AM AKST THIS MORNING FOR AKZ023-026-028-
     029.
MARINE...STORM WARNING FOR PKZ036.
         GALE WARNING FOR PKZ011>013-021-022-031>035-041>043-051-053.
         SMALL CRAFT ADVISORY FOR PKZ052.

&&

BEZENEK/CCC