Wind Advisory 88, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
159 PM AKST TUE NOV 24 2009

.SHORT TERM...A 966 MB LOW IS LOCATED SOUTH OF 50N ALONG 150W
THIS MORNING. SATELLITE IMAGERY SHOWS THE ASSOCIATED FRONT PUSHED
WAY OUT IN FRONT OF THE LOW AND APPEARS TO BE DE-COUPLING AS IT
GETS SHEARED IN THE MIDDLE. A SECOND WRAP IS FORMING ALONG THE
SOUTHERN PORTION OF THE CIRCULATION CLOSE IN TO THE LOW CENTER.
BEHIND THE MAIN FRONT...LARGE AREAS OF POORLY ORGANIZED
CONVECTION ARE DEVELOPING AS COLD AIR IS ENTRAINED. RADAR
REFLECTIVITY IMAGERY SHOWING A SOLID AREA OF FRONTAL
PRECIPITATION JUST ARRIVING OVER THE CENTRAL OUTER COAST AS OF
LATE THIS MORNING. NO RAIN AT SITKA YET...BUT KLAWOCK AND
KETCHIKAN BOTH REPORTING LIGHT PRECIP AT THIS TIME WHICH IS
ALMOST CERTAINLY FRONTAL RAIN BEYOND THE VIEW OF THE RADAR. WIND
ADVISORY FOR ZONE 27 BEGAN AT 9 AM AND GUSTS AT HYDABURG ARE JUST
NOW GETTING INTO THE MIDDLE 30S. STILL NO SIGNIFICANT WINDS IN
SITKA OR PORT ALEXANDER...WHERE THE ADVISORY DOES NOT BEGIN UNTIL
NOON...BUT DO NOW HAVE ADVISORY GUSTS IN KETCHIKAN SO HAVE BEGUN
THEIR ADVISORY A LITTLE EARLY.

THIS SYSTEM IS PRIMARILY A RAIN MAKER AND ALL ZONE WILL GET
CATEGORICAL POPS AT LEAST FOR SOME PART...IF NOT ALL...OF THE
SHORT TERM FORECAST PERIOD. DID ADJUST THE OVERNIGHT LOWS DOWN BY
1 TO 2 DEGREES FOR MOST LOCATIONS AND THAT WAS ENOUGH TO GIVE THE
NORTHERN INNER CHANNELS 1 TO 2 INCHES OF SNOW DOWN NEAR SEA LEVEL
OVERNIGHT. ADDITIONALLY...2 TO 4 INCHES ALONG THE HAINES AND
KLONDIKE HIGHWAYS. POSSIBLY ANOTHER 1 TO 2 ALONG THE HIGHWAYS FOR
THE FIRST HALF OF TOMORROW. NOT CONFIDENT ENOUGH TO ISSUE A WINTER
WEATHER ADVISORY FOR JUST THE HIGHWAYS...BUT THIS WILL HAVE TO BE
WATCHED CLOSELY.

A BRIEF LULL IN THE WINDS OVERNIGHT TONIGHT AFTER THE FRONT CLEAR
THE FORECAST AREA TO THE EAST...BUT THE PARENT LOW...STILL QUITE
POTENT AT 976 MB...IS FORECAST TO APPROACH THE CENTRAL OUTER COAST
FROM THE SOUTHWEST TOMORROW. THIS WILL GENERATE ANOTHER ROUND OF
ADVISORY LEVEL WINDS/WIND GUSTS FOR SOUTHERN ZONES 27 AND 28 AGAIN
TOMORROW.

.LONG TERM...BOTH THE 12Z GFS 5 WAVE AND THE 12Z NAEFS/ECMWF
ENSEMBLES INDICATE THE LONG WAVE TROUGH WILL REMAIN LOCATED ALONG
THE ALASKAN PENINSULA THROUGH THE WEEKEND...AT WHICH POINT A
SUBSTANTIAL LONG WAVE RIDGE BUILDS ACROSS THE GULF AND PANHANDLE
EARLY NEXT WEEK. THERE IS LARGE CONFIDENCE THAT THE LONG WAVE
RIDGE WILL DEVELOP BUT STILL LARGE ENSEMBLE SPREAD ON WHERE THE
LONG WAVE RIDGE AXIS WILL DEVELOP AND THIS WILL HAVE IMPLICATIONS
ON THE PANHANDLES WEATHER NEXT WEEK. WITH THE LONG WAVE TROUGH
ALONG THE ALASKAN PENINSULA TWO MORE GALE TO STORM FORCE LOWS WILL
MOVE INTO THE WESTERN GULF THROUGH THE WEEKEND BUT WITH THE PARENT
LOW ADVECTING TOWARD KODIAK KEPT THE STRONGEST WINDS ALONG THE
OUTER COAST. WILL SEE THE RAIN/SNOW LINE REMAIN IN THE NORTHERN
PANHANDLE THROUGH FRIDAY AS 850 MB TEMPERATURES FOR JUNEAU AND
POINTS SOUTHWARD REMAIN ABOVE -5 C. BLENDED INHERITED GRIDS TOWARD
THE 12Z GFS/ECMWF THROUGH 12Z SATURDAY WHICH KEPT IN LINE WITH THE
PREVIOUS FORECAST ONLY SLOWING THE ADVECTION OF A FRONT ACROSS THE
PANHANDLE ON FRIDAY. BY SATURDAY AFTERNOON MODEL DIFFERENCES BEGIN
TO DEVELOP WITH THE 12Z GFS BEING MUCH QUICKER AND FURTHER
SOUTHEAST WITH A STORM FORCE LOW WEST OF SITKA...WHILE THE 12Z
ECMWF KEEPS THE STORM FORCE LOW WEST OF 140W. WITH THE LONG WAVE
TROUGH ALONG THE ALASKAN PENINSULA PREFER THE 12Z ECMWF
SOLUTION...HOWEVER BOTH 12Z OPERATIONAL AND ENSEMBLE MODELS HAVE
SHIFTED THEIR TRACKS EASTWARD FROM THE 00Z MODEL RUNS. HPC
GUIDANCE WAS VERY CLOSE TO INHERITED GRIDS DAY 4 ONWARD AND SO
PREFERRED NO CHANGE PAST DAY 4 TO WAIT FOR BETTER MODEL RUN TO RUN
CONSISTENCY.

AS DISCUSSED IN THE SHORT TERM ANOTHER WRAP OF STRONG 850 MB WINDS
TO 55 KNOTS AND A STRONG SOUTHWESTERLY PRESSURE GRADIENT WILL
ADVECT ACROSS THE OUTER COAST AND SOUTHERN PANHANDLE TOMORROW
AFTERNOON AND EVENING AND THEREFORE EXTENDED THE WIND ADVY TO
MIDNIGHT IN AKZ023/027. AS THE SURFACE AND MID LEVEL LOW ADVECT
INTO THE YUKON BY THURSDAY AFTERNOON WILL SEE A STRONG SOUTHERLY
SURFACE PRESSURE BUILD INTO THE PANHANDLE AND SO WILL SEE WINDY
CONDITIONS ACROSS THE NORTHERN PANHANDLE WITH GALES AND POSSIBLE
WIND ADVY GUSTS NEAR TAIYA INLET. RAIN SHOWERS WILL CONTINUE
ACROSS THE PANHANDLE WITH ONSHORE FLOW...MIXING WITH SNOW AT
HIGHER ELEVATIONS AND ALONG THE HIGHWAYS NEAR THE BORDER. A
WEAKENING FRONT APPROACHES THE PANHANDLE FRIDAY BUT WITH MOST OF
THE UPPER LEVEL SUPPORT IN THE WESTERN GULF THIS FRONT WONT PACK
MUCH OF A PUNCH WITH MOST OF THE RAINFALL AND LOCALLY BREEZY
CONDITIONS ALONG THE OUTER COAST. A STORM FORCE LOW MOVES OUT OF
THE NORTHEASTERN PACIFIC AND THROUGH THE PANHANDLE OVER THE
WEEKEND AND WILL HAVE TO MONITOR THE MOVEMENT OF THIS LOW AS COULD
SEE STRONG NORTHERLY WINDS ADVECT COOLER AIR ACROSS THE NORTHERN
PANHANDLE BEFORE FRONTAL PASSAGE KEEPING THE PRECIP SNOW...WITH
THE HIGHEST ACCUMULATIONS ALONG THE HIGHWAYS NEAR THE BORDER.
EXPECT STORM FORCE WINDS ALONG THE NORTHERN GULF WITH THE ENHANCED
BARRIER FLOW OVER THE WEEKEND WITH AT LEAST WIND ADVY GUSTS ALONG
THE OUTER COAST. WILL HAVE TO MONITOR THE MOVEMENT OF THE SURFACE
LOW WITH WIND ADVY GUSTS ALSO POSSIBLE ACROSS THE INNER CHANNELS.
AFTER THIS STORM FORCE LOW WEAKENS BY LATE SUNDAY A LONG WAVE
RIDGE BUILDS OVER THE GULF AND PANHANDLE WITH THE PLACEMENT OF THE
RIDGE AXIS STILL UNCERTAIN. 12Z MODELS ARE INDICATING CAA THROUGH
700 MB BY EARLY NEXT WEEK WHICH COULD ALLOW THE RAIN/SNOW LINE TO
SHIFT SOUTH OF THE ICY STRAIT CORRIDOR...HOWEVER IT IS STILL TO
EARLY TO TELL THE MOVEMENT OF THE ARCTIC FRONT WITH THE LARGE
UNCERTAINTY IN THE LONG WAVE RIDGE AXIS PLACEMENT.

FORECAST CONFIDENCE IS ABOVE AVERAGE THROUGH 12Z SATURDAY WITH
ABOVE NORMAL PRECIP AND LOCALLY WINDY CONDITIONS ACROSS THE
PANHANDLE THROUGH THE WEEK...ESPECIALLY NEAR TAIYA INLET AND ALONG
THE OUTER COAST. EXPECT MOST OF THE PRECIP TO REMAIN IN LIQUID
FORM THROUGH THE WEEKEND EXCEPT ACROSS THE NORTHERN PANHANDLE AND
THE HIGHWAYS NEAR THE BORDER.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND ADVISORY UNTIL 9 PM AKST THIS EVENING FOR AKZ022-023-027-
     028.
         WIND ADVISORY FROM 6 AM WEDNESDAY TO MIDNIGHT AKST WEDNESDAY
     NIGHT FOR AKZ027.
         WIND ADVISORY FROM NOON WEDNESDAY TO MIDNIGHT AKST WEDNESDAY
     NIGHT FOR AKZ023.
         WIND ADVISORY FROM 9 AM TO 6 PM AKST WEDNESDAY FOR AKZ028.
         WIND ADVISORY UNTIL 6 PM AKST THIS EVENING FOR AKZ029.
MARINE...STORM WARNING FOR PKZ042-043-051.
         GALE WARNING FOR PKZ021-022-033-036-041-052.
         SMALL CRAFT ADVISORY FOR PKZ011>013-031-032-034-035.

&&

FRITSCH/PSS