FXAK67 PAJK 052207
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
104 PM AKST SAT DEC 5 2009

.SHORT TERM...SCATTERED SKIES AND DRY CONDITIONS ARE THE RULE
TODAY ACROSS THE PANHANDLE. PAGS WAS AN EXCEPTION THIS MORNING
WITH IFR CIGS AND PAPG MANAGED A FEW HOURS OF IFR CIGS AND LIGHT
SNOW. WINDS IN THE OFF SHORE AND OUTSIDE WATERS ARE GENERALLY
LIGHT WITH SMALL CRAFT DUE TO SEAS IN THE NORTH. INNER CHANNELS
WINDS ARE GENERALLY AT SCA LEVELS OR LOWER. NORTHERN LYNN CANAL
FLIRTING WITH GALES WITH MODERATING PRESSURE GRADIENT BETWEEN THE
PANHANDLE AND 1060 MB HIGH PRESSURE IN THE SOUTHERN YUKON. 

 AS THE HIGH CONTINUES TO MOVE SOUTH INTO BC THE GRADIENT WILL
TURN PARALLEL TO THE COASTAL MOUNTAINS IN THE NORTHERN ZONES AND
DECREASE GAP FLOW WINDS THERE. GAP FLOWS HAVE INCREASED THIS
AFTERNOON IN THE CENTRAL PANHANDLE WITH POINT BISHOP PEAK WIND OF
40 KTS BUT HAS DROPPED ON LAST COUPLE OF OBS. EXPECT GAP WINDS TO
INCREASE THIS EVENING ALONG THE STIKINE RIVER AND PORTLAND CANAL.
AS GRADIENT ORIENTATION IMPROVES. WINDS WILL SUBSIDE LATE TONIGHT
IN THESE AREAS AS THE HIGH CONTINUES TO MOVE SOUTHEAST INTO
CENTRAL AND SOUTHERN BC. 

 SCATTERED SKIES AND LIGHT WINDS WILL ALLOW FOR STRONG
RADIATIONAL COOLING AGAIN TONIGHT. UPPER TEENS TO LOW TWENTIES ON
TAP FOR MOST OF THE INNER CHANNEL LOCATIONS AND MID TWENTIES TO
UPPER TWENTIES FOR COASTAL LOCATIONS TONIGHT. WIND SHELTERED
LOCATIONS IN THE NORTHERN INTERIOR CHANNELS AND ALONG THE HAINES
HIGHWAY COULD DIP TO THE SINGLE DIGITS OVERNIGHT. 

 MODEL AGREEMENT CONTINUES TO BE GOOD WITH THE EXCEPTION OF THE
STRENGTH OF THE YUKON HIGH. GFS AND UKMET MODELS BOTH MAX THE
HIGH AT AROUND 1056 MB BUT SEVERAL 1060 MB OBS NOTED IN CANADIAN
INTERIOR. BOTH THE ECMWF AND THE NAM12 MAX THE HIGH AT 1060 MB
BUT PLACEMENT OF THE MAX WAS BETTER WITH THE NAM12. USED THE
NAM12 TO UPDATE GRIDS AS IT CONTINUES TO HANDLE GRADIENT ALONG
COASTAL MOUNTAINS THE BEST AND BETTER LOCATED THE HIGH PRESSURE
CENTER. FORECAST CONFIDENCE IS ABOVE AVERAGE THROUGH THE SHORT
TERM PERIOD. 

&&

.LONG TERM...BLOCKING PATTERN IN PLACE THROUGH MID WEEK BEFORE
BEING UNDERCUT. AS HIGH RETROGRADES DEEP UPPER LOW OVER THE N
POLE WILL TRACK SOUTH. THE TRACK OF THIS LOW IS THE NEXT BIG
FORECAST QUESTION FOR THE END OF THE WEEK. IN THE MEAN TIME DRY
AND MOSTLY CLEAR SKIES WILL CONTINUE WITH OFFSHORE FLOW OVER THE
REGION.

AS HIGH PRESSURE OVER THE YUKON TRACKS SOUTH EAST WEST GRADIENT
WILL SUBSIDE WILL GAP WINDS DIMINISHING THROUGH THE START OF THE
WEEK. N REGIONS KEEPING A FAIR GRADIENT SO WILL SEE SMCR WINDS IN
N LYNN CANAL CONTINUE WITH SOME BREEZY CONDITIONS IN PKZ18 AND
19. WAVES GENERATED FROM 985 LOW S OF THE ALEUTIANS...BUT KEPT
WELL WEST OF THE AK GULF...WILL BRING COASTAL WATERS INTO SMCR
RANGE.

MODELS WERE IS GOOD AGREEMENT AT THE START OF THE LONG TERM AND
INITIALIZED WELL. USED A BLEND OF NAM12 WITH INHERITED GRIDS AS
NAM SHOWED A BIT MORE DETAIL IN PRESSURE SURFACES. FOR THE
REMAINDER OF THE LONG TERM MODELS BEGAN TO DIVERGE SIGNIFICANTLY.
12Z GFS AT 500MB SPLITS THE POLAR LOW WITH ONE LOBE MOVING S OVER
CANADA INTO THE CENTRAL US WITH THE SECOND TRACKING INTO THE
ARCTIC OCEAN. 12Z EC BRINGS THE POLAR LOW S AND RETROGRADES OVER
THE AK INTERIOR. THIS TRACK IS FURTHER NORTH THAN THE 1204 12Z
RUN BUT ON LINE WITH THE 1205 00Z TRACK. THAT SAID RMOP VALUES
ARE LOW FOR THIS TIME PERIOD AND WITH LOW CONFIDENCE IN THE
OPERATIONS RUNS OPTED TO KEEP FORECAST GRIDS AS IS. WITH HPC
USING MORE OF AN ENSEMBLE BLEND THAT TRENDED MORE TOWARD EC WILL
FELL MORE CONFIDENT AFTER CHECKING TOMORROWS MODEL RUNS. WITH THE
EC SOLUTION WILL KEEP DRIER PATTERN A BIT LONGER BUT WITH A
TIGHTENING TEMPERATURE AND PRESSURE GRADIENT WILL SEE AN INCREASE
IN GAP WINDS AND LOWER TEMPS. A MORE NORTHERLY TRACK OF THE POLAR
LOW AS PROPOSED BY THE GFS WILL ALLOW LOW TO TRACK INTO THE AK
GULF WITH A POSSIBLE WARMER WETTER FORECAST.

FORECAST CONFIDENCE IS ABOVE AVERAGE FOR THE THE START OF THE
LONG TERM AND THEN DROPS SIGNIFICANTLY WILL MODEL UNCERTAINTY.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ012. 
         SMALL CRAFT ADVISORY FOR
PKZ011-013-021-022-031-034>036-041. 
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ043-051-052. 

&&

$$

CCC/PRB