FXAK67 PAJK 072307
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
206 PM AKST MON DEC 7 2009

.SHORT TERM...TRANQUIL WEATHER ACROSS THE PANHANDLE TODAY AS A
STRONG UPPER LEVEL RIDGE CONTINUES OVER THE GULF OF ALASKA.
SCATTERED SKIES DOMINATE THE PANHANDLE WITH ALL TAF LOCATIONS AT
VFR CONDITIONS. WEAK INVERTED TROUGH BUILDING NORTH INTO THE
PANHANDLE AS 1036 MB HIGH CONTINUES TO BUILD SOUTHEAST OUT OF THE
YUKON AND INTO NORTHERN BC. CYXY TO PAJN PRESSURE DIFF OF OVER
10 MB FCST AND NEARLY 5 MB PRESSURE DIFFERENCE FOR NORTHERN LYNN
CANAL FOR LATE AFTERNOON. EXPECT GALES FOR THE NORTHERN LYNN
CANAL AND MINIMAL WIND ADVISORY LEVEL GUSTS IN PAGY WHERE A WIND
ADVISORY HAS BEEN POSTED. GUSTY GAP FLOW WINDS WILL DEVELOP IN
INTERIOR PASSES THROUGH THE EVENING BUT ARE EXPECTED TO REMAIN
BELOW ADVISORY LEVEL AS THE HIGH PRESSURE SYSTEM SLIDES SOUTH. 

 SATELLITE REVEALS AREAS OF CIRRUS SPILLING OVER THE RIDGE AXIS
AND MOVING SOUTH THROUGH THE PANHANDLE ATTM. ANOTHER FROSTY NIGHT
ON TAP FOR THE PANHANDLE AS LIGHT WINDS AND INVERSION WILL ALLOW
FOR RADIATIONAL COOLING ALTHOUGH THE THIN HIGH CLOUDS WILL KEEP
TEMPERATURES A COUPLE OF DEGREES WARMER THAN LAST NIGHT. PATCHY
FOG POSSIBLE AT INTERIOR LOCATIONS NEAR OPEN WATER. 

 MODEL OF CHOICE CONTINUES TO BE THE NAM AS IT HAS THE BEST
REPRESENTATION OF THE GRADIENT ALONG THE COASTAL MOUNTAINS
ASSOCIATED WITH THE 1036 MB HIGH IN THE YUKON. RUN TO RUN
CONSISTENCY WITH THE NAM12 REMAINS STRONG AND WAS THE PREFERRED
GUIDANCE THROUGH THE SHORT TERM. FORECAST CONFIDENCE REMAIN HIGH
WITH SLOWLY EVOLVING WEATHER PATTERN. 

&&

.LONG TERM...PREVIOUS MODEL CONSISTENCY AND AGREEMENT NO LONGER
THE CASE FOR THE LONG TERM. RUN TO RUN AND MODEL TO MODEL
VARIANCE HAVE INCREASED TODAY WITH INCREASED UNCERTAINTY WITH THE
TRACK OF THE POLAR LOW AND TIMING OF THE RETROGRADING RIDGE.

THE START OF THE LONG TERM STILL HAS GOOD MODEL CONSISTENCY AS
THE UPPER LEVEL RIDGE REMAINS AS THE DOMINANT FEATURE. WILL SEE
DRY CONDITIONS COOL TEMPS AND LIGHT WINDS MID WEEK WITH SURFACE
HIGH IN THE GULF. NEW MODEL RUNS NOW HAVE THE UPPER LVL RIDGE
REMAINING OVER THE AREA THROUGH THE WEEKEND BEFORE RETROGRADING
WEST. THIS IS A BIT MORE IN LINE WITH LOCAL GUIDANCE OF A 10 DAY
RIDGE. COLD POLAR ARE ASSOCIATED WITH THE MAIN VORTEX NOW STAYING
TO THE EAST OF AK WITH A WEAKER SPLIT OVER THE YUKON AND N
BRITISH COLUMBIA. WITHOUT A FORCING MECHANISM FELT THIS NEW POLAR
LOW TRACK A VIABLE OPTION. WITH THIS NEW PATTERN DIFFERENT FROM
INHERITED GRIDS MADE SOME SIGNIFICANT UPDATED TO GRIDS. NAM12 WAS
STILL RELIABLE OUT TO DAY 4 WITH THE DETAILS ION THE PRESSURE
GRADIENT. FOR THE REMAINDER TO THE PERIODS USED HPC GUIDE BLENDED
WITH SOME EC AND GFS. MADE MINOR CHANGES TO TEMPS BUT COULD SEE A
DROP ALONG COASTAL AREAS WITH THE COLD AIR MASS BUILDING ALONG
THE COASTAL MOUNTAINS. WINDS IN THE GULF SAW ONLY MINIMAL
CHANGES. TIGHTENING PRESSURE GRADIENT ALONG THE INNER CHANNELS
WILL PRODUCE AN INCREASE IN INSIDE WATER WINDS...TEMPERED DOWN
SOME OF THE HIGHER WIND FIELDS DUE TO REMAINING UNCERTAINTY. WITH
THE HIGH REMAINING IN PLACE THE OTHER SIGNIFICANT CHANGE WAS
KEEPING THE AREAS DRIER. BACKED OFF LIKELY POPS TO CHANCE.

FORECAST CONFIDENCE WAS AVERAGE FOR THE START OF THE LONG TERM
AND THEN DROPS SIGNIFICANTLY TOWARD THE END OF THE PERIOD. WHILE
MODELS HAVE BEEN MORE INCONSISTENT INTRA OFFICE DISCUSSIONS HAVE
MADE THE NEW MODEL RUNS SEEM MORE IN LINE.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND ADVISORY UNTIL 3 AM AKST TUESDAY FOR AKZ018.
MARINE...SMALL CRAFT ADVISORY FOR PKZ011>013-031-035. 
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ041>043-051-052.

&&

$$

CCC/PRB