000 
FXAK67 PAJK 251337
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
537 AM ADT SUN MAY 25 2008

.SHORT TERM...BREAKING OMEGA BLOCK IS IN PROCESS EARLY THIS
SUNDAY MORNING ACROSS THE EASTERN GULF AND SOUTHEAST ALASKA. THE
UPPER LEVEL RIDGE OF HIGH PRESSURE BECOMES A CLOSED ONE WITH ITS
CENTER OVER THE CENTRAL PANHANDLE. MODELS ARE IN GOOD AGREEMENT
FOR THE SHORT TERM FORECAST PERIODS WITH WEAKENING CLOSED HIGH
ALOFT THROUGH TONIGHT. FOR A BETTER CONSISTENCY...USED THE 00Z
GFS SOLUTION PRIMARILY WITH INHERITED GRIDS AS A SMOOTHING TOOL
FOR TODAY AND TONIGHT. AT THE LOWER LEVELS...A WEAK COLD FRONT IN
THE CENTRAL GULF WILL DISSIPATE ALONG THE COASTAL AREAS BY LATE
THIS AFTERNOON AS IT REACHES THE FAR EASTERN GULF...AND HIGH
PRESSURE WILL REBUILD BEHIND THE FRONT ACROSS THE GULF OF ALASKA.
SATELLITE LOOP SHOWS INCREASING CLOUDINESS ALONG THE LEADING EDGE
OF THE FRONT JUST WEST OF SITKA TO THE NORTH. THE PANHANDLE
SHOULD SEE INCREASING CLOUDS THIS MORNING WITH NO RAIN CHANCE
OVER THE HORIZON. A WEAK AREA OF LOW PRESSURE WILL EXPAND FROM
CANADA LATE THIS EVENING AND MOVE OVER THE SOUTHEAST ALASKA
TONIGHT. WITH REBUILDING HIGH OVER THE GULF AND EXPANDING LOW
FROM THE CANADA...THE FORECAST AREA WILL EXPERIENCE INCREASING
PRESSURE GRADIENT. SMALL CRAFT ADVISORY WILL REMAIN FOR ALL
OUTSIDE WATERS THROUGH TONIGHT INCLUDING CROSS SOUND. AHN 


.LONG TERM...THE LARGE SCALE PATTERN WILL HAVE LITTLE PROGRESSION
UNTIL ABOUT FRI. THE EXISTING OMEGA BLOCK, DISCUSSED IN THE SHORT 
RANGE SECTION ABOVE, WILL BE REPLACED BY ANOTHER ONE FARTHER UPSTREAM.
THE NEW OMEGA BLOCK WILL BE POORLY ORGANIZED BUT WILL DEVELOP
A CENTRAL RIDGE ALF EXTENDING N FM THE NPAC TO OVER SEWARD. THE
500H LOW ANCHORING THE WEST SIDE WILL BE ABT 600 NM SSW OF COLD BAY
AT 18Z TUE, WITH THE EAST ANCHOR ABOUT ABT 600 NM SW OF SEATTLE.

THE GFS AND ECMWF SOLUTIONS HAVE A USEFUL CONSENSUS THAT THE BLOCK
WILL BREAKDOWN EASTWARD AND PERMIT SW FLOW ALOFT OVER THE PNHDL
BGNG ABT 00Z SAT. THE MODEL SOLNS SPREAD OUT ON HOW FAST TO PERMIT
THE POLAR FRONT ZONE TO EXPAND ACROSS THE GLFALSK.  

DURING A COORD CALL WITH PAFC WE AGREED THAT THE GFS SOLN TO BE
USEFUL AS PRIMARY GUIDANCE, BUT IS TOO FAST TO BRING TRIPLE POINT
FEATURES ACROSS THE GLFALSK THIS WEEKEND. THE GFS SOLN IS SLOWED
DOWN BEGINNING ABT 12Z SAT, WITH THE ONSET OF FRONTAL RAINFALL
SUNDAY INSTEAD OF SATURDAY.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ022-041>043-051-052. 

&&

$$

SJA/JBT