Gale Warning 181, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM ADT TUE APR 24 2007

.SHORT RANGE...PARENT LOW 985 MB 200 NM S OF KODIAK HAS LARGE
SCALE CIRCULATION...THE CYCLONIC FLOW INCLUDES ALL OUR FORECAST
DOMAIN THROUGH WED.  1000 MB LOW 500 NM SW OF KETCHIKAN IS
WITHIN THE LARGER CYCLONIC FLOW.  THIS SMALLER LOW CAN BE
FOUND IN ALL THE MODELS BUT IS DISSIPATES ON THE ECMWF.
THIS SMALL LOW TENDS TO REMAIN A SURFACE TROUGH IN THE GFS...
BUT ENSEMBLE SOLUTION NUMBER 9 DOES HAVE IT CLOSED AND IN
IN USEFUL AGREEMENT WITH MOST OF THE OTHER MODELS.  NAM 40 KM
USED FOR PRIMARY GUIDANCE FOR SURFACE PRESSURES AND WINDS.

LITTLE OR NO CHANGE TO RAIN OR WIND FORECASTS THROUGH
DAYTIME WED EXCEPT FOR INCREASE IN WINDS FOR ZONE 27 WED
DUE TO THE SMALL LOW DISCUSSED ABOVE.

.LONG RANGE...
DESPITE INITIALIZATION PROBLEMS ON SECONDARY LOW IN THE 12Z RUNS
TODAY...ALL MODELS IN REASONABLE AGREEMENT BY TRANSITION TIME 06Z
THU WITH MATURE LOW IN THE 970S CENTERED AROUND 53N 148W. ALL
SLOW THIS SYSTEM DOWN AS IT GOES INTO OLD AGE AND THE GFS
ENSEMBLES HAVE MORE MEMBERS KEEPING THE LOW CENTER SLIGHTLY
FURTHER TO THE SW ON THU THAN THE DETERMINISTIC SOLUTIONS. WILL
FIRST MATCH 12Z NAM-40 AT TRANSITION THEN CONTINUE WITH USE OF
AK-GFS-40 FOR GRID EDITING WITH MODERATE CONFIDENCE. AT ANY
RATE...THE RESULT STILL MEANS THAT SE ALASKA REMAINS IN A WET
PATTERN DUE TO SOUTHERLY FLOW ALOFT WITH PERIODS OF WIND DUE TO
MODERATE GULF LOWS AND FRONTS INTO NEXT WEEK. THE PREVIOUS SHIFT
IDENTIFIED SOME COOLER AIR ALOFT ON FRI FOR SOME SNOW POSSIBLE AT
LOWER LEVELS. THE 12Z AK-GFS-40 SHOWS 1000 TO 850 THICKNESS
VALUES LOWERING BELOW 1300 METERS AT 12Z FRI BUT WARMING AGAIN
SAT.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...NONE
MARINE...SCA PKZ022-035>036-041>043-051-052
JT/JC