000
AXPZ20 KNHC 040334
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU SEP 04 2008

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...ITCZ...

INTERTROPICAL CONVERGENCE ZONE...AXIS 12N86W TO 10N120W TO 
07N140W. SCATTERED MODERATE CONVECTION WITHIN 150 NM N OF AXIS 
BETWEEN 98W AND 110W.

...DISCUSSION...

TROPICS...
A WELL-DEFINED MONSOON TROUGH IS LOCATED OFFSHORE THE W COAST OF 
MEXICO...WITH THE ASSOCIATED LOW-LEVEL SW TO W WINDS REACHING AT 
LEAST AS FAR N AS 20N E OF 120W. THE TROUGH AXIS ITSELF EXTENDS 
ROUGHLY FROM THE REMNANTS OF TROPICAL DEPRESSION KARINA NEAR 
20.9N 114.6W SE THROUGH SOUTHWEST MEXICO TO NEAR THE CENTRAL 
PART OF THE OF THE HONDURAN/NICARAGUAN BORDER. THIS FEATURE HAS 
BEEN DOMINANT OVER THE TROPICAL EAST PACIFIC FOR MORE THAN A 
WEEK AND IS PARTLY A RESULT OF DEEP LOW PRESSURE OVER THE 
WESTERN PART OF THE ATLANTIC BASIN. THE MEAN POSITION OF THIS 
FEATURE OVER LAND HAS MADE TROPICAL CYCLOGENESIS OVER THE 
TROPICAL EAST PACIFIC LESS LIKELY SINCE LATE AUGUST. 
MOISTURE-LADEN AIR EMBEDDED WITHIN THIS FLOW AND CONVERGENCE 
ALONG THE TROUGH IS PRODUCING SCATTERED MODERATE AND ISOLATED 
STRONG CONVECTION ON THE WINDWARD SIDE OF THE HIGHER TERRAIN OF 
SOUTHWEST MEXICO AND ALONG 12N BETWEEN 98W AND 110W WHERE 
SOUTHERLY FLOW INTERSECTS SW TO W FLOW.

ELSEWHERE...8-9 FT S TO SW SWELLS FROM THE SOUTHERN HEMISPHERE 
CONTINUE TO ARRIVE OVER MUCH OF THE EASTERN PACIFIC BASIN... 
GENERALLY SW OF LINE FROM 12N140W TO 17N118W TO 30N120W. MODEL 
GUIDANCE SUGGESTS THAT THESE SWELLS WILL SUBSIDE SOME OVER THE 
NEXT 24 HRS BUT A NEW SWELL TRAIN WILL CROSS THE EQUATOR BY FRI 
MORNING...WITH SEAS REBUILDING AGAIN TO 8-11 FT BY SAT.

SUBTROPICS...
THE REMNANTS OF TROPICAL DEPRESSION KARINA ARE LOCATED NEAR 
20.9N 114.6W...OR ABOUT 280 NM WSW OF CABO SAN LUCAS MEXICO... 
WITH A PRESSURE OF 1006 MB DRIFTING SLOWLY NE TO E. EARLIER THIS 
EVENING SATELLITE IMAGERY INDICATED A NEW BURST OF CONVECTION 
FORMING ABOUT 80 NM W OF THE CIRCULATION CENTER. SINCE THEN... 
THE STRONG EASTERLY SHEAR OF AROUND 25 KT HAS STRIPPED THE 
CONVECTION EVEN FARTHER AWAY FROM THE CENTER...WITH WHAT IS LEFT 
WINDING DOWN WELL TO THE WNW.

OTHERWISE...A MID- TO UPPER-LEVEL ANTICYCLONE IS CENTERED OVER 
THE MOUTH OF THE GULF OF CALIFORNIA WITH THE ASSOCIATED AXIS 
EXTENDING ALONG 23N TO 24N E OF 130W INTO NORTHERN MEXICO. TO 
THE W...AN UPPER TROUGH LIES ACROSS THE NW PART OF THE REGION 
FROM 30N135W TO 20N140W...AND BOTH FEATURES ARE PRODUCING MOSTLY 
MODERATE/STRONG SUBSIDENCE ACROSS THE REGION. THE TWO EXCEPTIONS 
ARE AREAS OF MOISTURE ASSOCIATED WITH THE CONVECTION DEVELOPING 
OVER THE HIGH TERRAIN OF NW MEXICO AND THE REMNANTS OF TROPICAL 
DEPRESSION KARINA. A MODEST JET LIES BETWEEN THE UPPER RIDGE AND 
TROUGH...EXTENDING NE OF 27N130W WITH WIND SPEEDS OF 40-50 KT 
SPREADING ACROSS NW MEXICO AND THE DESERT SW.

EARLIER GALES OFF THE CALIFORNIA COAST HAVE PRODUCED 8 TO 10 FT 
N TO NE SWELLS WHICH CONTINUE TO PROPAGATE INTO THE NW THIRD OF 
THE AREA. NE WINDS OF UP TO 20 KT ARE ALSO BLOWING OVER A 
PORTION OF THIS AREA...GENERALLY NW OF A LINE FROM 23N140W TO 
30N125W. THESE SWELLS ARE EXPECTED TO SUBSIDE WITHIN THE NEXT 24 
TO 48 HOURS...WITH ONLY A SMALL AREA OF SWELLS GREATER THAN 8 FT 
CONTINUING OVER THE FAR NW PART.

$$
KIMBERLAIN/BERG