000
AXPZ20 KNHC 171549
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN AUG 17 2008

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1545 UTC.

...TROPICAL WAVES...
NONE.

...ITCZ...
ITCZ IS ALONG THE LINE...08N78W TO 10N105W TO 11N115W TO 
09N140W. SCATTERED MODERATE TO STRONG CONVECTION WITHIN 120-150 
NM N OF THE AXIS BETWEEN 87W AND 92W...113W AND 116W...AND 
BETWEEN 120W AND 124W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION ELSEWHERE WITHIN 180 NM N OF THE AXIS BETWEEN 105W 
AND 125W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 
60 NM EITHER SIDE OF AXIS W OF 132W.

...DISCUSSION...
EAST OF 110W...QUIKSCAT AND SHIP OBSERVATIONS SHOW MODERATE SW 
FLOW S OF THE ITCZ...ENHANCING MODEST SHOWERS S OF PANAMA. A 
LINE OF CONVECTION IS NOTED PARALLEL TO THE CENTRAL AMERICAN 
COAST APPROXIMATELY OFFSHORE AROUND 120 NM. THIS IS MOSTLY DUE 
TO LOW LEVEL CONVERGENCE OF THE SW WINDS WITH NOCTURNAL DRAINAGE 
OFF THE COAST...BUT IT IS ALSO IN AN AREA OF WEAK EAST SHEAR 
ALOFT...SOUTH OF AN UPPER LOW CENTERED OVER THE NW CARIBBEAN OFF 
BELIZE. FURTHER WEST...A BROAD UPPER ANTICYCLONE CENTERED OVER 
NORTH CENTRAL MEXICO CONTINUES TO PROVIDE STRONGER EASTERLY 
SHEAR ACROSS THE AREA MAINLY S OF 20N AND W OF 100W. 
MEANWHILE...SOUTHERLY SWELL OF UP TO 6 FT WITH PERIODS TO 17S 
ARE EXPECTED TO MOVE INTO THE COSTA RICAN AND PANAMANIAN COASTS 
STARTING LATE MONDAY.

WEST OF 110W...THE REMNANT OF ISELLE IS LOCATED NEAR 19N113W 
WITH A PRESSURE ESTIMATED AROUND 1007 MB. SCATTEROMETER DATA 
SHOW WINDS ON THE WEST SIDE OF THE STORM AROUND 20 KT. THE LOW 
IS MOVING INTO COOLER WATER AND IS UNDER AN AREA OF EASTERLY 
SHEAR. NO CONVECTION IS NOTED WITH THE LOW...AND IT IS EXPECTED 
TO CONTINUE TO WEAKEN OVER THE NEXT COUPLE OF DAYS. WESTERLY 
SURFACE FLOW TO THE SOUTH OF THE LOW IS NOTED IN QUIKSCAT AS 
WELL...CONVERGING WITH SW FLOW S OF THE ITCZ. THE STRONGER LOW 
LEVEL CONVERGENCE ALONG WITH WEAKENING UPPER SHEAR ON THE SW 
SIDE OF THE UPPER ANTICYCLONE TOGETHER ARE ENHANCING STRONGER 
CLUSTERS OF CONVECTION ALONG THE ITCZ GENERALLY BETWEEN 112W AND 
124W. DRY DEEP LAYERS INHIBIT ANY ORGANIZED CONVECTION W OF 
125W. FURTHER NORTH...AN UPPER TROUGH IS DIGGING SOUTH OF 30N W 
OF 130W...PUSHING AN ASSOCIATED COLD FRONT INTO THE AREA BUT NO 
APPRECIABLE INCREASE IN WINDS OR SEAS.

$$
CHRISTENSEN