000
AXPZ20 KNHC 172112
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SUN AUG 17 2008

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2045 UTC.

...TROPICAL WAVES...
NONE.

...ITCZ...
ITCZ IS ALONG THE LINE...09N83W TO 11N106W TO 11N132W TO 
09N140W. SCATTERED MODERATE CONVECTION WITHIN 120 NM N OF AXIS 
BETWEEN 89W AND 93W. SCATTERED MODERATE CONVECTION WITHIN 60 NM 
S OF AXIS BETWEEN 98W AND 101W...AND 103W AND 105W. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION WITHIN 180 NM N OF AXIS 
BETWEEN 110W AND 115W...AND BETWEEN 119W AND 125W.

...DISCUSSION...
EAST OF 110W...MORNING 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 19N114W 
WITH A PRESSURE ESTIMATED AROUND 1008 MB. SCATTEROMETER DATA 
SHOW WINDS AROUND 20 KT MAINLY WITHIN 120 NM IN THE NW 
SEMICIRCLE OF THE CENTER. THE LOW IS MOVING INTO COOLER WATER 
AND IS UNDER AN AREA OF EASTERLY SHEAR. MODERATE TO STRONG 
CONVECTION FORMED EARLY THIS AFTERNOON TO THE WEST AND DOWNSHEAR 
OF THE CENTER...FROM 18N TO 20N BETWEEN 115W AND 117W. WHILE 
CONVECTION WILL OCCUR OFF AN ON...THE LOW PRES 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 110W AND 
125W. 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