000
AXPZ20 KNHC 182021
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON AUG 18 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 
2000 UTC.

...TROPICAL WAVES...

NONE.

...ITCZ...

ITCZ IS ALONG THE LINE...09N84W TO 14N100W TO 12N117W TO 12N128W 
TO 09N140W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION 
IS WITHIN 180 NM OF THE AXIS BETWEEN 112W TO 123W AND WITHIN 210 
NM S OF AXIS BETWEEN82W TO 86W.

...DISCUSSION...

LOW...REMNANT OF ISELLE...LOCATED NEAR 19N117W WITH CENTRAL 
PRESSURE 1009 MB AND MOVING SLOWLY TO THE W. THE LOW LEVEL 
CIRCULATION CONTINUES TO BE WELL DEFINED WITH A QUIKSCAT PASS AT 
1340 UTC SHOWING WINDS IN EXCESS OF 25 KT WITHIN 150 NM NW 
QUADRANT. AN AREA OF SCATTERED MODERATE AND ISOLATED STRONG 
CONVECTION LIES WITHIN 210 NM W SEMICIRCLE. EASTERLY SHEAR OVER 
THE LOW HAS FOCUSED THE CONVECTION W OF THE CENTER AND THE 
REMNANT OF ISELLE IS EXPECTED TO SLOWLY DIMINISH OVER THE NEXT 
SEVERAL DAYS DUE TO THIS SHEAR AND COOLER SEA SURFACE 
TEMPERATURES AS IT MOVES W. CURRENTLY...UPPER LEVEL DIFFLUENCE 
IS GREATEST TO THE S OF THE ISELLE REMNANT WHERE SCATTERED 
MODERATE AND ISOLATED STRONG CONVECTION CAN BE FOUND BETWEEN 08N 
AND 15N BETWEEN 111W AND 123W. WIDESPREAD CONVECTION WILL BE 
MORE LIKELY TO TRACK W WITH THIS REGION OF BETTER DEFINED UPPER 
LEVEL DIFFLUENCE AS OPPOSED TO THE SURFACE LOW CENTER OVER THE 
NEXT DAY OR TWO.

A MID TO UPPER LEVEL TROUGH OVER NW WATERS IS EXPECTED TO LIFT 
NE INTO THE W COAST BUT LEAVE BEHIND AN UPPER LEVEL LOW THAT 
WILL RETROGRADE W OF 140W TUE INTO WED. AS THE TROUGH LIFTS 
OUT...THE ANTICYCLONE OVER NW MEXICO SHOULD PUSH W THROUGH THE 
BAJA ALONG 25N...CARRYING THE STRONG E FLOW ON ITS S EDGE 
FARTHER W INTO THE PACIFIC PRIMARILY BETWEEN 10N AND 20N E OF 
120W. VERTICAL SHEAR IS A FACTOR DUE TO THIS RELATIVELY STRONG E 
FLOW ALOFT AND THIS SHOULD ACT TO INHIBIT CONVECTION OVER THIS 
REGION. 

WEAK MID LEVEL SHORTWAVE ENERGY PASSING ALONG THE E AND 
SE EDGE OF THE ANTICYCLONE OVER MAINLAND MEXICO SHOULD HELP 
TRIGGER CONVECTION...ESPECIALLY WITH AFTERNOON HEATING...WITH 
DEBRIS POTENTIALLY BEING PUSHED W SW UNDER THE DOMINANT NE 
STEERING FLOW TOWARD THE COAST.

$$
SCHAUER CLARK