000
AXPZ20 KNHC 151625
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI AUG 15 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 
1500 UTC.

...SPECIAL FEATURE...

TROPICAL STORM ISELLE AT 17.7N 111.4W 1004 MB AT 1500 UTC MOVING 
W NW OR 285 DEG AT 04 KT. MAXIMUM SUSTAINED WIND 35 TO 45 KT. 
SCATTERED MODERATE CONVECTION IS WITHIN 150 NM W QUADRANT WITH 
ISOLATED MODERATE ALSO FOUND S OF THE SYSTEM TO 12N BETWEEN 110W 
AND 116W. ISELLE IS FORECAST TO BECOME A TROPICAL DEPRESSION 
TODAY AS COOL SEA SURFACE TEMPERATURES CUT OFF ITS SOURCE OF 
HEAT AND MODERATE EASTERLY SHEAR TAKE ITS TOLL AGAINST THE DEEP 
CONVECTION. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO 
HEADER MIATCMEP5/WTPZ25 KNHC FOR MORE DETAILS.

...TROPICAL LOW...

LOW PRES 14N121W 1011 MB MOVING W AT 5 KT. MODERATE CONVECTION 
CAN BE FOUND WITHIN 90 NM W QUADRANT. DEVELOPMENT OF THIS SYSTEM 
IS NOT EXPECTED.

...TROPICAL WAVES...

TROPICAL WAVE ALONG 108W FROM 05N TO 14N MOVE W 15 KT. NO 
CONVECTION IS NEAR THE WAVE AXIS. DEVELOPMENT OF THIS SYSTEM IS 
NOT EXPECTED.

TROPICAL WAVE ALONG 98W FROM 05N TO 15N MOVE W 12 KT. SCATTERED 
MODERATE TO ISOLATED STRONG CONVECTION CAN BE FOUND WITHIN 210 
NM W OF THE WAVE AXIS N OF 07N AND WITHIN 180 NM E OF THE AXIS N 
OF 14N. DEVELOPMENT OF THIS SYSTEM IS NOT EXPECTED.

...ITCZ...

ITCZ AXIS IS ALONG THE LINE 05N77W TO 08N96W TO 09N111W TO 
08N124W TO 07N140W. SCATTERED MODERATE TO ISOLATED STRONG 
CONVECTION CAN BE FOUND WITHIN 180 NM OF THE AXIS E OF 90W AND
FROM 96W TO 104W. WIDELY SCATTERED MODERATE CONVECTION IS NOTED 
WITHIN 120 NM EITHER SIDE OF THE AXIS FROM 95W TO 103W AND FROM 
117W TO 130W.

...DISCUSSION...

THE UPPER LEVEL MEAN TROUGH OVER NW WATERS IS EXPECTED TO 
MAINTAIN ITSELF NEAR 130W AS REINFORCING SHORTWAVE ENERGY MOVES 
SW FROM THE N CENTRAL PACIFIC PASSING N OF THE AREA TOWARD THE 
MEAN TROUGH AXIS OVER THE NEXT 2 DAYS. THIS TROUGHING WILL HELP 
STEER THE LOW NEAR 14N121W N OF W AND INTO AN ENVIRONMENT OF 
INCREASING VERTICAL SHEAR AND COOLER SEA SURFACE TEMPERATURES 
OVER THE NEXT FEW DAYS.  

STRONG E UPPER LEVEL FLOW ON THE S EDGE OF THE UPPER ANTICYCLONE 
CENTERED OVER NW MEXICO CAN BE FOUND OVER MUCH OF THE REGION 
WITH THE MOST ABUNDANT TROPICAL MOISTURE E OF 120W BETWEEN 13N 
AND 20N. THE VERTICAL SHEAR INDUCED BY THESE STRONG UPPER LEVEL 
WINDS IS CONTRIBUTING TO THE WEAKENING OF T.S. ISELLE AS WELL AS 
INHIBITING CONVECTION WITH THE TROPICAL WAVES OVER THE REGION.  

MODERATE TO STRONG CONVECTION CAN BE FOUND NEAR THE MOUTH OF THE 
GULF OF CALIFORNIA WITHIN 120 NM OF THE MAINLAND MEXICAN COAST 
BETWEEN BETWEEN 23N AND 26N. THE SMALL MID LEVEL SHORTWAVE 
SYSTEM TRIGGERING THIS CONVECTION IS CURRENTLY PASSING JUST S OF 
THE UPPER LEVEL ANTICYCLONE CENTER IN A REGION OF LIGHTER 
VERTICAL SHEAR AND ABUNDANT MOISTURE IN PLACE DUE TO THE EARLIER 
SOUTHERLY LOW LEVEL FLOW E OF ISELLE. EXPECT CONVECTION TO 
DISSIPATE AS THE SYSTEM PASS NW.

$$
SCHAUER CLARK