000
AXPZ20 KNHC 150349
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI AUG 15 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 
0315 UTC.

...SPECIAL FEATURE...
TROPICAL STORM ISELLE AT 17.7N 111.1W 1002 MB AT 0300 UTC MOVING 
W OR 280 DEG AT 8 KT.  MAXIMUM SUSTAINED WIND 40 TO 50 KT. 
MODERATE TO STRONG CONVECTION WITHIN 120 NM S AND 45 NM N 
SEMICIRCLES.  ISELLE FORECAST TO REMAIN TROPICAL STORM AT LEAST 
24 HRS BEFORE COOL SEA SURFACE TEMPERATURES CUT OFF ITS SOURCE 
OF HEAT AND MODERATE ELY 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 LOWS...
LOW PRES 1010 MB 15N121W AT 1010 MB MOVING W-NW AT 8 KT.  NO SO 
UNFAVORABLE UPPER LEVEL ENVIRONMENT HAS ALLOWED BURSTS OF DEEP 
CONVECTION AROUND OTHERWISE DESOLATE LOW LEVEL CENTER...BUT 
SHORT MOMENTS OF STRONG WINDS HAVE BEEN NOTED FOR LAST 30-36 HRS 
WITH THIS SYSTEM.  NUMEROUS STRONG CONVECTION WITHIN 120 NM W 
QUADRANT AT PRESENT SHOULD WEAKEN IN INTENSITY AND COVERAGE NEXT 
24 HRS AS MODERATE TO STRONG ELY WIND SHEAR CURTAIL CLOUD HEIGHT.

REMNANT LOW PRES OF HERNAN W OF 140W ONLY HAVE LINGERING AND 
SUBSIDING SEAS W OF 137 FROM 15N-19N. EFFECTS SHOULD NOT LAST 
BEYOND 24 HRS.  

...TROPICAL WAVES... 
TROPICAL WAVE ALONG 105W FROM 05N-15N MOVING W AT 15 KT HAS 
SCATTERED MODERATE CONVECTION WITHIN 120 NM OF AXIS JUST N OF 
ITCZ.  SYSTEM DEEP CONVECTION IS GROWTH CURTAILED BY CONVERGING 
OUTFLOW FROM ISELLE AND ELY FLOW FROM UPPER LEVEL RIDGE JUST N 
OF WAVE.  LITTLE POTENTIAL FOR GROWTH FOR SYSTEM. 

TROPICAL WAVE ALONG 95W N OF 03N MOVING W AT 15 KT HAS SCATTERED 
MODERATE CONVECTION WITHIN 150 NM W OF AXIS FROM 08N TO 12N.  
SYSTEM UNDER MODERATE NELY WIND SHEAR SHOULD HAVE HARD TIME 
DEVELOPING SIGNIFICANT DEEP CONVECTION WITHIN NEXT 24-36 HRS OR 
AS LONG AS IT REMAINS UNDER THIS POOR SUPPORT ALOFT. 

...ITCZ...
ITCZ AXIS LIES ALONG 08N78W TO 07N80W TO 12N106W TO 09N123W TO 
12N135W TO 09N140W.  SCATTERED MODERATE ISOLATED STRONG 
CONVECTION WITHIN 120 NM N AND 45 NM S OF AXIS E OF 101W.

...DISCUSSION...
UPPER LEVEL TROUGH OVER NW E PAC WATERS FROM 32N122W TO 20N130W 
GETTING SQUEEZED BY RIDGES CENTERED ON BOTH SIDES...ONE CENTERED 
AT 21N140W AND ANOTHER AT 27N105W.  LARGE AREA OF SUBSIDING AIR 
MASS KEEP VERY DRY E PAC N OF 15N W OF 120W.  REINFORCED UPPER 
RIDGE EXTENDS FROM GULF OF MEXICO ACROSS MEXICO AND BAJA 
CALIFORNIA 15N125W.  

ABUNDANT TROPICAL MOISTURE ADVECTED BY MODERATE ELY FLOW FEEDING 
WATER INTO TROPICAL WAVES...BUT LACKING UPPER SUPPORT CURTAILS 
THEIR DEVELOPMENT AS NOTED ABOVE. 

$$
WALLY BARNES