000
AXPZ20 KNHC 140351
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU AUG 14 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 
0300 UTC.

...SPECIAL FEATURE...
TROPICAL STORM ISELLE AT 16.6N 106.7W AT 0300 UTC WITH MAXIMUM 
SUSTAINED WIND AT 35 GUSTS TO 45 KT.  ISELLE CENTRAL PRES IS 
1003 MB MOVING W-NW OR 285 DEGREES AT 09 KT.  NUMEROUS MODERATE 
STRONG CONVECTION WITHIN 45 NM OF CENTER AND SCATTERED MODERATE 
CONVECTION ELSEWHERE WITHIN 240 NM SW SEMICIRCLE.  ISELLE 
FORECAST TO MOVE W NW OVER THE NEXT 48 HOURS. SEE THE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMEP5/WTPZ24 KNHC 
FOR MORE DETAILS.

...TROPICAL LOWS...
LOW PRES 1012 MB...REMNANT OF HERNAN...AT 17N137W.  NO DEEP 
CONVECTION LEFT AS AIR MASS IS EXTREMELY DRY AND COOL WATER 
TEMPERATURES MAINTAINS STABLE ATMOSPHERE.  WEAK CIRCULATION  
SHOULD CROSS 140W AND EXIT E PAC WITHIN NEXT 36 HRS. 

LOW PRES SYSTEM 1010 MB AT 14N119W WITH SCATTERED MODERATE 
ISOLATED STRONG CONVECTION WITHIN 210 NM W QUADRANT.  SYSTEM IS 
STILL UNDER FAVORABLE UPPER LEVEL ENVIRONMENT BUT STRUGGLES 
AGAINST COOL WATER TEMPERATURES AND STABLE AIR MASS.  SOME DEEP 
CONVECTION MIGHT STILL BURST OUT OF SYSTEM NEXT 24-36 HRS DUE TO 
INCREASED UPPER DIFFLUENCE BUT SHOULD BE SHORT LIVED. 

...TROPICAL WAVES... 
TROPICAL WAVE ALONG 98W MOVING W AT 20 KT HAS LITTLE DEEP 
CONVECTION ASSOCIATED WITH IT AND NO CYCLONIC ORGANIZATION AT 
THIS TIME.  SYSTEM UNDER MODERATE NE WIND SHEAR WHICH EXPECTED 
TO DECREASE AS WAVE PULLS AWAY FROM ANTICYCLONE CENTERED OVER 
BIG BEND TEXAS.

TROPICAL WAVE ALONG 88W MOVING W AT 18 KT HAS SCATTERED DEEP 
CONVECTION OVER HONDURAS...EL SALVADOR AND GUATEMALA.  MAXIMUM 
DAYTIME HEATING AND SLIGHTLY FAVORABLE UPPER ENVIRONMENT 
ENHANCED ITS ACTIVITY.  SYSTEM SHOULD LOSE SOME UPPER SUPPORT 
WITHIN NEXT 24 HRS AS IT MOVES INTO AREA OF STRONGER ELY SHEAR  
...BUT LIKELY REGAIN IT AGAIN AS ANTICYCLONE DRIFT E DECREASING 
SUCH SHEAR.

...ITCZ...
ITCZ AXIS ALONG 09N83W TO 13N114W TO 14N131W 10N140W. SCATTERED 
MODERATE CONVECTION WITHIN 180 NM OF AXIS FROM 105W-113W.  
ISOLATED MODERATE CONVECTION WITHIN 90 NM S OF AXIS E OF 87W. 

...DISCUSSION...
LONGWAVE UPPER TROUGH  ENTERS E PAC NW CORNER WITH VERY DRY AIR 
MASS DUE TO STRONG SUBSIDENCE WITHIN 3-5 DEG FROM AXIS.  TROUGH 
WILL TRACK E FOR NEXT 24 HRS FORCING ANTICYCLONE CENTERED OVER 
TEXAS BIG BEND TO DISPLACE EWD.  BUT EVENTUALLY RIDGE WILL 
PREVAIL DISPLACING TROUGH NE AND REESTABLISHING ITSELF AGAIN 
OVER NRN MEXICO.  RIDGE E MOVE ALLOWS UPPER ELY WIND SHEAR TO 
DECREASE OVER CYCLONIC SYSTEMS AND TROPICAL WAVES NOW UNDERWAY  
E OF 110W ALLOWING MINOR STRENGTHENING BEFORE IT REBUILDS.  

UPPER LEVEL CYCLONIC VORTEX AT 26N120W OUGHT TO BE SWEPT BY 
LONGWAVE TROUGH NE SHIFT.  AIR MASS VERY DRY AND STABLE W OF 
128W WHILE MOISTURE IS ABUNDANT E OF 115W DUE TO ADVECTION BY 
TEXAS UPPER RIDGE.   

ELSEWHERE AT THE SURFACE...
BROAD HIGH PRES CENTER 1022 MB AT 34N138W HAS RIDGE EXTEND TO 
19N110W CAPPING CLOUD DEVELOPMENT UNDER ITS COVERAGE.    

$$
WALLY BARNES