000
AXPZ20 KNHC 010308
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC MON AUG 01 2011

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0315 UTC.

...SPECIAL FEATURES...
TROPICAL STORM EUGENE CENTERED AT 11.3N 102.3 AT 01/0300 MOVING 
W-NW OR 285 DEGREES AT 9 KT WITH CENTRAL PRES 1002 MB.  MAXIMUM 
SUSTAINED WINDS 40 GUSTS TO 50 KT.  NUMEROUS STRONG CONVECTION 
WITHIN 120 NM SW AND 30 NM NE SEMICIRCLES.  SCATTERED MODERATE 
TO STRONG ELSEWHERE WITHIN 240 NM W SEMICIRCLE.  DEEP CONVECTION 
AROUND CENTER OF EUGENE UNDER DIVERGENT FLOW WITH LITTLE OR NO 
WIND SHEAR AS ANTICYCLONIC FLOW TRIES TO GET ESTABLISHED OVER 
REGION.  MID-LEVEL RIDGE STEERS EUGENE W-NW OVER NEXT FEW DAYS 
AS IT GRADUALLY STRENGTHENS OVER WARM E PAC SEA SURFACE 
TEMPERATURES AND EXPECTED TO REACH MINIMAL HURRICANE FORCE LATE 
TUE BEFORE ENTERING AREA WITH ADVERSE UPPER LEVEL ENVIRONMENT... 
COOLER SEA TEMPERATURES AND DRIER AIR MASS SAPPING ITS STRENGTH. 
SEE LATEST NHC PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS 
TCPEP5/WTPZ35 KNHC AND FULL FORECAST/ADVISORY UNDER AWIPS/WMO 
HEADERS TCMEP5/WTPZ25 FOR MORE DETAILS.

...ITCZ/MONSOON TROUGH...
MONSOON TROUGH AXIS EXTENDS FROM 111N86W TO 14N97W TO 13N100W 
THEN CONTINUES FROM 10N104W TO 09N107W TO 12N116W TO 1008 MB LOW 
PRES AT 11N120W TO 10N124W TO SECOND LOW PRES 1010 MB AT 11N131W 
THEN TO 09N140W.  SCATTERED MODERATE ISOLATED STRONG CONVECTION 
WITHIN 90 NM OF 11N121W AND WITHIN 120 NM OF AXIS W OF 127W.

...DISCUSSION...
LARGE AMPLITUDE UPPER LEVEL TROUGH DIGS INTO NW CORNER OF E PAC 
FROM 32N131W TO 23N140W SUPPORTING SURFACE TROUGH MENTIONED 
BELOW.  LARGE ANTICYCLONIC GYRE AT 21N123W COMBINES WITH TROUGH 
TO KEEP A VERY DRY AIR MASS OVER REGION N OF MONSOON TROUGH AND 
W OF 116W.  ILL-DEFINED UPPER LEVEL RIDGE TRYING TO ESTABLISH 
OVER EUGENE BRINGS UNUSUAL LARGE AREA OF NE WINDS ALOFT ACROSS E 
PAC S OF 10N AND A VERY MOIST MODERATE EASTERLY FLOW E OF 110W N 
OF 10N.  

ELSEWHERE AT THE LOW LEVELS...
WEAK SURFACE TROUGH FROM 32N124W TO 25N135W WEAKENS AS IT MOVES 
E AND DISSIPATES MON.  BROAD AND WEAKENING HIGH PRES CENTER 1030 
MB FOLLOWS IN WAKE OF TROUGH ESTABLISHES A MODERATE NE BREEZE  
FROM 10N-15N W OF 135W WHICH BECOME FRESH NE BREEZE LATE MON AND 
TUE. 

INCREASED PRES GRADIENT BETWEEN GULF OF MEXICO AND TROPICAL 
STORM EUGENE IN THE E PAC PROMPTING N FLOW ACROSS CHIVELAS PASS 
INTO GULF OF TEHUANTEPEC.  WINDS INCREASE A STRONG BREEZE BUT 
ARE SHORT-LIVED AS EUGENE DRIFT W AWAY FROM AREA. 

APPROACHING ATLANTIC TROPICAL WAVE N OF 12N ALONG 90W-91W 
EXPECTED TO BECOME CAUGHT IN MONSOON FLOW MON AND DISSIPATE.

$$
WALLY BARNES