000
AXPZ20 KNHC 021548
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON MAY 02 2011

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 
1545 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ANALYZED FROM 06N77W 
TO 05N86W TO 08N101W TO 02N140W. ISOLATED MODERATE AND STRONG 
CONVECTION IS DISSIPATING WITHIN 30 NM EITHER SIDE OF A LINE 
FROM 07N77W TO 06N93W AND IS INCREASING IN COVERAGE AND 
INTENSITY WITHIN AREA FROM 01N TO 05N BETWEEN 104W AND 115W. 
A LOW LEVEL TROUGH EXTENDS FROM 06N116W NE TO 11N114W WITH 
SCATTERED MODERATE ISOLATED STRONG CONVECTION FLARING WITHIN 120 
NM W OF TROUGH. NE WINDS AT 15 TO 20 KT ARE NOTED WITHIN ABOUT 
150 NM W OF THE TROUGH IN THE CONVECTION.  

...DISCUSSION...
AN UPPER CYCLONE IS FILLING NEAR 27N131W WITH AN UPPER TROUGH 
EXTENDING SE TO A BASE AT 01N121W. UPPER MOISTURE IS NOTED N OF 
25N WITHIN ABOUT 300 NM OF THE CYCLONE...BUT THE UPPER LEVELS 
APPEAR DRY WITHIN 150 NM EITHER SIDE OF THE UPPER TROUGH. A 
SECOND UPPER TROUGH IS NOTED ALONG 32N110W TO 26N108W 
ACCOMPANIED BY DRY UPPER AIR SPREADING SE OVER THE AREA N OF 27N 
BETWEEN 120W AND 105W. AN UPPER LEVEL ANTICYCLONE IS CENTERED AT 
10N96W WITH A RIDGE NW AND CRESTING AT 30N124W...WITH THE RIDGE 
SEPARATING THE TWO UPPER TROUGHS. UPPER DIFFLUENCE BETWEEN THE 
WESTERN UPPER TROUGH AND THIS RIDGE IS ENHANCING CONVECTION IN 
THE DEEP TROPICS S OF 11N BETWEEN 104W AND 120W INCLUDING THE 
CONVECTION ASSOCIATED WITH THE PREVIOUSLY MENTIONED LOW LEVEL 
TROUGH ALONG 15N. THE DEBRIS MOISTURE SPREADS N MERGING WITH 
ADDITIONAL UPPER MOISTURE NOTED UNDER THE UPPER RIDGE. SOME OF 
THIS MOISTURE IS SPREADING NE ACROSS OLD MEXICO AND FUELING 
CONVECTION OVER CENTRAL TEXAS. THIS PATTERN SHOULD SHIFT 
SLIGHTLY NORTHEASTWARD OVER THE NEXT 24 HOURS. 

A THIRD UPPER TROUGH ORIGINATES FROM AN UPPER CYCLONE OVER 
WESTERN CUBA AND EXTENDS SW ACROSS THE W CARIBBEAN AND CENTRAL 
AMERICA TO A BASE OVER THE TROPICAL PACIFIC AT 07N87W. AN UPPER 
RIDGE CONTINUES TO EXTEND NW FROM OVER COLOMBIA TO OVER PANAMA 
AND COSTA RICA. CONVECTION ALONG THE ITCZ FLARED LAST NIGHT JUST 
TO THE S OF THE BASE OF THE UPPER TROUGH...BUT IS NOW 
DECREASING. SOME OF THE DEBRIS MOISTURE SPREADS NE ACROSS COSTA 
RICA ALONG THE NW PERIPHERY OF THE RIDGE. THE UPPER LEVELS 
APPEAR VERY DRY ELSEWHERE S OF 20N E OF 100W.

AT THE LOW LEVELS A RIDGE EXTENDS FROM 32N134W TO 15N110W. THE 
LOW LEVEL FLOW HAS DECREASED OVER THE PACIFIC WATERS NE OF THE 
RIDGE...BUT IS INCREASING OVER THE WATERS SW OF THE RIDGE. AS 
THE RIDGE SHIFTS NE OVER THE NEXT 24 HOURS THE AREA OF NE TRADES 
S OF THE RIDGE WILL EXPAND EASTWARD. 
 
GULF OF CALIFORNIA...THE TIGHT PRESSURE GRADIENT IS SUPPORTING 
NW WINDS 20 TO 30 KT OVER THE ENTIRE GULF THIS MORNING AND IS 
EXPECTED TO DIMINISH TO 20 TO 25 KT EARLY TUE...AND CONTINUE TO 
DIMINISH TO LESS THAN 20 KT LATE TUE. MAXIMUM SEAS OF 9 FT ARE 
EXPECTED IN CENTRAL WATERS IN THE AREA OF THE LONGEST NW FETCH 
NEAR 26N110W...WITH SEAS SUBSIDING TO 5 FT OR LESS THROUGHOUT BY 
LATE TUE NIGHT.
   
GULF OF PAPAGAYO...NE TO E WINDS AT 20 TO 25 KT WILL CONTINUE TO 
PULSE THROUGH TUE IN THE AREA FROM 09N TO 12N E OF 92W.

GULF OF TEHUANTEPEC...NORTHERLY WINDS WILL BEGIN TO SURGE INTO 
THE NORTHERN GULF AT 20 KT AROUND SUNRISE TUE MORNING BUT 
QUICKLY INCREASE TO STRONG GALE FORCE TUE AFTERNOON. GALE 
CONDITIONS WILL CONTINUE THROUGH EARLY THU MORNING THEN 
DIMINISH. THERE IS POTENTIAL FOR THESE NORTHERLY WINDS TO REACH 
MINIMAL STORM FORCE BRIEFLY LATE TUE CONTINUING INTO EARLY WED. 
THIS IS SIGNIFICANT AS GALE EVENTS IN THE MONTH OF MAY ARE 
RARE...AND STRONG GALE AND MINIMAL STORM FORCE EVENTS ARE VERY 
RARE.   

$$
NELSON