000
AXPZ20 KNHC 011546
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN MAY 01 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 05N77W 
TO 02N96W TO 05N119W TO 02N135W TO 03N140W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION IS OBSERVED WITHIN 90 NM EITHER SIDE 
OF A LINE FROM 06N77W TO 02N100W AND ALSO DISSIPATING WITHIN 150 
NM OF 05N112W. A LOW LEVEL TROUGH EXTENDS FROM 10N108W TO 
06N116W WITH SCATTERED MODERATE ISOLATED STRONG CONVECTION 
FLARING WITHIN 240 W OF TROUGH. NE WINDS AT1 5 TO 20 KT ARE 
NOTED WITHIN ABOUT 240 NM W OF THE TROUGH IN THE CONVECTION.  

...DISCUSSION...
AN UPPER CYCLONE IS NEAR 28N133W WITH AN UPPER TROUGH EXTENDING 
S TO A BASE AT 13N134W. A SECOND UPPER TROUGH IS NOTED ALONG 
32N112W TO 21N108W. AN UPPER LEVEL ANTICYCLONE IS CENTERED AT 
10N100W WITH A RIDGE N TO 28N124W EFFECTIVELY SEPARATING THE 
UPPER TROUGHS. UPPER DIFFLUENCE IS ENHANCING CONVECTION ALONG 
THE ITCZ BETWEEN 108W AND 121W...WITH THE DEBRIS MOISTURE 
SPREADING NE...BUT MOSTLY EVAPORATING ALONG A NARROW PLUME OVER 
EASTERN OLD MEXICO. ADDITIONAL UPPER MOISTURE IS NOTED ELSEWHERE 
UNDER THE UPPER RIDGE...IN THE AREA BOUNDED BY 10N TO 25N 
BETWEEN 115W AND 133W...AND ALSO ROTATING AROUND THE UPPER 
CYCLONE AT 28N133W. A LARGE AREA OF UPPER DRY AIR IS OBSERVED N 
OF 22N BETWEEN 118W AND 103W. THIS PATTERN SHOULD SHIFT SLIGHTLY 
EASTWARD OVER THE NEXT 24 HOURS. 

A THIRD UPPER TROUGH EXTENDS SW ACROSS THE W CARIBBEAN AND 
CENTRAL AMERICA AND OVER THE AREA FROM 12N87W TO 04N89W. AN 
UPPER RIDGE EXTENDS NW FROM OVER COLOMBIA TO OVER PANAMA. THE 
ITCZ IS FLARING OVER THE DEEP TROPICS FROM COLOMBIA TO 
02N100W...BUT THE DEBRIS MOISTURE QUICKLY EVAPORATES AS THE 
UPPER LEVELS APPEAR VERY DRY S OF 20N BETWEEN 103W AND 80W. 
LITTLE CHANGE EXPECTED OVER THE NEXT 24 HOURS.    

AT THE LOW LEVELS A RIDGE EXTENDS FROM 32N130W TO 13N108W. THE 
LOW LEVEL NORTHERLY FLOW ALONG THE W COAST OF THE BAJA 
CALIFORNIA PENINSULA HAS DIMINISHED TO 15 TO 20 KT THIS MORNING.
N TO NE WINDS 15 TO 20 KT AND SEAS 8 TO 11 FT IN MIXED NORTHERLY 
SWELL IS NOTED OVER THE PACIFIC WATERS NW OF LINE FROM THE 
CENTRAL BAJA PENINSULA TO NEAR 15N140W. WINDS AND SEAS ARE 
EXPECTED TO DIMINISH SOME OVER THE NEXT 24 HOURS...BUT THEN 
RESTRENGTHEN AGAIN MON NIGHT INTO TUE. 

GULF OF CALIFORNIA...TIGHT PRESSURE GRADIENT IS SUPPORTING NW 
WINDS 20 TO 25 KT OVER THE NORTHERN GULF AND EXPECTED TO 
INCREASE TO 20 TO 30 KT AND SPREAD S OVER THE SOUTHERN WATERS 
TONIGHT. SEAS WILL BUILD TO NEAR 9 FT IN CENTRAL WATERS IN THE 
AREA OF THE LONGEST NW FETCH. THE GRADIENT WILL BEGIN TO RELAX 
EARLY TUE.
   
GULF OF PAPAGAYO...NE TO E WINDS AT 20 TO 25 KT WILL CONTINUE 
THROUGH TUE IN THE AREA FROM 09N TO 12N E OF 92W.

GULF OF TEHUANTEPEC...NORTHERLY WINDS AT 20 KT WILL BEGIN TO 
SURGE INTO THE AREA TUE MORNING AND QUICKLY INCREASE TO GALE 
FORCE LATE TUE... CONTINUING THROUGH WED NIGHT.

$$
NELSON