000
AXPZ20 KNHC 301605
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT APR 30 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 CENTERED ALONG 5N78W
5N91W 6N106W 5N121W 7N131W 6N140W. SCATTERED MODERATE/ISOLATED
CONVECTION IS NOTED WITHIN 180 NM N OF THE AXIS BETWEEN 122W-126W
...AND 120 N OF THE AXIS BETWEEN 113W-115W. SCATTERED MODERATE 
CONVECTION IS WITHIN 120 NM S OF THE AXIS BETWEEN 93W-97W AND 
FROM 4N-7N BETWEEN 105W-108W.

...DISCUSSION...

W OF 110W...
A WELL AMPLIFIED MID TO UPPER LEVEL RIDGE IS PRESENT N OF 25N 
ALONG 139W. IT IS AHEAD OF DEEP LAYER TROUGH MOVING TO THE N OF 
THE HAWAIIAN ISLANDS. THE RIDGE IS MAINTAINING STRONG SURFACE
HIGH PRES ACROSS THIS AREA. THE PRES GRADIENT BETWEEN THE RIDGE 
AND SURFACE TROUGHING ALONG THE NORTHERN BAJA CALIFORNIA AND
CALIFORNIA COASTS IS ALLOWING FOR A TIGHT PRES GRADIENT THERE
TO INDUCE NW WINDS OF 20 TO 25 KT N OF 23N E OF 118W TO THE COAST
OF CALIFORNIA. THESE WINDS ARE EXPECTED TO DIMINISH OVER THE
NEXT 24-30 HOURS AS THE RIDGE WEAKENS AND THE DEEP LAYER TROUGH
MOVES EASTWARD. THE PRES DIFFERENCE BETWEEN THE RIDGE AND LOWER 
PRES ALONG THE ITCZ IS ALLOWING FOR NE-E 20 KT TRADES TO EXIST N 
OF 18N W OF 118W. THIS AREA OF TRADES IS FORECAST TO SHRINK SOME 
IN AREAL COVERAGE IN 24 HOURS...AND BECOME SPORADIC IN COVERAGE 
BY 48 HOURS.
 
TO THE SOUTH...A SHORTWAVE TROUGH S OF 22N BETWEEN 120W AND 135W
IS AIDING THE ENHANCEMENT OF ITCZ CONVECTION BETWEEN 122W AND 
126W. THIS SHOULD CONTINUE THROUGH THE NEXT 36 TO PERHAPS 48 
HOURS.

E OF 110W...DIVERGENCE ALOFT BETWEEN AN UPPER ANTICYCLONE NEAR 
13N104W AND THE ABOVE SHORTWAVE TROUGH ALONG IS SUPPORTING A 
SURFACE TROUGH MOVING W ABOUT 7 KT IDENTIFIED ALONG 109W. WIDELY
SCATTERED SHOWERS AND TSTMS ARE WITHIN 120 NM E OF THE TROUGH.
E OF THE UPPER ANTICYCLONE...THE TAIL END OF DEEP LAYER TROUGH
EXTENDS SW FROM WESTERN CARIBBEAN TO ACROSS HONDURAS...AND SW
TO NEAR 4N98W. STRONG SUBSIDENCE THROUGHOUT THIS AREA IS 
INHIBITING CONVECTION THAT DEVELOPS TO BECOME TOO EXPANSIVE. 
ONLY ISOLATED TO WIDELY SCATTERED SHOWERS AND TSTMS ARE NOTED 
OVER THIS PORTION OF THE AREA ELSEWHERE N OF THE ITCZ. SCATTERED 
MODERATE CONVECTION EARLIER NOTED FROM 11N TO 12N BETWEEN 87W 
AND 90W IS RAPIDLY WEAKENING.

GAP WINDS...
N FLOW TO 20 KT WILL PUSH FROM THE SW CARIBBEAN THROUGH THE 
ISTHMUS OF PANAMA INTO THE GULF OF PANAMA THROUGH THE NEXT 6 
HOURS BEFORE DIMINISHING. NE WINDS TO 20 KT THROUGH THE GULF OF 
PAPAGAYO WILL PULSATED ON AND OFF THROUGH THE NEXT 48 HOURS...
WITH MAIN OCCURRENCES LATE AT TONIGHT WITH THE AID OF OVERNIGHT 
DRAINAGE INFLUENCE.

GULF OF CALIFORNIA...THE GRADIENT BETWEEN HIGH PRES OVER THE NE 
PACIFIC AND TROUGH OVER THE GULF OF CALIFORNIA AND NW MEXICO 
WILL ALLOW FRESH W TO NW FLOW TO COVER THE FAR NORTHERN GULF. 
SEAS WILL REMAIN BELOW 8 FT HOWEVER DUE TO FETCH LIMITATIONS.

$$
AGUIRRE