000
AXPZ20 KNHC 211542
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC WED APR 21 2010

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 
1500 UTC.

...ITCZ...

THE ITCZ AXIS EXTENDS FROM 06N77W TO 07N101W TO 06N114W TO 
07N122W TO 06N130W TO 04N140W. SCATTERED MODERATE TO STRONG 
CONVECTION WITHIN 150 NM EITHER SIDE OF AXIS BETWEEN 81W AND 
87W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 270 NM 
N OF AXIS AND 180 NM S OF AXIS BETWEEN 107W AND 120W. SCATTERED 
MODERATE TO STRONG CONVECTION WITHIN 90 NM N OF AXIS AND 150 NM 
S OF AXIS W OF 120W. 

...DISCUSSION...

AN UPPER TROUGH HAS ITS MEAN AXIS ALONG 30N121W TO 
17N127W...WITH SUBSIDENCE AND DRY UPPER LEVEL AIR W OF THE 
TROUGH AXIS. IN THE DEEP TROPICS...UPPER LEVEL RIDGING PREVAILS 
W OF 104W AND E OF 90W...AND IS BEING MAINTAINED BY LATENT HEAT 
RELEASE OF ITCZ CONVECTION. TROUGHING PREVAILS BETWEEN 90W AND 
104W WITH LIMITED ITCZ CONVECTION AND RESULTANT LACK OF LATENT 
HEAT RELEASE. 

AT THE SURFACE...STRONG HIGH PRESSURE 1034 MB IS CENTERED NEAR 
35N145W. THIS IS CREATING A TIGHT PRESSURE GRADIENT BETWEEN THE 
ITCZ...AND RESULTING IN A LARGE AREA OF 20 TO 25 KT NE TRADES 
OVER THE N AND W PART OF THE AREA. NW SWELLS WILL PROPAGATE SE 
THROUGH THE AREA MIXING WITH THE ASSOCIATED NEW NE SWELLS 
DEVELOPING IN THE LONG FETCH OF NORTHERLY 20 TO 25 KT WINDS. 
SOUTHERLY SWELLS ARE CROSSING THE EQUATOR BETWEEN 93W AND 135W 
MIXING WITH THE NE AND NW SWELL COMPONENTS.

WITH THE INCREASE IN NORTHEASTERLY TRADES...COMBINED WITH STRONG 
SOUTHEASTERLY TRADES FROM THE SOUTHERN HEMISPHERE...THERE IS 
ENHANCED MOISTURE CONVERGENCE INTO THE ITCZ...PARTICULARLY W OF 
121W. THIS IS RESULTING IN A SIGNIFICANT INCREASE IN ITCZ 
CONVECTION FROM THE PAST COUPLE OF DAYS. 

$$
AL/NELSON