000
AXPZ20 KNHC 281548
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU APR 28 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 
1515 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS ANALYZED FROM 08N82W TO 
05N92W TO 08N110W TO 02N138W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION NOTED FROM 03N TO 08N E OF 86W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION NOTED WITHIN 150 NM N AND 180 NM S OF 
AXIS FROM 100W TO 115W. SCATTERED MODERATE CONVECTION NOTED 
WITHIN 60 NM OF AXIS W OF 115W.

...DISCUSSION...
A COMPLEX UPPER LEVEL PATTERN PREVAILS ACROSS THE TROPICAL AND 
SUBTROPICAL PACIFIC W OF 125W THIS MORNING. E OF 125W...A BROAD 
AND FLAT UPPER RIDGE PREVAILS N OF 20N...EXTENDING E INTO THE 
GULF OF MEXICO. S OF 20N...ACTIVE TROPICAL CONVECTION ACROSS NRN 
S AMERICA AND W INTO THE EPAC IS HELPING TO MAINTAIN UPPER 
RIDGING BETWEEN THE EQUATOR AND 20N FROM COLOMBIA W TO 120W. AN 
UPPER LEVEL RIDGE ALONG 145W AND N OF 30N OVER THE N CENTRAL 
PACIFIC WILL STRENGTHEN AS IT SHIFTS EAST THROUGH 48 HOURS. THIS 
WILL ACT TO REINFORCE A 1030 MB SURFACE CURRENTLY NEAR 42N145W 
AS IT SHIFTS EASTWARD. SCATTEROMETER DATA FROM 05Z LAST NIGHT 
WAS ALREADY SHOWING 20 KT TRADES S OF THE ADVANCING HIGH PRES 
GENERALLY N OF 22N...AND THESE WINDS WILL INCREASE SLIGHTLY AND 
SPREAD SE AS THE HIGH PRES BUILDS INTO THE LOCAL AREA. SIMILARLY 
FRESH NW TO N WINDS OFF THE NORTHERN BAJA COAST WILL PERSIST AND 
INCREASE TO 20 TO 25 KT THROUGH SAT. SEAS ALONG THE OFFSHORE 
WATERS OF THE UPPER BAJA PENINSULA WILL BUILD TO 13 FT IN N 
SWELL IN THE AREA N OF 24N E OF 122W.

FURTHER EAST...LIGHT AND VARIABLE WINDS CONTINUES ACROSS THE 
TROPICAL EPAC E OF 120W...WITH WEAK MONSOONAL FLOW E OF 90W. GAP 
WIND FLOW TO 20 KT WILL BEGIN THU NIGHT THROUGH THE GULF OF 
TEHUANTEPEC AS A WEAK COLD FRONT MOVES INTO THE SW GULF OF 
MEXICO...AND INCREASE TO NEAR 30 KT FRI MORNING  BEFORE QUICKLY 
DIMINISHING BELOW 20 KT BY LATE FRI AS THE AIRMASS TO THE NORTH 
MODIFIES AND SHIFTS E. FRESH TRADES OVER THE SW CARIBBEAN WILL 
ALSO ENHANCE FLOW THROUGH THE GULF OF PAPAGAYO BY LATE THU AND 
CONTINUE INTO FRI. CONVECTION ALONG AND NEAR THE ITCZ HAS 
INCREASED OVERNIGHT AND WAS ACTIVE W OF 100W...WHERE MODERATE 
LOW LEVEL CONFLUENCE WAS PROVIDING AMPLE TROPICAL MOISTURE AND 
FORCING.   

$$
STRIPLING