000
AXPZ20 KNHC 162136
TWDEP 

TROPICAL WEATHER DISCUSSION      
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED MAY 16 2012

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...SPECIAL FEATURE...
TROPICAL STORM ALETTA IS CENTERED NEAR 11.4N 113.5W AT 16/2100 
UTC MOVING W OR 270 DEG AT 8 KT. ALETTA IS EXPECTED TO MOVE WNW 
DURING THE NEXT 24 HOURS. ESTIMATED MINIMUM CENTRAL PRES 1004 MB.
MAXIMUM SUSTAINED WINDS 35 KT GUSTS TO 45 KT. PLEASE REFER TO 
THE LATEST PUBLIC ADVISORY TCPEP1/WTPZ31 KNHC FOR MORE DETAILS. 
SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 90 NM NE AND 
60 NM SW SEMICIRCLES. A GRADUAL WEAKENING IS FORECAST DURING THE 
NEXT 48 HOURS AS VERTICAL SHEAR INCREASES AND DRY AIR APPROACHES.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH EXTENDS FROM 07N78W TO LOW PRES NEAR 11N98W 1008 
MB TO 12N108W. ITCZ EXTENDS FROM 06N118W TO 03N140W. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION FROM 11N TO 14N BETWEEN 97W 
AND 104W. SCATTERED MODERATE CONVECTION WITHIN 45 NM OF ITCZ W 
OF 130W.

...DISCUSSION...
AN ACTIVE MONSOON TROUGH E OF 115W IS ANCHORED BY TS ALETTA NEAR 
11.4N 113.5W AND A DEVELOPING LOW PRES AREA CENTERED NEAR 11N98W.
A BROAD UPPER LEVEL ANTICYCLONE CENTERED NEAR 13N91W IS ENHANCING
THE DEEP CONVECTION E OF 115W. A WEAK HIGH PRES RIDGE EXTENDING 
FROM 35N136W TO AROUND 22N115W IS SUPPORTING FRESH NW WINDS N OF 
28N W OF THE BAJA PENINSULA...WITH NLY SWELL MAINTAINING SEAS OF 
7-8 FT IN NE PORTION OF THE DISCUSSION AREA. NE TRADE WINDS W OF 
115W ARE RELATIVELY WEAK AT 10-15 KT...AND ARE EXPECTED TO REMAIN
GENTLE TO MODERATE THROUGH THE WEEKEND DUE TO A WEAK SUBTROPICAL 
RIDGE N OF 30N AND NORMAL PRESSURE IN THE NEAR-EQUATORIAL TROUGH.

HIGH PRES BUILDING SOUTHWARD ALONG THE GULF COAST OF MEXICO WILL 
INDUCE 20-25 KT N-NE WINDS INTO THE GULF OF TEHUANTEPEC TODAY 
THROUGH EARLY FRI.

IN THE LONG TERM...THE AREA OF LOW PRES NEAR 11N98W IS EXPECTED 
TO SLOWLY INTENSIFY THROUGH SUN. THIS DISTURBANCE CURRENTLY HAS 
A MEDIUM CHANCE...30 PERCENT...OF BECOMING A TROPICAL CYCLONE 
WITHIN THE NEXT 48 HOURS. GLOBAL MODELS SHOW STRONG DEEPENING OF 
THE LOW SUN NIGHT AND MON AS A SECOND SURGE OF N-NE WINDS FROM 
THE GULF OF TEHUANTEPEC GIVES ADDED VORTICITY TO THE PRE-EXISTING
CIRCULATION. 

$$
MUNDELL