000
AXPZ20 KNHC 152138
TWDEP 

TROPICAL WEATHER DISCUSSION      
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE MAY 15 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 CENTERED NEAR 11.2N 110.4W AT 15/2100 UTC 
MOVING W OR 280 DEG AT 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE 
1003 MB. MAXIMUM SUSTAINED WIND SPEED 40 KT GUSTS TO 50 KT. 
LITTLE CHANGE IN MOTION AND INTENSITY EXPECTED THE NEXT 24 HOURS.
PLEASE REFER TO THE LATEST PUBLIC ADVISORY TCPEP1/WTPZ31 KNHC 
FOR MORE DETAILS. SCATTERED MODERATE TO STRONG CONVECTION IS 
WITHIN 180 NM N SEMICIRCLE. ALETTA IS EXPECTED TO PEAK AT AROUND 
45 KT WITHIN THE NEXT 12 TO 24 HOURS THEN WEAKEN AS INCREASED SW 
VERTICAL SHEAR INHIBITS FURTHER DEVELOPMENT.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM 11N86W TO 11N92W TO 08N98W TO 
12N106W...THEN RESUMES W OF T.S. ALETTA NEAR 08N111W TO 1008 MB 
LOW PRES NEAR 05N126W. ITCZ EXTENDS FROM 05N126W TO 02N140W. 
SCATTERED MODERATE TO STRONG CONVECTION IS FROM 07N TO 13N 
BETWEEN 86W AND 98W.

...DISCUSSION...
ACTIVE MONSOON TROUGH E OF 125W DOMINATES THE TROPICAL NE PACIFIC
THIS AFTERNOON. IN ADDITION TO TS ALETTA CHURNING AWAY NEAR 110W
A LOW NEAR 05N126W AND A BROAD CYCLONIC CIRCULATION CENTERED NEAR
10N96W ARE ACTING AS ANCHORS FOR AN UNUSUALLY ACTIVE START TO THE
2012 EASTPAC HURRICANE SEASON...WHICH OFFICIALLY BEGAN TODAY. A 
BROAD UPPER LEVEL ANTICYCLONE CENTERED NEAR 11N91W IS PROVIDING A
FAVORABLE ENVIRONMENT FOR ACTIVE CONVECTION EAST OF 113W. 

A SURFACE RIDGE EXTENDS SE FROM 1025 MB HIGH PRES NEAR 33N136W TO
AROUND 20N114W. A SURFACE TROUGH IS ANALYZED ALONG THE WEST COAST
OF MEXICO FROM 20N101W TO YUMA AZ. THE RESULTING PRES GRADIENT 
BETWEEN THE OCEANIC RIDGE AND THE CONTINENTAL TROUGH IS PRODUCING
AN AREA OF FRESH NW WINDS NEAR THE COAST OF BAJA CALIFORNIA N OF 
26N E OF 118W. THE PRES GRADIENT BETWEEN THE HIGH AND TS ALETTA 
IS ALSO PRODUCING AN AREA OF ENHANCED NE TRADES FROM 20N TO 23N 
BETWEEN 123W AND 129W. THE HIGH IS EXPECTED TO WEAKEN AND REMAIN 
NEARLY STATIONARY THROUGH WED. FRESH NW WINDS ARE EXPECTED TO 
REDEVELOP N OF 27N E OF 120W THU AND FRI. 

HIGH PRES BUILDING SOUTHWARD ALONG THE GULF COAST OF MEXICO WILL
INDUCE FRESH TO STRONG N-NE FLOW INTO THE GULF OF TEHUANTEPEC 
THU. ELSEWHERE OUTSIDE THE CLOSE PROXIMITY OF TS ALETTA...LIGHT 
TO MODERATE WINDS AND SEAS 7 FT OR LESS ARE EXPECTED THROUGH FRI.

$$
MUNDELL