000
AXPZ20 KNHC 150952
TWDEP 

TROPICAL WEATHER DISCUSSION      
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0845 UTC.

...SPECIAL FEATURE...
TROPICAL DEPRESSION ONE-E IS CENTERED NEAR 10.8N 108.7W AT 
15/0900 UTC MOVING WNW OR 290 DEG AT 8 KT...AND THIS GENERAL 
MOTION IS EXPECTED TO DURING THE NEXT 48 HOURS. ESTIMATED 
MINIMUM CENTRAL PRESSURE IS 1004 MB. MAXIMUM SUSTAINED WIND 
SPEED IS 35 KT GUSTS 45 KT. PLEASE SEE THE LATEST PUBLIC 
ADVISORY UNDER AWIPS/WMO HEADER MIATCPEP1/WTPZ31 KNHC FOR MORE 
DETAILS. THE CLOUD PATTERN ASSOCIATED WITH ALETTA HAS CHANGE 
LITTLE OVERNIGHT. NUMEROUS STRONG CONVECTION IS NOTED WITHIN 90 
NM NW SEMICIRCLE AND 30 NM SE SEMICIRCLE OF T.S. ALETTA. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS ELSEWHERE 
WITHIN 180 NM NE SEMICIRCLE OF CENTER. THE FORECAST CALLS FOR 
ONLY A MODEST INTENSIFICATION DURING THE NEXT 24 HOURS BEFORE 
INCREASING SOUTHWESTERLY VERTICAL SHEAR BEGINS TO PREVENT ANY 
FURTHER DEVELOPMENT. WINDS ARE EXPECTED TO INCREASE AND PEAK 
NEAR 45 KT TUE NIGHT OR EARLY WED MORNING...BEFORE WEAKENING 
COMMENCES. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH EXTENDS FROM 09N84W TO 11N83W THEN RESUMES AT 
08N110W TO 06N122W. ITCZ CONTINUES TO 03N130W TO 02N140W.  
SCATTERED MODERATE TO STRONG N OF TROUGH TO 13N E OF 98W TO THE 
COAST OF CENTRAL AMERICA. SCATTERED MODERATE TO ISOLATED STRONG 
S OF TROUGH TO 04N BETWEEN 86W AND 102W.
 
...DISCUSSION...
ALOFT...MID/UPPER LEVEL RIDGE WITH AXIS ROUGHLY ALONG 125W 
CONTINUES TO DOMINATE THE N WATERS WHILE A SHARP LONGWAVE TROUGH 
PERSISTS W OF 140W. S AND SW WIND FLOW AHEAD OF THE TROUGH IS 
TRANSPORTING ABUNDANT MID/UPPER LEVEL MOISTURE FROM THE TROPICS 
ALL THE WAY NE INTO THE FORECAST WATERS PARTICULARLY W OF 125W.  
AN ANTICYCLONIC CIRCULATION REMAINS CENTERED OVER NORTHERN 
CENTRAL AMERICA WITH A RIDGE COVERING THE DISCUSSION AREA E OF 
110W. A DIFFLUENT PATTERN ALOFT ASSOCIATED WITH THIS FEATURE 
CONTINUES TO SUPPORT THE DEVELOPMENT OF DEEP CONVECTION ON 
EITHER SIDE OF THE MONSOON TROUGH.  

AT LOWER LEVELS...A 1026 MB HIGH PRES LOCATED N OF AREA NEAR 
32N135W EXTENDS A RIDGE SE TO NEAR 20N110W. PRES GRADIENT 
BETWEEN THIS HIGH AND A TROUGH OVER SOUTHERN CALIFORNIA AND 
WESTERN MEXICO IS MAINTAINING FRESH TO STRONG NW WINDS E OF 120W 
TO THE W COAST OF BAJA CALIFORNIA N OF 24N. THE 0434 UTC ASCAT 
PASS PROVIDED OBSERVATIONS OF THESE WINDS. THIS HIGH PRES IS 
FORECAST TO REMAIN NEARLY STATIONARY DURING THE NEXT 24 HOURS...
AND WILL MAINTAIN FRESH TO STRONG NWLY WINDS JUST W OF BAJA 
CALIFORNIA N OF 24N. WINDS ARE FORECAST TO DIMINISH TO 20 KT IN 
ABOUT 48 HOURS AS HIGH PRES MOVES N AND AWAY FROM THE AREA.  

STATIONARY FRONT OVER THE ERN BAY OF CAMPECHE AND A WAVE LIKE 
FEATURE ALONG ABOUT 90W IN THE EPAC ARE COMBINING TO MAINTAIN 
FRESH NLY WINDS ACROSS CHIVELA PASS AND THROUGH GULF OF 
TEHUANTEPEC. THE MOST RECENT SCATTEROMETER DAT SHOWED 20-25 KT 
ACROSS THIS AREA. MARINE GUIDANCE SUGGESTS THAT WINDS WILL BE 
BELOW 20 KT TONIGHT.  

OF NOTE...TODAY MARKS THE BEGINNING OF THE TROPICAL SEASON IN 
THE EASTERN NORTH PACIFIC...AND ALETTA...THE FIRST TROPICAL 
CYCLONE OF THE SEASON HAS ALREADY FORMED. LONG-TERM AVERAGES OF 
TROPICAL STORMS...HURRICANES AND MAJOR HURRICANES IN THIS BASIN 
ARE 15...9...AND 4 RESPECTIVELY.

$$
GR