000
AXPZ20 KNHC 171531
TWDEP 

TROPICAL WEATHER DISCUSSION      
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU MAY 17 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...SPECIAL FEATURES...
TROPICAL DEPRESSION ALETTA IS CENTERED NEAR 12.1N 114.8W MOVING 
W OR 310 DEG AT 4 KT 17/1500. ESTIMATED MINIMUM CENTRAL PRES 
1006 MB. MAXIMUM SUSTAINED WINDS 30 KT GUSTS TO 40 KT. PLEASE 
REFER TO THE LATEST PUBLIC ADVISORY TCPEP1/WTPZ31 KNHC FOR MORE 
DETAILS. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS 
WITHIN 60 NM SE AND 90 NM NE QUADRANT OF THE CENTER. ALETTA WILL 
CONTINUE TO WEAKEN DURING THE NEXT 48 HOURS AS VERTICAL SHEAR 
INCREASES AND DRY AIR APPROACHES.

SHOWER ACTIVITY ASSOCIATED WITH A BROAD LOW PRES AREA ANALYZED 
NEAR 12N101W 1008 MB REMAINS POORLY ORGANIZED. SATELLITE IMAGERY 
SHOWS SCATTERED TO NUMEROUS MODERATE TO STRONG CONVECTION N OF 
THE LOW CENTER TO THE COAST OF MEXICO NEAR ACAPULCO BETWEEN 98W 
AND 103W. ENVIRONMENTAL CONDITIONS ARE FORECAST TO BECOME MORE 
CONDUCIVE FOR SLOW DEVELOPMENT DURING THE NEXT FEW DAYS. GLOBAL 
MODELS SHOW A DEEPENING LOW PRES SYSTEM DURING THE UPCOMING 
WEEKEND. THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A TROPICAL 
CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES SLOWLY TO THE NW.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH FROM 7N78W TO LOW PRES NEAR 13N102W 1008 MB TO 
11N107W. ITCZ FROM 6N120W 6N130W TO 2N140W. SCATTERED MODERATE 
ISOLATED STRONG WITHIN 75 NM S OF AXIS FROM 78W-84W. SCATTERED 
TO NUMEROUS STRONG WITHIN 100 NM S OF AXIS FROM 94W-97W AND 
WITHIN 240 NM N OF AXIS FROM 99W-103W.

...DISCUSSION...
AN UPPER LEVEL TROUGH OVER THE FAR NW PORTION OF THE 
DISCUSSION AREA ACROSS 30N140W AND EXTENDS SW TO A CUT-OFF LOW W 
OF THE AREA. THE DOWNSTREAM RIDGE WITH AXIS FROM 32N120W TO 
13N132W CONTINUES TO DOMINATE THE N PORTION OF THE DISCUSSION 
AREA. S AND SW WINDS BETWEEN THE TROUGH AND THE RIDGE ARE 
TRANSPORTING MID/UPPER LEVEL MOISTURE ACROSS THE NW CORNER OF 
THE AREA. STRONG MID/UPPER LEVEL SUBSIDENCE WITH DRY STABLE AIR 
MASS AT THE MIDDLE AND UPPER LEVELS COVERS THE AREA N OF 20N E 
OF 120W INCLUDING THE BAJA CALIFORNIA PENINSULA AND NW MEXICO. A 
TROUGH EXTENDS FROM NW MEXICO TO NEAR 15N120W. AN ANTICYCLONIC 
CIRCULATION REMAINS CENTERED OFF THE W COAST OF GUATEMALA WITH A 
RIDGE DOMINATING THE AREAS E OF 110W. THIS FEATURE IS HELPING TO 
SUPPORT THE CONVECTIVE ACTIVITY NEAR THE MONSOON TROUGH AND THE 
LOW PRES AT 12N101W.

WEAK HIGH PRES RIDGE EXTENDING FROM 32N133W TO AROUND 20N118W IS 
SUPPORTING MODERATE NW WINDS N OF 28N W OF THE BAJA CALIFORNIA 
PENINSULA...WITH NLY SWELL MAINTAINING SEAS OF 6-7 FT IN NE 
PORTION OF THE DISCUSSION AREA.

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

$$
DGS