000
AXPZ20 KNHC 160936
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
1005 UTC THU MAY 16 2013

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 
0900 UTC.

...SPECIAL FEATURE...

TROPICAL STORM ALVIN CENTERED NEAR 9.1N 106.9W AT 16/0900 UTC 
MOVING WNW AT 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE 1003 MB. 
MAXIMUM SUSTAINED WINDS 45 KT GUSTS TO 55 KT. SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC 
FOR MORE DETAILS. NUMEROUS MODERATE TO STRONG CONVECTION WITHIN 
75 NM OF CENTER. SCATTERED MODERATE CONVECTION ELSEWHERE WITHIN 
300 NM E AND 120 NM W SEMICIRCLES. ALVIN IS ON THE SW PERIPHERY 
OF A MID-LEVEL RIDGE AND THIS FEATURE SHOULD CONTINUE TO STEER 
THE STORM W-NW THE NEXT FEW DAYS. ALVIN IS EXPECTED TO BECOME A 
HURRICANE BY FRI MORNING.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM 07N77W TO LOW PRES NEAR 06N79W 
1007 MB TO 09N86W TO 08N101W THEN RESUMES FROM 08N109W TO 
08N120W. THE ITCZ AXIS FROM 08N120W TO 07N140W. SCATTERED 
MODERATE AND ISOLATED STRONG CONVECTION IS FROM 04N TO 08N 
BETWEEN 82W AND 87W...WITHIN 60 NM EITHER SIDE OF THE MONSOON 
TROUGH BETWEEN 110W AND 120W...AND ALSO WITHIN 180 NM N OF THE 
ITCZ W OF 127W.

...DISCUSSION...

HIGH PRES CENTERED NEAR 32N144W EXTENDS A RIDGE ACROSS THE NW 
PORTION OF THE REGION...N OF 12N AND W OF 115W. ELSEWHERE A WEAK 
PRES PATTERN REMAINS IN PLACE.

FRESH OCCASIONALLY STRONG E-NE WINDS WILL PULSATE NEAR THE GULF 
OF PAPAGAYO TODAY WITH WINDS AND SEAS DIMINISHING THIS AFTERNOON.
 
WEAK LOW PRES S OF THE PANAMA CANAL WILL ENHANCE CYCLONIC WINDS 
IN THE GULF OF PANAMA THROUGH TONIGHT. THE LOW IS EXPECTED TO 
MOVE NNW ACROSS THE ISTHMUS OF PANAMA THROUGH FRI MORNING AND 
WEAKEN.

LONG PERIOD SW SWELL MOVING FROM THE SOUTHERN HEMISPHERE WILL 
MIX WITH SWELL GENERATED BY ALVIN AND PRODUCE SEAS GREATER THAN 
8 FT IN EQUATORIAL WATERS BETWEEN 105W AND 118W. MIXED SWELL AND 
WIND WAVES ASSOCIATED WITH MODERATE TO FRESH TRADES WILL BUILD 
SEAS TO 8-9 FT FROM 13N TO 20N W OF 136W FRI AND SAT.

$$
MUNDELL