000
AXPZ20 KNHC 132121
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
2205 UTC MON MAY 13 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

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

THE MONSOON TROUGH EXTENDS FROM 09N84W TO LOW PRES NEAR 07N93W 
1010 MB TO 10N110W TO 09N119W WHERE LOW LEVEL WINDS SUGGEST A 
TRANSITION TO ITCZ WHICH EXTENDS TO 08N128W TO BEYOND 06N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS NOTED FROM 05N 
TO 10N E OF 90W. NUMEROUS MODERATE SCATTERED STRONG CONVECTION 
WAS NOTED FROM 05N TO 11N BETWEEN 90W AND 100W. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION WAS NOTED WITHIN 90 NM N OF 
AXIS BETWEEN 100W AND 113W. SCATTERED MODERATE CONVECTION 
WAS NOTED WITHIN 90 NM N AND 30 NM S OF AXIS W OF 125W.

...DISCUSSION... 

LOW PRESSURE NEAR 07N93W IS EMBEDDED WITHIN THE MONSOON TROUGH. 
THE LOW HAS STRENGTHENED OVER THE PAST 24 HOURS WITH THE HELP OF 
SHEAR VORTICITY ASSOCIATED WITH GAP WINDS FROM THE GULFS OF 
TEHUANTEPEC AND PAPAGAYO...AND CONVECTION REMAINS ACTIVE 
ASSOCIATED WITH THE LOW PRESSURE CENTER AS MENTIONED ABOVE. THE 
LOW IS WITHIN A BAROTROPICALLY UNSTABLE ENVIRONMENT WHICH IS 
FAVORABLE FOR THE CONTINUED GROWTH OF THIS FEATURE...AND THE 
EVENTUAL BREAKDOWN OF THE MONSOON TROUGH. MODEL GUIDANCE IS 
DEPICTING A BREAKDOWN OF THE MONSOON TROUGH THE MIDDLE OF THE 
WEEK. THE BREAKDOWN OF THE MONSOON TROUGH ASSOCIATED WITH A 
WESTWARD PROPAGATING DISTURBANCE...IN THIS CASE A CARIBBEAN WAVE 
THAT PROPAGATED INTO THE EASTERN NORTH PACIFIC...HAS BEEN 
ASSOCIATED WITH TROPICAL CYCLOGENESIS. IT STILL REMAINS TO BE 
SEEN WHETHER THE MONSOON TROUGH WILL BREAK DOWN...AND IF WE WILL 
SEE TROPICAL CYCLOGENESIS IN THIS CASE...BUT IT WILL BE 
INTERESTING TO WATCH OVER THE NEXT SEVERAL DAYS. 

ELSEWHERE...HIGH PRESSURE 1029 MB IS CENTERED NW OF THE AREA 
NEAR 32N146W WITH ASSOCIATED RIDGE EXTENDING SE TO NEAR 20N114W. 
THE PRESSURE GRADIENT BETWEEN THE AREA OF HIGH PRESSURE AND 
LOWER PRESSURE IN THE VICINITY OF THE ITCZ IS MAINTAINING 
MODERATE TO FRESH TRADES N OF THE ITCZ TO NEAR 20N AND W OF 125W 
AS DEPICTED BY THE LATEST SCATTEROMETER PASSES. THESE WINDS ARE 
PRODUCING ENOUGH CONVERGENCE INTO THE ITCZ TO PRODUCE CONVECTION 
ALONG THE ITCZ AS MENTIONED IN THE SECTION ABOVE. THE AREA OF 
FRESH WINDS IS RESULTING IN SEAS TO 8 FT...MAINLY FROM 10N TO 
15N W OF 135W. THE HIGH PRESSURE CENTER WILL SHIFT NE OVER THE 
NEXT 24 HOURS. THIS WILL LOOSEN THE PRESSURE GRADIENT TO 
SLIGHTLY WEAKEN THE TRADES ENOUGH WHERE SEAS WILL SUBSIDE BELOW 
8 FT. 

$$
AL