000
AXPZ20 KNHC 192122
TWDEP 

TROPICAL WEATHER DISCUSSION      
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT MAY 19 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.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM 09N85W TO 12N95W TO BROAD LOW 
PRES AREA NEAR 11N100W 1006 MB TO 08N105W TO 09N111W TO 07N125W. 
ITCZ AXIS EXTENDS FROM 07N125W TO 03N140W. SCATTERED MODERATE TO 
STRONG CONVECTION ASSOCIATED WITH MONSOON TROUGH FROM 05N TO 12N 
E OF 102W.

...DISCUSSION...
THE MONSOON TROUGH THAT STRETCHES EASTWARD FROM SOUTH OF REMNANT 
LOW ALETTA THROUGH A BROAD AREA OF LOW PRES CENTERED NEAR 11N100W
TO A WEAK LOW NEAR 09N86W REMAINS VERY ACTIVE CONVECTIVELY E OF 
102W. SATELLITE IMAGERY SHOWS STRONG CONVECTION SE OF THE ANCHOR 
MONSOON LOW NEAR 11N100W. ASCAT PASS AT 1540 UTC SHOWS CONVERGENT
S-SW WINDS TO 20-25 KT ALTHOUGH MOST OF THE WIND BARBS ARE RAIN 
FLAGGED DUE TO HEAVY CONVECTION. A BROAD UPPER LEVEL ANTICYCLONE 
CENTERED NEAR 11N93W IS PROVIDING EXCELLENT DIFFLUENCE ALOFT AND 
ENHANCING CONVECTIVE ACTIVITY ALONG AND S OF THE MONSOON TROUGH 
AXIS E OF 102W.

EXPECT THE BROAD AREA OF LOW PRES NEAR 11N100W TO REMAIN NEARLY 
STATIONARY NEAR 10N100W WHILE THE CENTRAL PRES GRADUALLY DEEPENS 
AND THE OUTER WIND FIELD STEADILY STRENGTHENS. THIS WILL ALLOW 
THE MONSOON TROUGH TO BECOME MORE FIRMLY ENTRENCHED ACROSS THE E 
PACIFIC E OF 110W. EXPECT TO SEE ENHANCED N-NE WINDS SPILLING 
ACROSS THE CHIVELA PASS INTO THE GULF OF TEHUANTEPEC SUN THROUGH 
MON BASED ON GFS AND ECMWF MODELS. A KEY FACTOR WILL BE FORMATION
OF A SURFACE TROUGH OVER THE YUCATAN PENINSULA WHILE HIGH PRES 
BUILDS S ALONG THE GULF COAST OF MEXICO. ONSET SHOULD OCCUR IN 
ABOUT 24 HOURS AND CONTINUE THROUGH TUE NIGHT. WINDS DOWNSTREAM 
FROM THE GULF OF TEHUANTEPEC WILL SUPPLY POSITIVE VORTICITY TO 
THE BROAD AREA OF LOW PRES EMBEDDED IN THE MONSOON TROUGH...AND 
MAY ALLOW TROPICAL CYCLOGENESIS TO EVENTUALLY OCCUR. GFS MODEL 
IS CONSIDERED AN OUTLIER FOR ITS AGGRESSIVE DEVELOPMENT OF THE 
LOW OVER THE NEXT FEW DAYS. UKMET AND ECMWF ARE MORE RESTRAINED 
IN DEVELOPING THE BROAD LOW PRES AREA THROUGH TUE...AND ARE THE 
BASIS FOR THE EXTENDED FORECAST GRIDS. 

GENTLE TO MODERATE TRADE WINDS WILL PREVAIL ELSEWHERE W OF 110W 
WITH SEAS SUBSIDING TO 4-6 FT OVER MOST OF THE DISCUSSION AREA 
OUTSIDE OF THE MONSOON TROUGH REGION BY SUN.

$$
MUNDELL