000
AXPZ20 KNHC 191528
TWDEP 

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

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

THE MONSOON TROUGH AXIS WAS ANALYZED FROM 10N85W TO 13N102W TO 
LOW PRES 1010 MB NEAR 09N111W TO 07N120W TO LOW PRES 1010 MB 
NEAR 12N127W TO 10N135W. ITCZ AXIS EXTENDS FROM 10N135W TO 
09N140W. SCATTERED MODERATE CONVECTION WITHIN 120 NM S OF AXIS 
BETWEEN 83W AND 86W...AND WITHIN 60 NM EITHER SIDE OF AXIS 
BETWEEN 89W AND 100W. 

...DISCUSSION...

CLUSTERS OF MODERATE TO STRONG CONVECTION ARE ACTIVE ALONG THE 
MEXICAN COAST FROM CABO CORRIENTES NORTHWARD TOWARD MAZATLAN. 
LOW LEVEL BANDING HAS BEEN NOTED OVER THE PAST SEVERAL HOURS 
CONVERGING TOWARD A POSSIBLE CENTRAL LOW PRES AREA HIDDEN 
BENEATH A LARGE CONVECTIVE CLOUD MASS. THE GENESIS OF THIS 
SYSTEM IS COMPLEX AND INVOLVES SEVERAL FACTORS. FOR THE PAST 
FEW DAYS GFS AND ECMWF MODEL INITIALIZATIONS HAVE 
CONSISTENTLY DEPICTED A LOWER TO MID LEVEL TROUGH/TROPICAL WAVE 
MIGRATING WESTWARD IN THE DEEP TROPICS FROM CENTRAL AMERICA TO 
ITS PRESENT POSITION NEAR 110W...INTERACTING WITH THE MONSOON 
TROUGH WHICH HAS GENERALLY BEEN SITUATED OFF THE COAST FROM NW 
COSTA RICA TO WITHIN 250 NM S OF THE GULF OF TEHUANTEPEC. WHILE 
THE LOW LEVEL CONVERGENCE INTO THE MONSOON TROUGH HAS BEEN 
MODEST DUE TO THE LIGHT TO MODERATE SW FLOW...THE INTERACTION 
WITH THE LOWER TO MID LEVEL WAVE HAS BEEN KEEPING CONVECTION 
ACTIVE E OF 110W. ADD HIGH PRECIPITABLE WATER VALUES...NOCTURNAL 
INFLUENCES ALONG THE MEXICAN COAST...DECENT OUTFLOW AND WEAK E 
SHEAR ALOFT S OF AN UPPER ANTICYCLONE CENTERED OVER SAN 
DIEGO...AND POSSIBLE ADDITIONAL MID LEVEL INFLUENCES FROM THE 
REMNANTS OF HELENE. THIS HAS ALL LED TO ENOUGH CONCENTRATED 
CONVECTION IN THE PAST FEW HOURS TO FORM A SMALL AREA OF LOW 
PRES OFF CABO CORRIENTES...NOW WEAKENING AS THE CONVECTION 
PROPAGATES FARTHER NORTH FOLLOWING THE EARLY MORNING CONVERGENCE 
ALONG THE COAST TO MAZATLAN. GLOBAL MODELS ARE NOT ESPECIALLY 
BULLISH CONCERNING THIS LOW...BUT THE GFS...ECMWF...AND UKMET 
ALL MAINTAIN AT LEAST A WEAK LOW CLOSE TO CABO CORRIENTES 
THROUGH MID WEEK.

1010 MB LOW PRES...THE REMNANTS OF HECTOR...PERSISTS NEAR 
23N116W...DRIFTING E AS IT IS BEING BLOCKED BY 1019 MB HIGH 
PRES NEAR 29N134W. THE LOW IS STILL PROGGED TO OPEN INTO A 
TROUGH THROUGH EARLY MON. 

WHILE THE MWW3 DOES NOT SHOW ANY SEAS TO 8 FT ANYWHERE IN THE 
DISCUSSION AREA THROUGH 48 HOURS...THE ECWAVE...UKWAVE...AND 
FNMOC WAVE MODELS SHOW SOUTHERLY SWELL TO 8 FT MOVING ACROSS THE 
EQUATOR AND REACH AS FAR N AS 03N E OF 110W TONIGHT...AND TO 05N 
BETWEEN 100W AND 120W THROUGH MON.

$$
CHRISTENSEN