000
AXPZ20 KNHC 201524
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON AUG 20 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 
1515 UTC.

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

THE MONSOON TROUGH AXIS WAS ANALYZED FROM 08N81W TO 07N98W THEN 
CONTINUES FROM 13N105W TO 11N114W TO 08N120W. ITCZ EXTENDS FROM 
08N120W TO LOW PRES 1011 MB NEAR 13N127W TO 09N140W. SCATTERED 
MODERATE CONVECTION WAS NOTED S OF AXIS TO 04N BETWEEN 80W AND 
82W...AND WITHIN 120 NM S OF THE AXIS BETWEEN 110W AND 122W.

...DISCUSSION...

CONVECTION W OF 110W HAS DIMINISHED IN BOTH INTENSITY AND AREAL 
EXTENT...WITH MOST CLUSTERS CONFINED TO THE NORMAL MORNING 
COASTAL CONVECTION FROM COSTA RICA TO SOUTHERN MEXICO. STRONGER 
AND MORE WIDESPREAD CONVECTION PERSIST ALONG 80W S OF PANAMA DUE 
TO INTERACTION BETWEEN THE MONSOON TROUGH AND A TROPICAL WAVE 
MOVING THROUGH THE SW CARIBBEAN.

PRECIPITABLE WATER VALUES REMAIN SOMEWHAT HIGH ACROSS BAJA AND 
THE GULF OF CALIFORNIA...DESPITE DIMINISHING CONSIDERABLY FROM 
PEAK LEVELS A FEW DAYS AGO IN THE AFTERMATH OF HECTOR. A MID TO 
UPPER LEVEL ANTICYCLONE REMAINS IN PLACE OVER YUMA ARIZONA. THE 
TRAILING END OF A MID LEVEL TROUGH MOVING INTO THE SOUTHERN 
PLAINS AND NORTHERN MEXICO WAS ABLE TO ALLOW STRONG CONVECTION 
TO PERSIST ACROSS NW MEXICO OVERNIGHT. THIS HAS SINCE DRIFTED 
INTO THE CENTRAL GULF OF CALIFORNIA AND LARGELY DISSIPATED THIS 
MORNING. THE MID TO UPPER ANTICYCLONE WILL START TO SHIFT E 
TODAY AHEAD OF A MID/UPPER LEVEL TROUGH THAT WILL MOVE E INTO 
THE CALIFORNIA COAST BY MID WEEK AND SHUNT MOST OF THE REMAINING 
MOISTURE EAST. MID LEVEL CYCLONIC CENTERS PERSIST NEAR 23N115W 
AND 19N108W...COLLOCATED WITH ASSOCIATED WEAK 1010 MB SURFACE 
LOWS. THE LOW PRES AREAS ARE EXPECTED TO OPEN INTO TROUGHS 
THROUGH TONIGHT. GLOBAL MODELS INCLUDING THE GFS...ECMWF...AND 
UKMET SHOW THE LOW PRES CENTERS GENERALLY OPENING INTO TROUGHS 
THROUGH TUE AND BEING ABSORBED INTO THE RESIDENT TROUGHING OVER 
THE GULF OF CALIFORNIA AS THE MAIN SYNOPTIC SCALE TROUGH DIGS 
INTO THE AREA THROUGH MID WEEK.

A BROAD LOWER TO MID LEVEL TROUGH/WAVE ORIENTED NE TO SW FROM 
THE MID LEVEL CENTER NEAR 19N108W THROUGH 10N115W IS AIDING 
MODEST CONVECTION ALONG THE MONSOON TROUGH BETWEEN 110W AND 
122W. FURTHER WEST...ANOTHER BROAD MID LEVEL WAVE FROM 15N130W 
TO 10N135W IS SUPPORTING A WEAK 1011 MB SURFACE LOW ALONG THE 
ITCZ NEAR 13N127W...EXPECTED TO DISSIPATE WITHIN 24 HOURS. MID 
TO UPPER LEVEL DRY AIR W OF 115W IS LIMITING CONVECTIVE GROWTH.

A PAIR OF ALTIMETER PASSES CROSSING THE EQUATOR NEAR 92W AND 96W 
AROUND 08 UTC CONFIRMED SEAS TO 8 FT S OF 03N...LENDING 
CREDENCE TO WAVE MODEL GUIDANCE SUGGESTING CROSS EQUATORIAL 
SWELL TO 8 FT WILL LIE OVER THE FORECAST AREA S OF 03N THE NEXT 
FEW DAYS. 

$$
CHRISTENSEN