000
AXPZ20 KNHC 190246
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC MON SEP 19 2011

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0245 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS W ACROSS COSTA RICA ALONG 10N TO 
09N84W TO 11N92W TO 08N102W...THEN RESUMES OVER THE PACIFIC FROM 
A 1009 MB LOW PRES AT 16N112W TO 10N140W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION IS OBSERVED FROM 04N TO 15N TO THE E 
OF 105W...AND ALSO ALONG THE W SEGMENT OF THE MONSOON TROUGH... 
WITHIN 150 NM EITHER SIDE OF A LINE FROM 21N110W TO 19N115W TO 
11N121W TO 09N140W.

...DISCUSSION... 

AN UPPER TROUGH IS N OF 24N ALONG 104W. A SECOND UPPER TROUGH 
EXTENDS ACROSS THE AREA THROUGH SMALL UPPER CYCLONES AT 34N133W 
AND 24N135W AND 13N140W. AN UPPER ANTICYCLONE IS AT 31N143W WITH 
AN UPPER RIDGE EXTENDING E TO A CREST AT 30N134W. UPPER MOISTURE 
REMAINS N OF 32N ALONG 132W. AN UPPER ANTICYCLONE IS OVER 
CENTRAL OLD MEXICO AT 22N101W WITH A RIDGE EXTENDING SW OVER THE 
TROPICAL PACIFIC TO A CREST AT 15N136W. A RIDGE ALSO EXTENDS NW 
TO A CREST AT 35N122W. UPPER DIFFLUENCE ALONG THE SW RIDGE IS 
ENHANCING THE PREVIOUSLY DESCRIBED CONVECTION ALONG THE AXIS OF 
THE MONSOON TROUGH WITH THE DEBRIS ADVECTED SW TO THE EQUATOR 
BETWEEN 125W AND 135W. DRY UPPER AIR IS INDICATED W OF A LINE 
FROM 13N140W TO 21N120W TO 27N100W.

AN UPPER TROUGH ALSO DOMINATES THE E COAST OF N AMERICA... 
CONTINUING SW ACROSS THE FLORIDA STRAITS THROUGH AN UPPER 
CYCLONE OVER N GUATEMALA...TO ANOTHER OVER THE PACIFIC AT 
10N102W. AN UPPER ANTICYCLONE IS OVER THE W CARIBBEAN AT 
12N80W WITH ITS ENVELOPE OF ANTICYCLONIC FLOW EXTENDING S OVER 
THE TROPICS BETWEEN 75W AND 90W. A LOW LEVEL TROUGH IS MOVING W 
ACROSS NICARAGUA UNDER THE ASSOCIATED UPPER RIDGE RESULTING IN 
CONSIDERABLE CONVECTION OVERLAND. DEBRIS MOISTURE FROM THIS 
CONVECTION OVER CENTRAL AMERICA...AND OVER THE PACIFIC ALONG THE 
E SEGMENT OF THE MONSOON TROUGH...IS SPREADING SW TO ALONG THE 
EQUATOR BETWEEN 98W AND 115W.

AT THE LOW LEVELS A BROAD RIDGE COVERING THE AREA N OF 17N W OF 
115W. AS PREVIOUSLY MENTIONED THE MONSOON TROUGH AXIS EXTENDS 
FROM 17N113W TO 13N120W TO 10N140W. NE WINDS AT 20 TO 25 
KT...SEAS 7 TO 10 FT...ARE OBSERVED WITHIN 180 NM N OF TROUGH 
AXIS BETWEEN 120W AND 140W. SOUTHWESTERLY WINDS AT 15 TO 20 
KT...SEAS 7 TO 10 FT IN S SWELL...ARE NOTED FROM 07N TO TROUGH AXIS 
BETWEEN 108W AND 135W. THE TROUGH AXIS IS EXPECTED TO SHIFT 
SLIGHTLY W WITH THE AREA OF SOUTHWESTERLY WINDS EXPANDING OUT TO 
ABOUT 480 NM SE OF THE TROUGH AXIS BY LATE TUE.
 
GAP WINDS...NORTHERLY WINDS AT 20 TO 25 KT CONTINUE OVER THE 
WATERS N OF 14N BETWEEN 94W AND 96W...AND ARE EXPECTED TO 
CONTINUE THROUGH TUE.
  
$$
NELSON