000
AXPZ20 KNHC 140303
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED SEP 14 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 E TO W ALONG 08N ACROSS PANAMA 
AND COSTA RICA FROM 78W TO 85W...THEN ACROSS THE E PACIFIC FROM 
09N85W TO 07N94W TO 1011 MB LOW PRESSURE EMBEDDED IN THE MONSOON 
TROUGH AT 11N111W. THE TROUGH AXIS THEN TURNS SW FROM 09N120W TO 
11N125W WHERE LOW LEVEL WINDS INDICATE THAT THE ITCZ AXIS BEGINS 
AND CONTINUES W TO BEYOND 09N140W. 

SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED OVER 
AND WITHIN 30 NM OF THE COAST OF CENTRAL AMERICA FROM 80W TO 86N 
AND ALSO FROM 92W TO 94W. A SURFACE TROUGH EXTENDS FROM 10N99W 
TO 15N95W WITH SCATTERED MODERATE ISOLATED STRONG CONVECTION 
OBSERVED WITHIN 90 NM OF 13N97W WHERE NUMEROUS LIGHTNING STRIKES 
ARE BEING DETECTED. 

...DISCUSSION...

AN UPPER CYCLONE IS OVER SOUTHERN CALIFORNIA WITH AN UPPER 
TROUGH EXTENDING SW FROM 32N117W TO 25N124W AND INTO AN UPPER 
CYCLONE JUST W OF THE AREA AT 16N143W. AN UPPER ANTICYCLONE IS  
NOTED NW OF THE TROUGH AT 32N139W. ANOTHER UPPER ANTICYCLONE IS 
E OF THE TROUGH OVER NW OLD MEXICO AT 25N107W WITH AN UPPER 
RIDGE EXTENDING SW TO A CREST AT 19N120W. ITS ENVELOPE OF 
ANTICYCLONIC FLOW DOMINATES THE TROPICS TO THE E OF 120W.  
CONVECTION WAS ENHANCED OVER THE MEXICAN SIERRA MADRE OCCIDENTAL 
WITH THE DEBRIS MOISTURE ADVECTED N AND NE OVER NW OLD MEXICO. 
CONVECTION WAS ALSO ENHANCED OVER THE NE SEMICIRCLE OF THE 
CALIFORNIA CYCLONE...WITH THE RESULTANT DEBRIS MOISTURE ADVECTED 
NE ACROSS ARIZONA AND WESTERN NEW MEXICO TONIGHT. DEBRIS 
MOISTURE ORIGINATING FROM CONVECTION OVER CENTRAL AMERICA IS 
ADVECTED ABOUT 600 NM SW OVER THE PACIFIC. OTHERWISE...THE UPPER 
LEVELS APPEAR VERY DRY W OF 120W AND N OF 20N W OF 110W.

AT THE LOW LEVELS HIGH PRESSURE IS CENTERED NW OF THE AREA WITH 
A RIDGE ALONG 32N135W TO 20N117W. A SMALL AREA OF NE TRADES AT 
15 TO 20 KT CONTINUE FROM 10N TO 17N W OF 135W. 

SOUTHERLY CROSS EQUATORIAL SWELL RESULTING IN COMBINED SEAS TO 9 
FT CONTINUE OVER THE TROPICAL WATERS S OF 12N BETWEEN 98W AND 
113W...AND ALSO S OF 07N TO THE W OF 113W. SOUTHWESTERLY WINDS 
ARE EXPECTED TO INCREASE TO 15 TO 20 KT...WITH COMBINED SEAS TO 
9 FT...IN THE AREA FROM 04N TO 08N BETWEEN 92W AND 115W THU 
NIGHT.   

GAP WINDS...NE WINDS AT 20 TO 25 KT ARE EXPECTED TO FUNNEL 
THROUGH THE CHIVELA PASS INTO THE GULF OF TEHUANTEPEC TONIGHT 
AND EARLY WED BEFORE DIMINISHING.

$$
NELSON