000
AXPZ20 KNHC 160255
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI SEP 15 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 10N FROM THE PANAMA 
AND COLOMBIA BORDER AT TO 10N78W...TURNS NW TO A 1010 MB LOW 
PRESSURE CENTER AT 14N101W...THEN TURNS SW TO 10N112W...TURNING 
NW TO A 1011 MB LOW PRESSURE AT 13N128W...THEN SW TO NEAR 
10N140W WHERE LOW LEVEL WINDS SUGGEST THE ITCZ AXIS BEGINS.

SCATTERED MODERATE ISOLATED STRONG CONVECTION...ACCOMPANIED BY 
NUMEROUS LIGHTNING STRIKES...IS OBSERVED WITHIN 90 NM OF THE 
COAST OF CENTRAL AMERICA BETWEEN 82W AND 88W. SCATTERED MODERATE
CONVECTION IS NOTED WITHIN 30 NM OF THE COAST FROM 90W TO 105W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 
150 NM EITHER SIDE OF A LINE FROM 06N80W TO 07N100W TO 10N109W 
TO 09N118W...WITHIN 90 NM EITHER SIDE OF A LINE FROM 16N101W TO 
13N106W...WITHIN 30 NM OF A LINE FROM 17N114W TO 11N123W...AND 
WITHIN THE AREA BOUNDED BY 07N TO 11N BETWEEN 128W AND 140W.

...DISCUSSION... 

AN UPPER CYCLONE IS OVER NEW MEXICO WITH AN UPPER SHORTWAVE 
TROUGH EXTENDING SW FROM 32N117W TO 20N124W TO 12N135W. 
AFTERNOON CONVECTION FLARED ALONG THE MEXICAN SIERRA MADRE 
OCCIDENTAL WITH THE DEBRIS MOISTURE NOW ADVECTED NE ACROSS 
NORTHERN OLD MEXICO AND E TEXAS. UPPER MOISTURE IS ALSO 
STREAMING NE OVER EASTERN ARIZONA AND MOST OF NEW MEXICO.  

AN UPPER ANTICYCLONE IN NOTED OVER THE NW CORNER AT 28N138W WITH 
A RIDGE EXTENDING SE TO A SHARP CREST AT 25N132W. ANOTHER UPPER 
ANTICYCLONE IS E OF THE TROUGH...OVER THE SW OLD MEXICO AT 
18N101W...WITH AN UPPER RIDGE EXTENDING SW OVER THE PACIFIC TO A 
CREST AT 15N123W. AN UPPER RIDGE ALSO EXTENDS SE ACROSS CENTRAL 
AMERICA TO A CREST OVER THE HONDURAN AND NICARAGUAN BORDER. THIS 
RIDGE MAINTAINS NE FLOW ALOFT ACROSS THE TROPICAL N PACIFIC TO 
THE E OF 100W WITH THE UPPER DIFFLUENCE ENHANCING CONVECTION IN 
THE SAME AREA. CONVECTION FLARED EARLIER OVER SE OLD MEXICO AND 
CENTRAL AMERICA WITH THE DEBRIS MOISTURE NOW ADVECTED SW TO 
ALONG 03N TO THE E OF 105W. THE WESTERN PERIPHERY OF THIS 
TROPICAL RIDGE IS IN PHASE WITH THE LOWER LEVEL MONSOON TROUGH 
AXIS AND IS SUPPORTING THE CONVECTION BETWEEN 110W AND 120W.
THE UPPER LEVELS APPEAR VERY DRY N OF 13N W OF 125W...AND N OF 
20N W OF 108W.

AT THE LOW LEVELS HIGH PRESSURE IS CENTERED NW OF THE AREA WITH 
A RIDGE ALONG 32N137W TO 15N113W. A SMALL AREA OF NE TRADES AT 
15 TO 20 KT CONTINUES FROM 11N TO 17N W OF 132W AND EXPECTED TO 
PERSIST THROUGH SAT. SOUTHWESTERLY SURFACE WINDS AT 15 TO 20 
KT...WITH COMBINED SEAS TO 9 FT...ARE OBSERVED IN THE AREA FROM 
04N TO 08N BETWEEN 95W AND 115W.   

$$
NELSON