000
AXPZ20 KNHC 132146 RRA
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON SEP 13 2010

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1845 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ANALYZED FROM 11N86W 
TO 10N106W TO LOW PRES NEAR 11N114W TO LOW PRES NEAR 11N124W TO 
LOW PRES NEAR 11N135W. SCATTERED MODERATE CONVECTION IS WITHIN 
150 NM S OF THE ITCZ AXIS BETWEEN 92W AND 105W...WITHIN 90 NM S 
OF THE ITCZ AXIS BETWEEN 111W AND 116W...AND WITHIN 150 NM S OF 
AXIS BETWEEN 129W AND 136W. A TROUGH EXTENDS THROUGH THE LOW 
PRES SYSTEM NEAR 11N124 FROM 14N122W TO LOW PRES TO 08N125W. 
SCATTERED MODERATE CONVECTION LIES WITHIN 60 NM W OF TROUGH N OF 
12N.

...DISCUSSION...

AN EXPANSIVE ANTICYCLONE CENTERED OVER SE TEXAS EXTENDS A RIDGE 
SOUTHWEST THROUGH A NEWLY DEVELOPING ANTICYCLONE OVER THE 
SOUTHERN GULF OF CALIFORNIA NEAR 26N109W AND CONTINUES TO 
18N120W. UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THIS RIDGE IS 
ENHANCING THE SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION 
FOUND WITHIN 120 NM OF THE COAST OF MAINLAND MEXICO FROM 22N TO 
25N. UPPER LEVEL DIFFLUENCE CAN ALSO BE FOUND BETWEEN THE E TO 
SE FLOW ON THE FAR SW SIDE OF THE ANTICYCLONE AND NE TO E FLOW 
WITHIN APPROXIMATELY 300 NM W OF AN UPPER TROUGH EXTENDING FROM 
THE NW CARIBBEAN NEAR 22N84W THROUGH CENTRAL AMERICA TO 10N90W. 
THIS DIFFLUENCE IS ENHANCING CONVECTION SW OF TEHAUNTEPEC WITH 
SCATTERED MODERATE NOTED WITHIN FROM 11N TO 15N BETWEEN 97W AND 
102W. N WINDS TO 25 KT ARE FUNNELING THROUGH THE ISTHMUS OF 
TEHAUNTEPEC ACCORDING TO THE 1542 UTC ASCAT PASS. THESE WINDS 
ARE EXPECTED TO BE AROUND 20 KT THROUGH TUE NIGHT AS A SURFACE 
TROUGH LINGERS FROM THE SW GULF OF MEXICO INTO THE 
ISTHMUS...DIRECTING NORTHERLY FLOW ON ITS W SIDE FROM HIGHER 
PRES OVER EASTERN MEXICO NEAR 20N SOUTHWARD INTO THE EASTERN 
PACIFIC.

A SW TO W UPPER JET LIES OVER FAR N WATERS. THIS MOSTLY ZONAL 
FLOW LIES BEHIND A MEAN TROUGH WHOSE LEADING EDGE IS NEAR THE 
CALIFORNIA COAST. THE REFLECTION OF THIS TROUGHING AT THE 
SURFACE IS EXPANDING THE USUAL TROUGHING OVER THE GULF OF 
CALIFORNIA NORTHWARD INTO CALIFORNIA AND OFFSHORE. THE PRES 
GRADIENT BETWEEN THIS TROUGHING AND THE SUBTROPICAL 
RIDGE...WHICH LIES FROM A 1023 MB HIGH NEAR 33N140W TO 
20N113W...IS YIELDING NW TO N WINDS IN THE 15 TO 20 KT RANGE OFF 
THE COAST OF NORTHERN BAJA CALIFORNIA ACCORDING TO SHIPS MQPF2 
NEAR 26N116W REPORTING 18 KT AND UNKNOWN SHIP NEAR 26N117W 
REPORTING 18 KT AT 1800 UTC. WINDS ARE EXPECTED TO BE STRONGEST 
HERE DURING THE OVERNIGHT HOURS.

$$
SCHAUER