000
AXPZ20 KNHC 272156
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SUN SEP 27 2009

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 
2130 UTC.

...ITCZ...
AXIS IS ALONG 08N82W TO 14N100W TO 11N110W TO 17N126W TO 
13N140W. SCATTERED MODERATE WITHIN 120 NM N OF AXIS BETWEEN 87W 
AND 94W.

...DISCUSSION...

W OF 100W...
LARGE SW-NE ELONGATED UPPER LEVEL CYCLONIC CIRCULATION WAS 
PIVOTING JUST TO THE W OF THE AREA NEAR 29N142W WITH ASSOCIATED 
CYCLONIC FLOW N OF 20N W OF 120W. AN AREA OF LOW AND MID LEVEL 
MOISTURE WITH ISOLATED EMBEDDED SHOWERS WAS NOTED FROM 25N-30N 
BETWEEN 124W-132W...ROTATING AROUND THE EAST SIDE OF THE 
CYCLONIC CIRCULATION WITHIN AN AREA OF DIFFLUENT UPPER LEVEL 
FLOW. AN AREA OF MODERATE TO STRONG SUBSIDENCE WITH DRY STABLE 
AIR AT THE MID TO UPPER LEVELS WAS NOTED WITHIN THE CYCLONIC 
CIRCULATION AND ALSO FROM 18N TO 30N W OF 127W AND WAS SWEEPING 
NORTHEASTWARD TOWARD THE AREA OF MOISTURE NOTED ABOVE. AXIS OF 
SUBTROPICAL JET EXTENDED THROUGH 17N140W TO 21N130W TO 26N122W
AND WAS SLICING ACROSS THE SOUTHERN EXTENT OF THE AREA OF DRY 
AIR. SATELLITE DERIVED WINDS WERE IN THE 60-90 KT RANGE. 

A RATHER FLAT UPPER LEVEL RIDGE IS LOCATED S OF THE CYCLONIC 
CIRCULATION AND EXTENDED FROM AN ANTICYCLONE CENTERED NEAR 
22N108W THROUGH 19N120W TO A COLD NEAR 16N130W AND CONTINUED
TO NEAR 12N135W. ANOTHER RIDGE AXIS EXTENDED EASTWARD ALONG 23N 
FROM THE ANTICYCLONIC CIRCULATION ACROSS NORTHERN MEXICO. DRY 
AIR AT THE MID AND UPPER LEVELS ACCOMPANIED THE ANTICYCLONE 
WHILE DIFFLUENT NE TO E FLOW WAS NOTED SOUTH OF THE ANTICYCLONE. 
THIS FLOW WAS SUPPORTING AREAS OF SCATTERED MODERATE CONVECTION 
FROM 15N TO 19N BETWEEN 108W AND 112W AND ALSO WITHIN 300 NM E 
OF TROUGH ALONG 104W FROM 12N TO 16N.

AT THE SURFACE...HIGH PRES RIDGE IS N OF 20N W OF 115W. THE 
REMNANT LOW OF NORA...1009 MB...CENTERED NEAR 18N129W AND IS 
EXPECTED TO DISSIPATE TONIGHT OR EARLY MONDAY. THERE IS NO DEEP 
CONVECTION ASSOCIATED WITH THE LOW. A 1458 UTC HIGH RESOLUTION
QUIKSCAT PASS STILL INDICATED WINDS OF 20 KT WITHIN 120 NM OF 
THE REMNANT LOW IN THE N SEMICIRCLE. A 1006 MB SURFACE LOW IS 
ANALYZED ALONG THE ITCZ NEAR 13N118W. SCATTERED MODERATE 
CONVECTION WAS NOTED WITHIN 150 NM W QUADRANT OF THIS LOW. THE 
EDGE OF A HIGH RESOLUTION 1320 UTC QUIKSCAT PASS INDICATED 
VERY LIGHT WINDS IN ASSOCIATION WITH THIS LOW. 

E OF 100W...
AN UPPER LEVEL CYCLONIC CIRCULATION IS CENTERED OVER EXTREME NW 
GUATEMALA AND IS MOVING INTO MEXICO TOWARD THE ISTHMUS OF 
TEHUANTEPEC. UPPER LEVEL DIFFLUENT FLOW BETWEEN THIS CIRCULATION 
AND THE ANTICYCLONE NEAR 22N108W IS ENHANCING CONVECTIVE 
ACTIVITY SW OF THE GULF OF TEHUANTEPEC AND ALSO ALONG THE ITCZ E 
OF 92W. 

$$
COBB