000
AXPZ20 KNHC 280310
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC MON SEP 28 2009

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0100 UTC.

...TROPICAL WAVE...
A TROPICAL WAVE IS OVER THE GULF OF PANAMA ALONG 80W N OF 07N. 
THIS WAVE IS EMERGING FROM THE WESTERN CARIBBEAN INTO THE 
EASTERN PACIFIC MOVING W NEAR 15 KT. SCATTERED MODERATE 
CONVECTION LIES WITHIN 330 NM W OF TROPICAL WAVE ALONG 80W N OF 
07N.


...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ALONG 08N81W TO 
14N102W TO 11N111W TO 18N126W TO 15N138W. SCATTERED MODERATE 
CONVECTION CAN BE FOUND WITHIN 90 NM S AND 60 NM N OF THE ITCZ 
AXIS BETWEEN 88W AND 90W AND WITHIN 120 NM N AND 75 NM S OF THE 
ITCZ AXIS BETWEEN 92W AND 96W.

...DISCUSSION...

W OF 100W...
LARGE SW-NE ELONGATED UPPER LEVEL CYCLONIC CIRCULATION IS 
CENTERED NEAR 30N140W WITH ASSOCIATED CYCLONIC FLOW N OF 20N W 
OF 120W. AN AREA OF LOW AND MID LEVEL MOISTURE WITH ISOLATED 
EMBEDDED SHOWERS IS NOTED N OF 25N AND W OF 118W. THE AXIS OF 
THE 70 KT SUBTROPICAL JET LIES ON THE SE SIDE OF THIS CYCLONIC 
CIRCULATION...EXTENDING THROUGH 21N140W TO 21N130W TO 30N110W. 
THE CIRCULATION WILL MEANDER OVER NW WATERS FOR THE NEXT FEW 
DAYS AS A MID LATITUDE TROUGH PASSES TO ITS N BUT DOES NOT 
AMPLIFY ENOUGH TO PICK UP THIS LOW. IN TURN...THE JET POSITION 
SHOULD VARY LITTLE OVER THE NEXT TWO DAYS. THIS PATTERN ALOFT 
WILL PREVENT THE SUBTROPICAL HIGH FROM REBUILDING SUBSTANTIALLY 
OVER NW WATERS AND SHOULD GENERALLY KEEP TRADE WINDS LIGHT. 

A RATHER FLAT UPPER LEVEL RIDGE IS LOCATED S OF THE CYCLONIC 
CIRCULATION AND EXTENDED FROM AN ANTICYCLONE CENTERED NEAR 
25N109W THROUGH 18N126W TO A COL NEAR 17N127W WITH ANOTHER RIDGE 
AXIS EXTENDING EASTWARD FROM 14N140W TO THE COL. GENERALLY DRY 
AIR AT THE MID AND UPPER LEVELS ACCOMPANIES THE ANTICYCLONE 
WHILE DIFFLUENT E FLOW IS GENERALLY NOTED SOUTH OF THE UPPER 
RIDGE AXIS. THIS FLOW IS SUPPORTING SCATTERED MODERATE 
CONVECTION SHEARED TO BETWEEN 120 NM AND 270 NM W QUADRANT OF A 
1006 MB LOW PRES NEAR 13N118W. 

AT THE SURFACE...A HIGH PRES RIDGE LIES ALONG 30N137W TO 21N110W 
OVER FORECAST WATERS. THE REMNANT LOW OF NORA...1009 
MB...CENTERED NEAR 18N129W IS EXPECTED TO DISSIPATE TONIGHT OR 
EARLY MONDAY. THERE IS NO DEEP CONVECTION ASSOCIATED WITH THE 
LOW. HOWEVER...THE 1500 UTC QUIKSCAT PASS SHOWED WINDS WERE 
STILL IN THE 20-25 KT RANGE IN THE N QUADRANT OF THE LOW. THE 
MODELS SHOW THE LOW LEVEL CIRCULATION BECOMING WEAKER AND MORE 
ELONGATED HERE OVER THE NEXT 24 HOURS.

E OF 100W...
AN INVERTED UPPER LEVEL TROUGH IS CENTERED OVER EXTREME SOUTHERN 
MEXICO AND IS MOVING THROUGH THE ISTHMUS OF TEHUANTEPEC. UPPER 
LEVEL DIFFLUENT FLOW BETWEEN THIS CIRCULATION AND THE 
ANTICYCLONE NEAR 25N109W IS ENHANCING CONVECTIVE ACTIVITY WITH 
SCATTERED MODERATE CONVECTION LYING WITHIN 60 NM OF MEXICAN 
COAST FROM 19N TO 22N. A SHARP RIDGE TO TROUGH PATTERN CAN BE 
FOUND E OF THIS INVERTED TROUGH...WITH UPPER LEVEL DIFFLUENCE 
OVER PANAMA AND COSTA RICA. AS A RESULT...SCATTERED MODERATE 
CONVECTION CAN BE FOUND WHERE THE LOW LEVEL MOISTURE IS 
CONVERGED WITHIN 330 NM W OF TROPICAL WAVE ALONG 80W N OF 07N.

$$
COBB/SCHAUER CLARK