000
AXPZ20 KNHC 202118
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON JUL 20 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 
2100 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE HAS ENTERED THE AREA FROM THE EAST AND IS ALONG 
81W N OF 05N. THE WAVE HAS BEEN MOVING WEST 20 KT IN THE 
ATLANTIC AREA. THERE IS A LARGE AREA OF MODERATE TO STRONG 
CONVECTION NORTH OF 05N EAST OF 86W. GOOD UPPER LEVEL DIFFLUENCE 
IS OBSERVED OVER THIS CONVECTION. DEVELOPMENT OF THIS SYSTEM IS 
NOT EXPECTED.

TROPICAL WAVE ALONG 116W FROM 05N TO 15N HAS MOVED WEST 20 KT 
DURING THE LAST 24 HOURS. SOME CONVECTION IS NOTED SOUTH OF 11N 
IN THE ITCZ. THE CONVECTION DOES NOT APPEAR TO BE ORGANIZED BY 
CYCLONIC CIRCULATION. THE WAVE IS FORECAST TO CONTINUE TO MOVE 
WEST 15 TO 20 KT AND CHANGE LITTLE.
 
TROPICAL WAVE ALONG 139W FROM 05N TO 18N HAS MOVED WEST 18 KT 
DURING THE LAST 24 HOURS. ONLY ISOLATED CONVECTION IS NOTED 
NEAR THE WAVE. THE WAVE WILL MOVE WEST OF 140W TONIGHT.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...06N77W TO 
07N110W TO 05N140W. SCATTERED MODERATE TO STRONG CONVECTION IS 
WITHIN 240 NM OF 07N82W. SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION IS WITHIN 60 NM EITHER SIDE OF THE LINE FROM 12N107W 
TO 10N112W TO 10N126W.

...DISCUSSION...

CYCLONIC CIRCULATION NORTH OF THE NORTHWEST PART OF THE AREA 
CENTERED NEAR 40N140W. ASSOCIATED SOUTHERLY FLOW IS OVER THE 
NORTHWEST PART OF THE AREA NW OF LINE FROM 32N125W TO 15N140W. 
THE AREA IS MOSTLY CLOUD FREE IN THE MIDDLE AND UPPER LEVELS 
WITH OVERCAST STRATOCUMULUS IN THE LOWER LEVELS. THE EXCEPTION 
IS A NARROW BAND OF BROKEN HIGH CLOUDS 100 NM WIDE ALONG THE 
EAST EDGE OF THE FLOW.

A WEAK CYCLONIC CIRCULATION IS CENTERED NEAR 21N125W. THE 
ASSOCIATED CIRCULATION EXTENDS OUT 400 NM FROM THE CENTER. THIS 
AREA IS CLOUD FREE AT ALL LEVELS EXCEPT FOR SCATTERED TO BROKEN 
STRATOCUMULUS NORTH OF 21N FROM 112W TO 125W. 

THE STRONG TROUGH OVER THE EASTERN UNITED STATES EXTENDS 
SOUTHWARD ACROSS THE GULF OF MEXICO AND ACROSS SOUTHERN MEXICO 
AND AFFECTS THE AREA NORTH OF THE ITCZ FROM 110W TO 90W.  
ENHANCED ITCZ CONVECTION IS NOTED SOUTHWEST OF THIS TROUGH.

GOOD UPPER LEVEL DIFFLUENCE IS NOTED OVER THE ITCZ EAST OF 130W 
WITH WIDESPREAD CONVECTION EAST OF 130W TO 107W FROM ABOUT 06N 
TO 13N. NO CONVECTION IN THIS AREA IS FORECAST TO BECOME AN 
ORGANIZED CIRCULATION. 

WEAK SURFACE RIDGE IS NORTH OF 19N WEST OF 118W. A WEAK SURFACE 
TROUGH IS ALONG THE ITCZ. ELSEWHERE AT THE SURFACE A FLAT 
PRESSURE PATTERN IS ANALYZED.

NE TO E GAP WINDS IN THE GULF OF PAPAGAYO REGION AND DOWNSTREAM 
WILL CONTINUE THROUGH TONIGHT THEN DIMINISH TUESDAY. 

$$
LL