000
AXPZ20 KNHC 210348
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE JUL 21 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 
0300 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE HAS ENTERED THE AREA FROM THE EAST AND IS ALONG 
82W N OF 04N. THE WAVE HAS BEEN MOVING WEST 20 KT IN THE 
ATLANTIC AREA. THERE IS A LARGE AREA OF MODERATE TO STRONG 
CONVECTION WITHIN 240 NM OF THE POINT 07N83W. GOOD UPPER LEVEL 
DIFFLUENCE IS OBSERVED OVER THIS CONVECTION. THE CONVECTION DOES 
NOT APPEAR TO BE ORGANIZED BY CYCLONIC CIRCULATION AND 
DEVELOPMENT OF THIS SYSTEM IS NOT EXPECTED.

TROPICAL WAVE ALONG 117W/118W 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 IS NOT ORGANIZED BY CYCLONIC 
CIRCULATION. THE WAVE IS FORECAST TO CONTINUE TO MOVE WEST 15 TO 
20 KT AND CHANGE LITTLE.
 
TROPICAL WAVE THAT WAS ALONG 139W FROM 05N TO 18N HAS MOVED WEST 
OF THE AREA.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...06N77W TO 
07N110W TO 05N140W. SCATTERED MODERATE TO STRONG CONVECTION IS 
WITHIN 240 NM OF THE POINT 06.5N83.5W. SCATTERED MODERATE TO 
STRONG CONVECTION IS WITHIN 90 NM OF THE POINT 06.5N92.5W. 
SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 100 NM OF THE 
POINT 08.5N121W.

...DISCUSSION...

CYCLONIC CIRCULATION NORTH OF THE NORTHWEST PART OF THE AREA 
CENTERED NEAR 41N139W. 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 50 NM WIDE ALONG THE 
EAST EDGE OF THE FLOW.

A WEAK CYCLONIC CIRCULATION IS CENTERED NEAR 26N125W. 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 118W 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 108W FROM ABOUT 06N 
TO 13N. NO CONVECTION IN THIS AREA IS FORECAST TO DEVELOP AN 
ORGANIZED CYCLONIC 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