000
AXPZ20 KNHC 021555
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN AUG 02 2009

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY 
THROUGH 1545 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS N OF 05N ALONG 92W AND IS MOVING W AT 15 TO 
20 KT. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS ENHANCED 
WITHIN 10 NM OF THE WAVE AXIS FROM 06N TO 12N. A LARGER CLUSTER 
OF STRONG CONVECTION IS NOTED WITHIN 120 NM OF 15N138.5W WITH 
LIGHTNING DATA INDICATING NUMEROUS TSTMS.

A TROUGH EXTENDS FROM 06N107W TO 16N102W AND IS MOVING WESTWARD 
SIMILAR TO THE TROPICAL WAVES TO ITS E AND W. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 60 NM OF THE 
WAVE AXIS.

A TROPICAL WAVE EXTENDS FROM 05N TO 17N ALONG 115W AND IS MOVING 
W AT 15 KT. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS 
OBSERVED FROM 06N TO 15N BETWEEN 108W AND 121W. BROAD CYCLONIC 
IS CURRENTLY CENTERED AROUND 11N117W.

A TROPICAL WAVE EXTENDS FROM 06N TO 19N ALONG 132W AND IS MOVING 
W AT 10 TO 15 KT. ONLY ISOLATED WEAK CONVECTION IS NOTED ALONG 
THE WAVE FROM 09N TO 13N.

...ITCZ...
THE AXIS IS ALONG 06N77W TO 10N91W TO 11N115W TO 09N122W TO 
12N134W TO 11N140W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION IS OBSERVED WITHIN 60 NM OF THE AXIS E OF 85W. 
ISOLATED MODERATE AND STRONG CONVECTION IS NOTED ELSEWHERE 
AROUND THE TROPICAL WAVE CONVECTION FROM 06N TO 16N BETWEEN 90W 
AND 122W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS ALSO 
NOTED FROM 07N TO 14N ALONG 139W.

...DISCUSSION...
A DEEP LAYERED CYCLONE IS CENTERED N OF THE AREA NEAR 37N131W 
WITH A TROUGH EXTENDING SE FROM 32N123W TO 24N115W. THE  
ASSOCIATED SURFACE TROUGH IS ANALYZED FROM 32N125W TO 27N131W. 
FURTHER S OVER THE TROPICS IS ANOTHER UPPER CYCLONE NEAR 15N123W 
MOVING W WITH TIME. THE RESULT IS A BROAD UPPER TROUGH...AND DRY 
AIR...OVER THE DISCUSSION AREA TO THE N OF 11N BETWEEN 121W AND 
127W. THIS TROUGH SEPARATES TWO UPPER ANTICYCLONES WITH THE 
WESTERNMOST ANTICYCLONE CENTERED AT 19N133W. ITS ENVELOPE OF 
ANTICYCLONIC FLOW DOMINATES THE AREA FROM 15N TO 28N W OF 131W 
AND IS ADVECTING DEBRIS MOISTURE FROM TROPICAL STORM LANA INTO 
THE AREA WITHIN 150 NM OF LINE 27N140W TO 23N127W WHERE IT 
IMMEDIATELY EVAPORATES AS IT ENCOUNTERS THE BROAD TROUGH AND 
ASSOCIATED DRY AIR PREVIOUSLY MENTIONED. THE SECOND UPPER 
ANTICYCLONE IS CENTERED NEAR 28N100W WITH A RIDGE EXTENDING SW 
TO A CREST AT 20N117W. THE ASSOCIATED UPPER LEVEL DIFFLUENCE IS 
SUPPORTING THE CONVECTION OVER THE TROPICS BETWEEN 100W AND 120W.

AN UPPER TROUGH EXTENDS SW ACROSS THE NW CARIBBEAN AND THE 
YUCATAN PENINSULA OVER THE DISCUSSION AREA TO NEAR 10N100W. 
EMBEDDED SMALL UPPER CYCLONES ARE NOTED ALONG THE TROUGH AT 
19N88W AND 13N95W WITH CONVECTION ENHANCED OVER THE E 
SEMICIRCLES OF BOTH FEATURES. THE UPPER LOW AT 13N95W IS 
CURRENTLY IN PHASE WITH A TROPICAL WAVE RESULTING IN THE 
CONVECTIVE BURST AT 15N138.5W. THE UPPER LEVELS APPEAR VERY DRY 
S OF THE ITCZ...BASICALLY S OF 03N TO BEYOND 20S SUPPRESSING 
DEEP CONVECTION.
        
AT THE LOW LEVELS...A SURFACE RIDGE HAS ITS AXIS FROM 32N141W TO 
10N110W. BROKEN TO LOCALLY OVERCAST STRATOCUMULUS CLOUDS ARE 
NOTED OVER THE AREA N OF 19N W OF 113W. 

GAP WINDS...NE TO E WINDS CONTINUE TO SURGE THROUGH AND JUST 
DOWNSTREAM OF THE GULF OF PAPAGAYO.

$$
NELSON