000
AXPZ20 KNHC 290216
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED JUL 29 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...

TROPICAL WAVE N OF 06N ALONG 79W.80W IN THE GULF OF PANAMA HAS 
ENTERED THE DISCUSSION AREA AND IS ESTIMATED TO BE MOVING W AT
12 KT. NO SIGNIFICANT CONVECTION IS ASSOCIATED WITH THE WAVE. 

TROPICAL WAVE FROM 06N TO 17N ALONG 112W MOVING W AT 13 KT OVER 
THE PAST 24 HOURS. SCATTERED MODERATE ISOLATED STRONG CONVECTION 
IS FROM 09N TO 15N WITHIN 240 NM W AND 120 NM E OF THE WAVE 
AXIS. MID LEVEL CYCLONIC TURNING WAS NOTED WITHIN THE CONVECTION 
AND WAS MOST PRONOUNCED IN THE LAST LIGHT VISIBLE SATELLITE 
IMAGES. THE GFS COMPUTER MODEL MOVES THE SYSTEM WEST AND 
MAINTAINS A LARGE BUT WEAK LOW WITH THE WAVE FOR THE NEXT 
SEVERAL DAYS AND DOES NOT DEVELOP THE CIRCULATION. WEAK UPPER 
LEVEL OUTFLOW IS NOTED. SOUTHERLY SHEAR IS SWEEPING OVER THE 
SYSTEM.

TROPICAL WAVE FROM 06N TO 16N ALONG 130W/131W MOVING W NEAR 15 
KT. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS FROM 08N TO 
14N WITHIN 180 NM EITHER SIDE OF THE WAVE AXIS. THE GFS COMPUTER 
MODEL MOVES THE SYSTEM W AND ONLY SLIGHTLY DEVELOPS THE 
CIRCULATION. THE WAVE IS EMBEDDED WITHIN AN AREA OF MODERATE 
UPPER LEVEL DIFFLUENCE. SOUTHERLY SHEAR IS BEGINNING TO IMPACT 
THE SYSTEM.

TROPICAL WAVE FROM 04N TO 12N ALONG 140W MOVING W 15-18 KT OVER 
THE PAST 24 HOURS. SCATTERED MODERATE TO STRONG CONVECTION IS 
NOTED WITHIN 60 NM OF 09N138W...BEHIND THE WAVE AXIS. THE WAVE 
IS IN THE PROCESS OF MOVING WEST OF THE AREA. 

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...09N84W TO 
07N94W TO 12N110W TO 10N120W TO 12N127W TO 08N140W. SCATTERED 
MODERATE ISOLATED STRONG WITHIN 90-180 NM OF THE AXIS BETWEEN 
110W AND 118W...AND WITHIN 180 NM EITHER SIDE OF THE AXIS W OF 
127W. SCATTERED MODERATE WITHIN 90-120 NM OF THE AXIS BETWEEN 
86W AND 97W. 

...DISCUSSION...

AN UPPER LEVEL TROUGH EXTENDS FROM A BLOCKED CYCLONIC 
CIRCULATION N OF THE DISCUSSION AREA NEAR 37N141W. THE TROUGH IS 
CONFINED TO THE NORTHWEST PORTION OF THE DISCUSSION AREA WEST OF 
A LINE THROUGH 32N128W TO 12N140W. A NARROWING RIDGE AND 
ASSOCIATED ANTICYCLONIC CIRCULATION CENTERED SE OF THE TROUGH 
NEAR 19N125W WITH ASSOCIATED UPPER DIFFLUENT FLOW EXTENDING OUT 
ABOUT 360 NM. THIS FLOW WAS ENHANCING CONVECTION IN ASSOCIATION 
WITH THE THE TROPICAL WAVE ALONG 130W/131W. 

ANOTHER LARGE UPPER ANTICYCLONIC CIRCULATION IS CENTERED OVER NW 
MEXICO NEAR 28N109W...DOMINATING THE FLOW OVER MOST OF MEXICO 
AND THE NE PACIFIC. UPPER LEVEL DIFFLUENT FLOW ON THE E SIDE OF 
THE ANTICYCLONE WAS RESULTING IN CLUSTERS OF STRONG CONVECTION 
ALONG THE SIERRA MADRE OCCIDENTAL RANGE FROM 20N TO THE U.S. 
BORDER. A FAIRLY LARGE CYCLONIC CIRCULATION...ABOUT 360 NM IN 
DIAMETER...SITUATED BETWEEN THE TWO ANTICYCLONES NOTED ABOVE 
NEAR 18N116W IS MOVING WEST AT 15 KT. THIS FEATURE WAS IMPINGING 
UPON THE ANTICYCLONE NEAR 19N125W. SOUTHWESTERLY FLOW ON THE E 
SIDE OF THIS CIRCULATION WAS PROVIDING SOUTHERLY SHEAR OVER THE 
TROPICAL WAVE ALONG 112W.
 
A FLAT UPPER LEVEL RIDGE COVERS THE TROPICAL PACIFIC S OF 15N 
BETWEEN 95W AND 110W. THIS AREA IS SLIGHTLY DIFFLUENT ALOFT WITH 
MOIST MIDDLE AND UPPER LEVELS AND ENHANCED CONVECTION WITHIN THE 
ITCZ W OF 100W. AN INVERTED UPPER LEVEL TROUGH FROM NICARAGUA 
TO 05N93W IS MOVING W AT 10-12 KT. DEEP LAYERED DRY AIR WAS 
WRAPPING SWD W OF THE TROUGH AXIS OVER THE REGION S OF THE GULF 
OF TEHUANTEPEC. 

AT THE SURFACE...MODERATE SURFACE RIDGE IS NORTH OF 16N WEST OF 
112W. NE TO E GAP WINDS OF 20 TO 25 KT CONTINUE IN AND 
DOWNSTREAM FROM THE GULF OF PAPAGAYO REGION. THESE WINDS ARE 
FORECAST TO DROP BELOW 20 KT WITHIN 48 HOURS. 

$$
COBB