000
AXPZ20 KNHC 291517
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC WED JUL 29 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 
1500 UTC.

...TROPICAL WAVES...

TROPICAL WAVE ALONG 85W N OF 05N MOVING W 20 KT. THE INTERACTION 
WITH AN UPPER TROUGH IS GENERATING SCATTERED SHOWERS AND 
ISOLATED TSTMS NEAR THE NORTHERN PART OF THE WAVE AXIS. 
CONVECTION IS NOT ORGANIZED.

TROPICAL WAVE FROM 08N TO 17N ALONG 113W/114W MOVING W 10-15  
KT. SATELLITE IMAGES SHOW AN ASSOCIATED AREA OF LOW TO MID LEVEL 
CYCLONIC TURNING WITH SOME EVIDENCE OF A MID-LEVEL LOW NEAR 
12N113W. AN EARLIER QUIKSCAT PASS AROUND 0130 UTC INDICATED A 
WELL DEFINED WIND SHIFT AT THE SFC EXTENDING N FROM THE ITCZ TO 
NEAR 22N. CONVECTION IS LIMITED AND BEING SHEARED BY STRONG SLY 
WINDS ALOFT ON THE E SIDE OF AN UPPER LOW...WHICH IS UNFAVORABLE 
FOR TROPICAL CYCLOGENESIS.  

TROPICAL WAVE FROM 07N133W TO 14N132W MOVING W 10-15 KT. 
CONVECTION HAS INCREASED OVER THE PAST SEVERAL HOURS NEAR THE 
WAVE. THE DEEPEST CONVECTION IS WITHIN 50 NM EITHER WIDE OF A 
LINE FROM 12.5N130.5W TO 08N135.5W. UPPER DIFFLUENCE IS 
ENHANCING THIS CONVECTIVE ACTIVITY. SHORTWAVE IR IMAGES REVEAL 
SOME LOW-MID LEVEL CYCLONIC TURNING.  

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...06N77W TO 
06N95W TO 09N105W TO 11N130W TO 09N140W. NUMEROUS MODERATE WITH 
SCATTERED STRONG CONVECTION IS WITHIN 120 NM OF THE  POINT 
06N78W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION IS 
WITHIN 90 NM OF THE POINT 07.5N92.5W. SCATTERED MODERATE TO 
STRONG CONVECTION IS WITHIN 120 NM OF A LINE FROM 13N131.5W TO 
08N140W.

...DISCUSSION...

A HIGHLY DIFFLUENT UPPER PATTERN OVER THE DEEP TROPICS IS 
ENHANCING CONVECTION NEAR THE TROPICAL WAVE ALONG 131W/132W AND 
IN THE ITCZ WEST OF 129W. A QSCAT PASS SHORTLY AFTER 0300 UTC 
DID NOT SHOW ANY INDICATION OF A SURFACE LOW OR EVEN WELL 
DEFINED SFC TROUGH. HOWEVER...THIS PASS DID INDICATE NE-E WINDS 
OF 20-25 KT IN THE VICINITY OF THE WAVE IN RESPONSE TO THE 
STEEPENED PRESSURE GRADIENT BETWEEN IT AND THE SUBTROPICAL 
RIDGE. ACCORDINGLY...INCREASED WINDS SLIGHTLY TO REFLECT THIS IN 
THE HIGH SEAS FORECAST. THIS WAVE IS EXPECTED TO CONTINUE W AT 
10-15 KT WITH THE 20-25 KT FLOW GRADUALLY SHIFTING W WITH IT. 

DIFFLUENT UPPER FLOW OVER NORTHERN MEXICO HAS PRODUCED 
WIDESPREAD MULTI LEVEL BROKEN TO OVERCAST CLOUDINESS OVER THIS 
AREA. OVERNIGHT CONVECTION HAS DIMINISHED BUT IS EXPECTED TO 
DEVELOP AGAIN LATER TODAY. 

BESIDES THE TROPICAL WAVES AND ITCZ RELATED CONVECTION...MUCH OF 
THE REMAINDER OF THE BASIN IS EXPERIENCING FAIR WEATHER. 

STRONG TRADES ACROSS THE CARIBBEAN CONTINUE TO FAVOR ENHANCED 
FLOW THROUGH THE GULF OF PAPAGAYO. A QUIKSCAT PASS JUST PRIOR TO 
00 Z REVEALED WINDS OF ONLY 15-20 KT IN THE GAP. HOWEVER...THIS 
PASS OCCURRED NEAR THE EXPECTED DIURNAL MINIMUM OF THIS GAP 
FLOW...SO WINDS MAY BE SLIGHTLY STRONGER AT THE MOMENT. 
HOWEVER...NWP MODELS AGREE IN DIMINISHING WINDS BELOW 20 KT 
WITHIN THE NEXT 36 HOURS.

$$
LL