000
AXPZ20 KNHC 290940
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED JUL 29 2009

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 83W N OF 06N MOVING W NEAR 20 KT. THE 
INTERACTION WITH AN INVERTED UPPER TROUGH IS GENERATING 
SCATTERED SHOWERS AND ISOLATED TSTMS OVER PORTIONS OF NICARAGUA 
AND HONDURAS. CONVECTION IS MORE ORGANIZED ALONG THE ITCZ 
ENHANCED BY WIND SPEED CONVERGENCE ASSOCIATED WITH THE GULF OF 
PAPAGAYO GAP WIND EVENT.  

TROPICAL WAVE EXTENDS FROM 19N111W TO 08N113W MOVING W 10 KT. 
SATELLITE IMAGES SHOW AN ASSOCIATED PRONOUNCED AREA OF LOW TO 
MID LEVEL CYCLONIC TURNING WITH SOME EVIDENCE OF A MID-LEVEL LOW 
NEAR 12N112W. A 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 EXTENDS FROM 16N130W TO 07N133W MOVING W 10-15 KT. 
CONVECTION HAS INCREASED OVER THE PAST SEVERAL HOURS NEAR THE 
WAVE. THE DEEPEST CONVECTION IS IN A NEARLY LINEAR NE-SW BAND 
FROM 13N-15N BETWEEN 128W-132W AND WITHIN THE INTERACTION OF THE 
ITCZ. UPPER DIFFLUENCE IS ENHANCING THIS CONVECTIVE ACTIVITY. 
SHORTWAVE IR IMAGES REVEAL SOME LOW-MID LEVEL CYCLONIC TURNING 
BUT THERE IS NO WELL DEFINED CIRCULATION CENTER.  

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 09N84W 08N110W 12N112W 12N130W 
09N140W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF THE 
AXIS E OF 93W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS 
WITHIN 120 NM S OF THE AXIS BETWEEN 93W AND 106W. SCATTERED 
MODERATE CONVECTION IS FROM 08N TO 13N BETWEEN 113W AND 122W. 
SCATTERED MODERATE TO STRONG CONVECTION IS FROM 07N TO 14N 
BETWEEN 128W AND 139W.   

...DISCUSSION...

A HIGHLY DIFFLUENT UPPER PATTERN OVER THE DEEP TROPICS IS 
ENHANCING SCATTERED MODERATE CONVECTION NEAR THE TROPICAL WAVE 
ALONG 131W/132W. A QSCAT PASS SHORTLY AFTER 0300 UTC DID NOT 
SHOW ANY INDICATION OF A SFC 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. 

NUMEROUS SHOWERS AND TSTMS ARE LOCATED OVER THE WRN PORTION OF 
MAINLAND MEXICO. THIS ACTIVITY IS BEGINNING TO SPREAD INTO THE 
GULF OF CALIFORNIA DRIVEN BY ELY FLOW ALOFT S OF AN UPPER HIGH 
CENTER NEAR 29N107W. BESIDES FOR 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.

$$
CANGIALOSI