000
AXPZ20 KNHC 020924
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU JUL 02 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 
0730 UTC.

...TROPICAL WAVE...

A TROPICAL WAVE ALONG 101W FROM 04N TO 16N IS MOVING W NEAR 10 
KT. THIS WAVE IS EMBEDDED IN THE ITCZ BUT THERE IS LITTLE DEEP 
CONVECTION ASSOCIATED WITH IT AS THE WAVE IS CURRENTLY UNDER 
STRONG UPPER LEVEL EAST-NORTHEASTERLY WINDS FUNNELING BETWEEN 
THE UPPER LEVEL ANTICYCLONE OVER CENTRAL MEXICO NEAR 21N101W AND 
THE WESTERN CARIBBEAN UPPER LOW NEAR 17N81W. EXPECT THE WAVE TO 
CONTINUE W AND GRADUALLY INCREASE IN SPEED OVER THE NEXT FEW 
DAYS AS DEEP LAYER EASTERLY FLOW EXPANDS WESTWARD BETWEEN 10N 
AND 20N E OF 120W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 06N78W TO 09N90W TO 09N98W TO 
10N110W TO 06N140W. SCATTERED MODERATE TO STRONG CONVECTION CAN 
BE FOUND WITHIN 210 NM S OF THE AXIS AND 150 NM N OF THE AXIS E 
OF 80W. ISOLATED MODERATE CONVECTION LIES BETWEEN 80W AND 88W 
WITHIN 180 NM S OF THE AXIS AND N OF THE AXIS TO THE COAST OF 
CENTRAL AMERICA.

...DISCUSSION...

TROPICS...
MID LEVEL RIDGING BUILDING OVER NORTHERN MEXICO AND THE GULF OF 
MEXICO WILL ALLOW EASTERLY FLOW TO EXPAND W THROUGH THE WESTERN 
CARIBBEAN AND INTO THE EASTERN PACIFIC OVER THE NEXT FEW 
DAYS...WITH A 30 TO 40 KT EASTERLY MID LEVEL JET EXPECTED TO 
MOVE INTO THE REGION E OF 95W ALONG 13N BY TONIGHT. GAP WINDS AT 
THE SURFACE IN THE GULF OF PAPAGAYO ARE EXPECTED TO RISE ABOVE 
20 KT BY TONIGHT AS A RESULT. THE AFOREMENTIONED TROPICAL WAVE 
WILL REMAIN UNDER STRONG MID TO UPPER LEVEL EASTERLY 
FLOW...MAKING CONDITIONS LESS THAN FAVORABLE FOR DEEP CONVECTION 
TO DEVELOP. FARTHER E...THE EASTERLY FLOW AT THE SURFACE WILL BE 
CENTERED FROM 10N TO 15N AND IS EXPECTED TO MEET UP WITH THE 
CROSS-EQUATORIAL FLOW E OF 100W. THE SUBSEQUENT ENHANCEMENT OF 
LOW LEVEL VORTICITY IN THE REGION IS EXPECTED TO INDUCE A 
SURFACE LOW NEAR 10N98W TONIGHT. WINDS ABOVE 20 KT WILL BUILD IN 
THE EASTERN SEMICIRCLE AS THE PRESSURE GRADIENT INCREASES 
BETWEEN THE STRONG SUBTROPICAL RIDGE IN THE SE PACIFIC AND THIS 
1008 MB LOW. DEEP CONVECTION NEAR THIS LOW WILL LIKELY BE 
INHIBITED BY THE STRONG WINDS ALOFT. CROSS-EQUATORIAL S WINDS TO 
20 KT ARE ALREADY OBSERVED S OF 05N BETWEEN 92W AND 98W WHERE 
THE PRESSURE GRADIENT IS SUFFICIENT. CROSS-EQUATORIAL WINDS 
ABOVE 20 KT ARE ALSO NOTED IN FAR SW WATERS WHERE THEY ARE 
EXPECTED TO SUBSIDE ON FRI. IN ADDITION...A STRONG SOUTHERN 
HEMISPHERE STORM IS BRINGING LONG PERIOD SW SWELL INTO FORECAST 
WATERS S OF 07N GENERALLY BETWEEN 95W AND 130W TODAY AND FRI.

SUBTROPICS...
THE UPPER LEVEL ANTICYCLONE CENTERED OVER W WATERS NEAR 17N130W 
WILL MOVE NORTHWARD OVER THE NEXT FEW DAYS AND JOIN FORCES WITH 
THE ANTICYCLONE OVER CENTRAL MEXICO. THE RESULTING UPPER RIDGE 
WILL STRETCH ACROSS N WATERS ALONG 24N BY FRI AND WILL FORCE THE 
BROAD UPPER TROUGH CURRENTLY OVER NW WATERS N OF THE AREA. THE 
SURFACE TROUGH FOUND FROM 30N123W TO 27N124W ASSOCIATED WITH THE 
LEADING EDGE OF THE MID TO UPPER LEVEL BROAD TROUGH WILL REMAIN 
STATIONARY INTO FRI AS THE TROUGH ALOFT IS PUSHED NE. THE 
SURFACE RIDGE WILL BUILD TO THE SOUTH OF THE SURFACE 
TROUGH...ALLOWING FOR AN INCREASED PRESSURE GRADIENT BETWEEN IT 
AND CLIMATOLOGICAL LOW PRESSURE OVER THE U.S. DESERT SW. WINDS 
OFF THE W COAST OF BAJA CALIFORNIA MAY BRIEFLY RISE ABOVE 20 KT 
IN THE AFTERNOON/EVENING HOURS WHEN SURFACE PRESSURES IN THE 
DESERT SW ARE LOWEST. STRONG SOUTHERLY FLOW ON THE SE EDGE OF 
THE UPPER LEVEL BROAD TROUGH HAS TRANSPORTED SOME MID TO UPPER 
LEVEL MOISTURE/CLOUDINESS INTO THE REGION FROM 14N TO 22N W OF 
132W BUT THIS CLOUDINESS IS ALREADY WANING AS THE BUILDING DEEP 
LAYER HIGH ENHANCES SUBSIDENCE OVER THE REGION. 

$$
SCHAUER CLARK