000
AXPZ20 KNHC 241535
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN JUL 24 2011

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...SPECIAL FEATURE...
TROPICAL STORM DORA CENTERED NEAR 23.5N 114.2W AT 24/1500 UTC 
MOVING NW OR 320 DEGREES AT 8 KT. THE MAXIMUM SUSTAINED WINDS 
ARE 35 KT WITH GUSTS TO 45 KT MAINLY WITHIN ABOUT 30 NM OF 
CENTER. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1004 MB. 
STRONG NORTHEASTERLY SHEAR CONTINUES TO IMPACT THE TROPICAL 
CYCLONE THAT HAS MAINTAINED A SMALL AREA OF DEEP CONVECTION OVER 
THE SOUTHWEST QUADRANT OF ITS CIRCULATION. IN ADDITION...DORA IS 
NOW OVER 21-22C WATER AND WILL BE UNABLE TO MAINTAIN PERSISTENT 
DEEP CONVECTION...SO IT IS LIKELY THAT IT WILL DEGENERATE TO A 
REMNANT LOW LATE TONIGHT. SWELLS ASSOCIATED WITH DORA WILL 
GRADUALLY SUBSIDE ALONG THE SOUTHWESTERN COAST OF BAJA 
CALIFORNIA OVER THE NEXT DAY OR TWO. SEE LATEST NHC FORECAST/ 
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC FOR MORE 
DETAILS.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH IS ALONG 08N84W TO 09N95W. THE ITCZ AXIS 
EXTENDS FROM 09N95W TO 08N110W TO 09N127W TO BEYOND 08N140W. 
SCATTERED MODERATE N OF 05N E OF 85W. SCATTERED MODERATE WITHIN 
AROUND 90 NM EITHER SIDE OF ITCZ FROM 98W TO 110W. SIMILAR 
CONVECTION IS NOTED WITHIN 150 NM N OF ITCZ AXIS BETWEEN 130W 
AND 136W. 

...DISCUSSION...
A DEEP LAYER UPPER LEVEL TROUGH IS APPROACHING THE NW PORTION OF 
THE DISCUSSION AREA WITH ITS AXIS EXTENDING ALONG 31N145W TO 
BEYOND 29N146W. AN UPPER ANTICYCLONE CURRENTLY CENTERED NEAR 
24N124W HAS FORMED ALONG AN UPPER RIDGE EXTENDING SW FROM THE SW 
U.S. ACROSS NORTHERN BAJA CALIFORNIA TO BEYOND 18N132W. AN 
INVERTED UPPER TROUGH EXTENDS FROM 24N116W TO 20N115W TO 
12N118W. THE DISSIPATING CYCLONE IS JUST E OF THE NORTHERN END 
OF THIS TROUGH.  

AN UPPER CYCLONE IS OVER DEEP TROPICAL PACIFIC AT 04N127W. UPPER 
DIFFLUENCE BETWEEN THIS FEATURE AND THE UPPER ANTICYCLONE 
PREVIOUSLY MENTIONED IS HELPING TO INDUCE CONVECTION N OF THE 
ITCZ W OF 130W. 
 
AN UPPER ANTICYCLONE DOMINATES SE MEXICO AND CENTRAL WITH THE 
ENVELOPE OF ANTICYCLONIC FLOW ENHANCING THE SCATTERED CONVECTION 
S OF THE MONSOON TROUGH AXIS PARTICULARLY N OF 05N E OF 85W. 

AT THE LOW LEVELS...A RIDGE EXTENDS FROM 32N140W TO 20N120W. 
WEAK TRADE WINDS OF 15 KT ARE NOTED ON THE SOUTHERN PERIPHERY OF 
THE RIDGE AND N OF THE ITCZ. A COUPLE OF WEAK TROUGHS ARE 
EMBEDDED IN THE ITCZ. THE EASTERNMOST IS ALONG 112W/113W FROM 7N 
TO 12N. THE OTHER EXTENDS FROM 12N127W TO 08N132W.  

CROSS EQUATORIAL SE SWELLS...RESULTING IN SEAS TO 9 FT...ARE 
PROPAGATING NW ACROSS THE WATERS SW OF A LINE FROM 14N140W TO 
THE EQUATOR AT 112W...MIXING WITH NE WIND WAVES TO THE N OF 10N 
BETWEEN 132W AND 140W. SOUTHERLY SWELL IS DOMINATE OVER THE MOST 
OF THE PACIFIC WATERS. A NEW SET OF LONG PERIOD CROSS-EQUATORIAL 
SW SWELL WILL BEGIN TO SPREAD ACROSS THE REGIONAL WATERS LATE 
MON INTO TUE...RAISING SEAS TO 10 FT MAINLY S OF 05N BETWEEN 95W 
AND 110W.

GAP WINDS...NE TRADES OVER THE SW CARIBBEAN ARE EXPECTED TO 
CONTINUE TO SURGE THROUGH THE GULF OF PAPAGAYO AT 15-20 KT 
THROUGH TONIGHT...THEN DIMINISH TO 10-15 KT LATE MON. NORTHERLY 
WINDS ARE BEGINNING TO SURGE INTO THE GULF OF TEHUANTEPEC. 
IXTEPEC IN THE STATE OF OAXACA MEXICO HAS REPORTED SUSTAINED 
WINDS OF 20 KT SINCE THIS MORNING. THE WIND ARE GREATEST DURING 
THE OVERNIGHT AND EARLY MORNING HOURS WITH THE ASSISTANCE OF THE 
NOCTURNAL DRAINAGE FLOW.  

$$
GR