000
AXPZ20 KNHC 231518
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT JUL 23 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 21.3N 111.9W AT 23/1500 UTC 
MOVING NW OR 305 DEGREES AT 08 KT. THE MAXIMUM SUSTAINED WINDS 
HAVE DIMINISHED TO 40 KT WITH GUSTS TO 50 KT MAINLY WITHIN ABOUT 
20 NM OF CENTER. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1001 
MB. STRONG NORTHERLY SHEAR CONTINUES TO IMPACT THE TROPICAL 
CYCLONE WHICH IS MOVING TOWARD THE NW UNDER A MID TO UPPER LEVEL 
RIDGE. THIS GENERAL MOTION IS EXPECTED TO CONTINUE DURING THE 
NEXT 48 HOURS. ON THE FORECAST TRACK...DORA SHOULD MOVE NEARLY 
PARALLEL AND WELL OFFSHORE OF THE WEST COAST OF SOUTHERN BAJA 
CALIFORNIA. MODERATE TO ISOLATED STRONG CONVECTION IS NOTED 
WITHIN 90 NM NE SEMICIRCLE. LARGE SWELLS GENERATED BY DORA WILL 
AFFECT THE COAST OF SOUTHWESTERN MEXICO AND BAJA CALIFORNIA 
DURING THE NEXT COUPLE OF DAYS. THESE SWELLS WILL LIKELY CAUSE 
LIFE-THREATENING SURF AND RIP CURRENT CONDITIONS. SEE LATEST NHC 
FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC 
FOR MORE DETAILS.

...ITCZ/MONSOON TROUGH...
MONSOON TROUGH 08N78W TO 09N85W TO 07N96W THEN ITCZ TO 08N106W 
TO 07N120W 08N135 TO 07N140W. SCATTERED MODERATE WITHIN 90 NM N 
OF ITCZ AXIS FROM 98W TO 102W. SIMILAR CONVECTION IS NOTED FROM 
10N TO 13N BETWEEN 118W AND 128W.

...DISCUSSION...
AN UPPER LEVEL TROUGH IS ALONG 141W PRODUCING S TO SW WINDS OVER 
THE NW CORNER OF THE FORECAST AREA. AN UPPER ANTICYCLONE IS 
CENTERED NEAR 26N116W. UPPER-LEVEL NE WINDS IN ASSOCIATION WITH 
THE CIRCULATION OF THIS ANTICYCLONE ARE IMPACTING TROPICAL 
CYCLONE DORA. AN UPPER CYCLONE IS OVER THE DEEP TROPICAL PACIFIC 
AT 04N124W. AN INVERTED TROUGH IS ALONG 102W N OF 5N. OTHERWISE 
UPPER ANTICYCLONIC FLOW DOMINATES THE TROPICAL PACIFIC E OF 
102W. UPPER DIFFLUENT IS HELPING TO INDUCE THE MODERATE TO 
STRONG CONVECTION E OF 80W PREVIOUSLY MENTIONED. 

AT THE LOW LEVELS A RIDGE EXTENDS FROM 32N140W TO 20N120W. NE 
TRADES TO THE S OF THE RIDGE CONTINUE TO PULSE AT 15 TO 20 KT 
MAINLY FROM 10N TO 15N W OF 135W AS NOTED ON THE LATEST ASCAT 
PASS. 

A WEAK TO MODERATE PAPAGAYO GAP WIND EVENT WILL PULSE THE NEXT 
SEVERAL DAYS WITH WINDS REACHING 20 TO 25 KT IN THE EARLY 
MORNING...AND FADING BY LATE AFTERNOON. FRESH TRADE WIND FLOW IN 
THE SW CARIBBEAN IS FUNNELING THROUGH THE GAP.

CROSS EQUATORIAL SE SWELLS ARE PROPAGATING NW ACROSS THE WATERS 
SW OF A LINE FROM 14N140W TO THE EQUATOR AT 110W...MIXING WITH 
NE TRADE SWELLS ALONG 10N BETWEEN 130W AND 140W. SOUTHERLY 
SWELLS PREVAIL OVER THE TROPICAL WATERS E OF 125W. N TO NW 
SWELLS ARE REACHING THE N WATERS PARTICULARLY N OF OF 25N 
BETWEEN 118W AND 124W. THESE SWELLS ARE MIXING WITH SE SWELLS 
GENERATED BY TROPICAL CYCLONE DORA. ANOTHER SET OF LARGE SWELLS 
FROM THE SOUTHERN HEMISPHERE IS FORECAST TO CROSS THE EQUATOR 
LATE SUN INTO EARLY MON SPREADING OVER THE SOUTH PORTION OF THE 
DISCUSSION AREA. 

$$
GR