000
AXPZ20 KNHC 220950
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI JUL 22 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0945 UTC.

...SPECIAL FEATURE...
HURRICANE DORA CENTERED NEAR 18.9N 108.8W AT 0900 UTC MOVING NW 
OR 315 DEGREES AT 8 KT. MAXIMUM SUSTAINED WINDS ARE 90 KT WITH 
GUSTS TO 110 KT MAINLY WITHIN ABOUT 20 NM OF CENTER. THE 
ESTIMATED MINIMUM CENTRAL PRESSURE IS 970 MB. STRONG NORTHERLY 
SHEAR HAS DISSIPATED CONVECTION OVER THE N SEMICIRCLE WITH 
SCATTERED STRONG CONVECTION NOW NOTED WITHIN 30 NM EITHER SIDE 
OF A LINE EXTENDING FROM 19N108W TO 17N108W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION IS OBSERVED ELSEWHERE S OF THE 
CENTER WITHIN THE AREA BOUNDED BY 14N TO 18N BETWEEN 107W AND 
110W. THE CYCLONE IS MOVING WESTERLY UNDER A MID TO UPPER LEVEL 
RIDGE AND WILL WILL CONTINUE TO TRACK OVER INCREASINGLY COOLER 
OCEAN WATERS. ASSOCIATED SWELLS WILL LIKELY CAUSE LARGE SURF AND 
RIP CURRENT CONDITIONS AS THEY REACH THE COAST OF CENTRAL MEXICO 
AND THE SOUTHERN PORTIONS OF THE BAJA CALIFORNIA PENINSULA. 
PLEASE SEE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM 07N77W TO 05N97W WITH HURRICANE 
DORA INTERRUPTING THE MONSOON GYRE BETWEEN 97W AND 110W. LOW 
LEVEL WINDS INDICATE THE TROUGH AXIS RESUMES NEAR 15N110W AND 
EXTENDS SW TO 12N120W WHERE LOW LEVEL WINDS THEN INDICATE THAT 
THE ITCZ AXIS BEGINS AND EXTENDS W TO TO BEYOND 08N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED  
WITHIN 15 NM OF 08N79W...AND WITHIN 30 NM EITHER SIDE OF A LINE 
FROM 04N78W TO 06N85W TO 05.5N88W. ISOLATED MODERATE TO STRONG 
CONVECTION IS NOTED WITHIN 60 NM OF 10N134W AND 07N140W. 

...DISCUSSION...
AN UPPER LEVEL TROUGH IS OVER THE NW PORTION WITH ITS AXIS 
EXTENDING SW FROM SOUTHERN CALIFORNIA TO NEAR 27N132W...THEN THE 
AXIS TURNS NW INTO AN UPPER CYCLONE NEAR 29N147W. THE UPPER 
LEVELS APPEAR VERY DRY TO THE N OF 27N W OF 120W...AND ELSEWHERE 
N OF 15N W OF 130W. AN UPPER LEVEL ANTICYCLONE IS CENTERED OVER 
NW OLD MEXICO AT 29N109W WITH AN UPPER RIDGE EXTENDING SW TO A 
CREST AT 18N140W. AN UPPER CYCLONE IS OVER THE DEEP TROPICAL 
PACIFIC AT 06N126W...WITH AN INVERTED UPPER TROUGH AMPLIFYING N 
AND BECOMING EMBEDDED IN THE ANTICYCLONIC FLOW DOMINATING THE 
SUBTROPICS...ROUGHLY FROM 14N129W TO 23N130W...ALL PROGRESSING W 
WITH TIME.   

CONVECTION WAS ENHANCED EARLIER OVER NW MEXICO UNDER THE UPPER 
ANTICYCLONE...AND ALSO OVER INTERIOR MEXICO. THE DEBRIS MOISTURE 
IS ADVECTED SW OVER THE PACIFIC MERGING WITH THE DEBRIS MOISTURE 
FROM DORA...RESULTING IN MOIST UPPER LEVELS TO THE N OF 14N 
BETWEEN 100W AND 115W. DEBRIS MOISTURE FROM THE ITCZ CONVECTION 
W OF 120W REMAINS WITHIN ABOUT 180 NM OF THE AXIS.       
 
AN UPPER CYCLONE IS PROGRESSING W ACROSS THE NW CARIBBEAN WITH 
AN UPPER TROUGH EXTENDING SW ACROSS HONDURAS TO BASE OVER THE 
PACIFIC AT 10N90W...WITH THE TROUGH ACCOMPANIED BY DEBRIS 
MOISTURE FROM AFTERNOON CONVECTION THAT FLARED OVER GUATEMALA. 
ANOTHER UPPER CYCLONE IS OVER PANAMA WITH AN UPPER TROUGH 
EXTENDING SW TO A BASE AT 04N84W. ASSOCIATED UPPER DIFFLUENCE E 
OF THIS TROUGH AXIS IS SUPPORTING THE CLUSTERS OF CONVECTION 
PREVIOUSLY DESCRIBED...WITH THE DEBRIS MOISTURE COVERING THE 
AREA N OF 03N E OF 85W. THE UPPER LEVELS OF THE DEEP TROPICS S 
OF 10N BETWEEN 85W AND 110W IS GENERALLY DRY ALOFT...WITH DEBRIS 
MOISTURE FROM CONVECTION S OF MONSOON TROUGH AXIS QUICKLY 
EVAPORATING.

AT THE LOW LEVELS A RIDGE EXTENDS FROM 32N140W TO 15N120W. NE 
TRADES TO THE S OF THE RIDGE CONTINUE TO PULSE AT 15 TO 20 KT 
NEAR 12N137W. CROSS EQUATORIAL SE SWELLS ARE PROPAGATING NW 
ACROSS THE WATERS SW OF A LINE FROM 09N140W TO THE EQUATOR AT 
110W...MIXING WITH NE TRADE SWELL ALONG 10N BETWEEN 130W AND 
140W. SOUTHERLY SWELL IS PREDOMINATE OVER THE TROPICAL WATERS E 
OF 125W...AND THE SECONDARY SWELL TO N OF 23N E OF 125W TO THE 
COAST OF CALIFORNIA MIXING WITH NW SWELL.

$$
NELSON