000
AXPZ20 KNHC 212138
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU JUL 21 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...SPECIAL FEATURE...
HURRICANE DORA IS CENTERED NEAR 17.7N 107.4W AT 1800 UTC OR 
ABOUT 190 NM SSW OF CABO CORRIENTES MEXICO MOVING NW OR 310 
DEGREES AT 8 KT. DORA IS A CATEGORY FOUR HURRICANE ON THE 
SAFFIR-SIMPSON HURRICANE WIND SCALE. MAXIMUM SUSTAINED WINDS ARE 
130 KT WITH GUSTS TO 160 KT. ESTIMATED MINIMUM CENTRAL PRESSURE 
IS 932 MB. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO 
HEADERS MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS. NUMEROUS 
MODERATE TO STRONG CONVECTION IS NOTED WITHIN 150 NM OF CENTER. 
LARGE SWELLS GENERATED BY DORA WILL AFFECT THE COAST OF 
SOUTHWESTERN MEXICO DURING THE NEXT COUPLE OF DAYS. SWELLS WILL 
BEGIN AFFECTING THE COAST OF THE SOUTHERN PORTION OF BAJA 
CALIFORNIA LATER TONIGHT. THESE SWELLS WILL LIKELY CAUSE 
LIFE-THREATENING SURF AND RIP CURRENT CONDITIONS.

...ITCZ/MONSOON TROUGH...
WEAK MONSOON TROUGH EXTENDS FROM 10N85W TO 13N91W THEN RESUMES 
AT 14N110W TO 12N120W THEN 10N132W TO 08N140W. SCATTERED 
MODERATE WITHIN 120 NM N OF ITCZ AXIS W OF 130W.

...DISCUSSION...
A MODEST PRESSURE GRADIENT EXISTS ACROSS W AND NW PORTIONS OF 
THE DISCUSSION AREA...YIELDING WEAK NE TRADE WINDS N OF THE ITCZ 
W OF 134W. NE WINDS TO 20 KT ARE FOUND ACROSS FAR NW PORTIONS OF 
THE AREA MAINLY N OF 22N W OF 132W. A WINDSAT PASS FROM THIS 
MORNING AND THE 1824 UTC ASCAT CORROBORATED THESE WIND SPEEDS. 
WINDS ARE FORECAST TO DIMINISH BELOW 20 KT IN ABOUT 24 HOURS.

CURRENTLY...A PAIR OF ASCAT PASSES INDICATE THAT THE MONSOON 
TROUGH IS FURTHER SOUTH LIKELY ALONG 5N-6N E OF 95W WITH WEAK S 
TO SW WINDS S OF THE AXIS. DEEP LAYER E WINDS ARE BEGINNING TO 
RETURN TO CENTRAL AMERICA...BRINGING ABOUT A MORE TYPICAL 
MID-SUMMER WEATHER PATTERN...AND A RETURN TO THE USUAL 
DIURNAL-NOCTURNAL CYCLES. A WEAK PAPAGAYO GAP WIND EVENT WILL 
PULSE DURING THE NEXT FEW DAYS WITH WINDS REACHING 15-20 KT IN 
THE EARLY MORNING...AND FADING BY LATE AFTERNOON. DUE TO THE 
WEAK PULSING NATURE OF THIS EVENT...THESE WINDS ARE NOT INCLUDED 
INTO THE HIGH SEAS FORECAST.

MODERATE PERIOD N TO NW SWELL WILL REACH 30N THIS EVENING WITH 
SEAS BUILDING TO 8 FT...PRODUCED BY STRONG NWLY WINDS EXPECTED 
TO DEVELOP OFF THE CALIFORNIA COAST. SEAS ACROSS NE PORTIONS OF 
THE AREA WILL PEAK AROUND 9 FT SAT MORNING THEN FADE THROUGH SUN.

$$
GR