000
AXPZ20 KNHC 170248
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC MON OCT 17 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0215 UTC.

...SPECIAL FEATURES...

AT 17/0000 UTC...THE LAST ADVISORY WAS ISSUED BY THE NATIONAL 
HURRICANE CENTER ON IRWIN. AT THIS TIME...TROPICAL DEPRESSION 
IRWIN IS CENTERED NEAR 14.1N 108.3W MOVING NORTHWEST OR 310 
DEGREES AT 4 KT. A TURN TOWARD THE WEST OR SOUTHWEST WITH A 
DECREASE IN FORWARD SPEED IS EXPECTED DURING THE NEXT DAY OR SO. 
THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. THE MAXIMUM 
SUSTAINED WIND SPEEDS ARE 25 KT WITH GUSTS TO 35 KT. WEAKENING 
IS EXPECTED DURING THE NEXT 48 HOURS AND THE REMNANT LOW IS 
FORECAST TO DISSIPATE IN TWO TO THREE DAYS. THERE IS NO DEEP 
CONVECTION NOTED WITH IRWIN. SEE LATEST NHC FORECAST/ADVISORY 
UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS. 
 
...ITCZ/MONSOON TROUGH...
MONSOON TROUGH EXTENDS FROM 16N98W TO 15N105W THEN RESUMES W OF 
IRWIN FROM 12N11OW TO 08N125W TO 10N140W. ISOLATED MODERATE FROM 
12N TO 15N BETWEEN 93W AND 96W AND FROM 07N TO 10N BETWEEN 115W 
AND 120W. 

...DISCUSSION...

A 1008 MB LOW PRESSURE CENTER IS NEAR 30N137W. THE MOST RECENT 
ASCAT PASS SHOWED WINDS OF 20 KT WITHIN 90 NM OF THE LOW CENTER. 
THE COLD FRONT ASSOCIATED WITH THIS SYSTEM IS ALREADY WEAKENING 
WHILE A TROUGH EXTENDS FROM THE LOW PRES TO NEAR 23N140W. SLY 
WINDS IN THE 20 TO 25 KT RANGE IS NOTED PER THE SAME ASCAT PASS 
BETWEEN THE TROUGH AND THE COLD FRONT. EXPECT WINDS TO DIMINISH 
BELOW 20 KT IN ABOUT 24 HOURS AS THE LOW PRES BEGINS TO MOVE 
AWAY FROM THE FORECAST WATERS AND THE FRONT DISSIPATES. SEAS 
WILL SLOWLY SUBSIDE TO NEAR 9 FT AS THEY CONTINUE MOVING FURTHER 
SOUTHWARD THROUGH THE FORECAST PERIOD. 

AN EXTENSIVE AREA OF FRESH TO STRONG SOUTHWESTERLY MONSOONAL FLOW
PERSISTS N OF 05N E OF 100W. SCATTEROMETER DATA CONFIRMED THE 
PRESENCE OF THESE WINDS WHICH ARE ADVECTING ABUNDANT TROPICAL 
MOISTURE OVER PORTIONS OF CENTRAL AMERICA AND SOUTHERN MEXICO. 
THIS WILL BRING PERIODS OF HEAVY RAINFALL INTO SECTIONS OF THE 
PACIFIC COASTS OF SOUTHEASTERN MEXICO...GUATEMALA...EL 
SALVADOR...SOUTHERN HONDURAS AND NICARAGUA. THE PERIODS OF HEAVY 
MONSOONAL RAINFALL HAVE THE POTENTIAL TO CREATE LIFE-THREATENING 
FLASH FLOODS AND MUD SLIDES IN SOME AREAS.

NORTHERLY FLOW OVER THE SW GULF OF MEXICO...ASSOCIATED WITH A 
BROAD AND ELONGATED AREA OF LOW PRESSURE LOCATED NEAR THE 
YUCATAN PENINSULA...CONTINUES TO FUNNEL THROUGH THE CHIVELA PASS 
INTO THE GULF OF TEHUANTEPEC WHERE WINDS OF 20 TO 25 KT ARE 
NOTED. WITH THIS CYCLONIC CIRCULATION EXPECTED TO PERSIST 
THROUGH THE FORECAST PERIOD...FRESH TO STRONG WINDS ARE EXPECTED 
TO CONTINUE BLOWING OVER THE GULF OF TEHUANTEPEC. 

THE REMAINDER OF THE REGIONAL WATERS S OF 20N E OF 130W ARE 
DOMINATED BY MERGING NORTHERLY AND SOUTHWESTERLY SWELL. THIS 
SWELL EVENT WILL CONTINUE TO SUBSIDE FROM THE NORTHWEST TO THE 
SOUTHEAST DURING THE NEXT 48 HOURS.

$$
GR