000
AXPZ20 KNHC 180244
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
0405 UTC SUN OCT 18 2015

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 
0230 UTC.               

...SPECIAL FEATURES...

TROPICAL STORM OLAF IS CENTERED NEAR 9.2N 131.0W AT 0300 UTC 
MOVING WEST OR 270 DEGREES AT 8 KT. ESTIMATED MINIMUM CENTRAL 
PRESSURE IS 994 MB. MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH 
GUSTS TO 65 KT. NUMEROUS MODERATE TO STRONG CONVECTION WAS NOTED 
WITHIN 90 NM OF CENTER. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION WAS NOTED ELSEWHERE FROM 05N TO 11N BETWEEN 127W AND 
134W. OLAF IS FORECAST TO CONTINUE TO INTENSIFY AS IT MOVES IN A 
GENERAL WESTWARD MOTION OVER THE NEXT COUPLE OF DAYS...AND IS 
FORECAST TO REACH HURRICANE STRENGTH EARLY SUNDAY. PLEASE SEE 
LATEST FORECAST ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS ON OLAF. 

GULF OF TEHUANTEPEC...WINDS OF MINIMAL GALE FORCE CONTINUE TO 
FUNNEL THROUGH THE CHIVELA PASS AND INTO THE GULF OF 
TEHUANTEPEC. WINDS WILL REMAIN AT NEAR GALE FORCE OR MINIMAL 
GALE FORCE OVER THE NEXT COUPLE OF DAYS. MAXIMUM SEAS OF 10-14 
FT ARE EXPECTED WITH THIS EVENT. 
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 
           
THE MONSOON TROUGH EXTENDS FROM 14N92W TO 12N99W TO 12N106W TO 
09N115W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS 
NOTED OVER FORECAST WATERS N OF 09N BETWEEN 85W AND 102W. 

...DISCUSSION... 

A WEAKENING COLD FRONT IS ANALYZED FROM NEAR 30N129W TO 26N136W. 
THE COLD FRONT WILL CONTINUE TO WEAKEN AS MOVES SLOWLY E THROUGH 
THE OVERNIGHT HOURS...AND IS EXPECTED TO DISSIPATE BY EARLY SUN 
MORNING. SEAS TO 9 FT IN NW SWELL CURRENTLY PREVAIL OVER THE 
WATERS W OF A LINE FROM 30N130W TO 20N140W. THIS SWELL WILL 
PROPAGATE SLOWLY SE WHILE SUBSIDING THE NEXT COUPLE OF DAYS. BY 
MON AFTERNOON...COMBINED SEAS ASSOCIATED TO THIS SWELL WILL 
SUBSIDE BELOW 8 FT. HIGH PRESSURE WILL BUILD IN THE WAKE OF THE 
FRONT OVER THE NORTHERN WATERS. THIS WILL HELP EXPAND THE AREA 
OF 20-33 KT WINDS AROUND TROPICAL STORM OLAF. 

SW SWELL WITH PERIODS IN THE 19-21 SECOND RANGE WILL REACH THE 
PACIFIC COAST S OF MAZATLAN MEXICO OVERNIGHT...AND STRETCH N 
ALONG THE PACIFIC COAST OF THE BAJA CALIFORNIA PENINSULA AFTER 
SUNRISE SUN. THIS LONG-PERIOD SWELL COULD MAKE FOR DANGEROUS 
CONDITIONS ENTERING AND EXITING PORTS AND WILL INCREASE THE 
THREAT OF RIP CURRENTS. 

A CENTRAL AMERICAN GYRE WILL HELP MAINTAIN WINDS OF NEAR GALE TO 
MINIMUM GALE FORCE FOR THE FORECAST PERIOD OVER THE GULF OF 
TEHUANTEPEC. THE TROPICAL WAVE THAT HAS PROPAGATED INTO THE 
REGION HAS BEEN ABSORBED INTO THIS LARGER SCALE GYRE. AS TYPICAL 
WITH CENTRAL AMERICAN GYRES...THE MONSOON TROUGH HAS BEEN LIFTED 
FURTHER NORTHWARD AND SW MONSOONAL FLOW HAS INCREASED. THIS 
ENHANCED MONSOON FLOW CONTINUES TO ADVECT ABUNDANT TROPICAL 
MOISTURE INTO THE EASTERN WATERS AND PORTIONS OF CENTRAL AMERICA 
AND SOUTHERN MEXICO WHICH WILL MAINTAIN THE POTENTIAL FOR ACTIVE 
WEATHER OVER THIS AREA FOR THE NEXT FEW DAYS. GLOBAL MODELS 
CONTINUE TO SUGGEST THAT THE INTERACTION OF THE GALE FORCE WINDS 
WITH THE MONSOON TROUGH WILL HELP TO GENERATE A LOW PRESSURE 
CENTER...WITHIN THIS LARGER SCALE GYRE...S OF THE GULF OF 
TEHUANTEPEC WHICH WILL HAVE THE POTENTIAL TO DEVELOP INTO A 
TROPICAL CYCLONE NEXT WEEK. REGARDLESS OF TROPICAL CYCLONE 
FORMATION...THIS SYNOPTIC SETUP WILL BRING THE POTENTIAL FOR 
LOCALLY HEAVY RAINFALL WHICH MAY LEAD TO FLASH FLOODING AND 
DANGEROUS MUDSLIDES OVER PORTIONS OF CENTRAL AMERICA AND 
SOUTHERN MEXICO THROUGH THE REMAINDER OF THE WEEKEND INTO EARLY 
NEXT WEEK. 

$$ 
AL