000
AXPZ20 KNHC 182106
TWDEP 

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

...SPECIAL FEATURES...

HURRICANE OLAF IS CENTERED NEAR 9.7N 134.3W AT 2100 UTC MOVING 
WEST OR 280 DEGREES AT 12 KT. ESTIMATED MINIMUM CENTRAL PRESSURE 
IS 989 MB. THE MAXIMUM SUSTAINED WIND SPEED IS 70 KT WITH GUSTS 
TO 85 KT. NUMEROUS MODERATE TO STRONG CONVECTION WAS NOTED 
WITHIN 60 NM OF CENTER. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION WAS NOTED FROM 04N TO 11N BETWEEN 130W AND 138W. 
SCATTERED MODERATE ISOLATE STRONG CONVECTION WAS NOTED WITHIN 30 
NM OF LINE 15N125W TO 15N131W TO 13N134W TO 11N136W. OLAF IS 
FORECAST TO CONTINUE TO INTENSIFY OVER THE NEXT COUPLE OF DAYS 
AS IT MOVES W-NW ACROSS WARM WATERS AND THROUGH A GENERALLY LOW 
SHEAR ENVIRONMENT. OLAF IS EXPECTED TO REACH MAJOR HURRICANE 
INTENSITY ON MON. PLEASE SEE LATEST FORECAST ADVISORY UNDER 
AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS ON 
OLAF. 

GULF OF TEHUANTEPEC...LATEST SCATTEROMETER PASS INDICATES THAT 
WINDS HAVE DIMINISHED BELOW GALE FORCE. LOW PRESSURE HAS FORMED 
AS A RESULT OF THE INTERACTION OF THE GALE FORCE GAP WIND EVENT 
AND THE MONSOON TROUGH. THIS LOW PRESSURE AREA IS EMBEDDED IN A 
LARGER SCALE CENTRAL AMERICAN GYRE. ABUNDANT TROPICAL MOISTURE 
REMAINS AROUND THE NORTHERN PART OF CENTRAL AMERICA AND SOUTHERN 
MEXICO ASSOCIATED TO THIS GYRE WILL KEEP THE POTENTIAL FOR 
ACTIVE WEATHER HIGH OVER THIS AREA FOR THE NEXT COUPLE OF DAYS. 
GLOBAL MODELS CONTINUE TO SUGGEST THE LOW COULD DEVELOP INTO A 
TROPICAL CYCLONE AROUND MID-WEEK AND THERE IS CURRENTLY A MEDIUM 
CHANCE FOR TROPICAL CYCLOGENESIS. REGARDLESS OF TROPICAL CYCLONE 
FORMATION...THIS SYNOPTIC SETUP WILL CONTINUE TO BRING THE 
POTENTIAL FOR LOCALLY HEAVY RAINFALL WHICH MAY LEAD TO FLASH 
FLOODING AND DANGEROUS MUDSLIDES OVER PORTIONS OF CENTRAL 
AMERICA AND SOUTHEASTERN MEXICO OVER THE NEXT COUPLE OF DAYS. 
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 
           
THE MONSOON TROUGH EXTENDS FROM 15N93W TO LOW PRES NEAR 12N95W 
TO LOW PRES NEAR 08N115W TO 09N122W. NUMEROUS MODERATE TO STRONG 
CONVECTION WAS NOTED OVER WATERS N OF 14N BETWEEN 96W AND 99W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS NOTED 
ELSEWHERE OVER WATERS N OF 11N BETWEEN 90W AND 100W. 

...DISCUSSION... 

HIGH PRESSURE OF 1025 MB CENTERED NEAR 34N140W EXTENDS A RIDGE 
SE TO NEAR 27N116W. THE BUILDING HIGH PRESSURE HAS HELPED EXPAND 
20-33 KT WINDS OVER THE NORTHERN PART OF OLAF. OUTSIDE OF THE 
CIRCULATION ASSOCIATED TO OLAF...GENTLE TO MODERATE TRADE WINDS 
PREVAIL OVER MUCH OF THE WESTERN PORTION OF THE DISCUSSION AREA. 
THE RIDGE WILL STRENGTHEN THROUGH TUE...AND HELP TO EXPAND THE 
AREA OF 20-33 KT WINDS N OF OLAF. 

LONG PERIOD SW SWELL WITH PERIODS IN THE 19-21 SECOND RANGE IS 
CURRENTLY AFFECTING WHOLE COAST OF CENTRAL AMERICA AND 
NORTHWARDS TO THE MEXICAN PACIFIC COAST NEAR THE BAJA CALIFORNIA 
PENINSULA. THIS LONG-PERIOD SWELL COULD MAKE FOR DANGEROUS 
CONDITIONS ENTERING AND EXITING PORTS AND WILL INCREASE THE 
THREAT OF RIP CURRENTS. 

$$ 
AL