000
AXPZ20 KNHC 200252
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
0405 UTC TUE OCT 20 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...

MAJOR HURRICANE OLAF IS CENTERED NEAR 10.1N 139.5W AT 0300 UTC 
MOVING WEST OR 275 DEGREES AT 9 KT. ESTIMATED MINIMUM CENTRAL 
PRESSURE HAS LOWERED TO 949 MB. THE MAXIMUM SUSTAINED WIND SPEED 
IS 120 KT WITH GUSTS TO 145 KT. NUMEROUS STRONG CONVECTION WAS 
NOTED WITHIN 60 NM OF CENTER. SCATTERED MODERATE TO STRONG 
CONVECTION WAS NOTED ELSEWHERE WITHIN 210 NM S SEMICIRCLE. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS NOTED OVER THE 
REMAINDER OF AREA FROM 04N TO 16N W OF 134W. OLAF IS FORECAST TO 
CONTINUE TO INTENSIFY AS THE SYSTEM MOVES W OF 140W OVERNIGHT. 
PLEASE SEE LATEST FORECAST ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS ON OLAF. 

GULF OF TEHUANTEPEC...LOW PRESSURE CENTERED SE OF THE GULF OF 
TEHUANTEPEC NEAR 13N94W IS EMBEDDED WITHIN A LARGER SCALE 
CENTRAL AMERICAN GYRE. GALE FORCE WINDS CONTINUE TO FUNNEL INTO 
THE GULF OF TEHUANTEPEC W OF THE LOW PRESSURE CENTER WITH SEAS 
IN THE 9 TO 14 FT RANGE. SATELLITE IMAGERY SUGGESTS THAT THE 
CENTRAL AMERICAN GYRE IS FINALLY STARTING TO SLOWLY BREAK DOWN. 
AS THE BREAKDOWN OF THE GYRE CONTINUES OVER THE NEXT 24-48 
HOURS...ENERGY WILL BE ABLE TO CONSOLIDATE AROUND THE LOW WHICH 
WILL ENABLE THE LOW TO FURTHER DEVELOP. THE LATEST FORECAST 
GIVES A HIGH PROBABILITY THAT THE LOW WILL DEVELOP INTO A 
TROPICAL CYCLONE WITHIN THE NEXT 48 HOURS. ABUNDANT TROPICAL 
MOISTURE CONTINUES ACROSS THE NORTHERN HALF OF CENTRAL AMERICA 
AND SOUTHERN MEXICO WHICH WILL MAINTAIN THE POTENTIAL FOR ACTIVE 
WEATHER OVER THIS AREA REGARDLESS OF TROPICAL CYCLONE FORMATION. 
THIS WILL KEEP THE POTENTIAL FOR LOCALLY HEAVY RAINFALL WHICH 
MAY LEAD TO FLASH FLOODING AND DANGEROUS MUDSLIDES OVER THE 
NORTHERN PORTIONS OF CENTRAL AMERICA AS WELL AS SOUTHERN MEXICO. 
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 
           
THE MONSOON TROUGH EXTENDS FROM 14.5N92W TO LOW PRES NEAR 13N94W 
TO 08N104W TO 08N122W. NUMEROUS MODERATE TO STRONG CONVECTION 
WAS NOTED OVER FORECAST WATERS N OF 12N BETWEEN 90W AND 98W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS NOTED FROM 09N 
TO 12N BETWEEN 90W ANS 98W. SCATTERED MODERATE CONVECTION WAS 
NOTED WITHIN 60 N OF TROUGH BETWEEN 102W AND 116W. 

...DISCUSSION... 

A 1026 MB SUBTROPICAL HIGH PRESSURE CENTER NEAR 35N137W EXTENDS 
A RIDGE SE NEAR 21N112W. THE PRESSURE GRADIENT BETWEEN THE RIDGE 
AND LOWER PRESSURE OVER THE SW UNITED STATES IS HELPING FOR 
FRESH TO STRONG NW WINDS OFF THE COAST OF CALIFORNIA. NW SWELL 
ASSOCIATED TO THESE WINDS ARE PROPAGATING INTO THE NORTHERN 
WATERS N OF 28N BETWEEN 118W AND 123W. THE BUILDING SUBTROPICAL 
HIGH HAS HELPED EXPAND THE 20-33 KT WINDS OVER THE NORTHERN PART 
OF OLAF. THE RIDGE WILL SHIFT SLIGHTLY TO THE W OVER THE NEXT 48 
HOURS IN TANDEM WITH HURRICANE OLAF...MAINTAINING THIS PRESSURE 
GRADIENT. OUTSIDE OF THE CIRCULATION ASSOCIATED WITH 
OLAF...MODERATE TO FRESH TRADE WINDS PREVAIL OVER MUCH OF THE 
DISCUSSION AREA N OF 15N W OF 115W.

SW SWELLS WITH PERIODS IN THE 16-18 SECOND RANGE CONTINUES TO 
AFFECT MUCH OF THE PACIFIC COAST OVER THE FORECAST AREA. THIS 
SWELL COULD MAKE FOR DANGEROUS CONDITIONS ENTERING AND EXITING 
PORTS AND WILL INCREASE THE THREAT OF RIP CURRENTS. CONDITIONS 
ARE EXPECTED TO IMPROVE OVER THE NEXT 24 HOURS AS THE SWELL 
SUBSIDES. 

$$ 
AL