000
AXPZ20 KNHC 192100
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
2205 UTC MON OCT 19 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...

MAJOR HURRICANE OLAF IS CENTERED NEAR 10.0N 138.7W AT 2100 UTC 
MOVING WEST OR 275 DEGREES AT 10 KT. ESTIMATED MINIMUM CENTRAL 
PRESSURE HAS LOWERED TO 954 MB. THE MAXIMUM SUSTAINED WIND SPEED 
IS 115 KT WITH GUSTS TO 140 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 ALSO NOTED 
FROM 04N TO 13N BETWEEN 133W AND 140W. 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 S OF THE GULF OF 
TEHUANTEPEC NEAR 13N95W 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 13 FT RANGE. SATELLITE IMAGERY SUGGESTS THAT THE 
CENTRAL AMERICAN GYRE IS FINALLY STARTING TO BREAK DOWN AND 
SHIFT WESTWARD. ONCE THIS BREAKDOWN IS COMPLETE...ENERGY WILL BE 
ABLE TO CONSOLIDATE AROUND THE LOW AND ENABLE IT TO FURTHER 
DEVELOP...AND THERE IS NOW A HIGH PROBABILITY THAT THIS 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 ASSOCIATED WITH THE CENTRAL 
AMERICAN GYRE WHICH WILL MAINTAIN THE POTENTIAL FOR ACTIVE 
WEATHER OVER THIS AREA UNTIL THE GYRE BREAKS DOWN OVER THE NEXT 
COUPLE OF DAYS. 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 13N95W 
TO 08N105W TO 08N120W. SCATTERED MODERATE TO STRONG CONVECTION 
WAS NOTED OVER FORECAST WATERS N OF 11N BETWEEN 89W AND 101W. 
SCATTERED MODERATE CONVECTION WAS NOTED WITHIN 90 NM S OF THE 
MONSOON TROUGH BETWEEN 94W AND 107W. SCATTERED MODERATE 
CONVECTION WAS NOTED WITHIN 60 OF THE MONSOON TROUGH BETWEEN 
110W AND 115W. 

...DISCUSSION... 

A 1028 MB SUBTROPICAL HIGH PRESSURE CENTER NEAR 34N138W 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 29N BETWEEN 120W AND 124W. THE BUILDING SUBTROPICAL 
HIGH HAS HELPED EXPAND THE 20-33 KT WINDS OVER THE NORTHERN PART 
OF OLAF TO WITHIN 420 NM N QUADRANT AS DEPICTED BY THE MOST 
RECENT ASCAT PASS. 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 17-18 SECOND RANGE CONTINUES TO 
AFFECT THE PACIFIC COAST OVER THE ENTIRE 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 24-48 HOURS AS THE SWELL 
SUBSIDES. 

$$ 
AL