000
AXPZ20 KNHC 140910
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL 
1005 UTC FRI SEP 13 2013

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0915 UTC.

...SPECIAL FEATURE... 

TROPICAL STORM MANUEL WAS NEAR 15.3N 102.4W 996 MB AT 0900 UTC 
AND IS STATIONARY. MAXIMUM SUSTAINED WINDS 40 KT GUSTS 50 KT. 
TROPICAL STORM FORCE WINDS ARE WITHIN 50 NM OF CENTER EXCEPT 0 
NM NW QUADRANT. STRONG CONVECTIVE BANDING HAS BECOME A LITTLE 
BETTER ORGANIZED WITHIN 90 NM OF THE CENTER ALONG THE SE 
SEMICIRCLE OF THE STORM. 

ADDITIONAL NUMEROUS STRONG CONVECTION IS BUILDING IN A LINE N OF 
THE CENTER...FROM 15N TO 22N BETWEEN 105W AND 107W. THIS IS DUE 
IN PART TO THE STORM...BUT ALSO OVERNIGHT OFFSHORE FLOW ENHANCED 
BY DIVERGENCE ALOFT ASSOCIATED WITH A SHARP UPPER TROUGH OVER N 
CENTRAL MEXICO. NUMEROUS MODERATE TO SCATTERED STRONG CONVECTION 
IS ALSO NOTED WITHIN 90 NM OF THE COAST OF MEXICO BETWEEN 90W 
AND 100W...WHERE STRONG TO NEAR GALE FORCE S TO SW FLOW IS 
CONVERGING INTO THE COAST. 

AN ELONGATED LOW TO MIDDLE LEVEL CYCLONIC GYRE EXTENDS FROM THE 
SW GULF OF MEXICO...SW ACROSS SOUTHERN MEXICO AND INTO THE 
EASTERN PACIFIC NEAR 10N110W. BOTH TROPICAL STORM MANUEL AND 
TROPICAL STORM INGRID...IN THE BAY OF CAMPECHE...ARE EMBEDDED 
WITHIN THIS ELONGATED CIRCULATION...WHICH IS FORECAST TO LIFT 
NORTH NORTHWESTWARD DURING THE NEXT FEW DAYS. TROPICAL STORM 
MANUEL WILL REMAIN EMBEDDED WITHIN THIS BROADER CIRCULATION AND 
IS EXPECTED TO MOVE NORTH TO NORTH-NORTHWESTWARD AND INLAND 
ACROSS COASTAL MEXICO IN THE GENERAL AREA OF MANZANILLO SUNDAY 
MORNING. ABUNDANT MOISTURE WITHIN THE ELONGATED GYRE WILL 
PRODUCE WIDESPREAD SHOWERS AND THUNDERSTORMS ACROSS SOUTHEAST 
AND CENTRAL PORTIONS OF MEXICO DURING THE NEXT FEW DAYS...AND 
WILL BE EXACERBATED BY TROPICAL STORM MANUEL. HEAVY RAINS 
ASSOCIATED WITH MANUEL COULD CAUSE LIFE-THREATENING FLASH FLOODS 
AND MUD SLIDES STARTING TODAY THROUGH SUNDAY...ESPECIALLY ALONG 
THE MOUNTAINOUS COASTLINE OF CENTRAL MEXICO. PLEASE SEE WMO 
HEADER/AWIPS HEADERS WTPZ23 KNHC/MIATCMEP3 FOR ADDITIONAL 
DETAILS.  

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

MONSOON TROUGH EXTENDS FROM COLOMBIA ACROSS CENTRAL AMERICA TO 
NORTHERN GUATEMALA WHERE IT FRACTURES...THEN RESUMES FROM 
TROPICAL STORM MANUEL TO 09N140W. NO SIGNIFICANT CONVECTION IS 
NOTED ALONG THE MONSOON TROUGH W OF ENVIRONMENT AROUND T.S 
MANUEL.

...DISCUSSION...

AN UPPER LOW MIGRATING W FROM THE WESTERN GULF OF MEXICO OVER N 
CENTRAL MEXICO IS COMING INTO PHASE WITH A SHARP MID LATITUDE 
TROUGH EXTENDING FROM THE GREAT BASING TO N CENTRAL MEXICO. THIS 
COMBINED UPPER TROUGH STRETCHES SOUTHWESTWARD TO NEAR 15N110W. 
WHILE THIS IS ENHANCING CONVECTION E OF 105W...NORTHERLY FLOW 
ALOFT BETWEEN THE UPPER TROUGH AND A BROAD ANTICYCLONE CENTERED W 
OF THE AREA NEAR 22N122W IS SUPPRESSING CONVECTION W OF 105W 
EXCEPT S OF 15N WHERE FRESH TO STRONG SW FLOW IS ALLOWING 
CONVECTION TO PULSE ALONG THE MONSOON TROUGH WITHIN 200 NM W OF 
MANUEL. 

ALTIMETER PASSES OVER THE PAST SEVERAL HOURS HAVE INDICATED SEAS 
APPROACHING 11 FT WITHIN 75 NM N AND S OF THE CENTER OF MANUEL. 
HIGHER SEAS ARE LIKELY HOWEVER OVER THE EASTERN EDGE OF OF THE 
LOBE OF PERSISTENT STRONG TO NEAR GALE SW WINDS NOTED ON 
MULTIPLE ASCAT PASSES AND OCCASIONAL SHIP OBSERVATIONS... 
GENERALLY COVERING THE AREA FROM 06N TO 15N BETWEEN 95W AND 
115W. GIVEN THE LONG FETCH AND DURATION OF THESE WINDS...SHORT 
PERIOD SEAS FROM 12 TO 15 FT ARE NOT OUT OF THE QUESTION MAINLY 
FROM 10N TO 15N BEWTEEN 95W AND 105W.

FARTHER NORTH...ASCAT AND ALTIMETER PASSES HAVE CONTINUED TO 
SHOW NW TO N WINDS UP TO 20 KT WITH SEAS TO 7 FT OFF THE COAST 
OF BAJA CALIFORNIA SUR OUT TO 115W...BETWEEN THE LOWER PRES OFF 
CENTRAL MEXICO AND A 1016 MB SURFACE HIGH PRES AREA CENTERED 
NEAR 26N140W. 

A RELATIVELY WEAK PRES PATTERN CONTINUES ELSEWHERE W OF 110W AND 
E OF 95W WITH LIGHT TO MODERATE WINDS AND SLIGHT SEAS 
PREVAILING. 

LOOKING AHEAD...GLOBAL MODELS INDICATE THAT THE GYRE WILL WEAKEN 
THROUGH MID WEEK WITH THE STRONG SW FLOW DIMINISHING INTO THE 
MONSOON TROUGH BETWEEN 95W AND 115W. SEAS WILL GRADUALLY 
DIMINISH AS WELL. UNTIL THEN...EXPECT THE COMBINED MARINE 
HAZARDS OF ROUGH SEAS AND DANGEROUS RIP CURRENTS ALONG THE COAST 
OF MEXICO FROM WESTERN OAXACA THROUGH GUERRERO THROUGH EARLY 
NEXT WEEK.

$$
CHRISTENSEN