000
AXPZ20 KNHC 151604 RRA
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN SEP 15 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1545 UTC.

...SPECIAL FEATURE... 

TROPICAL STORM MANUEL VERY NEAR THE MEXICAN CENTERED NEAR 18.5N 
103.9W AT 1500 UTC...OR ABOUT 45 NM SE OF MANZANILLO MEXICO 
MOVING NW 320 DEG AT 9 KT. MAXIMUM SUSTAINED WINDS REMAIN 60 KT 
WITH GUSTS TO 75 KT. ESTIMATED MINIMUM PRESSURE IS 985 MB. 
TROPICAL STORM FORCE WINDS ARE OCCURRING WITHIN 30 NM NE...90 NM 
SE...50 NM SW...AND 60 NM NW OF CENTER. MANUEL REMAINS EMBEDDED 
WITHIN A CYCLONIC GYRE ALIGNED NE TO SW THAT EXTENDS ACROSS S 
CENTRAL MEXICO AND INTO THE SW GULF OF MEXICO...WHERE HURRICANE 
INGRID REMAINS EMBEDDED WITHIN THE NE END OF THE GYRE. NUMEROUS 
STRONG CONVECTION IS WITHIN 120 NM OF THE CENTER IN THE SE 
QUADRANT...AND WITHIN 180 NM OF THE CENTER IN THE SW QUADRANT. 
SCATTERED STRONG CONVECTION IS ELSEWHERE WITHIN 300 NM OF THE 
CENTER IN THE SE QUADRANT...420 NM IN THE SW QUADRANT..60 NM IN 
THE NW QUADRANT AND 90 NM IN THE NE QUADRANT. MANUEL IS FORECAST 
TO MOVE INLAND THE COAST OF MEXICO THIS AFTERNOON 
...REACHING TO JUST INLAND THE COAST NEAR 19.5N 104.7W WITH 
MAXIMUM WINDS OF 50 KT WITH GUSTS TO 60 KT. MANUEL IS FORECAST 
TO WEAKEN TO A DEPRESSION AS THEN TURNS NW REACHING NEAR 20.3N 
105.3W BY EARLY MON...THEN WEAKENING FURTHER TO A POST-
TROPICAL/REMNANT LOW NEAR 21.2N 106.2W BY MON EVENING. 
WIDESPREAD RAINFALL LIKELY TO RESULT IN EXTREME RAINFALL 
ACCUMULATIONS ARE LIKELY TO RESULT IN LIFE-THREATENING FLASH 
FLOODS AND MUD SLIDES...ESPECIALLY IN REGIONS OF MOUNTAINOUS 
TERRAIN WILL AFFECT SOUTHERN MEXICO...INCLUDING INTERIOR 
PORTIONS...OVER THE NEXT SEVERAL DAYS AS A VERY LONG FETCH OF 
STRONG AND MOIST SOUTHWESTERLY WINDS EXTENDING FROM THE DEEP 
TROPICS NORTHEASTWARD INTO MEXICO BETWEEN PUERTO ANGEL AND 
ZIHUATENEJO CONTINUES TO IMPINGE AGAINST THE SOUTHERN SLOPES OF 
THE SIERRA MADRE DEL SUR. PLEASE SEE WMO HEADER/AWIPS HEADERS 
WTPZ23 KNHC/MIATCMEP3 FOR ADDITIONAL DETAILS.  

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...             
THE MONSOON TROUGH AXIS EXTENDS FROM NW COLOMBIA ACROSS THE GULF 
OF PANAMA NEAR 08N79W TO 09N91W WHERE IT ENDS. THE TROUGH 
RESUMES TO THE SW OF TROPICAL STORM MANUEL NEAR 11N111W TO 
09N120W TO 08N131W TO 08N140W. SCATTERED MODERATE TO ISOLATED 
STRONG CONVECTION IS SEEN WITHIN 120 NM S OF THE TROUGH BETWEEN 
78W AND 80W...AND ALSO WITHIN 60 NM S OF THE TROUGH BETWEEN 82W 
AND 86W.

...DISCUSSION...

AN UPPER TROUGH EXTENDING N TO S OVER N CENTRAL MEXICO ROUGHLY  
ALONG 105W CONTINUES TO PROVIDE DECENT OUTFLOW TO BOTH MANUEL 
AND HURRICANE INGRID IN THE SW GULF OF MEXICO. DRY AND SUBSIDENT 
NW FLOW BETWEEN THE UPPER TROUGH AND AN UPPER ANTICYCLONE 
CENTERED NEAR 22N123W IS SUPPRESSING CONVECTION W OF 105W 
ALLOWING FOR VERY DEEP ATMOSPHERIC MOISTURE AND ASSOCIATED 
CONVECTION CONFINED TO MANUEL AND VICINITY AND WITH THE VERY WELL 
PRONOUNCED MONSOONAL FLOW TO ITS SW. SW WINDS OF 20-30 KT WITH 
SEAS TO 15 FT ARE WITHIN THE MONSOON GYRE OVER THE AREA DEPICTED 
BY A LINE FROM 16.5N104W TO 16N100W TO 10N108W TO 12N111W TO 
16.5N104W. THIS PATTERN HAS PERSISTED FOR THE PAST SEVERAL DAYS 
AS THE LARGE GYRE THAT FOSTERED MANUEL DEVELOPED. THE LONG FETCH 
AND DURATION OF THIS EVENT IS CAUSING ROUGH AND CONFUSED SEAS 
ALONG MUCH OF THE MEXICAN COAST FRONT THE GULF OF TEHUANTEPEC TO 
MANZANILLO...ALONG WITH THE POTENTIAL FOR DANGER RIP CURRENTS 
ALONG THE COAST. LOOKING AHEAD...GLOBAL MODELS CONTINUE TO 
INDICATE THAT THE SW FLOW WILL GRADUALLY BEGIN TO WEAKEN 
MON...AND INTO WED WITH SEAS SLOWLY SUBSIDING.

ELSEWHERE AT THE SURFACE...A WEAK SURFACE HIGH PRES AREA IS 
CENTERED NW OF THE AREA WITH RIDGE EXTENDING W TO THE COAST OF 
THE BAJA PENINSULA. SCATTEROMETER DATA FROM LATE LAST NIGHT 
INDICATED NW TO N 15-20 KT WINDS OFF THE SOUTHERN COAST OF BAJA 
PENINSULA. IN ADDITION...FRESH TO STRONG NW WINDS WERE NOTED OF 
THE COAST OF SOUTHERN CALIFORNIA...THOUGH THESE WINDS ARE 20 KT 
OR LESS S OF 30N. NO SIGNIFICANT CHANGES ARE EXPECTED THROUGH 
MID WEEK.
 
$$
AGUIRRE