000
AXPZ20 KNHC 150303
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT SEP 14 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0215 UTC.

...SPECIAL FEATURE... 

TROPICAL STORM MANUEL CENTERED NEAR 17.2N 102.3W AT 0300 UTC... 
OR ABOUT 50 NM SW OF ZIHUATENEJO MEXICO...MOVING NORTH OR 350 
DEG AT 5 KT. MAXIMUM SUSTAINED WINDS HAVE INCREASED TO 60 KT 
GUSTS 75 KT. ESTIMATED MINIMUM PRESSURE IS 985 MB. TROPICAL 
STORM FORCE WINDS ARE OCCURRING WITHIN 80 NM NE...240 NM SE...60 
NM SW...AND 70 NM NW OF CENTER. THE LATEST SATELLITE IMAGERY 
SHOWS STRONG TSTORMS INCREASING IN THE VICINITY OF MANUEL...AND 
RECENT MICROWAVE PASSES SUGGEST THAT AN EYE WALL IS ATTEMPTING 
TO DEVELOP. THESE SIGNS VERIFY THAT MANUEL HAS BEGUN TO  
INTENSIFY IN THE SHORT TERM AS IT MOVES NORTHWARD TOWARDS THE 
MEXICAN COAST...AND IS EXPECTED TO REACH HURRICANE STRENGTH AS 
IT REACHES THE COAST SUNDAY MORNING. 

MANUEL REMAINS EMBEDDED WITHIN A CYCLONIC GYRE ALIGNED NE TO SW 
THAT EXTENDS ACROSS S CENTRAL MEXICO INTO THE SW GULF OF 
MEXICO...WHERE HURRICANE INGRID REMAINS EMBEDDED WITHIN THE NE 
END OF THE GYRE. THIS ALIGNMENT CONTINUES TO PRODUCE A VERY LONG 
FETCH OF STRONG AND MOIST SOUTHWESTERLY WINDS EXTENDING FROM THE 
DEEP TROPICS NORTHEASTWARD INTO MEXICO BETWEEN PUERTO ANGEL AND 
ZIHUATENEJO. THIS SOUTHWESTERLY FLOW OF MOIST TROPICAL AIR WILL 
CONTINUE TO SLAM AGAINST THE SOUTHERN SLOPES OF THE SIERRA 
MADRES DEL SUR DURING THE NEXT FEW DAYS TO PRODUCE TREMENDOUS 
RAINFALL ACCUMULATIONS...BOTH NEAR AND WELL REMOVED FROM THE 
PATH OF MANUEL...WHICH WILL LEAD TO LIFE THREATENING FLASH 
FLOODING AND MUDSLIDES. 

MANUEL IS EXPECTED TO MOVE ASHORE ACROSS SOUTHWEST MEXICO SUNDAY 
MORNING...AND INLAND THROUGHOUT THE DAY. WIDESPREAD RAINFALL 
WILL DOMINATE SOUTHERN MEXICO...INCLUDING INTERIOR PORTIONS... 
FOR THE NEXT FEW DAYS AS THIS BROAD CYCLONIC CIRCULATION DRIFTS 
N-NW. PLEASE SEE WMO HEADER/AWIPS HEADERS WTPZ23 KNHC/MIATCMEP3 
FOR ADDITIONAL DETAILS.  

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

MONSOON TROUGH AXIS EXTENDS FROM COLOMBIA NEAR 07N74W AND 
MEANDERS THROUGH 15N87W...AND HAS FRACTURED FROM HURRICANE 
INGRID IN THE BAY OF CAMPECHE. THE TROUGH RESUMES TO THE SW OF 
T.S. MANUEL NEAR 14N105W TO LOW PRES NEAR 11.5N114.5W 1003 MB TO 
10N137W... WHERE IT TRANSITIONS TO ITCZ...CONTINUING BEYOND 
10N140W. SCATTERED MODERATE TO STRONG ELSEWHERE WITHIN 200 NM 
EITHER SIDE OF LINE FROM 17.5N101.5W TO 13N105W TO 10N111W. 

...DISCUSSION...

BLOCKING UPPER LEVEL PATTERN PERSISTS ACROSS MUCH OF AREA W OF 
110W...WITH BROAD UPPER RIDGE CENTERED NEAR 27N124W EXTENDING E 
TO NW MEXICO. RIDGE HAS FLATTENED SOMEWHAT IN PAST 24 HOURS AND 
HAS ALLOWED DEEP LAYERED UPPER CYCLONE OVER NE PACIFIC TO SHIFT 
SLIGHTLY NE. AN UPPER CYCLONE SHIFTING W ACROSS THE N HALF OF 
MEXICO PAST 36 HOURS IS COMING INTO PHASE WITH A SHARP MID 
LATITUDE TROUGH EXTENDING FROM THE GREAT BASIN TO N CENTRAL 
MEXICO. THIS MERGING TROUGH STRETCHES SW TO NEAR 22N110W. THIS 
SET-UP CONTINUES TO PROMOTE ANTICYCLONIC OUTFLOW ACROSS SOUTHERN 
MEXICO...INCLUDING ACROSS HURRICANE INGRID AND TROPICAL STORM 
MANUEL. ABUNDANT MOISTURE AND VERY LOW SURFACE PRESSURES ARE 
FOUND WITHIN A CYCLONIC GYRE SPANNING FROM THE EPAC NEAR 13N111W 
NORTHEASTWARD ACROSS SOUTHERN MEXICO AND INTO THE SOUTHWEST GULF 
OF MEXICO AND YUCATAN PENINSULA. SCATTERED TO NUMEROUS CLUSTERS 
OF MODERATE TO DEEP CONVECTION CONTINUE TO DEVELOPING WITHIN AND 
AROUND THE PERIPHERY OF THIS CIRCULATION...WITH BROAD 
ANTICYCLONIC FLOW AIDING IN MAINTAINING THIS BROAD REGION OF 
RISING MOTION. GLOBAL MODELS SUGGEST THESE FAVORABLE UPPER LEVEL 
CONDITIONS COULD BECOME SLIGHTLY LESS FAVORABLE DURING THE NEXT 
FEW DAYS.

THIS SCENARIO CONTINUES TO PRODUCE A LONG FETCH OF STRONG SW 
WINDS AT THE SURFACE EXTENDING FROM NEARLY 09N115W TO THE COAST 
OF MEXICO. SMALL AREAS OF SW WINDS JUST BELOW GALE FORCE WERE 
DEPICTED BY AFTERNOON SCATTEROMETER PASSES...WHICH IS GENERATING 
A VERY LARGE SWATH OF 12-15 FT SEAS THAT SPREAD TO THE MEXICAN 
COAST AS FAR EAST AS ACAPULCO. THESE ROUGH AND CONFUSED SEAS 
CONSISTING OF MODERATE WAVE PERIOD ARE NOT TYPICAL FOR THIS 
AREA...AND WILL CONTINUE TO CREATE EXTREMELY ROUGH MARINE 
CONDITIONS ACROSS THIS AREA...AND POUND THE COASTLINE WITH LARGE 
SURF.  

LOOKING AHEAD...GLOBAL MODELS INDICATE THAT THE CYCLONIC GYRE 
WILL WEAKEN THROUGH MID WEEK WITH THE STRONG SW FLOW DIMINISHING 
S OF 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.

$$
STRIPLING