000
AXPZ20 KNHC 112143
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SUN AUG 11 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 ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2030 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...        
MONSOON TROUGH AXIS EXTENDS FROM COLOMBIA NEAR 10N74W TO 
11.5N80W TO 08N94W TO LOW PRES NEAR 09.5N106.5W WHERE IT HAS 
FRACTURED. TROUGH RESUMES NEAR 16N120W TO LOW PRES NEAR 
13.5N122.5W TO 12N126W TO 14N134W TO LOW PRES NEAR 12N138W TO 
11N140W. SCATTERED MODERATE TO STRONG CONVECTION NOTED FROM 
04.5N TO 09N E OF 82W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION NOTED WITHIN 180 NM S OF TROUGH BETWEEN 88W AND 93W. 
SCATTERED MODERATE CONVECTION NOTED WITHIN 210 NM S OF TROUGH 
BETWEEN 124W AND 129W. SCATTERED MODERATE CONVECTION NOTED 
WITHIN 90 NM EITHER SIDE OF TROUGH W OF 134W. SCATTERED MODERATE 
TO STRONG CONVECTION FROM 15N TO 20N BETWEEN 103W AND 109W.

...DISCUSSION...
WATER VAPOR IMAGERY SHOWS UPPER RIDGE BISECTING AREA HAS 
REALIGNED IN PAST 24 HOURS...NOW MORE NE TO SW FROM ELONGATED 
UPPER ANTICYCLONE NEAR 27N114W TO 17N147W. BROAD UPPER LEVEL SW 
TO W FLOW IS SEEN N OF THE RIDGE...WHERE VERY DRY AND STABLE 
CONDITIONS PREVAIL WITHIN THE RIDGE AND TO ITS NW. E TO NE WINDS 
ALOFT GENERALLY PREVAIL ACROSS THE REMAINDER OF THE AREA S AND 
SE OF THE RIDGE...CONTINUING TO PRODUCE A GENERALLY LIGHTLY 
SHEARED ENVIRONMENT. A TUTT LOW THAT HAS SHIFTED WWD ACROSS THE 
TROPICAL EPAC DURING THE PAST SEVERAL DAYS HAS WEAKENED TO AN 
OPEN TROUGH NOW ALONG ABOUT 119W AND CONTINUES TO SHIFT W. 
CONVERGENCE CONTINUES ACROSS NW PORTIONS OF THIS UPPER LEVEL 
WAVE...AND ACROSS THE NE PORTIONS OF THE SURFACE LOW NEAR 
13.5N122.5W...AND IS CONTRIBUTING TO AN UNFAVORABLE ENVIRONMENT 
FOR SHORT TERM DEVELOPMENT OF THE LOW.

AT THE SURFACE...A WEAK 1021 MB HIGH IS ANALYZED NEAR 29N129W 
WITH A RIDGE EXTENDING SE TO NEAR 22N116W. THE WEAK PRES 
GRADIENT BETWEEN THE HIGH AND PERSISTENT LOW PRES ALONG THE 
SIERRA MADRES OCCIDENTALES IS PRODUCING NNW WINDS NEAR 20 KT 
ALONG AND OFFSHORE OF THE W COAST OF BAJA CALIFORNIA TO ABOUT 
116W...WHERE WAVE MODEL GUIDANCE AND A FEW SHIP OBSERVATIONS 
FROM THE PAST 24 HOURS INDICATED PEAK SEAS ARE 5-6 FT. THESE 
CONDITIONS ARE FORECAST TO GENERALLY PREVAIL OVER THE NEXT 24-48 
HOURS...WITH A BRIEF AND MILD INCREASE IN WINDS AND SEAS EACH 
EVENING. A DISSIPATING COLD FRONT IS OVER THE FAR NW CORNER OF 
THE AREA FROM 31N130W TO 28N140W. THE HIGH IS FORECAST TO WEAKEN 
SLIGHTLY AS IT SHIFTS ESE TO NEAR 31N136W IN 24 HOURS. 
 
THE PRES GRADIENT BETWEEN THE HIGH AND THE MONSOON TROUGH TO THE 
S IS MODEST AT BEST...AND IS AIDING IN PRODUCING SMALL AREAS OF 
FRESH NE TRADES TO THE N AND NW OF TWO LOW PRES CENTERS EMBEDDED 
ALONG THE MONSOON TROUGH...MENTIONED ABOVE. THESE TWO LOW PRES 
CENTERS WILL SHIFT GENERALLY W DURING THE NEXT 48 HOURS AND 
MAINTAIN ZONES OF FRESH NE TO E TRADES ACROSS THE N AND NW 
SEMICIRCLES...WHERE PEAK SEAS WILL PERSIST NEAR 8-9 FT. ALTHOUGH 
GLOBAL MODELS HAD BEEN SUGGESTING FOR THE PAST FEW DAYS THAT THE 
LOW ALONG 122.5W HAD POTENTIAL FOR INTENSIFICATION TO A TROPICAL 
CYCLONE...ATMOSPHERIC CONDITIONS ACROSS MUCH OF THE E HALF OF 
THIS SYSTEM REMAIN STABLE...AS MENTIONED ABOVE...AND THIS SYSTEM 
NOW HAS LOW POTENTIAL FOR IMPROVED ORGANIZATION AND TROPICAL 
CYCLONE DEVELOPMENT.

SATELLITE IMAGERY CONTINUES TO SHOW A LARGE CLUSTER OF MODERATE 
TO STRONG TSTMS ALONG THE MEXICAN COAST FROM CABO CORRIENTES TO 
NEAR ACAPULCO AND EXTENDING W TO NEAR 11W. A BROAD LOW LEVEL 
TROUGH HAS DEVELOPED ACROSS THIS AREA...WHERE A POOL OF ABUNDANT 
MOISTURE RESIDE. OCEAN TEMPERATURES ACROSS THE AREA ARE SOME OF 
THE WARMEST ACROSS THE REGION...ALL SUGGESTING UNSTABLE 
CONDITIONS...AND VERY ACTIVE WEATHER WILL LIKELY PERSIST THERE 
FOR THE NEXT 6-12 HOURS.

NORTH TO NORTHEASTERLY WINDS FLOWING THROUGH THE CHIVELA PASS 
WILL PULSATE THROUGH TUE ALLOWING PERIODS OF 15-20 KT WINDS 
ACROSS THE FAR NORTHERN GULF TEHUANTEPEC DURING THIS TIME 
PERIOD. HOWEVER WITH VERY LIMITED FETCH AND DURATION OF THESE 
WINDS THERE SHOULD LIMIT SEAS TO 4-6 FT.

$$ 
STRIPLING