000
AXPZ20 KNHC 280304
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SUN AUG 28 2011

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0245 UTC.

...ITCZ/MONSOON TROUGH...
MONSOON TROUGH 15N92W TO 18N101W TO LOW PRES 19N118W TO 15N124W 
TO 10N140W. SCATTERED MODERATE ISOLATED STRONG FROM 05N TO 10N 
BETWEEN 81W AND 87W.  SCATTERED MODERATE FROM 12N TO 16N BETWEEN 
97W AND 110W AND FROM 12N TO 14N BETWEEN 112W AND 116W.

...DISCUSSION...
THE SUBTROPICAL RIDGE EXTENDS FROM A 1024 MB HIGH PRES SYSTEM 
NEAR 33N143W SOUTHEASTWARD TO 28N115W. THIS RELATIVELY WEAK HIGH 
WILL FURTHER WEAKEN OVER THE NEXT FEW DAYS AS A COLD FRONT 
IMPINGES UPON IT FROM THE NW. THIS COMPROMISED SUBTROPICAL HIGH 
IS RESPONSIBLE FOR THE RELAXED PRES GRADIENT BETWEEN IT AND THE 
MONSOON TROUGH TO ITS S. TRADE WINDS ARE EXPECTED TO REMAIN 
GENTLE TO MODERATE THE NEXT FEW DAYS AS A RESULT.

A 1006 MB LOW PRES SYSTEM ALONG THE MONSOON TROUGH NEAR 19N118W 
IS ASSOCIATED WITH LARGE BUT WEAK CYCLONIC WIND FIELD. THE 
STRONGEST WINDS LIE IN THE NE QUADRANT WHERE THE GRADIENT 
BETWEEN THE LOW AND THE SUBTROPICAL RIDGE IS GREATEST. 
HOWEVER...WINDS ARE ONLY IN THE 10 TO 15 KT RANGE IN THIS 
REGION. NO DEEP CONVECTION IS OCCURRING WITHIN THE VICINITY OF 
THE LOW. THIS SYSTEM IS BEING AFFECTED BY UPPER LEVEL NE WINDS 
OF APPROXIMATELY 20 KT OVER THE SYSTEM. THIS LOW IS HAS BEEN 
MOVING W-NW AT 10-15 KT OVER THE PAST 24 HOURS. WATER VAPOR 
IMAGERY SHOWS DRY AIR HAS WRAPPED AROUND THE SOUTH SIDE OF THE 
LOW AND IS WORKING ITS WAY AROUND THE EASTERN SIDE. THE LOW IS 
EXPECTED TO WEAKEN...SLOW DOWN AND TRACK MORE DUE W INTO COOLER 
WATERS THROUGH SUN BEFORE DISSIPATING TO A TROUGH ON MON.

S OF THE LOW...A LARGE AREA OF FRESH TO STRONG SW MONSOONAL FLOW 
EXTENDS FROM 06N TO 12N BETWEEN 114W AND 124W AND FROM 09N TO 
15N BETWEEN 106W AND 114W AS SEEN BY AN EARLIER HIGH RESOLUTION 
ASCAT PASS. THESE WINDS ARE EXPECTED TO GRADUALLY DIMINISH AS 
THE AFOREMENTIONED BROAD LOW PRES ALONG THE MONSOON TROUGH 
WEAKENS. SW SWELL GENERATED BY THIS STRONG MONSOONAL FLOW AS 
WELL AS SOUTH OF THE EQUATOR HAS BROUGHT SEAS TO 12 FT IN THIS 
REGION. SEAS HERE WILL SUBSIDE AS THE WINDS DIMINISH THROUGH 
MON.  IT IS QUITE LIKELY THAT WITHIN 24 HOURS THAT THERE WILL BE 
NO 20 KT WINDS ANYWHERE IN OUR AREA OF RESPONSIBILITY.

A LONG-PERIOD SW SWELL TRAIN WILL MOVE INTO SW AND S CENTRAL 
WATERS BEGINNING MON MORNING. SIGNIFICANT WAVE HEIGHTS WILL 
QUICKLY RISE TO 9 FT. WAVE PERIODS OF 19-21 SECONDS ARE 
EXPECTED. 

$$
COBB/LANDSEA