000
AXPZ20 KNHC 272200
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT AUG 27 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2145 UTC.

...ITCZ/MONSOON TROUGH...
MONSOON TROUGH 13N89W TO 16N101W TO LOW PRES 19N118W TO 11N129W 
TO 09N140W. SCATTERED MODERATE ISOLATED STRONG FROM 03N TO 10N 
BETWEEN 80W AND 87W AND 12N TO 16N BETWEEN 97W AND 106W. 
SCATTERED MODERATE FROM 12N TO 15N BETWEEN 112W AND 116W.

...DISCUSSION...
THE SUBTROPICAL RIDGE EXTENDS FROM A 1026 MB HIGH PRES SYSTEM 
NEAR 39N137W SOUTHEASTWARD THROUGH 32N131W TO 25N114W. THIS HIGH 
WILL WEAKEN OVER THE NEXT FEW DAYS AS A COLD FRONT IMPINGES UPON 
IT FROM THE NW. THIS COMPROMISED SUBTROPICAL HIGH IS RESPONSIBLE 
FOR THE WEAK 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 1008 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. SCATTERED MODERATE LIES WITHIN 150 NM OF THE NW QUADRANT 
OF THE LOW. THIS CONVECTION IS BEING SHEARED FROM THE CENTER 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 MONSOON FLOW 
EXTENDS FROM 06N TO 12N BETWEEN 114W AND 124W AND FROM 09N TO 
15N BETWEEN 106W AND 114W ACCORDING TO A 1722 UTC 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 MONSOON 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.

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