000
AXPZ20 KNHC 271520
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1330 UTC.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM NORTHERN PANAMA TO THE 
BORDER OF COSTA RICA AND NICARAGUA...THEN MOVES OFFSHORE NEAR 
11N86W TO 18N105W TO LOW PRES 19N118W TO 12N122W TO 10N140W. 
SCATTERED MODERATE CONVECTION LIES FROM 12N TO 17N BETWEEN 89W 
AND 106W AS WELL AS FROM 06N TO 09N BETWEEN 82W AND 92W.

...DISCUSSION...
THE SUBTROPICAL RIDGE EXTENDS FROM A 1024 MB HIGH PRES SYSTEM 
NEAR 38N138W SOUTHEASTWARD THROUGH 32N125W TO 25N112W. 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 BARELY FRESH IN THIS REGION. SCATTERED 
MODERATE LIES WITHIN 150 NM OF THE NW QUADRANT OF THE LOW. THIS 
CONVECTION IS SKEWED FROM THE CENTER BY UPPER LEVEL 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 THE 0450 UTC 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. 

$$
SCHAUER