000
AXPZ20 KNHC 131526
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU SEP 13 2012

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 
1500 UTC.

...SPECIAL FEATURE...
TROPICAL STORM KRISTY CENTERED NEAR 18.9N 109.3W AT 1500 UTC 
MOVING WNW 9 KT WITH MAXIMUM SUSTAINED WINDS 45 KT GUSTS TO 55 
KT AND MINIMUM PRESSURE OF 1002 MB. THE CLOUD PATTERN HAS NOT 
BECOME MUCH BETTER ORGANIZED DURING THE PAST 12 HOURS. MICROWAVE 
DATA SHOWS THE CENTER IS LOCATED ON THE NW EDGE OF THE CONVECTION
DUE TO NORTHWESTERLY SHEAR. NUMEROUS MODERATE-STRONG CONVECTION 
IS FROM 16N TO 20N BETWEEN 106W AND 110W. KRISTY IS EXPECTED TO 
INTENSIFY ONLY SLIGHTLY AS IT MOVES NW OVER THE NEXT 24 TO 48 
HOURS. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH EXTENDS FROM 09N83W TO 08N114W. ITCZ FROM 11N133W 
TO 09N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION FROM 
09N TO 14N W OF 129W.

...DISCUSSION...
A 1011 MB SURFACE LOW IS ANALYZED SW OF T.S. KRISTY NEAR 16N116W.
SCATTERED MODERATE-STRONG CONVECTION IS LOCATED WITHIN 90 NM W 
OF THE CENTER. THE LOW IS EXPECTED TO MOVE SLOWLY W THEN NNW 
WITH LITTLE DEVELOPMENT THROUGH THE WEEKEND. AN AREA OF LOW PRES 
IS EXPECTED TO DEVELOP ALONG THE WESTERN END OF THE CONVERGENCE 
ZONE NEAR 13N130W BY TONIGHT...THEN DRIFT W THROUGH SUN WITH AS 
A WEAK LOW.

NEARLY STATIONARY SUBTROPICAL HIGH CENTERED NEAR 40N140W EXTENDS 
A WEAK RIDGE SOUTHWESTWARD INTO NORTH-CENTRAL PORTION OF THE 
DISCUSSION AREA. LIGHT TO MODERATE WINDS PREVAIL OVER MOST OF 
THE REGION...EXCEPT WITHIN 300 NM N OF THE CONVERGENCE ZONE W OF 
130W IN ENHANCED NE TRADE WIND FLOW...AND JUST W OF THE GULF OF 
PAPAGAYO IN FRESH E-NE GAP WINDS FUNNELING FROM THE W CARIBBEAN 
THROUGH CENTRAL AMERICA...BUILDING SEAS DOWNWIND FROM THE GULF 
OF PAPAGAYO TO AROUND 7 FT.

FRESH NE WINDS WITH SEAS AROUND 7 FT ARE EXPECTED TO PERSIST N 
OF THE CONVERGENCE ZONE W OF 130W THROUGH FRI. FRESH WINDS AND 
HIGHER SEAS ARE EXPECTED TO PERSIST DOWNSTREAM OF THE GULF OF 
PAPAGAYO THROUGH FRI EVENING. GFS AND ECMWF MODELS INDICATE 
DIURNAL PULSES OF NORTHERLY DRAINAGE FLOW INTO THE GULF OF 
TEHUANTEPEC BEGINNING EARLY FRI...CONTINUING THROUGH THE WEEKEND 
WITH WINDS TO 20-25 KT PRIMARILY AROUND SUNRISE. SEAS SHOULD 
REMAIN 8 FT OR LESS DOWNWIND FROM THE GULF OF TEHUANTEPEC.

$$
MUNDELL