000
AXPZ20 KNHC 201600
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON SEP 20 2010

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...ITCZ...
MONSOONAL S TO SW FLOW DOMINATES THE DEEP TROPICS ACROSS THE 
AREA...WITH A MONSOON TROUGH EXTENDING FROM 16N103W TO 13N112W 
TO LOW PRES 13N124W 1009 MB TO 11N130W TO 10N140W. SCATTERED 
MODERATE CONVECTION WITHIN WAS NOTED WITHIN 270 NM S OF AXIS E 
OF 110W. SCATTERED TO LOCALLY NUMEROUS ISOLATED STRONG 
CONVECTION WAS NOTED WITHIN 180 NM S OF AXIS W OF 110W. 

...DISCUSSION...

ALOFT...
A RIDGE EXTENDS WSW FROM AN ANTICYCLONE CENTERED NEAR 25N123W TO 
BEYOND 20N140W. THE RIDGE WILL REMAIN NEARLY STATIONARY NEXT 12- 
24 HOURS THEN SHIFT ESE TUE THROUGH WED AS A SHORT WAVE TROUGH 
APPROACHES THE W COAST OF THE U.S. AN ANTICYCLONE IS CENTERED S 
OF BROWNSVILLE TEXAS DOMINATES THE GULF OF MEXICO AND MOST OF 
MEXICO. FAVORABLE DIVERGENT UPPER LEVEL FLOW SW OF THIS HIGH IS 
ENHANCING DEEP NOCTURNAL CONVECTION MOVING OFF THE SLOPES OF THE 
SIERRA MADRE INTO THE MEXICAN COASTAL WATERS. LIGHT TO MODERATE 
EASTERLY WINDS ACROSS THE AREA S OF THE RIDGE IS ENHANCING DEEP 
CONVECTION ON THE S SIDE OF THE MONSOON TROUGH BETWEEN 107W AND 
134W...AND MODERATE TO STRONG CONVECTION N OF 10N BETWEEN 91W 
AND 103W FROM DIFFLUENT FLOW ALOFT. MODEL GUIDANCE SHOWS WINDS 
ALOFT CONTINUING TO DECREASE SOMEWHAT OVER THE NEXT COUPLE OF 
DAYS...WHICH MAY ALLOW A LOW CENTERED NEAR 20N108W TO BECOME A 
TROPICAL CYCLONE. THERE IS A MEDIUM CHANCE OF THIS SYSTEM 
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

SURFACE...
WEAK RIDGE EXTENDS SE FROM 1018 MB HIGH CENTERED NEAR 32N137W TO 
NEAR 25N125W. PRESSURE GRADIENT BETWEEN RIDGE AND A STATIONARY  
THERMAL TROUGH OVER GULF OF CALIFORNIA IS PRODUCING 20-25 KT NW 
WINDS N OF 25N E OF 121W TO W COAST OF BAJA CALIFORNIA WITH SEAS 
TO 9 FT. WINDS AND SEAS ARE EXPECTED TO DIMINISH THERE IN ABOUT 
24 HOURS. THE MONSOON TROUGH AND ASSOCIATED FLOW MENTIONED ABOVE 
DOMINATES REST OF THE BASIN AND EXTENDS ENE INTO CENTRAL AMERICA 
AND THE FAR SW CARIBBEAN. SCATTEROMETER DATA SHOWS FRESH S-SW 
WINDS SOUTH OF THE TROUGH AXIS AS FAR WEST AS 130W. 

MARINE...
FRESH TO STRONG SW WINDS PERSIST UP TO 200 NM S OF THE MONSOON 
TROUGH AXIS...AND ARE PRODUCING 10 FT SEAS BETWEEN 101W AND 115W 
AND SEAS TO 9 FT BETWEEN 115W AND 129W. MODEL GUIDANCE SHOWS 
ISOLATED AREAS OF WINDS TO 30 KT IN ABOUT 48 HOURS IN THIS AREA. 
LARGE SWELLS WILL CONTINUE TO PROPAGATE FROM SW TO NE OVER A 
BROAD PORTION OF THE AREA THROUGH MONDAY.

$$
MUNDELL