000
AXPZ20 KNHC 210241
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE SEP 21 2010

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...ITCZ...
A MONSOON TROUGH NOT DESCRIBED BY AN ITCZ EXTENDS FROM 18N111W 
TO TO LOW PRES 13N123W 1007 MB TO 11N140W. SCATTERED MODERATE 
WITHIN 40 NM EITHER SIDE OF TROUGH AXIS W OF 132W.

...DISCUSSION...

ALOFT...
AN ANTICYCLONIC CIRCULATION CENTERED NEAR 27N121W EXTENDS A 
RIDGE ACROSS THE N WATERS TO BEYOND 20N140W. THE RIDGE WILL 
REMAIN NEARLY STATIONARY THE NEXT 12-24 HOURS THEN SHIFT ESE TUE 
THROUGH WED AS A SHORT WAVE TROUGH APPROACHES THE W COAST OF THE 
U.S. ANOTHER ANTICYCLONE LOCATED SW OF BROWNSVILLE TX DOMINATES 
THE GULF OF MEXICO AND MOST OF MEXICO. LIGHT TO MODERATE 
EASTERLY WINDS ACROSS THE AREA S OF THE RIDGE IS ENHANCING DEEP 
CONVECTION MAINLY SOUTH OF THE MONSOON TROUGH W OF 105W. 

SURFACE...
CONVECTION ASSOCIATED WITH THE AREA OF LOW PRESSURE CENTERED 
NEAR 21N109W HAS DIMINISHED TONIGHT WITH ONLY INTERMITTENT BURST 
OF CONVECTION TO THE SE AND NW. THAT MEANS...THAT THE SYSTEM 
LACKS SUFFICIENT ORGANIZED THUNDERSTORM ACTIVITY TO BE 
CLASSIFIED AS A TROPICAL CYCLONE. HOWEVER...AN EARLIER ASCAT 
PASS SHOWED WINDS OF 25 TO 35 KT WITHIN 90 NM OF THE LOW CENTER 
WHICH PROMPTED THE ISSUANCE OF A GALE WARNING. ALTHOUGH 
UPPER-LEVEL WINDS DO NOT APPEAR CONDUCIVE FOR SIGNIFICANT 
DEVELOPMENT...AN INCREASE IN THUNDERSTORMS WOULD LIKELY RESULT 
IN THE FORMATION OF A TROPICAL STORM. INTERESTS IN SOUTHERN BAJA 
CALIFORNIA SHOULD MONITOR THE PROGRESS OF THIS SYSTEM. THERE IS 
A HIGH CHANCE OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING 
THE NEXT 48 HOURS. 

PRES GRADIENT BETWEEN A SURFACE RIDGE EXTENDING FROM 30N140W TO 
20N118W AND LOWER PRES OVER NW MEXICO IS PRODUCING NW WINDS IN 
THE 20 TO 25 KT RANGE AND SEAS OF UP TO 9 FT N OF 25N BETWEEN 
116W AND 122W. THESE MARINE CONDITIONS WILL PERSIST DURING THE 
NEXT 12-24 HOURS.  

MARINE...
FRESH TO STRONG SW WINDS PERSIST UP TO 200 NM S OF THE MONSOON 
TROUGH AXIS...AND ARE PRODUCING SEAS 8 TO 12 FT IN A BROAD AREA 
PARTICULARLY FROM 09N TO 13N BETWEEN 105W AND 130W. 

$$
GR