000
AXPZ20 KNHC 101549
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON SEP 10 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 
1545 UTC.

...SPECIAL FEATURE...

.A BROAD AREA OF LOW PRESSURE HAS CONTINUED TO ORGANIZE AND A 
1009 MB SURFACE LOW HAS BEEN ANALYZED NEAR 13N96W AT 1200 UTC. 
EASTERLY WINDS HAVE INCREASED TO 20 TO 25 KT WITHIN 180 NM OF 
THE CENTER OVER THE N SEMICIRCLE WITH SEAS OF 8 TO 11 FT. THE 
LOW...POSSIBLE TROPICAL CYCLONE...IS FORECAST TO MOVE JUST N OF 
DUE W TO A POSITION NEAR 13.5N101W 1008 MB ON TUE AND NEAR 
17N106W ON WED WITH WINDS 20 TO 25 KT EXPECTED WITHIN 300 NM OF 
THE CENTER. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS WESTWARD FROM THE COLOMBIAN AND 
PANAMA BORDER ACROSS WESTERN PANAMA AND SOUTHERN COSTA RICA 
TURNING NW OVER THE EAST PACIFIC TO AN EMBEDDED LOW PRES AT 
13N96W...THEN THE TROUGH CONTINUES NW TO 15N110W...THEN TURNS SW 
TO NEAR 09N130W WHERE LOW LEVEL WINDS INDICATE A TRANSITION TO 
AN ITCZ...WHICH IN TURN CONTINUES W TO BEYOND 09N140W. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 150 NM OF 
06N79W AND WITHIN 180 NM EITHER SIDE OF A LINE FROM 11N90W TO 
15N100W TO 12N96W...THEN NARROWS TO WITHIN 150 NM EITHER SIDE OF 
A OF LINE FROM 11N124W TO 08N140W. SIMILAR CONVECTION IS NOTED 
OVER AND WITHIN 30 NM OF THE MEXICAN COAST FROM 102W TO 106W.

...DISCUSSION...

A DEEP LAYERED CYCLONE IS OVER THE NORTHERN GULF OF CALIFORNIA 
WITH AN UPPER TROUGH EXTENDING SW TO 20N118W. AN ASSOCIATED 1009 
MB SURFACE LOW IS ANALYZED AT 31N116W. BROKEN TO OVERCAST 
MULTILAYERED CLOUDS WITH EMBEDDED SHOWERS IS OBSERVED OVER AND 
ALONG THE BAJA PENINSULA AND THE GULF OF CALIFORNIA TO THE N OF 
27.5N. LOW LEVEL SOUTHWESTERLY WINDS ARE 10 TO 15 KT OVER THE 
NORTHERN GULF OF CALIFORNIA. ALTHOUGH NW WINDS ARE MOSTLY 5 TO 
10 KT...SEAS ARE RUNNING AT 3-6 FT ALONG THE ENTIRE PACIFIC 
COAST OF THE BAJA PENINSULA...PRIMARILY DUE TO LONG PERIOD NW 
SWELL. 

AN UPPER ANTICYCLONE IS CENTERED AT 24N139W WITH A RIDGE 
EXTENDING NE TO A CREST AT 31N127W. UPPER MOISTURE IS WRAPPING 
COMPLETELY AROUND THE DEEP LAYERED CYCLONE...WITHIN 240 NM OF 
THE CENTER AT 31.5N114.5W...AND IS ALSO SPREADING NE ACROSS ALL 
OF ARIZONA AND WESTERN NEW MEXICO. OTHERWISE THE UPPER LEVELS 
ARE VERY DRY TO THE N OF 15N AND W OF 119W. 
   
ANOTHER UPPER ANTICYCLONE IS CENTERED AT 21.5N108W WITH A RIDGE 
EXTENDING SE ALONG THE PACIFIC COAST OF CENTRAL AMERICA TO A 
CREST AT 10N89W. THE UPPER LEVELS ARE SOMEWHAT DIFFLUENT ACROSS 
THE TROPICS AND SUPPORTING THE CONVECTION ALONG THE MONSOON 
TROUGH AND ITCZ AS PREVIOUSLY DESCRIBED. THE RESULTANT UPPER  
DEBRIS MOISTURE IS ADVECTED SW BETWEEN 90W AND 113W BUT 
EVAPORATING COMPLETELY ALONG 03N. THE DEBRIS MOISTURE IS 
ADVECTED W IN A BAND FROM 05N TO 13N BETWEEN 113W AND 145W.

A SURFACE RIDGE AXIS EXTENDS SE FROM NEAR 31N142W TO 21N118W. 
NORTHEAST TRADES S OF THIS RIDGE ARE ENHANCED TO 20 TO 25 
KT...SEAS TO 9 FT...IN THE AREA FROM 09N TO 16N BETWEEN 135W AND 
140W. THIS AREA OF ENHANCED WINDS IS EXPECTED TO SHRINK SLIGHTLY 
ON TUE AND DIMINISH COMPLETELY TUE NIGHT. 

$$
NELSON