000
AXPZ20 KNHC 310304
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED OCT 31 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0230 UTC.

...SPECIAL FEATURE...
TROPICAL STORM ROSA CENTERED NEAR 14.5N 117.0W AT 0000 UTC 
MOVING W OR 275 DEGREES AT 4 KT. ESTIMATED MINIMUM CENTRAL 
PRESSURE IS 1003 MB. MAXIMUM SUSTAINED WINDS ARE 40 KT GUSTS TO 
50 KT. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION E OF THE 
TROPICAL STORM FROM 12N TO 17N BETWEEN 113W AND 118W. SEE LATEST 
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 
KNHC FOR MORE DETAILS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH FROM 07N78W TO 08N90W TO 13N100W TO LOW PRES AT 
15N108W 1011 MB. ITCZ FROM 11N134W TO 10N140W. SCATTERED 
MODERATE CONVECTION IS FROM 12N TO 15N BETWEEN 105W AND 110W. 

...DISCUSSION...
UPPER LEVEL TROUGH ACROSS THE FAR NW PORTION OF THE DISCUSSION 
AREA FROM 32N131W TO 25N140W. DOWNSTREAM UPPER LEVEL RIDGE 
EXTENDS FROM AN ANTICYCLONIC CIRCULATION CENTERED NEAR 11N130W
THEN NE ACROSS THE BAJA PENINSULA INTO THE SOUTHWESTERN UNITED 
STATES. THE RIDGE DOMINATES MOST OF THE DISCUSSION AREA. 
MODERATE TO STRONG SUBSIDENCE WITH DRY AND STABLE AIR AT THE 
MIDDLE AND UPPER LEVELS IS N OF 20N...INCLUDING THE BAJA 
CALIFORNIA PENINSULA AND NORTH-CENTRAL MEXICO.

1020 MB SURFACE HIGH IS ANALYZED NEAR 31N127. A SURFACE RIDGE 
AXIS EXTENDS SE TO NEAR 25N113W. NE TRADE WINDS REMAIN RATHER 
LIGHT TO THE S AND SW OF THE RIDGE WITH SPEEDS OF 10-15 KT.  

COLD FRONT IS FORECAST TO MOVE ACROSS THE NW PORTION OF THE AREA 
WED EXTENDING FROM 30N133W TO 27N140W WED EVENING. THE FRONT 
WILL MOVE N OUT OF THE AREA THU THEN DISSIPATE. NW SWELL IN THE 
WAKE OF THE FRONT WILL RAISE SEAS TO 9 FT.

A 1011 MB LOW PRES IS ANALYZED ALONG THE MONSOON TROUGH CENTERED 
NEAR 15N108W. SCATTERED MODERATE CONVECTION IS FROM 12N TO 15N 
BETWEEN 105W AND 110W. 

A 1011 MB LOW IS ANALYZED W OF ROSA AT 14N125W WITH NO 
SIGNIFICANT CONVECTION.
 
ANOTHER 1010 MB LOW IS ANALYZED FURTHER W AT 11N131W WITH NO 
SIGNIFICANT CONVECTION. 

NLY WINDS 20-25 KT CONTINUE TO BLOW THROUGH THE GULF OF 
TEHUANTEPEC...HOWEVER THE PRES GRADIENT IS FORECAST TO RELAX AND 
WINDS WILL DECREASE TO LESS THAN 20 KT WED EVENING.

$$
FORMOSA