000
AXPZ20 KNHC 311521
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...SPECIAL FEATURE...
TROPICAL STORM ROSA CENTERED NEAR 14.5N 117.6W AT 1500 UTC 
MOVING W OR 275 DEGREES AT 3 KT. ESTIMATED MINIMUM CENTRAL 
PRESSURE IS 1002 MB. MAXIMUM SUSTAINED WINDS ARE 45 KT GUSTS TO 
55 KT. WESTERLY SHEAR IS DISPLACING THE CONVECTION E OF THE 
LOW-LEVEL CENTER. NUMEROUS CONVECTION ASSOCIATED WITH ROSA IS 
FROM 13N-16N BETWEEN 113W-118W. ROSA WILL SLOW WEAKENING ON THU 
AND WEAKEN TO TROPICAL DEPRESSION FRI NIGHT. ROSA IS FORECAST TO 
MOVE VERY LITTLE DURING THE NEXT FEW DAYS...AND COULD BECOME 
NEARLY STATIONARY BY THU NIGHT. SEE LATEST NHC FORECAST/ 
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC FOR MORE 
DETAILS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH 8N83W TO 6N95W TO LOW PRES NEAR 15N1009W 1010 
MB TO 15N125W TO 8N140W. NO SIGNIFICANT CONVECTION.

...DISCUSSION...
UPPER LEVEL RIDGE ACROSS THE FAR NW PORTION OF THE DISCUSSION 
AREA FROM 32N125W TO 27N132W. DOWNSTREAM UPPER LEVEL SHORTWAVE 
TROUGH WITH AXIS FROM SOUTHERN CALIFORNIA TO 32N118W TO 27N123W. 
A 75 KT JETSTREAM IS SE OF THE TROUGH FROM 24N126W TO 26N115W.
AN UPPER LEVEL RIDGE EXTENDS FROM AN ANTICYCLONIC CIRCULATION 
CENTERED NEAR 13N121W 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.

A 1018 MB SURFACE HIGH IS CENTERED TO 28N126W WITH RIDGE FROM 
THE HIGH SE TO NEAR 25N118W. NE TRADE WINDS REMAIN RATHER LIGHT 
TO THE S OF THE RIDGE WITH SPEEDS OF 10-15 KT.

COLD FRONT ACROSS THE FAR NW PORTION OF THE AREA EXTENDING FROM 
32N134W TO 28N140W. THE FRONT WILL WEAKEN AND EXTEND FROM 
30N130W TO 26N140W THU THEN DISSIPATE FRI. NW SWELL BEHIND THE 
FRONT WILL BUILD SEAS 8 TO 10 FT.

A 1010 MB LOW PRES IS ANALYZED ALONG THE MONSOON TROUGH CENTERED 
NEAR 15N109W. NUMEROUS MODERATE TO STRONG CONVECTION FROM 
12N-15N BETWEEN 106W-108W.

ELY WINDS 20-25 KT ARE BLOWING THROUGH THE GULF OF PAPAGAYO ARE 
EXPECTED TO CONTINUE THROUGH THU THEN DECREASE TO LESS THEN 20 
KT FRI.

$$
DGS