000
AXPZ20 KNHC 041606
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN NOV 04 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 DEPRESSION ROSA AT 12.5N 121.2W AT 1500 UTC DRIFTING W 
AT 1 KT WITH CENTRAL PRES 1009 MB.  MAXIMUM SUSTAINED WIND 25 
GUSTS TO 30 KT.  STRONG SOUTHWESTERLY SHEAR CONTINUES AFFECTING 
ROSA WHILE THE LITTLE CONVECTION LEFT QUICKLY DRIES OUT AND 
PULLS AWAY FROM CENTER.  SCATTERED MODERATE CONVECTION...NOW 
OVER 90 NM SEPARATED FROM CENTER...MAINLY RESTRICTED TO E 
QUADRANT.  ROSA EXPECTED TO DRIFT NW BECOME A POST-TROPICAL 
REMNANT LOW PRES LATER TODAY.  SEE LATEST NHC FORECAST/ADVISORY 
UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC FOR MORE DETAILS.

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

MONSOON TROUGH FROM 05N77W TO 08N85W TO 05N96W THEN ITCZ TO 
09N103W.  MONSOON TROUGH RESUMES SW OF ROSA FROM 11N122W TO 
09N131W THEN ITCZ TO 07N140W.  SCATTERED MODERATE ISOLATED 
STRONG CONVECTION WITHIN 45 NM OF AXIS E OF 82W.  ISOLATED 
MODERATE CONVECTION WITHIN 30 NM OF AXIS W OF 124W.

...DISCUSSION...
LARGE AMPLITUDE DEEP LAYERED TROUGH DIGS SW FROM 32N110W TO 
11N131W BRINGING DRY STABLE AIR MASS RIGHT NEXT TO TROPICAL 
DEPRESSION ROSA.  CONVECTION HAS QUICKLY DIMINISHED AS STRONG SW 
WIND SHEAR BLOWS OVER ROSA WITH ONLY SCATTERED MODERATE TSTMS 
LEFT ON E QUADRANT AND PULLING AWAY FROM CENTER.  WELL DEFINED 
MID TO UPPER LEVEL ANTICYCLONE AT 22N136W EXTEND DRY AIR MASS 
BEYOND 140W N OF 15N.  SECOND UPPER LEVEL ANTICYCLONE S OF 
EQUATOR ALSO BRINGS DRY STABLE AIR MASS E OF 120W S OF 10N 
MAKING IT DIFFICULT FOR LOW PRES CENTERS ALONG MONSOON TROUGH TO 
DEVELOP TROPICAL ORGANIZATION IN SUCH UNFAVORABLE ENVIRONMENT.   

...ELSEWHERE AT THE LOWER LEVELS...
WELL SUPPORTED HIGH PRES CENTER 1023 MB AT 32N136W KEEPS STABLE 
AIR MASS IN PLACE N OF MONSOON TROUGH/ITCZ WITH MODERATE TO 
FRESH TRADE WINDS ALONG ITS SOUTHERN PERIPHERY W OF 130W.  TRADE 
WINDS DIMINISH THROUGH NEXT 48 HOURS AS THE SURFACE HIGH PRES 
LIFTS N.  LOW PRES SYSTEM IN CENTRAL PAC GENERATING LONG PERIOD 
NW SWELL PROPAGATING SE INTO BASIN WITH SEAS TO 9 FT REACHING AS 
FAR S AS 11N W OF 120W.

GAP WINDS...EARLIER SATELLITE WIND MEASURES SHOWED GULF OF 
TEHUANTEPEC N WINDS INCREASING WELL AHEAD OF GULF OF MEXICO COLD 
FRONT INTRUSION.  GUIDANCE MODELS ALSO SUPPORT EARLIER 
OBSERVATIONS OF STRONG WINDS SEEPING THROUGH CHIVELAS PASS INTO 
TEHUANTEPEC.  THE COLD FRONT IS EXPECTED TO EXACERBATE THESE 
WINDS WITH THE POSSIBILITY OF REACHING NEAR GALE FORCE STRENGTH 
BY EARLY TUE.

$$
WALLY BARNES