000
AXPZ20 KNHC 181011
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT NOV 18 2006

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0845 UTC.

...SPECIAL FEATURE...
TROPICAL STORM SERGIO AT 14.9N 103.3W...OR 220 NM SSW OF 
ZIHUATANEJO MEXICO...AT 0900 UTC MOVING NW 6 KT.  MAXIMUM 
SUSTAINED WIND SPEED 40 GUSTS TO 50 KT.  ESTIMATED MINIMUM 
CENTRAL PRESSURE IS 1000 MB.  SERGIO HAS BEEN UNDER ADVERSE SW 
UPPER WIND SHEAR BUT HAS MANAGED TOP DEVELOP DEEP CONVECTION 
AGAIN TONIGHT.  SCATTERED MODERATE TO STRONG CONVECTION COVER 
FROM 14N-17N BETWEEN 100W-105W. SEE LATEST NHC FORECAST/ 
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE 
DETAILS. 

...ITCZ...
ITCZ AXIS ALONG  6N78W  8N90W  14N100W  9N117W 8N140W. 
SCATTERED MODERATE WITHIN 210 NM OF AXIS FROM 104W TO 117W.

...DISCUSSION...
UPPER LEVEL CYCLONIC VORTEX AT 23N114W EMBEDDED IN WEAK TROUGH 
EXTENDING FROM 32N120W TO 11N114W.  MODERATE SUBSIDENCE KEEPS 
DRY AIR MASS ALOFT N OF 22N E OF 122W.  REMAINDER BASIN REMAIN 
UNDER TWO BROAD RIDGES ON EITHER SIDE OF TROUGH.  RIDGE ON THE 
EAST HAS BEEN ENHANCING OUTFLOW FROM SERGIO...BUT NOW TROUGH 
SEEMS TO BE INCREASING SW SHEAR OVER SYSTEM DISRUPTING FAVORABLE 
CONDITIONS ALOFT AND WEAKENING THE TROPICAL STORM.

WEAK SURFACE LOW PRES AT 11N114W HAS VERY FAVORABLE DIFFLUENT 
FLOW ALOFT ENHANCING DEEP CONVECTION...BUT BEING ENTRENCHED IN 
ITCZ RESTRICTS ITS ABILITY TO DEVELOP AND HAS MODERATELY DRY 
AIRMASS IN ITS WLY DRIFT.  NOT MUCH CHANCE OF DEVELOPING.  

ANOTHER AREA OF LOW PRES 1009 MB AT 8N88W NOW UNDER NEUTRAL 
CONDITIONS ALOFT DRIFTING INTO MORE ADVERSE UPPER ENVIRONMENT 
MAKING IT DIFFICULT TO SURVIVE.

SURGE OF WIND ACROSS GULF OF MEXICO PROMISES TO SEND ANOTHER 
BLAST OF NLY WINDS ACROSS ISTHMUS OF TEHUANTEPEC IN LESS THAN 48 
HRS PROMPTING ANOTHER GALE EVENT OVER GULF OF TEHUANTEPEC IN E 
PAC.  POSSIBILITY OF WIND APPROACHING STORM FORCE BEING 
CONSIDERED GIVEN PRES GRADIENT BUILDUP.

$$
WALLY BARNES