Tropical Weather Discussion

000
AXPZ20 KNHC 180951
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON OCT 18 2004

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 
0915 UTC.

...SPECIAL FEATURES...
1007 MB LOW CENTER NEAR 15.5N109W AT 0600 UTC MOV W 10 KT. 
CHANNEL 2 INFRARED SATELLITE IMAGERY INDICATES THAT  THE LOW 
PRESSURE AREA MAY BE ELONGATED ALONG A SW-NE AXIS WITH ANOTHER 
LOW LEVEL CENTER NEAR 15N110.7W...CLOSER TO A BURST OF SCATTERED 
STRONG CONVECTION WHICH EXISTS FROM 14.5N TO 16.5N BETWEEN 
111.5W AND 113W. EASTERLY SHEAR IS OCCURRING IN THE VICINITY OF 
THE SYSTEM...THUS INHIBITING ANY DEVELOPMENT FOR NOW. 

...TROPICAL WAVES...
TROPICAL WAVE N OF 7N ALONG 99W/100W MOVING W 10-15 KT. CYCLONIC
TURNING NOTED EARLIER ALONG THE ITCZ HAS WEAKENED. WIDELY 
SCATTERED MODERATE CONVECTION ACCOMPANIES THE WAVE AT ITS 
INTERSECTION WITH THE ITCZ. 

...ITCZ...
INTERTROPICAL CONVERGENCE ZONE AXIS...8N83W 6N90W 10N105W 12N114W
8N127W 11N140W. WIDELY SCATTERED MODERATE ISOLATED STRONG WITHIN 
150 NM EITHER SIDE OF AXIS BETWEEN 85W AND 100W...WITHIN 150 NM 
S OF THE AXIS BETWEEN 107W AND 110W...AND WITHIN 150-180 NM N OF 
THE AXIS W OF 138W. 

...DISCUSSION...
W OF 120W...
RATHER COMPLEX PATTERN W OF 120W AT THIS TIME. AT THE MID AND 
UPPER LEVELS A SHEARING TROUGH EXTENDS FROM 32N122W SOUTHWESTWARD
ALONG 25N135W TO AN MID LEVEL CYCLONE WELL W OF THE AREA NEAR 
21N149W. STRONG MID LEVEL SUBSIDENCE NOTED WITHIN 90 NM EITHER 
SIDE OF SHEAR AXIS W OF 132W. BROAD SWLY FLOW AT THE UPPER 
LEVELS AND ASSOCIATED MOISTURE PLUME IS RIDING OVER THE MID 
LEVEL SUBSIDENCE W OF 135W...THIS MOISTURE SPREADS 
ANTICYCLONICALLY NE ACROSS THE NORTHERN BAJA PENINSULA AND SEA 
OF CORTEZ...ACROSS NORTHERN OLD MEXICO AND TEXAS. SATELLITE 
DERIVED WINDS INDICATED AN UPPER LEVEL WIND MAX OF 70-90 KT 
ALONG 24N140W THROUGH 32N124W. AT THE SURFACE A FRONTAL TROUGH 
EXTENDS FROM 30N127W TO 29N140W AND IS MOVING SE AT 10-15 KT.

E OF 120W...
UPPER LEVEL ANTICYCLONE CENTERED NEAR 21N109W DOMINATES THE FLOW 
BETWEEN 100W AND 120W. ASSOCIATED RIDGE AXIS EXTENDS WESTWARD 
FROM THE SOUTHERN GULF OF MEXICO NEAR 23N95W THROUGH 16N120W.
EASTERLY FLOW S OF THE ANTICYCLONE IS SHEARING CONVECTION WELL 
AWAY FROM THE 1007 MB LOW NEAR 15.5N109W. A BAND OF MODERATE MID 
TO UPPER LEVEL SUBSIDENCE COVERS THE AREA FROM 12N TO 25N 
BETWEEN 90W AND 120W...WITH THE STRONGEST SUBSIDENCE NOTED OVER 
THE YUCATAN PENINSULA/BAY OF CAMPECHE AND BUILDING TOWARD THE 
GULF OF TEHUANTEPEC. 

AN UPPER ANTICYCLONE SE OF AREA NEAR 12S87W HAS RIDGE AXIS NW 
ACROSS THE EQUATOR TO 10N100W. ANOTHER UPPER ANTICYCLONE IS 
NOTED NEAR 13N78W. RESULTANT UPPER DIFFLUENCE IS ENHANCING ITCZ 
CONVECTION BETWEEN 85W AND 100W. MID LEVEL CYCLONIC TURNING WAS 
NOTED ALONG THE ITCZ IN THE VICINITY OF 9N94W AND 8N87W.
 
$$
COBB