000
AXNT20 KNHC 071038
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE OCT 07 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST
FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1015 UTC.

...SPECIAL FEATURES...
TROPICAL STORM MARCO IS CENTERED NEAR 20.1N 96.1W AT 07/0900 UTC 
OR ABOUT 90 NM SE OF TUXPAN MEXICO MOVING WNW AT 7 KT. ESTIMATED 
MINIMUM CENTRAL PRESSURE IS 998 MB. MAXIMUM SUSTAINED WIND SPEED 
IS 55 KT WITH GUSTS TO 65 KT. SEE THE LATEST NHC FORECAST/ 
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE 
DETAILS. MARCO IS A RELATIVELY SMALL TROPICAL STORM WITH 
TROPICAL STORM FORCE WINDS ONLY EXTENDING OUTWARD UP TO ABOUT 10 
NM FROM THE CENTER. MARCO IS EXPECTED MAKE LANDFALL LATE 
MORNING/EARLY AFTERNOON TODAY. SCATTERED MODERATE/ISOLATED 
STRONG CONVECTION IS WITHIN 45/60 NM OF THE CENTER IN ALL 
QUADRANTS TO JUST INLAND ALONG THE COAST OF MEXICO. 

...TROPICAL WAVES...
TROPICAL WAVE IS 20W S OF 10N MOVING W NEAR 10 KT. MID LEVEL 
INVERTED-V CURVATURE IS OBSERVED ON SATELLITE IMAGERY. A LAYER 
OF AFRICA DUST IS AGAIN MOVING OFF W AFRICA SUPPRESSING THE WAVE 
TO THE S. CONVECTION IS EMBEDDED WITHIN THE ITCZ. 

TROPICAL WAVE IS ALONG 37W/38W S OF 15N MOVING W NEAR 10 KT. A 
SMALL MID-LEVEL CIRCULATION IS OBSERVED ON SATELLITE IMAGERY 
CENTERED ALONG THE WAVE NEAR 11N. SCATTERED SHOWERS ARE FROM 
11N-14N BETWEEN 35W-39W. 

TROPICAL WAVE IS ALONG 65W S OF 18N MOVING W NEAR 10 KT. WEAK 
INVERTED-V CURVATURE IN THE LOW/MID LEVEL CLOUD FIELD. WAVE IS 
MOVING BENEATH STRONG NW WINDS ALOFT...AND THEREFORE NO SHOWERS 
OR DEEP CONVECTION ARE ASSOCIATED WITH THE WAVE. 

TROPICAL WAVE IS ALONG 75W S OF 19N MOVING W NEAR 10 KT. WAVE IS 
MOVING BENEATH AN UPPER LOW WITH NO ASSOCIATED 
SHOWERS/CONVECTION. 

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 10N12W 6N26W 12N40W 10N44W 
11N50W 10N55W 11N62W. SCATTERED MODERATE/STRONG CONVECTION HAS 
MOVED OFF W AFRICA WITHIN 75/100 NM OF LINE FROM 4N9W TO 8N15W 
WITH CLUSTERS OF SIMILAR CONVECTION FROM 8N-15N BETWEEN 45W-53W. 
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE 
FROM 4N-10N BETWEEN 16W-21W AND FROM 8N-14N BETWEEN 19W-25W AND 
WITHIN 75 NM OF LINE FROM 14N50W TO 20N52W. SMALL CLUSTERS OF 
SCATTERED MODERATE CONVECTION ARE WITHIN 60 NM OF LINE FROM 
5N39W TO 8N48W. 

...DISCUSSION...

GULF OF MEXICO...
TROPICAL STORM MARCO IS LOCATED ALONG THE COAST OF MEXICO IN THE 
W BAY OF CAMPECHE...SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. 
A BROAD UPPER RIDGE COVERS THE GULF ANCHORED ALONG THE N COAST 
OF THE YUCATAN PENINSULA BRINGING MOIST TROPICAL AIR ACROSS MOST 
OF THE GULF. DIFFLUENCE ALOFT IS GENERATING CLUSTERS OF 
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE NE GULF N OF 
25N TO INLAND OVER TH N GULF COAST STATES E OF 89W TO JUST OFF 
THE FLORIDA PENINSULA. SIMILAR ACTIVITY IS DEVELOPING WITHIN 60 
ALONG THE TEXAS COAST. THE NEXT FRONTAL BOUNDARY EXPECTED TO 
ENTER THE GULF LATE TODAY.  

CARIBBEAN SEA...
UPPER LOW COVERS THE W CARIBBEAN CENTERED ALONG THE COAST OF NE 
HONDURAS NEAR 15N84W GENERATING SCATTERED SHOWERS FROM 15N-19N W 
OF 75W TO THE COAST OF HONDURAS AND THE YUCATAN PENINSULA. THE 
REMAINDER OF THE CARIBBEAN IS DOMINATED BY A BROAD UPPER RIDGE 
ANCHORED OVER NW VENEZUELA E OF 76W TO OVER THE LESSER ANTILLES. 
DIFFLUENCE ALOFT GENERATING SCATTERED SHOWERS/ISOLATED 
THUNDERSTORMS E OF 72W ACROSS THE E CARIBBEAN TO THE LESSER 
ANTILLES. 

ATLANTIC OCEAN...
A WEAK UPPER RIDGE EXTENDING FROM THE GULF OF MEXICO DOMINATES 
THE W ATLC W OF 78W GENERATING ISOLATED SHOWERS FROM 27N-29N W 
OF 78W TO THE COAST OF THE FLORIDA PENINSULA. A LARGE CUT-OFF 
UPPER LOW IS IN THE W/CENTRAL ATLC CENTERED NEAR 22N62W WITH A 
SURFACE TROUGH EXTENDING FROM 28N59W TO 21N63W PRODUCING 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 22N-26N 
BETWEEN 55W-58W AND SCATTERED SHOWERS/ISOLATED THUNDERSTORMS 
ACROSS THE REMAINDER OF THE AREA FROM 21N-30N BETWEEN 54W-59W. 
AN UPPER RIDGE TO THE N NEAR 29N38W EXTENDING NE BETWEEN THE 
AZORES AND MADEIRA ISLANDS. AN UPPER TROUGH CONTINUES TO DIG SW 
OVER THE E/CENTRAL ATLC INTO THE TROPICAL ATLC ACROSS THE CANARY 
ISLANDS SW TO A SMALL UPPER LOW NEAR 22N32W TO 15N45W WITH 
SCATTERED SHOWERS W OF THE CAPE VERDE ISLANDS FROM 14N-21N 
BETWEEN 26W-32W. A SURFACE RIDGE IS COVERS THE E ATLC N OF 20N E 
OF 50W ANCHORED BY A 1025 MB HIGH W OF MADEIRA ISLANDS NEAR 
32N22W. 

$$
WALLACE