000
AXNT20 KNHC 171021
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN MAR 17 2013

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL 
ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0945 UTC.

...ITCZ/MONSOON TROUGH... 

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL 
ATLC NEAR 8N13W AND CONTINUES TO 6N16W WHERE THE ITCZ CONTINUES 
ALONG 2N23W EQ36W TO THE NORTHERN COAST OF BRAZIL NEAR EQ49W. A 
LARGE CLUSTER OF MODERATE TO ISOLATED STRONG CONVECTION IS FROM 
THE EQUATOR TO 4N BETWEEN 20W AND 28W. SMALLER CLUSTERS OF 
MODERATE CONVECTION ARE FROM 5S TO THE EQUATOR BETWEEN 24W AND 
33W. SCATTERED SHOWERS CAN BE FOUND FROM 3N-6N BETWEEN 34W AND 
38W.

...DISCUSSION...

GULF OF MEXICO...                                               
SOUTHWESTERLY-WESTERLY FLOW CONTINUE TO DOMINATE THE GULF IN THE 
MIDDLE TO UPPER LEVELS AND WATER VAPOR IMAGERY INDICATE 
CONTINUAL MOISTURE ADVECTION FROM THE E PACIFIC WHICH IS 
SUPPORTING BROKEN SKIES OVER MOST OF THE GULF. GOES IR SATELLITE 
IMAGERY ENHANCEMENT INDICATE THAT RAINSHOWERS ARE OCCURRING OVER 
THE NW GULF N OF 27N W OF 89W WHEREAS ISOLATED SHOWERS ARE 
MOSTLY OVER THE CENTRAL AND SW GULF. RADAR IMAGERY CONFIRM 
RAINSHOWERS OVER THE NW GULF FROM THE SE COAST OF LOUISIANA TO 
THE SOUTHERN TIP OF TEXAS. SOUTHERLY-SOUTHEASTERLY FLOW IN THE 
RANGE OF 10-15 KT DOMINATE THE GULF WATERS. HOWEVER STRONGER 
WINDS OF 20 KT CAN BE FOUND W OF 93W AS WELL AS N OF THE YUCATAN 
PENINSULA. RETURN FLOW IN THE SAME MAGNITUDE WILL PERSIST OVER 
THE COURSE OF 24 HOURS.

CARIBBEAN SEA...                                                
THE CARIBBEAN IS UNDER THE INFLUENCE OF A MIDDLE TO UPPER LEVEL 
RIDGE ANCHORED BY AN ANTICYCLONIC CIRCULATION OVER FRENCH GUIANA 
IN SOUTH AMERICA. SOUTHWESTERLY FLOW BY THIS RIDGE IS SUPPLYING 
MOISTURE FROM THE E PACIFIC AND S OF THE EQUATOR TO MOST OF THE 
BASIN WHICH IS SUPPORTING LOW LEVEL CLOUDINESS AND ISOLATED 
SHOWERS OVER THE REGION. EASTERLY TRADEWINDS UP TO 25 KT SPREAD 
OVER THE WEST...CENTRAL AND EASTERN CARIBBEAN DUE TO THE 
CONTINUATION OF A TIGHT PRESSURE GRADIENT ACROSS THE BASIN. THE 
STRONGEST WINDS CONCENTRATE MOSTLY OVER THE CENTRAL CARIBBEAN.  
IN THE SOUTHERN CARIBBEAN...NORTHEASTERLY TRADEWINDS OF NEAR 
GALE FORCE ARE ALONG THE COLOMBIA COAST. STRONGER TRADEWINDS 
WILL CONTINUE OVER THE CENTRAL CARIBBEAN WITHIN THE NEXT 24 
HOURS.  
 
ATLANTIC OCEAN...                                             
A BROAD SURFACE RIDGE ANCHORED BY A 1022 MB HIGH NEAR 27N62W 
COVERS THE W ATLC N OF 20N W OF 52W. IN THE MIDDLE TO UPPER 
LEVEL NEARLY WESTERLY FLOW AND DRY AIR ALOFT IS SUPPORTING FAIR 
WEATHER CONDITIONS OVER THIS REGION. A BROAD UPPER LEVEL TROUGH 
SUPPORTS A COLD FRONT THAT ENTERS THE CENTRAL ATLC REGION NEAR 
30N38W AND EXTENDS ALONG 24N45W TO 19N56W WHERE IT TRANSITIONS 
TO A DISSIPATING COLD FRONT THAT CONTINUES TO 18N62W. SATELLITE 
COMPOSITE TOTAL PRECIPITABLE WATER IMAGERY INDICATE THAT 
ISOLATED SHOWERS ARE ALONG THE COLD FRONT WITHIN 100 NM EAST OF 
THE BOUNDARY N OF 23N AS WELL AS 150 NM WEST OF THE REMAINING 
FRONTAL BOUNDARY. THE RIGDE OVER THE W ATLC IS EXPECTED TO 
BECOME STATIONARY WHILE IT BROADENS COVERING THE WEST AND 
CENTRAL N TROPICAL ATLC.

FOR ADDITIONAL INFORMATION PLEASE VISIT 
HTTP://WWW.HURRICANES.GOV/MARINE

$$
NR