000
AXNT20 KNHC 181752
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON MAR 18 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1715 UTC.

...ITCZ/MONSOON TROUGH... 

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 09N13W TO 
05N18W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 
05N18W TO THE EQUATOR NEAR 36W. WIDELY SCATTERED MODERATE 
CONVECTION IS WITHIN 120 NM EITHER SIDE OF A LINE FROM 05N12W TO 
01N37W.

...DISCUSSION...

GULF OF MEXICO...                                           
MOIST SOUTHWESTERLY UPPER LEVEL FLOW IS EVIDENT ON WATER VAPOR 
IMAGERY WITH A MIDDLE TO UPPER LEVEL TROUGH AXIS PROGRESSING 
ACROSS THE SOUTHERN PLAINS WITH AXIS FROM OVER NE OKLAHOMA NEAR 
36N95W TO NORTHERN MEXICO NEAR 25N104W. THIS FEATURE ALOFT IS 
PROVIDING FOR INCREASED CLOUDINESS AND SCATTERED SHOWERS AND 
TSTMS ACROSS THE EASTERN GULF FROM 25N-28N BETWEEN 82W-88W. 
OTHERWISE...SOUTH-SOUTHWESTERLY RETURN FLOW DOMINATES ACROSS THE 
GULF THIS AFTERNOON ON THE WESTERN PERIPHERY OF A BROAD EAST-
WEST ORIENTED RIDGE ANCHORED IN THE SW NORTH ATLC. WITH THE 
APPROACH OF THE UPPER LEVEL TROUGHING AND THE ASSOCIATED AREA OF 
DEVELOPING LOW PRESSURE OVER THE SOUTHERN PLAINS...SOUTHERLY 
SURFACE WINDS ARE EXPECTED TO PERSIST THROUGH LATE MONDAY AS THE 
RIDGING GRADUALLY SLIDES EASTWARD. BY EARLY TUESDAY...A WEAK 
COLD FRONT IS EXPECTED TO EMERGE OFF THE TEXAS AND LOUISIANA 
COAST.

CARIBBEAN SEA...                                            
UPPER LEVEL RIDGING IS NOTED ON WATER VAPOR IMAGERY OVER THE 
ENTIRE CARIBBEAN SEA DUE TO AN ANTICYCLONIC CIRCULATION CENTERED 
OVER NORTHERN COLOMBIA NEAR 10N75W. WHILE MOST OF THE MIDDLE TO 
UPPER LEVELS OF THE ATMOSPHERE ARE DRY AND STABLE...A FEW AREAS 
OF LOW-LEVEL MOISTURE AND FAST-MOVING ISOLATED SHOWERS ARE 
OCCURRING ACROSS THE BASIN. REMNANT MOISTURE FROM A WASHED OUT 
FRONTAL BOUNDARY OVER THE CENTRAL ATLC CONTINUES TO ADVECT 
ACROSS PORTIONS OF THE NE AND NORTH-CENTRAL CARIBBEAN WITH 
ISOLATED SHOWERS REMAINING N OF 16N E OF 73W. MOST OF THE 
REMAINDER OF THE CARIBBEAN IS UNDER THE INFLUENCE OF TRADE WINDS 
IN THE RANGE OF 10 TO 20 KT WITH THE STRONGEST AREA LOCATED 
GENERALLY S OF 17N BETWEEN 70W-78W...AND IN CLOSE PROXIMITY TO 
THE COAST OF COLOMBIA. THIS SYNOPTIC PATTERN IS EXPECTED TO 
PERSIST THROUGH MID-WEEK.
 
ATLANTIC OCEAN...                                       
GENERALLY WESTERLY MIDDLE TO UPPER LEVEL FLOW IS DOMINATE OVER 
MUCH OF THE ATLC BASIN W OF 45W WITH A FAIRLY BROAD SURFACE 
RIDGE COMPLETING THE VERTICAL PROFILE OF OVERALL STABLE 
CONDITIONS THIS AFTERNOON. THE SURFACE RIDGING IS ANCHORED BY A 
1025 MB HIGH CENTERED NEAR 28N68W AND A 1024 MB HIGH CENTERED 
NEAR 28N50W. NORTH OF THIS RIDGE...A COLD FRONT EXTENDS FROM 
34N50W WESTWARD TO 33N70W AND BECOMES STATIONARY TO THE SOUTH 
CAROLINA COAST NEAR 33N79W. LOW-LEVEL MOISTURE CONTINUES TO 
INCREASE N OF 30N WITH WIDELY SCATTERED SHOWERS POSSIBLE BETWEEN 
55W-81W. TO THE EAST...A MID-LEVEL SHORTWAVE TROUGH IS NOTED ON 
WATER VAPOR IMAGERY CENTERED IN THE VICINITY OF 36N23W THAT 
SUPPORTS A DISSIPATING COLD FRONT ANALYZED INTO THE DISCUSSION 
AREA NEAR 32N24W. THE FRONT EXTENDS SW TO 23N30W AND BECOMES A 
SHEAR LINE TO 19N43W. ISOLATED SHOWERS ARE OCCURRING WITHIN 90 
NM EITHER SIDE OF THE BOUNDARY.

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

$$
HUFFMAN