000
AXNT20 KNHC 091733
TWDAT 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL 
205 PM EDT TUE APR 09 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 07N12W TO 
03N16W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 
03N16W TO 01N20W TO THE EQUATOR NEAR 32W. SCATTERED MODERATE AND 
ISOLATED STRONG CONVECTION IS FROM 01N-06N BETWEEN THE PRIME 
MERIDIAN AND 03W.

...DISCUSSION...

GULF OF MEXICO...                                          
MIDDLE TO UPPER LEVEL SOUTHWESTERLY FLOW DOMINATES OVER THE GULF 
BASIN THIS AFTERNOON BETWEEN MID-LEVEL RIDGING CENTERED ON AN 
AXIS ALONG 81W AND A VIGOROUS MIDDLE TO UPPER LEVEL LOW AND 
ASSOCIATED TROUGHING CENTERED OVER THE FOUR CORNERS REGION. 
WATER VAPOR IMAGERY INDICATES MODERATELY DRY AIR AND GENERAL 
SUBSIDENCE ALOFT THAT CONTINUES TO SUPPORT THE WESTERN PERIPHERY 
OF SURFACE RIDGING ANCHORED BY HIGH PRESSURE CENTERED OVER THE 
SW NORTH ATLC. SUSTAINED SOUTHEASTERLY WINDS IN THE RANGE OF 15 
TO 25 KT ARE NOTED ACROSS THE GULF WITH WINDS FORECAST TO 
GRADUALLY INCREASE THROUGH WEDNESDAY AS LOW PRESSURE DEVELOPS 
ACROSS THE SOUTHERN U.S. PLAINS DUE TO AN INCREASED PRESSURE 
GRADIENT. THE DEVELOPING LOW PRESSURE IS POISED TO TRACK NE 
TOWARDS THE GREAT LAKES REGION WEDNESDAY INTO THURSDAY WITH HIGH 
PRESSURE REMAINING NEARLY STATIONARY ACROSS THE SW NORTH ATLC. 
IN THE MEANTIME...SOUTHERLY RETURN FLOW IS FORECAST TO PERSIST 
UNTIL THE ASSOCIATED COLD FRONT EMERGES OFF THE TEXAS AND 
LOUISIANA COASTS EARLY THURSDAY.

CARIBBEAN SEA...                                            
NORTHWESTERLY MIDDLE TO UPPER LEVEL FLOW DOMINATES OVER THE 
CARIBBEAN WITH WATER VAPOR IMAGERY INDICATING MOSTLY DRY AIR AND 
SUBSIDENCE PROVIDING OVERALL STABLE CONDITIONS AND FAIR SKIES 
THIS AFTERNOON. TRADES PERSIST IN THE RANGE OF 10 TO 25 KT WITH 
THE STRONGEST OF THESE WINDS NOTED GENERALLY S OF 15N BETWEEN 
68W-78W...AND IN CLOSE PROXIMITY TO THE COAST OF COLOMBIA. THIS 
SYNOPTIC SETUP IS EXPECTED TO LAST THROUGH MUCH OF THE WEEK AS 
HIGH PRESSURE WILL REMAIN ANCHORED ACROSS THE SW NORTH ATLC AND 
WILL BE SLOW TO DRIFT EASTWARD.

ATLANTIC OCEAN...                                            
MIDDLE TO UPPER LEVEL RIDGING CONTINUES TO BUILD EASTWARD FROM 
THE EASTERN GULF OF MEXICO INTO THE SW NORTH ATLC REGION THIS 
AFTERNOON. THIS ATMOSPHERIC SETUP WILL CONTINUE TO SUPPORT A 
SURFACE RIDGE ANCHORED BY A 1027 MB HIGH CENTERED JUST WEST OF 
BERMUDA NEAR 33N67W. WHILE OVERALL FAIR CONDITIONS ARE NOTED W 
OF 53W IN ASSOCIATION WITH THIS HIGH...A STATIONARY FRONT LIES 
FROM 25N53W TO 22N70W THAT CONTINUES TO PROVIDE ISOLATED SHOWERS 
WITHIN 90 NM EITHER SIDE OF THE BOUNDARY. THIS FRONT IS AN 
EXTENSION OF A CENTRAL ATLC COLD FRONT ANALYZED INTO THE 
DISCUSSION AREA NEAR 32N41W THEN SW TO 25N53W. ISOLATED SHOWERS 
ARE OCCURRING WITHIN 120 NM EITHER SIDE OF THE FRONT THAT 
REMAINS SUPPORTED ALOFT BY WEAK MIDDLE TO UPPER LEVEL SHORTWAVE 
TROUGHING BETWEEN 45W-60W. FINALLY...THE REMAINDER OF THE 
EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED 
BY A 1023 MB HIGH CENTERED W-NW OF THE CANARY ISLANDS NEAR 
31N24W. 

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

$$
HUFFMAN