000
AXNT20 KNHC 171051
TWDAT 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL 
805 AM EDT WED APR 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 
1015 UTC.

...ITCZ/MONSOON TROUGH... 

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W TO 
04N21W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 
04N21W TO THE EQUATOR NEAR 29W. ISOLATED MODERATE CONVECTION IS 
WITHIN 90 NM FROM THE EQUATOR NEAR 01W TO 03N03W TO 04N08W.

...DISCUSSION...

GULF OF MEXICO...                                               
A MIDDLE TO UPPER LEVEL RIDGE IS NOTED ON WATER VAPOR IMAGERY 
WITH AXIS ALONG 86W THAT CONTINUES TO SUPPORT SURFACE RIDGING 
AND PRIMARILY EAST-SOUTHEAST WINDS IN THE RANGE OF 10 TO 20 KT. 
AN UPPER LEVEL TROUGH AXIS EXTENDS FROM OVER EASTERN TEXAS NEAR 
30N96W TO A BASE OVER SOUTHERN MEXICO NEAR 18N92W. WHILE THIS 
REMAINS AN UPPER LEVEL FEATURE...THE TROUGHING IS ENHANCING 
CLOUDINESS OVER THE CENTRAL GULF BETWEEN 84W-94W. THE SURFACE 
RIDGE IS EXPECTED TO PERSIST THROUGH LATE THURSDAY WHEN INTO 
EARLY FRIDAY THE NEXT COLD FRONT IS FORECAST TO EMERGE OFF THE 
TEXAS AND LOUISIANA COAST. WINDS WILL SHIFT NORTH-NORTHEASTERLY 
WEST OF THE FRONT AS IT MOVES EASTWARD OVER THE UPCOMING WEEKEND.

CARIBBEAN SEA...                                               
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER 
NORTHERN COLOMBIA NEAR 09N75W THAT IS PROVIDING MOSTLY WEST-
NORTHWESTERLY FLOW ALOFT OVER MUCH OF THE BASIN. WATER VAPOR 
IMAGERY INDICATES THAT DRY AIR AND OVERALL SUBSIDENCE CONTINUES 
TO PROVIDE TRANQUIL CONDITIONS THIS MORNING WITH THE EXCEPTION 
OF AN AREA OF WIDELY SCATTERED SHOWERS OCCURRING IN THE VICINITY 
OF THE LESSER ANTILLES FROM 13N-19N BETWEEN 57W-62W. 
OTHERWISE...TRADES PERSIST IN THE RANGE OF 10 TO 20 KT WITH THE 
HIGHEST WINDS ANTICIPATED S OF 15N BETWEEN 68W-78W...AND IN 
CLOSE PROXIMITY TO THE COAST OF COLOMBIA. THIS OVERALL SYNOPTIC 
PATTERN IS EXPECTED TO CONTINUE THROUGH EARLY THURSDAY. 
THEREAFTER INTO THE WEEKEND...THE TRADES WILL GRADUALLY 
INCREASING E OF 80W BY EARLY FRIDAY DUE TO AN INCREASED PRESSURE 
GRADIENT AND HIGH PRESSURE RIDGE ANCHORED OVER THE SW NORTH ATLC 
REGION.

ATLANTIC OCEAN...                                               
AS MIDDLE TO UPPER LEVEL RIDGING BUILDS EASTWARD FROM THE GULF 
OF MEXICO INTO THE SW NORTH ATLC...DRY AND SUBSIDENT NORTHWEST 
FLOW DOMINATES W OF 65W THIS MORNING. HOWEVER...AN AREA OF WEAK 
LOW PRESSURE EXISTS ALONG 30N WITH TWO DIFFERENT 1019 MB LOW 
CENTERS...ONE NEAR 30N75W AND THE OTHER NEAR 30N68W. THESE LOWS 
ARE CONNECTED BY WAY OF A STATIONARY FRONT WITH POSSIBLE 
ISOLATED LOW-TOPPED SHOWERS OCCURRING N OF 30N BETWEEN 67W-76W. 
FARTHER EAST...LONGWAVE TROUGHING IS NOTED ON WATER VAPOR 
IMAGERY BETWEEN 35W-65W WITH AXIS EXTENDING FROM 38N40W TO A 
BASE NEAR 22N64W. THIS TROUGHING SUPPORTS A STATIONARY FRONT 
ANALYZED FROM 32N36W TO 30N42W TO 27N53W. ISOLATED SHOWERS ARE 
OCCURRING WITHIN 90 NM EITHER SIDE OF THE FRONT AND N OF 25N 
BETWEEN 47W-63W. THE REMAINDER OF THE EASTERN ATLC SOUTH AND 
EAST OF THE FRONTAL BOUNDARY IS UNDER THE INFLUENCE OF A 
WEAKENING AND NARROW SURFACE RIDGE ANCHORED BY A 1023 MB HIGH 
CENTERED NEAR 31N31W.

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

$$
HUFFMAN