000
AXNT20 KNHC 130534
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON MAY 13 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0445 UTC.

...ITCZ/MONSOON TROUGH...                                     

THE MONSOON TROUGH EXTENDS FROM THE COAST OF SIERRA LEONE NEAR 
8N13W TO 5N17W. A WEAK SURFACE TROUGH IS ANALYZED ALONG 9N18W TO 
3N18W. THE ITCZ BEGINS ON THE WEST SIDE OF THE TROUGH ALONG 
4N19W TO 1N24W. SCATTERED MODERATE CONVECTION IS WEST OF THE 
SURFACE TROUGH FROM 3N-5N BETWEEN 20W-25W. 

...DISCUSSION...

GULF OF MEXICO...                                               
A COLD FRONT CONTINUES TO MOVE THROUGH THE GULF OF MEXICO 
CURRENTLY EXTENDING FROM THE BIG BEND OF FLORIDA NEAR 29N83W TO 
THE SW GULF ALONG 25N90W 19N96W. A PRE-FRONTAL SURFACE TROUGH IS 
ACROSS THE FLORIDA PENINSULA FROM 28N81W TO 25N82W. A SECOND PRE-
FRONTAL TROUGH IS IN THE SW GULF ALONG 22N93W 18N93W. SCATTERED 
SHOWERS/ISOLATED THUNDERSTORMS EXTEND UP TO 350 NM NW OF THE 
FRONT WEST OF 92W. ISOLATED SHOWERS ARE WITHIN 150 NM NORTH OF 
THE AXIS ELSEWHERE...AND UP TO 100 NM TO THE SOUTH. A LARGE 
CLUSTER OF CONVECTION IS ALSO OVER THE YUCATAN PENINSULA AND 
SOUTHERN MEXICO FROM 16N-19N BETWEEN 89W-94W. MAINLY NE SURFACE 
WINDS OF 15-20 KT ARE NORTH OF THE FRONT WITH LIGHTER E-NE FLOW 
TO THE SOUTH. THE FRONT HAS BECOME NEARLY STATIONARY EXCEPT FOR 
THE NE PORTION. THE SOUTHERN PORTION WILL STALL OVER THE SW GULF 
AND DISSIPATE WHILE THE NE PORTION CONTINUES TO MOVE EASTWARD. 
MOISTURE WILL REMAIN OVER THE WESTERN GULF AND LIFT NORTH AS 
RETURN FLOW BUILDS AS SURFACE RIDGING RETURNS TO THE BASIN. 
ALOFT...SOUTHWESTERLY FLOW DOMINATES BETWEEN AN UPPER LEVEL 
TROUGH ACROSS WESTERN MEXICO AND AN UPPER LEVEL RIDGE ACROSS THE 
WESTERN CARIBBEAN. 
 
CARIBBEAN SEA...                                                 
MOSTLY FAIR CONDITIONS SPREAD ACROSS THE CARIBBEAN TONIGHT DUE 
TO DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE ACROSS THE WESTERN 
CARIBBEAN ALONG 78W...AND AN UPPER LEVEL TROUGH ACROSS THE 
EASTERN CARIBBEAN ALONG 18N63W TO 12N67W. ONLY A SMALL CLUSTER 
OF SHOWERS AND THUNDERSTORMS IS OFF THE COAST OF NORTHERN 
PANAMA. A FEW POSSIBLE ISOLATED SHOWERS ARE ALSO MOVING THROUGH 
THE NORTHERN LEEWARD ISLANDS. TRADEWIND FLOW OF 10-15 KT 
DOMINATES THE MAJORITY OF THE AREA EXCEPT FOR 20-25 KT WINDS 
OVER THE SW CARIBBEAN AND AROUND THE COAST OF COLOMBIA. LITTLE 
CHANGE IS EXPECTED OVER THE NEXT 24 HOURS. 

ATLANTIC OCEAN...                                               
AN UPPER LEVEL TROUGH NORTH OF THE DISCUSSION AREA SUPPORTS A 
COLD FRONT THAT CLIPS THE CORNER OF THE AREA ALONG 32N77W TO 
30N81W. A PRE-FRONTAL TROUGH IS EAST OF THE FRONT ALONG 32N75W 
TO 29N81W CONTINUING OVER THE FLORIDA PENINSULA. A CLUSTER OF 
HEAVY SHOWERS AND THUNDERSTORMS IS JUST SOUTH OF THE TROUGH 
FROM 28N-29N BETWEEN 77W-80W. UPPER LEVEL RIDGING COVERS THE 
AREA IMMEDIATELY TO THE WEST OF THE UPPER TROUGH. 
HOWEVER...ANOTHER UPPER TROUGH EXTENDS ALONG 31N48W TO 18N63W 
SUPPORTING A 1014 MB SURFACE LOW NEAR 24N68W. A SURFACE TROUGH 
EXTENDS THROUGH THE LOW CENTER ALONG 30N68W 24N68W 20N70W. A FEW 
LOW-LEVEL CLOUDS AND POSSIBLE ISOLATED SHOWERS ARE NEAR THE LOW 
CENTER. DIFFLUENCE ALOFT AROUND THE EAST SIDE OF THE UPPER 
TROUGH IS SUPPORTING A WIDE AREA OF ISOLATED SHOWERS 15N-26N 
BETWEEN 49W-60W. BROAD SURFACE RIDGING DOMINATES THE REMAINDER 
OF THE CENTRAL AND EASTERN ATLC ANCHORED BY A 1038 MB HIGH NW OF 
THE AZORES ISLANDS NEAR 44N32W. THE RIDGE IS PROVIDING FAIR 
CONDITIONS ACROSS THIS AREA. THE RIDGE IS SUPPORTED BY BROAD 
UPPER RIDGING COVERING THE TROPICAL ATLC. A HORIZONTALLY 
ALIGNED UPPER TROUGH IS JUST NORTH OF THE AREA ALONG 36N EAST OF 
44W SUPPORTING A WEAK SURFACE TROUGH THAT EXTENDS INTO THE RIDGE 
ALONG 30N32W 29N24W. NO SHOWERS ARE ASSOCIATED WITH THE TROUGH.
 
FOR ADDITIONAL INFORMATION PLEASE VISIT 
HTTP://WWW.HURRICANES.GOV/MARINE

AT THE REQUEST OF METEO-FRANCE AND THE METEOROLOGICAL SERVICES OF 
HAITI AND THE DOMINICAN REPUBLIC...THE TROPICAL ANALYSIS AND 
FORECAST BRANCH (TAFB) WILL BEGIN PROVIDING...ON A TEMPORARY 
BASIS...A SEPARATE DETAILED SECTION WITHIN THE ATLANTIC TROPICAL 
WEATHER DISCUSSION (TWDAT). IT WILL COVER BOTH HAITI AND THE 
DOMINICAN REPUBLIC DUE TO THE SHARED GEOGRAPHY OF BOTH COUNTRIES 
ON THE ISLAND OF HISPANIOLA.

THE SECTION BEGINS ON MAY 15 2013 AT 1800 UTC...2 PM EDT. IT 
WILL PROVIDE GUIDANCE FOR SIGNIFICANT WEATHER EVENTS THAT ARE 
EXPECTED TO IMPACT THE REGION THROUGH 48 HOURS...WITH THE FOCUS 
ON ASSESSING THE POTENTIAL FOR HEAVY RAINFALL.

$$
WALTON