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Atlantic Tropical Weather Discussion (Text)

000
AXNT20 KNHC 130603
TWDAT 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL 
105 AM EST FRI DEC 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
0515 UTC.

...ITCZ/MONSOON TROUGH...                                     
THE MONSOON TROUGH AXIS EXTENDS ACROSS AFRICA INTO THE EAST 
TROPICAL ATLC NEAR 09N13W TO 07N17W. THE ITCZ AXIS EXTENDS FROM 
07N17W TO 03N30W TO 0N46W. ISOLATED SHOWERS ARE WITHIN 100 NM 
EITHER SIDE OF THE AXES.

...DISCUSSION...

GULF OF MEXICO...                                                
A BROAD MIDDLE TO UPPER LEVEL TROUGH WITH AXIS EXTENDING ALONG 
THE NORTHWESTERN ATLC SUPPORTS A FRONTAL SYSTEM ANALYZED AS A 
STATIONARY FRONT FROM THE FLORIDA STRAITS NEAR 23N81W TO THE 
YUCATAN CHANNEL NEAR 21N86W...REGION OF THE SE GULF WHERE RADAR 
IMAGERY SHOW ISOLATED SHOWERS. A 1033 MB HIGH CENTERED OVER 
WESTERN TENNESSEE NEAR 35N88W EXTENDS A RIDGE INTO THE GULF AND 
PROVIDES NORTHEASTERLY WIND FLOW UP TO 25 KT ACROSS THE BASIN. 
SSMI TPW IMAGERY DEPICT AN ARCTIC AIR MASS PUSHING INTO THE NE 
GULF AND ALSO VERY DRY AIR ACROSS THE REMAINDER BASIN WHICH IS 
SUPPORTING FAIR WEATHER. IN THE UPPER-LEVEL...SOUTHWESTERLY WIND 
FLOW ADVECTS MOISTURE FROM THE EPAC ITCZ REGION TO SUPPORT 
BROKEN TO OVERCAST SKIES ACROSS THE NORTHERN GULF N OF 26N W OF 
87W. HIGH PRESSURE AND NORTHEASTERLY WIND FLOW ARE EXPECTED TO 
CONTINUE ACROSS THE GULF THROUGHOUT FRI MORNING. RETURN FLOW 
STARTS TO BUILD ACROSS THE GULF FRI AFTERNOON AS THE HIGH 
PRESSURE CENTER MOVES TO NW ATLC WATERS NEAR THE COAST OF NORTH 
CAROLINA. THE PORTION OF THE FRONTAL BOUNDARY ACROSS THE SE GULF 
IS FORECAST TO DISSIPATE EARLY FRI. A NEW COLD FRONT IS 
FORECAST TO EMERGE ACROSS THE NW GULF SAT AFTERNOON.

CARIBBEAN SEA...                                              
LOW-LEVEL MOISTURE CONVERGENCE IS ALONG THE COASTLINE FROM THE 
YUCATAN PENINSULA TO CENTRAL PANAMA TO SUPPORT SCATTERED 
MODERATE CONVECTION WITHIN 120 NM FROM THE COAST. OVER THE 
CENTRAL BASIN...A MIDDLE-LEVEL INVERTED TROUGH SUPPORTS A 
SURFACE TROUGH FROM THE WINDWARD PASSAGE NEAR 20N73W TO NORTHERN 
COLOMBIA NEAR 11N73W. ISOLATED SHOWERS ASSOCIATED WITH THE 
TROUGH ARE N OF 14N BETWEEN 71W-77W. ANOTHER SURFACE TROUGH 
APPEARS TO BE S OF PUERTO RICO WHICH IS GENERATING SHOWERS S OF 
17N BETWEEN 61W-68W. ACROSS THE REMAINDER BASIN DRY AIR 
SUBSIDENCE FROM THE MIDDLE LEVELS DOMINATE TO SUPPORT FAIR 
WEATHER. OTHERWISE...A RELATIVELY TIGHT PRESSURE GRADIENT OVER 
THE CENTRAL-EASTERN BASIN SUPPORTS 20-25 KT WINDS EXPECTED TO 
PERSIST THROUGHOUT SAT MORNING.

HISPANIOLA...                                                   
AN INVERTED TROUGH AT THE MIDDLE-LEVEL OVER THE CENTRAL 
CARIBBEAN SUPPORTS A SURFACE TROUGH EXTENDING ACROSS THE 
WINDWARD PASSAGE NEAR 20N73W TO NORTHERN COLOMBIA NEAR 11N73W. 
ISOLATED SHOWERS ASSOCIATED WITH THE TROUGH ARE N OF 14N BETWEEN 
71W-77W. ISOLATED SHOWERS COULD BE EXTENDING TO HAITI AS THE 
TROUGH SLOWLY DRIFTS WESTWARD TONIGHT. OTHERWISE...FAIR WEATHER 
IS FORECAST THROUGHOUT SAT AFTERNOON.

ATLANTIC OCEAN...                                               
A BROAD MIDDLE TO UPPER LEVEL TROUGH WITH AXIS EXTENDING ALONG 
THE NORTHWESTERN ATLC SUPPORTS A FRONTAL SYSTEM ANALYZED AS A 
COLD FRONT FROM 30N64W SW TO 25N73W TO 23N81W. VERY DRY AIR 
ACROSS THE SW NORTH ATLC AND CENTRAL ATLC HINDERS CONVECTION AT 
THE TIME. FARTHER EAST OVER THE CENTRAL ATLC...A 1028 MB HIGH IS 
NEAR 29N40W WHICH IS EXPECTED TO DRIFT NE OVER THE NEXT 24 HOURS 
MAINTAINING FAIR WEATHER CONDITIONS ACROSS MOST OF THE ATLC. A 
WEAK SURFACE TROUGH IS FARTHER EAST ACROSS THE CANARY ISLANDS 
FROM 33N17W SE TO INLAND AFRICA NEAR 23N15W WITH NO CONVECTION 
ASSOCIATED WITH IT AT THE TIME. OTHERWISE...AN AREA OF SCATTERED 
SHOWERS IS LOCATED FROM 12N-18N E OF 37W...INCLUDING THE CAPE 
VERDE ISLANDS. 

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

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NR