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Atlantic Tropical Weather Discussion (Text)



000
AXNT20 KNHC 202353
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT SEP 20 2014

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2330 UTC.

...TROPICAL WAVES...                                     

A TROPICAL WAVE IS OVER THE E ATLANTIC AND CAPE VERDE ISLANDS 
WITH AXIS EXTENDING FROM 13N23W TO 21N22W MOVING W AT 5 KT. THIS 
SLOW MOVING WAVE IS EMBEDDED IN A LARGE AREA OF DEEP MOISTURE 
ALONG THE MONSOON TROF S OF 19N. DRY SAHARAN AIR IS LOCATED N OF 
19N ALONG THE WAVE. ISOLATED MODERATE CONVECTION IS FROM 12N-19N 
BETWEEN 18W AND 26W. 

A TROPICAL WAVE IS OVER THE CENTRAL TROPICAL ATLANTIC WITH AXIS 
EXTENDING FROM 10N54W TO 21N53W...MOVING W AT 15-20 KT. SSMI TPW 
SHOWS A LARGE AREA OF DEEP MOISTURE AHEAD AND BEHIND THE WAVE 
FROM 9N-18N BETWEEN 47W AND 60W. SCATTERED MODERATE CONVECTION 
IS OCCURRING FROM 12N-19N BETWEEN 49W AND 53W. 

A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN WITH AXIS 
EXTENDING FROM 12N75W TO 22N74W...MOVING W AT 10-15 KT. MODERATE 
MOISTURE IS SUPPORTING MAINLY DIURNAL THUNDERSTORMS ACROSS 
JAMAICA AND E CUBA. DEEP LAYER SHEAR IS INHIBITING CONVECTION 
ELSEWHERE ALONG THE WAVE. 

...ITCZ/MONSOON TROUGH...                                     

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 16N16W TO 
09N39W. THE ITCZ AXIS EXTENDS FROM 09N39W TO 09N51W. OTHER THAN 
THE CONVECTION MENTIONED IN THE TROPICAL WAVE SECTION...ISOLATED 
MODERATE CONVECTION IS FROM 07N-13N BETWEEN 26W-37W.

...DISCUSSION... 

GULF OF MEXICO...  

NORTHERLY UPPER LEVEL FLOW DOMINATES THE GULF BETWEEN AN UPPER 
LEVEL ANTICYCLONE OVER N MEXICO AND AN UPPER TROUGH OVER THE SE 
CONUS. LOW PRESSURE THAT DEVELOPED OVER THE ATLANTIC OFFSHORE 
WATERS OFF THE SE CONUS HAS HELPED TRANSITION A STATIONARY FRONT 
OVER THE GULF INTO A COLD FRONT. THIS COLD FRONT EXTENDS FROM 
28N94W TO THE FL W COAST NEAR 27N82W. SCATTERED MODERATE 
CONVECTION IS OCCURRING ALONG AND WITHIN 200 MILES SOUTH OF THE 
COLD FRONT. OVER THE NEXT 24 HOURS THE COLD FRONT IS EXPECTED TO 
STALL OUT ACROSS THE SE GULF AND DIFFLUENT FLOW ALOFT IS 
FORECAST TO DEVELOP. THESE FACTORS WILL LIKELY ENHANCE 
CONVECTION ACROSS THE SE GULF THROUGH SUNDAY. 

CARIBBEAN SEA...         

WEAK UPPER LEVEL DIFFLUENCE PERSISTS ACROSS THE W CARIBBEAN 
BASIN BETWEEN UPPER LEVEL RIDGES...ONE ACROSS N MEXICO...AND THE 
OTHER OVER THE W ATLANTIC CENTERED NEAR 27N72W. THIS DIFFLUENCE 
IS INTERACTING WITH MODERATE MOISTURE TO PRODUCE ISOLATED 
THUNDERSTORMS FROM 13N-22N BETWEEN 80W AND 85W. SOME OF THE 
THUNDERSTORM ACTIVITY IN THE EXTREME NW CORNER OF THE CARIBBEAN 
MAY BE ENHANCED DUE TO A SOUTHWARD MOVING COLD FRONT IN THE 
GULF. CONVECTION IN THE CENTRAL CARIBBEAN IS ASSOCIATED WITH A 
TROPICAL WAVE DISCUSSED IN THE TROPICAL WAVES SECTION. ANOTHER 
REGION OF UPPER LEVEL DIFFLUENCE IS LOCATED ACROSS THE WINWARD 
AND LEEWARD ISLANDS BETWEEN THE UPPER RIDGE IN THE W ATLANTIC 
AND ANOTHER UPPER RIDGE IN THE CENTRAL ATLANTIC NEAR 15N43W. 
THIS DIFFLUENCE IS INTERACTING WITH A VERY MOIST AIRMASS TO 
PRODUCE SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE WINDWARD 
AND LEEWARD ISLANDS. OVER THE NEXT 24 HOURS THE REGION OF UPPER 
LEVEL DIFFLUENCE IN THE W CARIBBEAN IS EXPECTED TO INTERACT WITH 
A SURFACE FRONTAL BOUNDARY TO THE NORTH TO ENHANCE CONVECTION 
ACROSS THE NW CARIBBEAN. THE REGION OF DIFFLUENCE AND DEEP 
MOISTURE ACROSS THE WINDWARD AND LEEWARD ISLANDS IS EXPECTED 
TO SHIFT WESTWARD. A TROPICAL WAVE APPROACHING THE E CARIBBEAN 
WILL BRING ADDITIONAL CHANCES FOR SHOWERS AND THUNDERSTORMS TO 
THE WINWARD AND LEEWARD ISLANDS THROUGH SUNDAY. 

...HISPANIOLA...                                             

A TROPICAL WAVE MOVED WEST OF HISPANIOLA TODAY. MODERATE 
MOISTURE REMAINS ACROSS THE AREA AND IS SUPPORTING MAINLY 
DIURNAL SCATTERED THUNDERSTORMS OVER LAND AREAS. OVER THE NEXT 
24 HOURS MODERATE MOISTURE IS EXPECTED TO REMAIN ACROSS 
HISPANIOLA WHICH WILL SUPPORT MAINLY DAYTIME SHOWERS AND 
THUNDERSTORMS. 

ATLANTIC OCEAN... 

FOR INFORMATION ABOUT THE TROPICAL WAVES...REFER TO THE TROPICAL 
WAVES SECTION ABOVE. AN UPPER LOW IS LOCATED NEAR 25N51W. 
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE OCCURRING UNDER 
THIS LOW FROM 25N-30N BETWEEN 47W AND 55W. SURFACE LOW PRESSURE 
IS LOCATED NEAR 30N78W MOVING NE. A COLD FRONT EXTENDS SOUTHWEST 
FROM THIS LOW AND CROSSES THE FL PENINSULA E COAST NEAR 28N81W. 
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 24N-34N 
BETWEEN 69W AND 80W. OVER THE NEXT 24 HOURS THE COLD FRONT WILL 
STALL OUT ACROSS S FL AND THE BAHAMAS. ENHANCED CONVECTION WILL 
LIKELY CONTINUE IN THE VICINITY OF THE FRONTAL BOUNDARY THROUGH 
SUNDAY.  

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

$$
LATTO


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Page last modified: Saturday, 20-Sep-2014 23:53:22 UTC