000 AXNT20 KNHC 202344 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN OCT 20 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 07N34W TO 16N34W MOVING W AT 10-15 KT. THE WAVE REMAINS EMBEDDED WITHIN THE MONSOON TROUGH AND ITCZ AXIS AND ALSO WITHIN VERY BROAD SURFACE TO 700 MB TROUGHING BETWEEN 30W-40W. ENERGY FROM THE WAVE IS CONTINUING TO FRACTURE ENERGY DUE TO AN UPPER LEVEL TROUGH AXIS NOTED ON WATER VAPOR IMAGERY FROM 20N26W TO 12N48W. VERY DRY AIR ALOFT IS NOTED IN THE VICINITY OF THE TROUGH AXIS AND AREAS TO THE NORTH OF THE AXIS BETWEEN 30W-50W THUS ANY SIGNIFICANT DEEP CONVECTION WITH THE WAVE IS LIMITED AT THIS TIME. ISOLATED MODERATE CONVECTION IS FROM 07N-12N BETWEEN 27W-39W. TROPICAL WAVE EXTENDS FROM 09N68W TO 17N67W MOVING W AT 10-15 KT. THE WAVE CONTINUES TO BE SOMEWHAT DIFFICULT TO TRACK GIVEN THAT UPPER LEVEL WESTERLIES DOMINATE OVER THE CARIBBEAN SEA AND THAT THE WAVE LACKS ANY STRONG 700 MB RELATIVE VORTICITY SIGNATURE IN GLOBAL MODEL DATA. HOWEVER...VERY WEAK SURFACE TO 700 MB TROUGHING EXISTS BETWEEN 62W-70W WITH MOST OF THE CONVECTION OCCURRING EAST OF THE AXIS ACROSS THE LEEWARD ISLANDS THIS EVENING AND ASSOCIATED WITH MIDDLE TO UPPER LEVEL DIFFLUENCE ON THE SOUTHEAST PERIPHERY OF AN UPPER LEVEL LOW CENTERED NORTH OF PUERTO RICO NEAR 22N65W. NO SIGNIFICANT CONVECTION IS NOTED IN THE VICINITY OF THE WAVE AXIS AT THIS TIME. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 15N17W TO 10N20W TO 07N33W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 07N35W TO 08N49W. ASIDE FROM THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE ALONG 34W...SCATTERED MODERATE CONVECTION IS FROM 05N-08N BETWEEN 21W-26W. ISOLATED MODERATE CONVECTION IS FROM 08N-11N BETWEEN 41W-51W. ...DISCUSSION... GULF OF MEXICO... MIDDLE TO UPPER LEVEL SOUTHWESTERLY FLOW ALOFT IS NOTED ON WATER VAPOR IMAGERY THIS EVENING OVER THE GULF BETWEEN LONGWAVE TROUGHING OVER THE WESTERN CONUS AND AN UPPER LEVEL ANTICYCLONE CENTERED OVER THE YUCATAN CHANNEL NEAR 22N85W. WHILE STRONGER UPPER LEVEL DYNAMICS ASSOCIATED WITH THE TROUGH REMAIN OVER NORTHERN MEXICO AND SECONDARY ENERGY OVER THE INTERMOUNTAIN WEST...A STATIONARY FRONT IS ANALYZED FROM THE CENTRAL FLORIDA PENINSULA NEAR 28N82W SW TO 24N91W WHERE THE FRONT BECOMES WARM TO 21N95W. THE FRONT IS FAIRLY PRECIPITATION-FREE THIS EVENING...HOWEVER MULTI-LAYERED CLOUDINESS INCREASES ACROSS THE WESTERN GULF W OF 90W WITH POSSIBLE ISOLATED SHOWERS OCCURRING S OF 27N W OF 92W AS THE WARM FRONT SLOWLY LIFTS NORTH. BY LATE MONDAY INTO EARLY TUESDAY THE NEXT COLD FRONT IS FORECAST TO EMERGE OFF THE TEXAS AND LOUISIANA GULF COAST SHIFTING WINDS NORTHERLY AS THE COLD FRONT CONTINUES SWEEPING ACROSS THE BASIN THROUGH LATE WEDNESDAY. CARIBBEAN SEA... AN UPPER LEVEL TROUGH AXIS EXTENDS FROM OVER EASTERN CUBA NEAR 19N77W SW TO 14N85W. WATER VAPOR IMAGERY INDICATES DRY AIR ALOFT NORTH OF THE TROUGH AXIS AND THIS IS RESULTING IN FAIRLY STABLE CONDITIONS THIS EVENING ACROSS THE NW CARIBBEAN. A FEW ISOLATED SHOWERS ARE HOWEVER OCCURRING OVER INLAND PORTIONS OF CUBA AND FROM 18N-21N BETWEEN 81W-87W IN THE AREA BETWEEN THE CAYMAN ISLANDS AND THE YUCATAN PENINSULA COAST. SOUTH OF THE TROUGH AXIS...LOW-LEVEL MOISTURE CONVERGENCE AND UPPER LEVEL DIFFLUENCE ARE PROVIDING AN UNSTABLE ENVIRONMENT ACROSS THE SW CARIBBEAN AND PORTIONS OF CENTRAL AMERICA THIS EVENING. SCATTERED SHOWERS AND TSTMS ARE OCCURRING S OF 16N BETWEEN 76W-87W...INCLUDING INLAND PORTIONS OF NICARAGUA AND HONDURAS. CLOSE PROXIMITY OF THE MONSOON TROUGH AXIS ALONG 10N IS ALSO ENHANCING CONVECTION OCCURRING ACROSS PANAMA AND COSTA RICA. FARTHER EAST...A TROPICAL WAVE IS ANALYZED ALONG 68W. WHILE NO SIGNIFICANT CONVECTION IS OCCURRING AT THIS TIME WITH THE WAVE ITSELF...A MIDDLE TO UPPER LEVEL LOW IS CENTERED NORTH OF PUERTO RICO NEAR 23N65W AND IS PROVIDING A FAVORABLE UPPER LEVEL DIFFLUENT ATMOSPHERE ON THE EASTERN AND SOUTHEASTERN PERIPHERY OF THE UPPER LEVEL LOW. MOIST SOUTHWESTERLY UPPER LEVEL FLOW ALOFT IS FUELING SCATTERED SHOWERS AND WIDELY SCATTERED TSTMS ACROSS THE NW CARIBBEAN THIS EVENING N OF 14N E OF 65W. THE STRONGEST CONVECTION REMAINS OVER THE OPEN WATERS OF THE SW NORTH ATLC IN THE VICINITY OF 19N60W TO THE NE OF THE LEEWARD ISLANDS. HISPANIOLA... CURRENTLY A FEW ISOLATED SHOWERS ARE NOTED ACROSS THE SOUTHERN COAST OF THE ISLAND BUT THESE ARE EXPECTED TO DIMINISH WITH THE LOSS OF DAYTIME HEATING. WATER VAPOR IMAGERY INDICATES A RELATIVELY DRY AND STABLE AIRMASS ALOFT WHICH WILL PROVIDE FOR MOSTLY CLEAR SKIES AND FAIR CONDITIONS OVERNIGHT INTO EARLY MONDAY. HISPANIOLA LIES ON THE SOUTHWESTERN PERIPHERY OF A MIDDLE TO UPPER LEVEL LOW CENTERED NEAR 23N65W AND THIS LOW IS EXPECTED TO SLOWLY DRIFT SOUTHWEST THROUGH EARLY TUESDAY. ATLANTIC OCEAN... SOUTHWEST UPPER LEVEL FLOW IS NOTED ON WATER VAPOR IMAGERY OVER MUCH OF THE SW NORTH ATLC N OF 26N W OF 68W THAT SUPPORTS A COLD FRONT ANALYZED INTO THE DISCUSSION AREA NEAR 32N74W. THE COLD FRONT CONTINUES TO 31N77W AND BECOMES STATIONARY TO THE CENTRAL FLORIDA PENINSULA COAST NEAR CAPE CANAVERAL NEAR 29N81W. ISOLATED SHOWERS ARE OCCURRING WITHIN 120 NM EITHER SIDE OF THE FRONT. TO THE EAST...ANOTHER WEAKER FRONT IS ANALYZED FROM 32N69W TO 31N71W WITH A SURFACE TROUGH EXTENDING TO 29N73W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING WITHIN 120 NM EITHER SIDE OF THIS BOUNDARY. OVER THE REMAINDER OF THE SW NORTH ATLC...A MIDDLE TO UPPER LEVEL LOW IS CENTERED NORTH OF PUERTO RICO NEAR 23N65W THAT SUPPORTS A LARGE AREA OF MIDDLE TO UPPER LEVEL DIFFLUENCE SE AND E OF THE UPPER LEVEL LOW GENERATING SCATTERED SHOWERS AND WIDELY SCATTERED TSTMS FROM 14N-24N BETWEEN 57W-65W. TO THE NORTHEAST OF THIS CONVECTION...A SURFACE TROUGH IS ANALYZED FROM 23N56W TO 29N54W AND IS PROVIDING FOCUS FOR SCATTERED SHOWERS AND ISOLATED TSTMS FROM 24N-28N BETWEEN 52W-61W. FINALLY...ACROSS THE CENTRAL AND EASTERN ATLC...A SURFACE RIDGE REMAINS DOMINATE ANCHORED BY A 1021 MB HIGH CENTERED NEAR 28N44W. FAIR WEATHER CONDITIONS STRETCH FROM THIS HIGH CENTER EASTWARD TO THE CANARY ISLANDS THEN NE TO THE IBERIAN PENINSULA. 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