000 AXNT20 KNHC 231741 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT MON SEP 23 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 08N20W TO 17N21W MOVING W AT 10-15 KT. THE WAVE COINCIDES WITH A BROAD SURFACE TO 700 MB CYCLONIC CIRCULATION LARGELY EMBEDDED WITHIN THE MONSOON TROUGH AXIS FROM 07N-17N BETWEEN 16W-25W WITH A GLOBAL MODEL INDICATED 700 MB RELATIVE VORTICITY MAXIMUM CENTERED ALONG THE WAVE AXIS NEAR 14N. SAHARAN DUST IS NOTED ON VISIBLE SATELLITE IMAGERY THUS REDUCING ANY SIGNIFICANT DEEP CONVECTION...HOWEVER ISOLATED MODERATE CONVECTION IS FROM 05N-12N BETWEEN 15W-24W. TROPICAL WAVE EXTENDS FROM 08N32W TO 19N33W MOVING W AT 10-15 KT. A WEAK 1014 MB SURFACE LOW IS ANALYZED AT THE SOUTHERN EXTENT OF THE WAVE AXIS AND REMAINS EMBEDDED WITHIN THE MONSOON TROUGH AXIS AND LOW-LEVEL CYCLONIC FLOW BETWEEN 28W-39W. GLOBAL MODELS INDICATE THE WAVE COINCIDES WITH A WEAK 700 MB TROUGH AXIS ALONG 33W WITH WIDELY SCATTERED MODERATE CONVECTION OCCURRING FROM 11N-14N BETWEEN 29W-33W. TROPICAL WAVE EXTENDS FROM 12N47W TO 21N47W MOVING W AT 10-15 KT. A WEAK 1017 MB SURFACE LOW IS ANALYZED ALONG THE WAVE AXIS NEAR 19N47W YET EXHIBITS NO SIGNIFICANT DEEP CONVECTION WITH IT AT THIS TIME. FURTHERMORE...A LACK OF CONVECTION IS NOTED IN THE VICINITY OF THIS WAVE DUE LARGELY IN PART TO VERY DRY CONDITIONS ALOFT AS INDICATED ON WATER VAPOR IMAGERY. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 09N16W TO 08N22W TO 09N30W TO 07N37W TO 08N41W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N41W TO 10N47W. ASIDE FROM CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...ISOLATED MODERATE CONVECTION IS FROM 03N-08N BETWEEN 25W-34W...AND FROM 05N-09N BETWEEN 39W-43W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL TROUGH AXIS EXTENDS FROM OVER THE FLORIDA PANHANDLE NEAR 30N85W S-SW TO A BASE OVER THE SOUTH-CENTRAL GULF WATERS NEAR 22N91W. THE TROUGHING CONTINUES TO PROVIDE AN OVERALL DIFFLUENT ATMOSPHERE OVER THE EASTERN GULF AND FLORIDA PENINSULA THIS AFTERNOON WITH SCATTERED SHOWERS AND TSTMS OCCURRING FROM 22N-28N BETWEEN 81W-87W. THIS AREA OF CONVECTION IS PRIMARILY LOCATED IN THE MOIST AND UNSTABLE WARM SECTOR OF A LOW PRESSURE SYSTEM FOCUSED ON A 1004 MB SURFACE LOW CENTERED OVER THE NW GULF WATERS NEAR 26N94W. BECOMING PARTIALLY OCCLUDED OVER THE PAST 6 HOURS...A WARM FRONT EXTENDS EAST-NORTHEAST FROM THE LOW CENTER TO THE FLORIDA PANHANDLE NEAR 30N86W WITH A STATIONARY FRONT CONTINUING EASTWARD ALONG 30N TO NEAR JACKSONVILLE. ISOLATED SHOWERS AND TSTMS ARE OCCURRING IN CLOSE PROXIMITY TO THE LOW CENTER AND ALSO WITHIN 180 NM SOUTH OF THE FRONT ACROSS THE NORTHERN GULF AND WITHIN 120 NM NORTH OF THE FRONT. IN ADDITION...A SURFACE TROUGH EXTENDS SOUTHWARD FROM THE LOW CENTER ALONG 24N92W TO 20N94W. WITH THE UPPER LEVEL DYNAMICS LARGELY EAST OF THIS SURFACE TROUGH...SHOWER AND TSTM ACTIVITY REMAINS LIMITED ALONG THIS BOUNDARY...HOWEVER SHOWERS AND TSTMS RESUME A MORE SCATTERED AREAL COVERAGE S OF 21N BETWEEN 90W-97W. THE LOW IS FORECAST TO REMAIN NEARLY STATIONARY OVER THE WESTERN GULF THROUGH LATE TUESDAY AND BEGIN DRIFTING NORTHEASTWARD EARLY WEDNESDAY INTO THURSDAY BECOMING ABSORBED INTO A FRONTAL TROUGH ALONG 28N/29N THEREAFTER MOVING INTO THE SW NORTH ATLC BY FRIDAY. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER WESTERN CUBA NEAR 23N83W THAT IS PROVIDING THE NW CARIBBEAN WITH EASTERLY FLOW ALOFT...AND THE SW CARIBBEAN WITH NE TO NORTHERLY FLOW ALOFT. WATER VAPOR IMAGERY INDICATES THAT BOTH OF THESE AREAS ARE RELATIVELY DRY AND OVERALL STABLE KEEPING MOSTLY FAIR CONDITIONS W OF 72W. ONE EXCEPTION IS AN AREA OF NUMEROUS SHOWERS AND SCATTERED TSTMS OCCURRING ALONG THE NICARAGUA COAST COVERING THE AREA FROM 09N-15N BETWEEN 77W-85W. THIS CONVECTION IS LIKELY DUE TO LOW-LEVEL MOISTURE CONVERGENCE IN CLOSE PROXIMITY TO THE MONSOON TROUGH AXIS AND A RELATIVELY DIFFLUENT ENVIRONMENT ALOFT. GIVEN THE RECENT MOVEMENT OF THIS AREA... HEAVY RAINFALL IS LIKELY OVER PORTIONS OF NICARAGUA AND EASTERN HONDURAS THIS AFTERNOON AND EVENING WITH HIGHER PROBABILITY OF LOCALIZED FLASH FLOODING AND MUD SLIDES. FARTHER EAST...A MIDDLE TO UPPER LEVEL RIDGE REMAINS ANCHORED OVER THE EASTERN CARIBBEAN NEAR 15N68W WITH WATER VAPOR IMAGERY INDICATING DRY AIR AND STABLE CONDITIONS ALOFT. AT THE SURFACE...DRY AND STABLE REMAINS THE THEME E OF 72W WITH ONLY A WEAK SURFACE TROUGH ANALYZED FROM 15N63W TO 20N62W EMBEDDED WITHIN SURFACE RIDGING EXTENDING FROM THE CENTRAL ATLC INTO THE EASTERN CARIBBEAN. A FEW ISOLATED SHOWERS ARE POSSIBLE ACROSS THE LESSER ANTILLES AND NE CARIBBEAN THIS AFTERNOON AND EVENING WITH THE PASSAGE OF THE SURFACE TROUGH. OTHERWISE...EAST-SOUTHEASTERLY TRADES ARE EXPECTED TO PERSIST THROUGH THE WEEK AHEAD WITH THE STRONGEST TRADES REMAINING GENERALLY S OF 16N BETWEEN 68W-78W. HISPANIOLA... CURRENTLY SKIES REMAIN CLEAR AND CONDITIONS FAIR AS STABLE NORTHEASTERLY FLOW ALOFT CONTINUES OVER THE ISLAND. THIS OVERALL SYNOPTIC PATTERN IS EXPECTED TO CHANGE LITTLE OVER THE NEXT FEW DAYS KEEPING AFTERNOON AND EVENING CONVECTION TO A RELATIVE MINIMUM. HOWEVER GIVEN PEAK DAYTIME HEATING AND INSTABILITY... ISOLATED SHOWERS AND TSTMS REMAIN POSSIBLE DURING THE AFTERNOON AND EVENING HOURS OVER THE NEXT FEW DAYS AS THE CENTRAL ATLC SURFACE RIDGE AXIS REMAINS EXTENDED ALONG 22N. ATLANTIC OCEAN... WESTERLY UPPER LEVEL FLOW BECOMES MOSTLY DIFFLUENT OVER THE SW NORTH ATLC BETWEEN AN ANTICYCLONIC CIRCULATION CENTERED OVER WESTERN CUBA NEAR 23N83W AND A BROAD MIDDLE TO UPPER LEVEL TROUGH OVER THE NW NORTH ATLC. FURTHERMORE...THE UPPER LEVEL TROUGH SUPPORTS A COLD FRONT EXTENDING FROM 32N74W TO THE FLORIDA PENINSULA NEAR JACKSONVILLE WITH WIDELY SCATTERED SHOWERS OCCURRING N OF 28N W OF 68W. THE REMAINDER OF THE SW NORTH ATLC REMAINS MOSTLY CLOUDY WITH ISOLATED SHOWERS POSSIBLE N OF 22N W OF 68W. FARTHER EAST...MIDDLE TO UPPER LEVEL DIFFLUENCE ON THE NORTHWESTERN PERIPHERY OF AN UPPER LEVEL ANTICYCLONE CENTERED NEAR 27N54W ALONG WITH A SURFACE TROUGH ANALYZED FROM 26N58W TO 32N54W IS GENERATING SCATTERED SHOWERS AND TSTMS WITHIN 120 NM EITHER SIDE OF A LINE FROM 32N52W TO 25N60W. FINALLY...AN UPPER LEVEL TROUGH AXIS APPROACHES THE IBERIAN PENINSULA AND EXTENDS SOUTHWEST TO 28N29W SUPPORTING A COLD FRONT ANALYZED FROM 32N22W TO 29N38W BECOMING STATIONARY TO 26N47W. ISOLATED SHOWERS ARE OCCURRING WITHIN 120 NM EITHER SIDE OF THE FRONT. THE WESTERN PORTION OF THE FRONT BRIDGES TWO SURFACE RIDGES...ONE A 1022 MB HIGH CENTERED NEAR 25N31W AND THE SECOND A 1026 MB HIGH CENTERED WEST OF THE AZORES NEAR 38N41W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN