000 AXNT20 KNHC 240005 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS MOVING ACROSS THE CAPE VERDE ISLANDS. ITS AXIS EXTENDS FROM 17N23W TO 09N22W AND IS MOVING W NEAR 10-15 KT. TOTAL PRECIPITABLE WATER IMAGERY SHOW THE WAVE IS EMBEDDED FOR THE MOST PART IN A MODERATE MOIST ENVIRONMENT. A CLUSTER OF MODERATE CONVECTION AND TSTMS IS WEST OF THE AXIS FROM 12N-15N COINCIDING WITH A SMALL SECTOR OF HIGH MOISTURE IN THE AFOREMENTIONED IMAGERY. STRONG NORTHEASTERLY WIND SHEAR IN THE NORTHERN REGION OF THE WAVE IS IN PART HINDERING FURTHER CONVECTIVE ACTIVITY. A TROPICAL WAVE AXIS EXTENDS FROM 18N36W TO 09N33W AND IS MOVING WEST AT 10-15 KT. A 1012 MB SURFACE LOW IS ANALYZED AT THE SOUTHERN EXTENT OF THE WAVE AXIS AND REMAINS EMBEDDED WITHIN THE MONSOON TROUGH AXIS NEAR 08N32W. TOTAL PRECIPITABLE WATER IMAGERY SHOW MOST OF THE WAVE IS EMBEDDED WITHIN A MODERATE MOIST ENVIRONMENT. SCATTERED MODERATE CONVECTION IS FROM 14N-17N BETWEEN 31W-36W. TROPICAL WAVE AXIS EXTENDS FROM 22N47W TO 14N49W AND IS MOVING W- NW NEAR 10 KT. WATER VAPOR AND TOTAL PRECIPITABLE WATER IMAGERY SHOW VERY DRY AIR WITHIN THE WAVE ENVIRONMENT WHICH ALONG WITH STRONG DEEP LAYER WIND SHEAR INHIBITS CONVECTIVE ACTIVITY AT THIS TIME. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM 09N18W TO A 1012 MB LOW NEAR 08N32W TO 07N42W. SCATTERED MODERATE CONVECTION IS FROM 03N- 08N BETWEEN 20W-35W. ...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 22N89W. THE TROUGHING CONTINUES TO PROVIDE AN OVERALL DIFFLUENT ATMOSPHERE OVER THE EASTERN GULF AND FLORIDA PENINSULA WITH SCATTERED SHOWERS AND TSTMS OCCURRING FROM 23N-29N BETWEEN 80W-85W. 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 27N94W. BECOMING PARTIALLY OCCLUDED OVER THE PAST SEVERAL HOURS...A WARM FRONT EXTENDS NORTHEAST FROM THE LOW CENTER TO LOUISIANA NEAR 29 N92W...ACROSS THE SOUTHERN STATES TO THE FLORIDA PANHANDLE NEAR 30N83W WHERE IT TRANSITIONS TO A STATIONARY FRONT THAT CONTINUES EASTWARD TO ATLC WATERS. A CLUSTER OF MODERATE CONVECTION COINCIDES WITH THE LOCATION OF THE LOW CENTER AND EXTENDS FROM 26N-27N BETWEEN 94W- 96W. IN ADDITION...A SURFACE TROUGH EXTENDS SOUTHWARD FROM THE FRONTAL BOUNDARY ALONG 28N93W TO 20N93W. THE LOW IS FORECAST TO REMAIN NEARLY STATIONARY OVER THE NW 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 23N84W 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 76W. DIFFLUENCE FROM THE FLOW ALOFT OCCURS OVER HONDURAS AND NICARAGUA TO SUPPORT SCATTERED MODERATE CONVECTION INLAND AND WITHIN 50 NM OF ITS COASTLINES. LOW-LEVEL MOISTURE CONVERGENCE FROM THE MONSOON TROUGH WHICH AXIS MOVES ACROSS NICARAGUA TO NORTHERN COLOMBIA SUPPORTS SCATTERED SHOWERS S OF 15N W OF 80W AND S OF 12N E OF 78W. FARTHER EAST...AN ELONGATED UPPER LEVEL LOW DEVELOPED OVER THE EASTERN CARIBBEAN WITH CENTER NEAR 14N68W. WATER VAPOR AND TOTAL PRECIPITABLE WATER IMAGERY SHOW DRY AIR IN THE MIDDLE AND LOWER LEVELS WHICH IS SUPPORTING FAIR WEATHER IN THIS REGION OF THE BASIN W OF 64W. OVER THE NE CARIBBEAN...A WEAK SURFACE TROUGH IS ANALYZED FROM 20N61W TO 16N63W. MOISTURE BEING CARRIED BY THIS FEATURE HAS BEEN ENHANCING SHOWERS ACROSS THE LESSER ANTILLES. ISOLATED SHOWERS ARE POSSIBLE ACROSS THE VIRGIN ISLANDS AND EASTERN PUERTO RICO TONIGHT ASSOCIATED 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... CLEAR SKIES AND FAIR WEATHER CONDITIONS CONTINUES DUE TO DRY STABLE AIR AND STRONG NORTHERLY WIND SHEAR MOVING ACROSS THE ISLAND. COMBINATION OF DRY AIR AND UNFAVORABLE MIDDLE TO UPPER LEVEL SYNOPTIC PATTERN WILL SUPPORT FAIR WEATHER THROUGH WED AFTERNOON. THUS...AFTERNOON AND EVENING CONVECTION IS EXPECTED TO BE RELATIVELY MINIMUM. ATLANTIC OCEAN... WESTERLY UPPER LEVEL FLOW BECOMES MOSTLY DIFFLUENT OVER THE SW NORTH ATLC BETWEEN AN ANTICYCLONIC CIRCULATION CENTERED OVER WESTERN CUBA NEAR 23N84W AND A BROAD MIDDLE TO UPPER LEVEL TROUGH OVER THE NW NORTH ATLC. FURTHERMORE...THE UPPER LEVEL TROUGH SUPPORTS A COLD FRONT EXTENDING FROM 30N75W TO 30N79W WHERE IT BECOMES STATIONARY TO JACKSONVILLE. WIDELY SCATTERED SHOWERS AND TSTMS ARE OCCURRING N OF 24N W OF 69W. FARTHER EAST...A SURFACE TROUGH EXTENDS FROM 32N54W TO 27N57W WITH NO CONVECTION ASSOCIATED WITH IT. FINALLY...AN UPPER LEVEL TROUGH AXIS SUPPORTS A COLD FRONT ANALYZED FROM 29N26W TO 29N31W WHERE IT BECOMES STATIONARY TO 25N48W. A 1020 MB HIGH IS CENTERED NEAR 25N30W AND IS EXPECTED TO MOVE WESTWARD WITHIN THE NEXT 24 HOURS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR