000 AXNT20 KNHC 181037 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT TUE AUG 18 2015 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1030 UTC. ...SPECIAL FEATURES... A TROPICAL WAVE IS OVER THE CENTRAL ATLC ASSOCIATED WITH A 1010 MB LOW PRESSURE CENTER EMBEDDED IN THE MONSOON TROUGH NEAR 10N34W. THE SYSTEM IS MOVING W AT 10-15 KT OVER A PERIOD OF 24 HOURS. CIRA LAYER PRECIPITABLE WATER IMAGERY FROM THE SURFACE TO 850 MB SHOW THE WAVE IS ASSOCIATED WITH A BROAD AREA OF MODERATE MOISTURE THAT ALONG WITH A DIVERGENT WIND ENVIRONMENT ALOFT SUPPORT SCATTERED MODERATE CONVECTION FROM 07N TO 12N BETWEEN 31W AND 39W. SAHARAN DRY AIR AND DUST ENGULF THE SYSTEM...THUS HINDERING CONVECTION ELSEWHERE. THERE IS A HIGH CHANCE THIS SYSTEM WILL DEVELOP INTO A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. SEE LATEST NHC TROPICAL WEATHER OUTLOOK UNDER AWIPS/WMO HEADERS MIATWOAT/ABNT20 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... A TROPICAL WAVE IS WITHIN 500 NM SE OF THE LESSER ANTILLES WITH AXIS NEAR 52W...MOVING W AT 10-15 KT OVER THE PAST 24 HOURS. CIRA LAYER PRECIPITABLE WATER IMAGERY FROM THE SURFACE TO 850 MB SHOW THE WAVE IS WITHIN A MODERATE MOIST ENVIRONMENT. MIDDLE TO UPPER LEVEL DIVERGENCE SUPPORT SCATTERED MODERATE CONVECTION AND TSTMS FROM 06N TO 12N BETWEEN 47W AND 55W. DRY AIR INTRUSION IN THE WAVE ENVIRONMENT FROM A SAHARAN AIRMASS HINDER CONVECTION ELSEWHERE. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 17N16W SW TO THE SPECIAL FEATURES 1010 MB LOW NEAR 10N34W TO 08N39W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N39W TO 05N52W. ASIDE FROM CONVECTION ASSOCIATED WITH THE SPECIAL FEATURES LOW AND TROPICAL WAVE ALONG 52W...ISOLATED MODERATE CONVECTION IS FROM 10N-17N E OF 27W. ...DISCUSSION... GULF OF MEXICO... A MIDDLE TO UPPER LEVEL LOW EXTENDS FROM SOUTHERN TEXAS TO NE MEXICO AND PART OF THE NW GULF WHILE A BROAD RIDGE COVERS THE REMAINDER BASIN. DIVERGENT WIND FLOW BETWEEN THESE TWO FEATURES ALOFT ALONG WITH MOISTURE INFLOW ACROSS THE BASIN FROM THE CARIBBEAN SEA SUPPORT SCATTERED MODERATE CONVECTION AND TSTMS S OF 24N W OF 90W. UPPER LEVEL DIVERGENCE IS ALSO OVER THE NORTHERN-CENTRAL GULF...THUS SUPPORTING ISOLATED SHOWERS N OF 27N BETWEEN 86W AND 94W. OTHERWISE...A WEAK SURFACE RIDGE AXIS EXTENDS ACROSS THE CENTRAL FLORIDA PENINSULA TO THE CENTRAL GULF WITH MOSTLY GENTLE TO MODERATE E-SE FLOW THAT IS EXPECTED THROUGH TUESDAY NIGHT LATE. THEREAFTER...THE S-SE WINDS WILL INCREASE SLIGHTLY ACROSS THE WESTERN GULF AS AN AREA OF LOW PRESSURE DEVELOPS ACROSS THE SOUTHERN PLAINS TUESDAY NIGHT INTO WEDNESDAY. CARIBBEAN SEA... SHALLOW MOISTURE OVER THE NW BASIN IS ENHANCING SHOWERS OVER SOUTHERN-EASTERN CUBA ADJACENT WATERS AND THE WINDWARD PASSAGE. THE OTHER AREA OF CONVECTION IS WITHIN 60 NM OFF THE COASTS OF COLOMBIA AND PANAMA BETWEEN 74W AND 79W WHERE SHOWERS AND TSTMS ARE BEING ENHANCED BY AN AREA OF LOW PRESSURE OVER NORTHERN COLOMBIA. DRY AIR SUBSIDENCE FROM ALOFT AND STRONG DEEP LAYER WIND SHEAR HINDER CONVECTION ELSEWHERE IN THE CENTRAL AND SOUTHERN CARIBBEAN. NE TO E WINDS OF 20 TO 25 KT ARE FROM 11N TO 13.5N BETWEEN 72W AND 77W WITH SEAS TO 9 FT. THESE CONDITIONS ARE EXPECTED TO PREVAIL IN THIS REGION FOR THE NEXT TWO DAYS. THE NEXT TROPICAL WAVE WILL ENTER THE E CARIBBEAN WED NIGHT. ...HISPANIOLA... SHALLOW MOISTURE ALONG WITH THE PRESENCE OF AN UPPER LOW CENTERED BETWEEN EASTERN CUBA AND JAMAICA SUPPORT CLOUDINESS ACROSS THE ISLAND WITH POSSIBLE ISOLATED SHOWERS. ISOLATED SHOWERS AND TSTMS ARE IN THE WINDWARD PASSAGE. SIMILAR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THIS EVENING AS THE UPPER LOW MOVES SW OF JAMAICA AND DRY AIR MOVES ACROSS THE ISLAND. ATLANTIC OCEAN... ISOLATED SHOWERS CONTINUE BETWEEN THE SOUTHERN FLORIDA PENINSULA AND THE NORTHERN BAHAMAS ASSOCIATED TO A FORMER SURFACE TROUGH. OTHERWISE...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1025 MB HIGH CENTERED JUST N OF THE AZORES ISLANDS. FOR TROPICAL WAVES SEE SECTION ABOVE. THERE IS A HIGH CHANCE OF TROPICAL CYCLONE DEVELOPMENT ASSOCIATED WITH THE EASTERNMOST TROPICAL WAVE. SEE SPECIAL FEATURES FOR DETAILS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR