000 AXNT20 KNHC 090004 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU OCT 08 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2345 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS OVER THE CENTRAL ATLC WITH AXIS EXTENDING FROM 12N31W TO 05N33W...MOVING W AT 10 TO 15 KT OVER THE PAST 24 HOURS. CIRA LAYER PRECIPITABLE WATER OR LPW IMAGERY FROM THE SURFACE TO 850 MB SHOW THE WAVE IS EMBEDDED IN A MODERATE MOIST ENVIRONMENT WITH PATCHES OF DRY AIR MAINLY AHEAD OF THE WAVE AXIS. RGB AIRMASS IMAGERY SHOW DRY AIR WNW OF THE WAVE AXIS COINCIDING WITH PATCHES OF DRY AIR IN THE LPW PRODUCT. UPPER LEVEL DIFFLUENCE SUPPORT SCATTERED MODERATE CONVECTION E OF THE AXIS FROM 07N TO 13N BETWEEN 25W AND 33W. A LOW AMPLITUDE TROPICAL WAVE IS JUST E OF THE WINDWARD ISLANDS WITH AXIS NEAR 61W...MOVING W AT 20 TO 25 KT OVER THE PAST 24 HOURS. THIS WAVE IS EMBEDDED IN A MODERATE MOIST ENVIRONMENT THAT ALONG WITH DIFFLUENCE ALOFT SUPPORT SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS S OF 15N BETWEEN 55W AND 61W. THE WAVE WILL MOVE OVER S AMERICA AND MODEL GUIDANCE INDICATES IT WILL ENTER THE EPAC WATERS SATURDAY. A TROPICAL WAVE IS OVER THE EASTERN CARIBBEAN WITH AN AXIS EXTENDING ALONG 65W...MOVING W AT AROUND 15 KT OVER THE PAST 24 HOURS. CIRA LAYER PRECIPITABLE WATER OR LPW IMAGERY FROM THE SURFACE TO 850 MB SHOW ABUNDANT MOISTURE IN THE NORTHERN WAVE ENVIRONMENT THAT ALONG WITH A MIDDLE LEVEL LOW SUPPORT SCATTERED SHOWERS AND TSTMS OVER THE NE CARIBBEAN INCLUDING THE LEEWARD AND VIRGIN ISLANDS AND PUERTO RICO. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR 16N16W TO 12N25W TO 09N32W. THE ITCZ AXIS BEGINS W OF THE CENTRAL ATLC TROPICAL WAVE NEAR 08N35W TO 08N54W. FOR CONVECTION INFORMATION SEE THE TROPICAL WAVES SECTION. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL RIDGE COVERS THE SSE CONUS AND EXTENDS ACROSS THE GULF TO SOUTHERN MEXICO AND CENTRAL AMERICA EPAC COASTAL WATERS. BROAD RIDGING IS ALSO AT THE SURFACE ANCHORED BY A 1020 MB HIGH IN NORTH CAROLINA. THE SURFACE RIDGE EXTENDS S TO CENTRAL GULF WATERS...EXCEPT S OF 26N E OF 86W WHERE SCATTEROMETER DATA AND SATELLITE IMAGERY INDICATE THE PRESENCE OF A SURFACE TROUGH WITH POSSIBLE ISOLATED SHOWERS WITHIN 20 NM E THE AXIS THAT IS ALONG 26N83W TO 22N85W. ISOLATED SHOWERS ARE OVER THE NNW GULF OFFSHORE WATERS BEING ENHANCED BY SHALLOW MOISTURE CONVERGING ALONG THE COAST AND A SLIGHT DIFFLUENT ENVIRONMENT ALOFT GENERATED BY A MIDDLE TO UPPER LEVEL LOW CENTERED OVER NW MEXICO. OTHERWISE...DRY AIR SUBSIDENCE FROM ALOFT AND STRONG DEEP LAYER WIND SHEAR INHIBIT CONVECTION IN THE REMAINDER BASIN. ENE WIND FLOW UP TO 15 KT IS N OF 26N...LIGHT VARIABLE WIND IS ELSEWHERE. A COLD FRONT WILL ENTER THE GULF SATURDAY AND MOVE ACROSS THE BASIN THROUGH LATE SUNDAY. CARIBBEAN SEA... UPPER LEVEL RIDGING DOMINATES ACROSS THE BASIN...EXCEPT THE CENTRAL CARIBBEAN WHERE A CYCLONIC CIRCULATION IS CENTERED S OF HISPANIOLA ENHANCING SHOWERS AND TSTMS ACROSS THE ISLAND AND ADJACENT S WATERS TO 14N. OVER THE WESTERN BASIN...A SURFACE TROUGH EXTENDS FROM 19N83W...ACROSS HONDURAS TO NW NICARAGUA NEAR 12N86W. E OF THIS TROUGH...A SECOND TROUGH EXTENDS FROM 17N82W TO 12N83W TO SOUTHERN COSTA RICA NEAR 09N83W GENERATING SCATTERED SHOWERS AND TSTMS S OF 18N W OF 81W. A TROPICAL WAVE IS OVER THE EASTERN CARIBBEAN WITH AXIS JUST E OF PUERTO RICO. A SECOND TROPICAL WAVE IS ESE OF THE WINDWARD ISLANDS...BOTH SUPPORTING CONVECTION AND TSTMS. PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. EXPECT SIMILAR CONDITIONS OVER THE NEXT 24 HOURS WITH CONVECTION OVER THE EASTERN CARIBBEAN SPREADING GRADUALLY OVER THE CENTRAL CARIBBEAN AS THE WAVES PROPAGATE WESTWARD. TRADE WINDS OF 20 KT OR LESS ARE FROM 12N TO 14N BETWEEN 73W AND 76W WITH SEAS TO 8 FT IN NE TO E SWELL. ...HISPANIOLA... AN UPPER LEVEL CYCLONIC CIRCULATION IS CENTERED S OF HISPANIOLA ENHANCING SHOWERS AND TSTMS ACROSS THE ISLAND AND ADJACENT S WATERS TO 14N. MOISTURE WILL INCREASE OVERNIGHT ACROSS THE ISLAND AS A TROPICAL WAVE APPROACHES HISPANIOLA FROM THE EAST. CONVECTION WILL LIKELY CONTINUE OVER THE ISLAND...INCREASING FRIDAY AND CONTINUE THROUGH SUNDAY. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE LATE TONIGHT THROUGH FRIDAY AS THE TROPICAL WAVE MOVES ACROSS THE AREA. ATLANTIC OCEAN... A SHORTWAVE UPPER TROUGH COVERS PORTIONS OF THE SW N ATLC AND CONTINUES TO SUPPORT A COLD FRONT THAT ENTERS OUR AREA OF DISCUSSION NEAR 30N66W TO 28N73W WHERE IT TRANSITIONS TO A SURFACE TROUGH THAT EXTENDS TO COASTAL CENTRAL FL NEAR 28N80W. SCATTERED SHOWERS AND THUNDERSTORMS ARE AHEAD OF THE FRONT FROM 24N TO 28N BETWEEN 72W AND 78W. A SURFACE TROUGH EXTENDS FROM 28N59W TO 21N62W AND IS A NORTHERN EXTENSION OF WAVE ENERGY FROM A TROPICAL WAVE OVER THE E CARIBBEAN. MIDDLE TO UPPER LEVEL DIFFLUENCE AND THE PRESENCE OF HIGH MOISTURE SUPPORTS SCATTERED MODERATE CONVECTION FROM 18N TO 28N BETWEEN 56W AND 66W. THE REMAINDER BASIN IS MAINLY BEING INFLUENCED BY SURFACE RIDGING ANCHORED BY A 1020 MB HIGH CENTERED NEAR 26N48W. OTHERWISE...THE TAIL OF A DISSIPATING COLD FRONT EXTENDS FROM 30N29W TO 26N37W...NO CONVECTION NOTED. TWO TROPICAL WAVES ARE OVER THE TROPICAL N ATLC. PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR