295
AXNT20 KNHC 181741
TWDAT
TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
141 PM EDT TUE SEP 18 2018
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.
...SPECIAL FEATURES
TROPICAL DEPRESSION JOYCE IS CENTERED NEAR 31.6N 27.4W AT 18/1500
UTC OR 385 NM S OF THE AZORES MOVING S AT 7 KT. JOYCE WILL
GRADUALLY TURN TO THE SOUTHWEST AND WEST OVER THE NEXT COUPLE OF
DAYS. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1009 MB. MAXIMUM
SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. GRADUAL
WEAKENING IS FORECAST DURING THE NEXT COUPLE DAYS, AND JOYCE IS
FORECAST TO BECOME A REMNANT LOW TOMORROW. SCATTERED MODERATE
CONVECTION IS NOTED BETWEEN 60-90 NM NORTHEAST OF THE CENTER AND
BETWEEN 45-75 NM SOUTH OF THE CENTER. SCATTEROMETER DATA SHOWS
THAT THE STRONGEST WINDS ARE LOCATED IN THE NORTHWEST SEMICIRCLE
OF JOYCE. SEE THE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO
HEADERS MIATCPAT5/WTNT35 KNHC FOR MORE DETAILS.
..TROPICAL WAVES
A TROPICAL WAVE IS APPROACHING THE LESSER ANTILLES WITH AXIS
ALONG 57W/58W FROM SURINAME TO 18N, MOVING WEST AT 20-25 KT.
MODEL GUIDANCE INDICATES THE WAVE IS ASSOCIATED WITH A 700 MB
TROUGH AND IS WELL-DEFINED ON THE TPW PRODUCT. IT IS NEAR THE
LEADING EDGE OF AN EXTENSIVE AREA OF DRY SAHARAN AIR FROM 12N-24N
BETWEEN 37W-57W. ONLY ISOLATED SHOWERS ARE NEAR THE WAVE AXIS AT
THIS TIME. MOISTURE ASSOCIATED WITH THE TROPICAL WAVE IS EXPECTED
TO MAINLY AFFECT THE WINDWARD ISLANDS LATER TODAY INTO EARLY WED.
..MONSOON TROUGH/ITCZ
THE MONSOON TROUGH AXIS EXTENDS FROM THE COAST OF GUINEA-BISSAU
NEAR 12N16W TO 10N20W. THE ITCZ EXTENDS FROM 10N20W TO 07N30W TO
NEAR THE COAST OF SURINAME. SCATTERED TO NUMEROUS MODERATE AND
ISOLATED STRONG CONVECTION IS WITHIN 300 NM SOUTH OF THE ITCZ FROM
20W-42W. SCATTERED MODERATE CONVECTION EXTENDS TO WITHIN 60 NM
SOUTH AND 300 NM NORTH OF THE ITCZ, BETWEEN 42W-50W. THE ITCZ IS
MUCH MORE CONVECTIVELY ACTIVE THAN 24 HOURS AGO, ESPECIALLY
BETWEEN 37W-43W.
..DISCUSSION
GULF OF MEXICO...
A WEAK 1015 MB SURFACE HIGH IS OVER THE WESTERN GULF NEAR 27N94W.
ANOTHER 1017 MB SURFACE HIGH IS CENTERED OVER NORTHERN FL NEAR
30N82W. LIGHT TO GENTLE BREEZES AND MINIMAL SEAS WILL CONTINUE
OVER MOST OF THE GULF DURING THE NEXT FEW DAYS. AN UPPER-LEVEL LOW
IS NEAR 26N94W WITH UPPER-LEVEL CYCLONIC FLOW COVERING THE
WESTERN GULF. A SURFACE TROUGH, ASSOCIATED WITH THE REMNANTS OF
ISAAC, IS OVER THE NORTHWEST CARIBBEAN ALONG 83W FROM WESTERN CUBA
TO NEAR CABO GRACIAS A DIOS, NICARAGUA. THE TROUGH WILL MOVE
ACROSS THE YUCATAN CHANNEL THROUGH WED, THEN ACROSS THE YUCATAN
PENINSULA INTO THE EASTERN BAY OF CAMPECHE LATE WED INTO THU.
CARIBBEAN SEA...
A TROUGH OVER THE NORTHWEST CARIBBEAN ALONG 83W FROM WESTERN CUBA
TO NEAR CABO GRACIAS A DIOS, NICARAGUA IS ASSOCIATED WITH THE
REMNANTS OF ISAAC. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM
WEST AND 120 NM EAST OF THE TROUGH AXIS FROM 17N-21N. THE TROUGH
WILL MOVE WEST OF THE AREA ON WEDNESDAY. A TROUGH OVER THE
SOUTHEAST BAHAMAS CONTINUES TO ENHANCE SOME SHOWER AND
THUNDERSTORM ACTIVITY ACROSS EASTERN CUBA, JAMAICA AND HISPANIOLA.
HIGH PRESSURE BUILDING FROM THE CENTRAL ATLANTIC INTO THE CENTRAL
BAHAMAS WILL SUPPORT MODERATE TO FRESH TRADE WINDS AND BUILDING
SEAS ACROSS THE ENTIRE BASIN LATE WED THROUGH FRI. NEAR THE COAST
OF COLOMBIA, FRESH TO STRONG WINDS ARE EXPECTED ALONG WITH 9 FT
SEAS THROUGH WED.
ATLANTIC OCEAN...
PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR DETAILS ON
TROPICAL DEPRESSION JOYCE.
AN UPPER-LEVEL LOW WITH A SURFACE REFLECTION IS SPINNING JUST
SOUTH OF BERMUDA. A SURFACE TROUGH EXTENDS FROM THIS FEATURE
SOUTHWESTWARD TO THE SOUTHEASTERN BAHAMAS. SCATTERED SHOWERS AND
THUNDERSTORMS ARE LOCATED ALONG AND EAST OF THE TROUGH AXIS WEST
OF 65W. THIS CONVECTIVE ACTIVITY IS AFFECTING THE SOUTHEAST
BAHAMAS AND THE TURKS AND CAICOS ISLANDS. ABUNDANT CLOUDINESS AND
SHOWERS EXTEND ELSEWHERE EAST OF THE TROUGH FROM 20N-31N BETWEEN
56W-65W. THE SURFACE TROUGH WILL LIKELY WEAKEN OVER THE NEXT
24-48 HOURS. ANOTHER TROUGH EXTENDS INTO THE FORECAST AREA FROM
T.D. JOYCE SOUTHWARD TO NEAR 21N32W. A NARROW BAND OF MAINLY LOW
CLOUDS WITH SHOWERS IS ASSOCIATED WITH THE TROUGH. A 1023 MB
SURFACE HIGH IS LOCATED IN BETWEEN THE TWO AFOREMENTIONED TROUGHS
NEAR 31N47W.
A TROUGH JUST INLAND OVER THE SOUTHEASTERN U.S. WILL MOVE
EASTWARD ACROSS THE WATERS EAST OF NORTH-CENTRAL FLORIDA TONIGHT
THROUGH WED NIGHT WHILE WEAKENING.
HOVEMOLLER DIAGRAMS AND SATELLITE IMAGERY INDICATE THAT A NEW
TROPICAL WAVE IS ABOUT TO MOVE OFF THE COAST OF AFRICA. THIS WAVE
WILL LIKELY BE ADDED TO THE 18Z MAP.
FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE
HAGEN/GR
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page