372
AXNT20 KNHC 180545
TWDAT
TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0500 UTC.
...SPECIAL FEATURES
TROPICAL DEPRESSION JOYCE WAS CENTERED NORTH OF THE AREA NEAR
33.2N 27.3W AT 0300 UTC OR 285 NM S OF THE AZORES, MOVING SSE AT
6 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB. MAXIMUM
SUSTAINED WINDS ARE 30 KT WITH GUSTS TO 40 KT. JOYCE REMAINS AN
ORGANIZED LOW LEVEL CIRCULATION UNDER STRONG WESTERLY VERTICAL
SHEAR, WITH MINIMAL DEEP CONVECTION. IT IS EXPECTED TO DRIFT
SOUTHWARD AND GRADUALLY WEAKEN THROUGH WEDNESDAY. SEE THE LATEST
NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT5/WTNT35
KNHC FOR MORE DETAILS.
..TROPICAL WAVES
A CENTRAL ATLANTIC TROPICAL WAVE IS ALONG 54W FROM 03N-18N,
MOVING WEST AT 20 KT. MODEL GUIDANCE INDICATES THE WAVE IS
ASSOCIATED WITH A 700 MB TROUGH. IT IS NEAR THE LEADING EDGE OF
AN EXTENSIVE AREA OF DRY SAHARAN AIR FROM BETWEEN 20W-50W.
SCATTERED MODERATE CONVECTION IS FROM 09N-13N BETWEEN 50W-56W.
..MONSOON TROUGH/ITCZ
THE MONSOON TROUGH AXIS EXTENDS FROM W AFRICA NEAR 14N17W TO
10N21W. THE ITCZ EXTENDS FROM 10N21W TO 07N31W TO 08N54W. WIDELY
SCATTERED MODERATE CONVECTION IS FROM 07N-12N BETWEEN 38W-50W,
AND FROM 02N TO 06N BETWEEN 25W-35W.
..DISCUSSION
GULF OF MEXICO...
AN UPPER LEVEL LOW IS OVER THE WESTERN GULF NEAR 25N94W. A WEAK
SURFACE HIGH IS OVER THE NW GULF NEAR 27N94W. LIGHT ANTICYCLONIC
WINDS PREVAIL OVER THE NW GULF. 10-15 KT NE TO E WINDS ARE OVER
THE REMAINDER OF THE GULF. A SURFACE TROUGH SOUTH OF CUBA, THE
REMNANTS OF ISAAC, WILL MOVE WEST INTO THE SW GULF ON WEDNESDAY.
CARIBBEAN SEA...
THE REMNANTS OF ISAAC, LOCATED SOUTH OF CUBA, HAVE WEAKENED TO A
SURFACE TROUGH. SHOWERS ASSOCIATED WITH THE DISTURBANCE ARE
MAINLY EAST OF THE TROUGH AXIS, FROM16N-21N BETWEEN 74W-81W.
ENVIRONMENTAL CONDITIONS ARE NOT CONDUCIVE FOR RE-DEVELOPMENT TO
OCCUR. GENTLE TRADES ARE WEST OF THE TROUGH AXIS, WHILE GENTLE
TO MODERATE TRADES ARE OVER THE REST OF THE CENTRAL AND EASTERN
CARIBBEAN. A TROPICAL WAVE ALONG 54W IS EXPECTED TO REACH THE
AREA WEDNESDAY, ACCOMPANIED BY FRESH TRADES AND BUILDING SEAS.
ATLANTIC OCEAN...
PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR DETAILS ON
TROPICAL DEPRESSION JOYCE. ALSO REFER TO THE TROPICAL WAVE
SECTION FOR A WAVE ALONG 54W.
A BROAD DEEP LAYER TROUGH EXTENDS ACROSS THE CENTRAL ATLANTIC
FROM A LARGE UPPER-LEVEL LOW CENTERED NEAR 28N65W. A SURFACE
TROUGH EXTENDS NE FROM THE TURKS AND CAICOS TO 31N61W. THIS
SYSTEM IS PRODUCING SCATTERED SHOWERS AND THUNDERSTORMS MAINLY
SE OF THE TROUGH AXIS FROM 21N-26N BETWEEN 60W-68W. BROAD HIGH
PRESSURE IS CENTERED NEAR 30N45W. THE SURFACE TROUGH WILL LIKELY
WEAKEN OVER THE NEXT 24-48 HOURS AS THE HIGH BUILDS WESTWARD.
FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE
MUNDELL
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