140
AXNT20 KNHC 181202
TWDAT
TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
742 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.
...SPECIAL FEATURES
TROPICAL DEPRESSION JOYCE CENTERED NEAR 32.9N 27.6W AT 18/0900
UTC OR 310 NM S OF THE AZORES MOVING SSE AT 5 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1008 MB. MAXIMUM SUSTAINED WIND
SPEED IS 30 KT WITH GUSTS TO 40 KT. JOYCE REMAINS AN ORGANIZED
LOW LEVEL CIRCULATION UNDER STRONG WESTERLY VERTICAL SHEAR, WITH
MINIMAL DEEP CONVECTION. A TURN TOWARD THE SOUTH IS FORECAST
LATER TODAY, FOLLOWED BY A MOTION TOWARD THE SOUTHWEST ON
WEDNESDAY AND THURSDAY. GRADUAL WEAKENING IS EXPECTED DURING THE
NEXT COUPLE OF DAYS, AND JOYCE IS FORECAST TO BECOME A REMNANT LOW
LATER TODAY OR TONIGHT. 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 56W 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 12N-25N BETWEEN 35W-55W.
SCATTERED SHOWERS ARE WITHIN 90 NM OF THE WAVE AXIS.
..MONSOON TROUGH/ITCZ
THE MONSOON TROUGH AXIS EXTENDS FROM W AFRICA NEAR 14N17W TO
10N20W. THE ITCZ EXTENDS FROM 10N20W TO 07N30W TO 06N56W.
SCATTERED MODERATE TO STRONG CONVECTION IS FROM 03N-09N BETWEEN
20W-40W, AND FROM 05N-12N BETWEEN 40W-51W.
..DISCUSSION
GULF OF MEXICO...
AN UPPER LEVEL LOW IS OVER THE WESTERN GULF NEAR 26N94W. A 1015 MB
SURFACE HIGH IS OVER THE NW GULF NEAR 27N94W. ANOTHER 1015 MB HIGH
IS OVER THE NE GULF NEAR 28N84W. LIGHT ANTICYCLONIC WINDS PREVAIL
OVER THE TWO SURFACE HIGHS. 10-15 KT 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, FROM 16N-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 56W 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 56W.
A BROAD DEEP LAYER TROUGH EXTENDS ACROSS THE CENTRAL ATLANTIC
FROM A LARGE UPPER-LEVEL LOW CENTERED NEAR 28N62W. 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
FORMOSA
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