387
AXNT20 KNHC 171747
TWDAT
TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
147 PM EDT MON SEP 17 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 CENTERED NEAR 34.0N 28.4W AT 17/1500
UTC OR 250 NM SSW OF THE AZORES MOVING ESE AT 7 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1008 MB. MAXIMUM SUSTAINED WIND
SPEED IS 30 KT WITH GUSTS TO 40 KT. LATEST SATELLITE IMAGERY
SHOWS THAT JOYCE IS A SHEARED SYSTEM UNDER STRONG WESTERN VERTICAL
SHEAR. SCATTERED MODERATE CONVECTION IS WITHIN 150 NM OF THE NE
QUADRANT. JOYCE IS FORECAST TO TURN TOWARD THE SOUTHEAST TODAY,
TURN SOUTH ON TUESDAY, AND THEN SOUTHWEST ON WEDNESDAY. SOME
WEAKENING IS FORECAST DURING THE NEXT 48 HOURS AND JOYCE IS
EXPECTED TO BECOME A REMNANT LOW TUESDAY. 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 46W FROM 02N-18N,
MOVING WESTWARD AT 15-20 KT. MODEL GUIDANCE INDICATES THAT THE
WAVE IS ASSOCIATED WITH A 700 MB TROUGH. THE WAVE MARKS THE
LEADING EDGE OF AN EXTENSIVE AREA OF DRY SAHARAN AIR WITH DUST
FROM 10N-25N BETWEEN 15W-45W. SCATTERED MODERATE CONVECTION IS
OVER THE SOUTHERN PORTION OF THE WAVE NEAR THE ITCZ FROM 05N- 10N
BETWEEN 38W-50W.
..MONSOON TROUGH/ITCZ
THE MONSOON TROUGH AXIS EXTENDS FROM W AFRICA NEAR 17N16W TO
09N20W. THE ITCZ EXTENDS FROM 09N20W TO 06N30W TO 07N44W. THE ITCZ
RESUMES W OF A TROPICAL WAVE NEAR 08N48W TO THE COAST OF SOUTH
AMERICA NEAR 08N60W. ASIDE FROM THE CONVECTION MENTIONED WITH THE
TROPICAL WAVE, WIDELY SCATTERED MODERATE CONVECTION IS FROM 07N-
12N BETWEEN 50W-60W.
..DISCUSSION
GULF OF MEXICO...
IN THE UPPER-LEVELS, A LOW IS OVER THE WESTERN GULF NEAR 25N94W,
AND A HIGH IS CENTERED OVER N FLORIDA NEAR 30N81W. UPPER LEVEL
MOISTURE IS OVER MOST OF THE GULF PRODUCING SCATTERED HIGH CLOUDS.
AT THE SURFACE, A 1016 MB HIGH IS OVER THE NW GULF NEAR 27N93W.
5-10 KT ANTICYCLONIC WINDS ARE OVER THE NW GULF. 05-10 KT SE TO S
WINDS ARE OVER THE REMAINDER OF THE GULF. THE REMNANTS OF
TROPICAL CYCLONE ISAAC, CURRENTLY NEAR JAMAICA, WILL MOVE WEST
ACROSS YUCATAN CHANNEL ON WED AND ACROSS THE SOUTHWEST GULF WATERS
ON THU.
CARIBBEAN SEA...
A WEAK AREA OF LOW PRESSURE, ASSOCIATED WITH HE REMNANTS OF
ISAAC, IS LOCATED JUST SOUTH OF JAMAICA. SHOWERS AND
THUNDERSTORMS ARE CURRENTLY LIMITED, AND ANY DEVELOPMENT SHOULD BE
SLOW TO OCCUR DURING THE NEXT DAY OR SO. BY WEDNESDAY,
ENVIRONMENTAL CONDITIONS ARE FORECAST TO BECOME LESS CONDUCIVE FOR
RE-DEVELOPMENT TO OCCUR WHEN THE SYSTEM MOVES TOWARD THE YUCATAN
PENINSULA. REGARDLESS OF DEVELOPMENT, LOCALLY HEAVY RAINS AND
GUSTY WINDS ARE POSSIBLE OVER PORTIONS OF HISPANIOLA, JAMAICA, AND
EASTERN CUBA DURING THE NEXT COUPLE OF DAYS AS THE SYSTEM MOVES
ACROSS THE NORTHWESTERN CARIBBEAN SEA. THE LATEST TROPICAL WEATHER
OUTLOOK GIVES THE SYSTEM A LOW CHANCE OF TROPICAL CYCLONE
DEVELOPMENT THROUGH THE NEXT 48 HOURS. GENTLE TRADES ARE WEST OF
THE ISAAC REMNANTS, WHILE GENTLE TO MODERATE TRADES ARE OVER THE
REMAINDER OF THE CENTRAL AND EASTERN CARIBBEAN. AN UPPER LEVEL
TROUGH NORTH OF HISPANIOLA IS ALSO ENHANCING CONVECTIVE ACTIVITY
OVER HISPANIOLA AND PUERTO RICO. THE TROPICAL WAVE CURRENTLY ALONG
46W IS EXPECTED TO ENTER THE CARIBBEAN SEA ON WED, ACCOMPANIED BY
FRESH TRADES AND BUILDING SEAS.
ATLANTIC OCEAN...
PLEASE REFER TO THE SPECIAL FEATURES SECTION ABOVE, FOR DETAILS
ON TROPICAL DEPRESSION JOYCE. ALSO REFER TO THE TROPICAL WAVE
SECTION FOR A WAVE ALONG 46W.
A BROAD DEEP LAYER TROUGH EXTENDS SW TO NE ACROSS THE CENTRAL
ATLANTIC FROM A LARGE UPPER-LEVEL LOW CENTERED NEAR 27N65W. THE
UPPER-LEVEL LOW WILL MOVE NORTHWARD OVER THE NEXT COUPLE OF DAYS.
AT THE SURFACE, A 1013 MB LOW IS NEAR 25N66W WITH A TROUGH
EXTENDING SOUTHWEST TO NEAR HISPANIOLA AT 29N59W. THE SYSTEM IS
PRODUCING SCATTERED SHOWERS AND THUNDERSTORMS EAST OF THE TROUGH
AXIS BETWEEN 20N-30W AND WEST OF 50W. WELL EAST OF THE TROUGH, A
1024 MB HIGH IS CENTERED NEAR 28N39W. THE SURFACE TROUGH AND LOW
ARE FORECAST TO WEAKEN OVER THE NEXT 24 TO 48 HOURS AS A RIDGE
BUILDS WESTWARD.
FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE
FORMOSA/HAGEN
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