000 AXNT20 KNHC 202344 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 744 PM EDT THU OCT 20 2016 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 2330 UTC. ...SPECIAL FEATURES... An elongated area of low pressure is located near 25.5N/73.0W. Although visible satellite imagery and surface observations suggest that the low-level circulation has become a little better defined since yesterday, preliminary reports from a NOAA reconnaissance aircraft indicate that the system does not have a well-defined center. Isolated showers prevail near the low center while scattered moderate convection is observed from 15N-30N between 61W-75W supported by a diffluent flow aloft. Scatterometer data depicts near gale winds prevailing within 150 nm in the northwest quadrant. The system could still become a subtropical or tropical cyclone before it merges with a cold front over the western Atlantic, well offshore of the United States east coast by Friday night. The chance of formation into a tropical cyclone remains in the medium category. Gale force winds are expected to develop in the southwest Gulf of Mexico Friday night associated with a cold front that will enter the northwest waters by early Friday morning. Northwest to north gale force winds are forecast for the area S of 22N and west of the front with seas to 12 ft. Please see the High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...TROPICAL WAVES... An Atlantic tropical wave extends its axis from 16N43W to 06N43W, moving westward 10 to 15 knots. The wave coincides with a 700 mb trough depicted by model guidance and abundant moisture is in the wave's environment as noted in TPW imagery. Scattered moderate convection prevails from 07N-13N between 39W-48W. ...ITCZ/MONSOON TROUGH... The Monsoon Trough passes through the coast of Africa reaching the eastern Atlantic near 14N17W to 08N27W to 10N40W. Aside of the convection related to the tropical wave, isolated showers prevail within 100 nm on either side of the boundary between 34W-39W. ...DISCUSSION... GULF OF MEXICO... A diffluent flow aloft prevails across the northwest Gulf supporting scattered moderate convection mainly north of 24N and west of 94W. At the surface, a trough extends from 27N96W to 29N95W. Another trough extends across the Bay of Campeche from 25N97W to 18N94W. No significant convection is observed with this feature at this time. Fair weather prevails across the remainder of the basin with light to gentle easterly winds as noted in scatterometer data. Expect during the next 24 hours for a cold front to enter the northwestern portion of the basin enhancing convection/winds. Gale force winds are expected over the Bay of Campeche behind the cold front. CARIBBEAN SEA... A 1008 mb surface low is centered over the southwest Caribbean near 15N83W. A surface trough extends from the low to 18N77W. Scattered moderate convection is observed near the low center from 14N-17N and west of 80W. To the east; a diffluent flow aloft related to the Special Features low described above, is enhancing convection across the northeastern waters affecting Hispaniola, the Mona Passage, and adjacent waters north of 15N between 67W- 75W. Scatterometer data depicts light to gentle easterly winds across the western half of the basin while moderate to fresh southeasterly winds prevail east of 75W. Expect during the next 24 hours for the low in the southwest Caribbean to dissipate. The convection over Hispaniola will weaken and drift northward as the surface low in the Atlantic moves northeast. ...HISPANIOLA... Please refer to the Special Features section for more information about an Atlantic Ocean's surface low pressure related to the convection currently affecting the island. This activity will weaken and drift northward during the next 24 hours as the surface low in the Atlantic moves northeast. ATLANTIC OCEAN... The 1004 mb surface low located in the west Atlantic is described in the Special Features section above. A tropical wave is moving across the eastern Atlantic waters. Please refer to the section above for details. A surface trough extends across the central Atlantic ahead of a cold front from 27N47W to 29N39W. No significant convection is related to this trough at this time. For additional information please visit http://www.hurricanes.gov/marine $$ ERA