000 AXNT20 KNHC 141215 TWDAT Tropical Weather Discussion...Updated NWS National Hurricane Center Miami FL 1205 UTC Tue Sep 14 2021 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 31N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Updated 1215 UTC for Special Features... Based on 0600 UTC surface analysis and satellite imagery through 1120 UTC. ...SPECIAL FEATURES... At 14/1200 UTC, Tropical Storm Nicholas is inland over Texas near 29.5N 95.5W, or about 15 nm SSW of Houston, moving NNE at 7 kt. Estimated minimum central pressure is 999 mb. Maximum sustained wind speed is 50 kt with gusts to 60 kt. Peak seas in the NW Gulf are 22 ft as of 14/0600 UTC. Numerous moderate and isolated strong convection is noted within 180 nm NE and 120 nm in the SE quadrant. Scattered moderate convection is noted along an outer band further southeast from the center north of 25N extending W of 90W to Matamoros, Mexico. On the forecast track, the storm should move more slowly to the northeast later today and then eastward by Wednesday over Louisiana. Little motion is anticipated on Thursday. Nicholas should weaken further today and is forecast to become a tropical depression by Wednesday morning. Nicholas is expected to produce heavy rain and flooding from the upper Texas coastal areas across central to southern Louisiana into Wednesday. Please read the latest High Sea Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest Nicholas NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. A tropical wave located just west of the African coast is producing a large area of showers and thunderstorms that are showing signs of organization. The tropical wave axis is along 18W with a 1008 mb low pressure near 12N18W. A large cluster of moderate to strong convection covers the area from 04N-17N between 15W-23W. Environmental conditions are conducive for a tropical depression to form during the next couple of days while the system moves generally westward at 15 kt across the eastern tropical Atlantic. This system has a high chance of tropical cyclone formation within 48 hours. Please, see the latest Tropical Weather Outlook at www.hurricanes.gov for more details. ...TROPICAL WAVES... A tropical wave is in the Atlantic Ocean along 38W from 1N southward, moving W at around 15 kt. Scattered moderate convection is noted on either side of the wave axis from 09N-14N between 37W-41W. A tropical wave over the Caribbean Sea with its axis along 62W. Scattered showers with embedded thunderstorms are seen ahead of the wave axis over the eastern Caribbean, particularly from 14N-18N between 60W-67W. The wave combined with an upper-level low spinning over Hispaniola will support showers and thunderstorms over the U.S. Virgin Islands, Puerto Rico and Hispaniola tonight and Wed. Another tropical wave is in the Caribbean Sea along 77W, and extends from eastern Cuba to northern Colombia. Isolated to scattered moderate convection is observed near the wave axis but mainly over northern Colombia, and near Cabo Cruz, Cuba. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from 12N16W to 10N30W to 07N43W. The ITCZ continues from 07N43W to the coast of Guyana near 06N58W. Scattered moderate convection is seen south of Sierra Leone and Liberia, and from 03N-09N between 21W-29W. ...GULF OF MEXICO... Attention remains focused on Tropical Storm Nicholas. Refer to the Special Features section above for more details. Outside of Nicholas, scatterometer data provide observations of gentle to moderate E-SE winds over the eastern half of the Gulf region, and over the SW Gulf. Seas are 3-5 in the eastern Gulf and 4-6 ft over the SW Gulf based on an altimeter pass. Fresh to strong winds in the outer periphery of Nicholas dominates the NW Gulf with seas of 8-12 ft. For the forecast, an area of fresh to strong winds will persist today over the NW Gulf between Nicholas and high pressure over the SE United States. A ridge will build westward across the Gulf waters in the wake of Nicholas producing mainly light to moderate SE to S winds. ...CARIBBEAN SEA... A pair of tropical waves are moving westward across the Caribbean Sea. Please see the Tropical Waves section for more information. Satellite derived wind data show mainly gentle to moderate trade winds across much of the basin. Moderate to locally fresh winds are noted in the Windward passage, Gulf of Honduras and near the coast of Colombia. Seas are generally 2-4 ft. For the forecast, gentle to moderate trades will prevail across the basin today and Wed. By Wed night, moderate to fresh winds will return in the Gulf of Honduras and the south-central Caribbean. This pattern will continue through the remainder of the forecast period. ...ATLANTIC OCEAN... High pressure dominates the Atlantic forecast waters with a 1021 mb high center W of Bermuda near 33N70W. Another high pressure center of 1023 mb is located near 33N41W. A trough, reflection of an upper-level is analyzed from 27N68W to 20N70W. Scattered moderate convection is noted on either side of the trough covering the waters from 20N-30N between 65W-70W. Based on streamlines analysis and scatterometer data another trough is W of the Cabo Verde islands and runs from 21N27W to 12N30W. A 1011 mb low is along the trough axis. Mainly low clouds are associated with these features. A stationary front cross the Canary Islands where northerly winds have been reported. Recent altimeter pass indicates seas 3 to 5 ft near the Canary Islands and north of 20N E of 55W. For the forecast west of 65W, an area of low pressure is expected to form by midweek a couple of hundred miles north of the southeastern or central Bahamas as a tropical wave interacts with an upper-level trough. Some gradual development of this system is possible thereafter, and a tropical depression could form later this week while the system moves north-northwestward or northward across the western Atlantic. For the forecast east of 65W, see the Special Features section for more details on the tropical wave located over the far eastern tropical Atlantic. $$ Hagen/Torres