000 AXNT20 KNHC 210521 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 121 AM EDT Fri Apr 21 2017 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 0515 UTC. ...SPECIAL FEATURES... The center of T.S. Arlene is located 39.4N 44.2W and is moving northwest at 24 knots. The estimated minimum central pressure is 993 mb. The maximum sustained wind speeds is 45 knots with gusts to 55 knots. Scattered moderate convection is observed from 37N- 41N between 32W-47W. Please refer to the public advisory under the WMO header WTNT31 KNHC and under the AWIPS header MIATCPAT1 for more details. A tight pressure gradient generated between a broad low pressure system centered southwest of T.S. Arlene and a high pressure to the west will support gale-force winds north of 30N between 49W-54W starting on 04/21 at 0600 UTC and continuing through the evening hours. Please see the latest High Seas Forecast product under the WMO header FZNT02 KNHC and under the AWIPS header MIAHSFAT2 for further details. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends across the western Africa coast from 07N12W to 03N19W. The Intertropical Convergence Zone continues from 03N19W to the coast of Brazil near 02S43W. Isolated showers prevail from 04N-04S between 08W-35W. ...DISCUSSION... GULF OF MEXICO... A mid to upper-level low is centered northwest of the Yucatan Peninsula near 23N91W. A diffluent flow aloft prevails to the east of the low supporting scattered light to moderate convection from 20N-27N between 80W-90W. A surface trough accompanies this convection, extending from the western Caribbean across the Yucatan Channel to 24N84W. A surface ridge extends across the basin anchored by a 1022 mb high centered over the west Atlantic. Scatterometer data depicts gentle to moderate easterly winds across the northern half of the basin while moderate to fresh easterlies prevail south of 26N. Expect for the upper-level low to dissipate in 24 hours. The surface trough is forecast to become a center of low pressure this weekend over the southeast Gulf. The low will move over northeast Gulf waters where it will dissipate by Sunday. CARIBBEAN SEA... The main feature in the basin is a surface trough that extends from 24N84W to 16N87W. This elongated area of low pressure is located under a broad area of mid to upper-level diffluent flow that along with abundant moisture in the region supports scattered to numerous mainly north of 20N west of 79W. This shower activity will continue overnight as the trough moves slowly west towards the Yucatan Peninsula. Latest scatterometer data depict fresh to locally strong easterly winds in the vicinity of the trough. An area of fresh trades extends across the central Caribbean north of 14N, including the Windward Passage. Moderate trades dominate elsewhere. ...HISPANIOLA... Broken to overcast skies persist across the island with possible isolated showers over the adjacent waters. These conditions are expected to continue during the next two days. ATLANTIC OCEAN... T.S. Arlene is over central Atlantic waters north of the area. See the Special Features section above for further details. A surface ridge extends across the western Atlantic anchored by a 1022 mb high centered near 33N70W. To the east, a cold front enters the area from 31N42W to 24N46W to 23N54W then dissipates to 23N59W. A surface trough, previously part of the front, extends from 24N62W to 28N75W. No convection is associated with these boundaries. A surface ridge dominates the remainder of the area, anchored by a 1017 mb high centered near 24N24W. T.S. Arlene is forecast to dissipate in 24 hours. An area of gale-force winds will develop today over the central Atlantic. Please refer to the section above for details. For additional information please visit http://www.hurricanes.gov/marine $$ ERA