000 AXNT20 KNHC 212353 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 805 PM EDT Thu May 21 2020 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 2345 UTC. ...TROPICAL WAVES... A tropical wave with axis along 72W and south of 20N is moving westward at about 15 knots. The surface reflection of this wave has become rather ill-defined per latest satellite imagery, but is noticeable at 700 mb as suggested in model diagnostics. Only isolated showers moving quickly westward are noted north of 15N and east of the wave to 69W. ...MONSOON TROUGH/ITCZ... The monsoon trough axis passes through the coastal sections of Sierra Leone near 08N13W to 06N20W, latest scatterometer data indicates it transitions to the ITCZ and continues to 04N30W and to the coast of Brazil near 01S45W. Scattered moderate to isolate strong convection is within 180 nm s of the trough and east of 17W to inland the coast of Africa near 09W. Scattered moderate convection is seen within 60 nm south of the ITCZ between 21W-26W, within 60 nm north of the ITCZ between 30W-32W and also between 43W-45W. Gulf of MEXICO... A mid to upper-level shortwave trough has moved offshore over the far western Gulf. Numerous thunderstorms moving quickly eastward have rapidly during the past few hours from 22N-26N and west of 95W to inland the coast of Mexico. This activity contains frequent lightning and possible strong gusty winds. A stationary front is analyzed from just inland South Carolina and northern Georgia southwestward to over the far northern Florida panhandle and northwestward from there to inland central Alabama, where it becomes a warm front. This frontal boundary continues to serve as a focus for scattered shower and thunderstorm activity as presently NWS composite doppler radar imagery shows scattered showers thunderstorms along and near this boundary, mainly over southeastern Georgia and northeastern Florida. The activity elsewhere along and near the boundary is less in coverage. Otherwise, rather weak high pressure extends from the Atlantic across the area. The associated gradient is allowing for generally moderate to fresh east-southeast winds across the Gulf along with wave heights in the range of 3-6 ft, except for lower heights of 2-4 ft in the NE Gulf. These conditions are forecast to change little into early next week. CARIBBEAN SEA... A tropical wave is now over the central Caribbean. See section above for details. Scattered showers and thunderstorms, embedded in rain areas, are concentrated over the western Caribbean waters from 11N to 20N and between 77W-83W. This activity is being sustained by a sharp mid to upper-level trough that extends from the southeastern Gulf of Mexico southeastward to just west of the western tip of Cuba and to Panama. The gradient between western Atlantic high pressure and the shower and thunderstorm activity is strong enough to allow for an area of strong east-southeast winds to exist from along the northeastern coast of Honduras northward to 19N and between 81W-85W. These winds are expected to diminish to mainly fresh speeds tonight as the shower and thunderstorms decrease some in intensity. A dry slot is noted in the wake of the trough from along the coast of Honduras northward to 20N. This dry is gradually intruding into the aforementioned shower and thunderstorm activity. An outflow boundary, consisting of scattered to numerous thunderstorms, is racing northwestward away from the shower and thunderstorm activity. It extends from just south of western Cuba to just east of the northeast tip of the Yucatan Peninsula. Strong gusty winds and rough seas may be possible with the thunderstorms along this feature. A 1008 mb low that is along the eastern edge of the Pacific monsoon trough is centered over northwestern Colombia near 10N75W. The gradient elsewhere across the Caribbean is supporting fresh to occasionally strong trade winds in the the south-central part of the sea and gentle to moderate trade winds elsewhere, except for fresh trade winds over the remainder of the central Caribbean. These winds will change little into early next week. Fresh to strong trade winds will pulse at night in the Gulf of Honduras through Sat. The tropical wave currently along 72W will continue to weaken as it move across the rest of the central Caribbean through Fri evening and into the western Caribbean Sat. ATLANTIC OCEAN... Broad upper-level troughing is present north of 30N between 51W- 64W. At the surface, a stationary front stretches from well northeast of the area southwestward to 32N45W where it transitions to a warm front to a 1014 mb low at 30N51W. Another stationary front extends from the low southwestward to 27N42W to 26N72W and northward from there to 30N75W, where it becomes a warm front to a 1015 mb low over northern South Carolina. Strong northeast to east winds along with wave heights in the range of 10-12 ft are north of the stationary front and low. Isolated showers and thunderstorms are seen between the stationary front and a line from 32N40W to 23N56W and to 20N70W. More active weather in the form of scattered showers and thunderstorms are noted south of 25N and between 70W and 80W, including most interior sections of Cuba. This activity is being enhanced by a mid to upper-level shortwave trough that extends from the eastern Gulf of Mexico to western Cuba. It is advancing eastward. Scattered showers and thunderstorms are just north of 30N and between 76W-80W due to a mid to upper-level shortwave trough rotating eastern through the southeastern periphery of slow moving upper-level low that is over the Ohio Valley. Otherwise, high pressure anchored by a 1024 mb high center at 29N27W and a 1025 mb high center at 33N20W, covers the remainder of the discussion Atlantic waters. As for the forecast, the 1014 mb low along the stationary front will drift southeastward and weaken through Fri. The strong northeast to east winds and wave heights to 12 ft north of the front and low will decrease Sat. Large long-period northeast swell derived from the low will propagate through the waters northeast of the Bahamas through Fri night, then subside Sat. Modest high pressure will build across the northern waters Fri through Sat night. A weak cold front may move off the SE U.S. coast Sun. $$ Aguirre