000 AXNT20 KNHC 210002 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 805 PM EDT Wed May 20 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 66W from 10N-21N is moving westward at 15 kt. Latest visible imagery suggest a weak signature in the low-level cloud pattern associated with this wave. Only isolated showers are along and near the wave at the present time. The wave axis is about 300 nm west of an area of scattered showers and isolated thunderstorms that lies to the east of the Leeward Islands from 10N to 15N and between 55W-60W. This activity is mainly attributed to a sharp upper-level trough in that vicinity. Expect for low-level moisture and resultant scattered showers to move across most of the Lesser Antilles through Thu. ...MONSOON TROUGH/ITCZ... The monsoon trough axis passes through Guinea near 10N14W and continues to 05N23W, where latest scatterometer data indicates it transitions to the ITCZ and continues to 04N31W to 05N42W and to the coast of Brazil at 04N52W. Scattered moderate convection is seen within 120 nm north of the ITCZ between 23W-28W and between 33W-39W. Similar activity is within 60 nm north of the ITCZ between 39W-42W. GULF OF MEXICO... Weak high pressure is across the basin. A stationary front is analyzed over the western Florida panhandle extending to near Gulfport, Mississippi. This front, with the aid of upper-level support from an upper trough, is serving as the focus for numerous showers and thunderstorms over most of the Florida panhandle and adjacent coastal waters. Some of this activity has reached the strong to severe range. To the southeast, a surface trough extends from southeastern Florida to just west of the lower Florida Keys as of 21 UTC. Scattered showers and thunderstorms are noted to the southeast of this trough over lower Straits of Florida. This activity is moving to the northeast and is capable of producing strong gusty winds. Another surface trough is analyzed from just northwest of the Yucatan Peninsula southwest from there to just inland the coast at 18N92W. The trough is no producing convection at the present time. As for the forecast, the high pressure will dominate much of the Gulf waters through Sun, with the associated gradient producing an east to southeast mainly moderate wind flow. A surface trough will develop over the Yucatan Peninsula during the evening hours, drift westward across the SW Gulf at night, and dissipate in the morning. Fresh to locally strong winds will be associated with this trough. The aforementioned stationary front over the Florida panhandle will lift back to the north as a warm front on Thu. CARIBBEAN SEA... Refer to the tropical waves section above for details on the tropical wave currently moving across the eastern Caribbean. Broad upper-level cyclonic wind flow, related to the Atlantic to Yucatan Peninsula trough, continues to cover the far northwest part of the Caribbean. Scattered showers and thunderstorms moving eastward are observed from 10N-15N and west of 77W to inland the coast of central America. This activity is being aided by upper-level divergence present over that part of the Caribbean. Isolated showers are seen over the northwest Caribbean. Broad upper-level anticyclonic wind flow covers the remainder of the basin, mainly to the east of 83W. Scatterometer data depicts gentle to moderate trade winds across the basin, except south of 14N between 66W-73W and near the Gulf of Honduras, where moderate to fresh trade winds are noted. As for the forecast, little change to be expected with the trade winds, except over the Gulf of Honduras where they will increase to strong speeds Fri and Fri night. The aforementioned tropical wave will move across the rest of the eastern Caribbean through Thu and over the eastern half of the central Caribbean Thu night and Fri. ATLANTIC OCEAN... Upper-level diffluence related to the eastern part of an upper- level trough over the western Atlantic in combination with a surface trough that extends from near 29N75W southwestward to southeastern Florida, is helping to sustain scattered showers and thunderstorms south of about 30N and between 65W and the 78W and also south of 25N from 78W to the Straits of Florida. This activity is quickly moving to the east, except in the Straits of Florida where it is moving to the northeast. A cold front extends from a triple point at 34N63W southwestward to 31N71W, where it becomes a stationary front to 31N75W and northwestward from there to inland the South Carolina coast at 33N80W. Isolated showers are possible along the cold front, while scattered showers and thunderstorms are quickly tracking northeastward just to the north of the stationary front west of 75W. Otherwise, surface high pressure, anchored by a 1022 mb high center at 27N33W and a 1023 mb high center at 31N23W, covers the remainder of the discussion Atlantic waters. As for the forecast, former Tropical Cyclone Arthur located north of the area near 34N65W will track south-southeastward over the discussion area on Thu and weaken. Large long-period northeast swell from former Arthur will affect the waters northeast of the Bahamas through Fri, then subside Fri night and Sat. The surface trough that extends from near 29N75W to southeastern Florida will weaken through Thu. High pressure will build modestly across the northern waters Fri through Sat night. $$ Aguirre