000 AXNT20 KNHC 042349 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 805 PM Tue Aug 04 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. ...SPECIAL FEATURES... Tropical Storm Isaias was located by NOAA Doppler weather radars and surface observations near 42.7N 74.2W at 04/2100 UTC, or about 20 miles west of Albany New York City moving quickly NNE at 35 kt. The estimated minimum central pressure is 995 mb. Maximum sustained winds are near 55 kt (65 mph) with higher gust. The NOAA Doppler weather radars along with surface observations and satellite imagery indicate that widespread areas of rain with embedded squalls and thunderstorms is racing across New England and is now between eastern New York to the western part of Maine, with a trailing line of squalls and strong thunderstorms reaching the coastal waters from southwestern Maine to across Cape Cod and southward from there to over the Atlantic waters to near 39N71W. A 20 nm wide line of scattered showers and thunderstorms extends from 42N69W to 40N70W. The present motion of Isaias is expected through tonight. On the current forecast track, the center of Isaias will continue to move farther inland over eastern New York and Vermont this evening, and over southern Canada tonight. Gradual weakening is expected this evening, followed by a faster rate of weakening tonight. Isaias is forecast to become post-tropical tonight or early on Wed. Please read the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPAT4.shtml and Forecast/Advisory at https://www.nhc.noaa.gov/text/MIATCMAT4.shtml for more details. ...TROPICAL WAVES... A far eastern Atlantic tropical wave has its axis along 25W from 02N-18N, moving westward at 10-15 kt. The wave is embedded within deep tropical moisture south of 13N as observed on satellite imagery and in the total precipitable water (TPW) imagery animation. Satellite imagery reveals convection that consists of the scattered moderate to isolated strong type intensity from 08N to 12N between 21W-24W. Scattered moderate convection is along the wave axis within 60 nm of 10N25W and within 30 nm of 08N25W. A mid-level cyclonic circulation is apparent in satellite imagery to be east of the wave axis near 11N20W and may be helping to enhance convection that is behind the wave and south of the monsoon trough. An eastern Atlantic tropical wave has its axis along 37W from 02N-18N, moving westward at 10-15 kt. This wave is embedded within deep tropical moisture south of 16N as noted in the the total precipitable water (TPW) imagery animation. Scattered showers and thunderstorms are within 120 nm east of the wave from 06N to 09N and within 120 nm west of the wave from 06N to 07N. Isolated showers and thunderstorms are within 30 nm of a line from 11N33W to 11N37W. A central Atlantic tropical wave has its axis along 49W from 01N to 17N, moving westward at 15-20 kt. Last GOES-16 visible imagery shows what appears to be an inverted-V shape pattern to the low- level clouds across the wave axis. The total precipitable water (TPW) imagery animation suggests this as well with the moisture. Scattered showers and thunderstorms are within 60 nm either side of the wave from 10N-13N. Isolated showers and thunderstorms are ahead of the wave from 09N to 12N between 51W-55W. A western Caribbean tropical wave has its axis along 79W and south of 19N to just south of Panama. It is moving westward around 15 kt. Scattered showers and thunderstorms are near the northern part of the wave from western Jamaica west to 81W and from 17N to 19N. Isolated showers and thunderstorms are elsewhere west of the wave north of 13N. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends from the coast Mauritania, Africa near 19N16W southwestward to 10N26W and to 08N35W to near 08N47W. The ITCZ extends west of a tropical wave from 08N51W to inland South America at 08N60W. The W African monsoon trough segment that extends out over the far eastern Atlantic has become energized somewhat as the tropical wave along 25W passes through it. Aside from convection associated with the tropical waves, scattered moderate to isolated strong convection is within 240 nm south of the monsoon trough between the coast of Africa and 21W. Scattered moderate convection is within 60 nm north of the ITCZ between 51W-54W. GULF OF MEXICO... Relatively weak high pressure remains across the basin, anchored by a 1016 mb high center near 25N91W as of 2100 UTC. Latest ASCAT data depicted light to gentle anticyclonic winds across the basin, with rather low seas in the range of 2-4 ft. Isolated showers and thunderstorms are confined mainly to the the Bay of Campeche and far SE Gulf waters. Scattered moderate to isolated strong convection is increasing just inland the coast of Mexico between 90W-95W. Isolated showers and thunderstorms are just inland the coast of Mexico from Tuxpan to just north of Tampico. As for the forecast, light to gentle variable wind will dominate the basin N of 22N through most of the period as a weak surface ridge prevails in the region. Otherwise, moderate to fresh northeast to east winds are expected at night in the eastern half of the Bay of Campeche and along the Yucatan peninsula associated with the nocturnal surface trough. CARIBBEAN SEA... Refer to the section above for details on the tropical wave over the western part of the basin. Scattered moderate to strong convection is over most Honduras and over the central and western sections of Nicaragua. Similar activity that is being enhanced by the eastern Pacific monsoon trough is over Panama. Scattered showers and thunderstorms are seen south of 13N and west of 76W. Mostly dry and stable conditions are over the eastern and central sections of the basin, with just quick westward moving isolated showers noted. A pretty light gradient is over the basin as was verified by an afternoon ASCAT pass that depicted gentle to moderate trades across the basin except south of 15N between 64W-75W, where fresh to strong easterly winds are present and are expected to change little through the rest of the week. As for the forecast, the Bermuda High pressure north of the area along with the eastward extension of the eastern Pacific monsoon trough to Colombia will support fresh to strong trades in the central basin extending to the southwestern Caribbean Wed night and continuing through the weekend. Simultaneously, moderate to fresh winds are expected in the Gulf of Honduras during this period as well as in the eastern Caribbean. ATLANTIC OCEAN Refer to the sections above for details on Tropical Storm Isaias and the tropical waves moving across the basin. A 1015 mb low is near 32N50W, with a stationary front extending to 30N57W and to northwestward to near 32N65W. Only isolated showers are near the low and front. A surface trough extends from near 30N65W to 26N75W. Isolated showers and isolated weak thunderstorms are north of 28N between 65W-69W. Another trough that trails from Tropical Storm Isaias, enters the area at 32N79W and continues to along the coast of South Florida to near Fort Lauderdale. Isolated showers and thunderstorms near and east of this trough from 26N to 32N between the trough and 75W. Scattered showers and thunderstorms are quite active over the interior of central Florida as very deep moisture in southwesterly flow contributes to the development of this activity. An eastern Atlantic trough extends along a position from near 30N39W to 20N40W. No convection is noted with the trough. Surface ridging extends from a 1022 mb high over the far northeastern Atlantic near 33N28W southwestward to the south of the aforementioned stationary front. As for the forecast, weak low pressure will develop over the NE offshore waters tonight and shift to the north-central waters by Fri before dissipating over the weekend. Otherwise, moderate to locally fresh east to southeast winds are expected across the Great Bahama Bank and north of Hispaniola through the weekend. Strong east winds are likely north of Hispaniola at night. $$ Aguirre