000 AXNT20 KNHC 010523 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 123 AM EDT Sun Jul 1 2018 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. ...TROPICAL WAVES... A tropical wave that has emerged off the west coast of Africa extends its axis along 18W from 04N-14N. Scattered to numerous moderate convection is noted on either side of the wave's axis from 08N- 14N and E of 20W to the coast of Africa. A moisture surge in the TPW product is observed with this wave. A tropical wave has an axis extending along 37W from 03N-18N, moving W at 10-15 kt. This wave was slightly repositioned based on visible satellite imagery, model diagnostics and TPW imagery. Scattered showers are present where the wave meets the ITCZ near 06N. This wave is surrounded by dry Saharan air which is inhibiting strong convection. A tropical wave has an axis extending along 54W from 04N-19N, moving westward at around 10-15 knots. Scattered showers are present where the wave meets the ITCZ near 08N. The wave shows up well in model diagnostics guidance and TPW product. African dust surrounds this wave also. A patch of moisture with embedded showers is noted ahead of the wave approaching the Windward Islands. Tropical moisture associated with this feature will reach the waters E of the Windward Islands through the morning hours, and move across the islands today, increasing the likelihood of showers and isolated tstms. A tropical wave has an axis extending N from northeast Colombia to the Windward Passage. This wave is moving W between 10 and 15 kt and has dry Saharan dust in its environment. As a result, there is no significant convection currently associated with it. The wave will reach Central America by Sun night. Another tropical wave has an axis extending over the Yucatan Peninsula into the eastern Pacific region. This wave is slowing down and moving W at only around 5 kt. TPW satellite imagery and model diagnostics show this wave to be poorly defined. ...MONSOON TROUGH/ITCZ... The monsoon trough develops over the Atlantic Ocean near 10N19W and continues to 06N36W. The ITCZ stretches from 06N39W to 06N52W. Aside from the convection associated with the tropical waves, scattered moderate convection is observed within about 150 nm on either side of the monsoon trough between 20W-26W. Scattered showers are noted along the ITCZ. ...DISCUSSION... GULF OF MEXICO... A surface trough extends over the northeastern Gulf from a 1014 mb low near 31N85W to 28N86W. Abundant cloudiness and scattered showers are associated with the low/trough affecting mainly the waters N of 28N and E of 87W. The low and trough will move little tonight, then they will drift northwestward through the day while weakening. Scattered showers and thunderstorms will continue over much of the NE/north-central Gulf waters through at least Mon. The remainder of the basin is under the influence of a weak high pressure center of 1016 mb located over the north-central Gulf near 27N90W. This system is producing light to gentle anticyclonic flow and seas of 2-3 ft over the eastern half of the Gulf, and gentle to moderate Se to S winds and seas of 3-5 ft over the western half of the Gulf. Moderate to fresh return flow is expected over the west-central and NW Gulf through the weekend. This weak high pressure will change little through mid-week. A surface trough will emerge off the Yucatan Peninsula each evening through Wed, enhancing nocturnal winds over the SW Gulf through this period. CARIBBEAN SEA... A tropical wave is moving across the central Caribbean. Please, see the Tropical Waves section for details. Recent scatterometer data depicted fresh to strong winds across the south-central Caribbean south of 14N between 72W-78W, while moderate to fresh trades prevail across the remainder of the basin S of 18N and E of 80W. Light to gentle winds are noted over the NW Caribbean. A surface ridge will remain north and northeast of the Caribbean and Tropical N Atlantic waters through the next few days. Fresh to strong winds across the south-central Caribbean will gradually diminish through Tue before strengthening again on Wed. Convection continues to flare up over the SW Caribbean mainly in the vicinity of the monsoon trough, which is along Central America at this time. The upper-level low, currently over Cuba, will drift westward into the NW Caribbean over the weekend, and will continue to enhance convection across the basin. ATLANTIC OCEAN... Three tropical waves are moving across the waters between the coast of West Africa and the Lesser Antilles. Refer to the Tropical Wave section above for details. A surface trough is over the central Atlantic and extends from 32N48W to 29N51W. Light winds are on either side of the trough axis based on scatterometer data. This trough is a surface reflection of an upper-level low spinning near 30N50W. Scattered showers are associated with this trough. A 1033 mb surface high located NW of the Azores near 45N36W is in control of the remainder of the forecast area, extending a ridge SW across the west-central Atlantic. Moderate to fresh winds are around the southern periphery of the ridge W of 50W to the Lesser Antilles. The ridge will weaken through Tue in response to the development of broad low pressure system NE of the Bahamas. A surface trough will develop from the low pressure and move westward across the NW Bahamas Tue, and inland Florida Wed. Scattered showers and thunderstorms are expected with the trough. Otherwise, generally tranquil marine conditions are expected across the region through the middle of next week. GOES-16 RGB Geocolor showed an extensive area of African dust that extends from the west coast of Africa to the eastern Caribbean this afternoon. The Saharan dust occasionally obscures sky conditions near the Caribbean islands. The dust turns skies hazy, reducing visibility and can result in poor air quality. For additional information please visit http://www.hurricanes.gov/marine $$ ERA