000 AXNT20 KNHC 221737 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 137 PM EDT Mon May 22 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 1200 UTC surface analysis and satellite imagery through 1715 UTC. ...TROPICAL WAVES... The tropical wave that came off the west African coast yesterday now extends from 12N18W to 05N19W. Scattered moderate convection is where the wave meets the ITCZ/Monsoon trough, mainly from 04N-08N between 17W-23W. The TPW animation shows a decent surge of moisture near the wave axis. A weak tropical wave extends from 12N36W to 05N37W, moving west at 10-15 kt. Based on current SAL analysis from UW-CIMSS, african dust surrounds the wave. As a result, only a few showers are noted near the wave axis. A tropical wave is moving across the Caribbean Sea. Its axis extends from eastern Dominican Republic to near Aruba in the ABC Islands, moving west at around 15 kt. Convection is limited in association with this wave. The TPW animation shows a modest surge of moisture near the wave axis. ...ITCZ/MONSOON TROUGH... The Monsoon Trough enters the tropical Atlantic through Sierra Leone near 08N13W and continues to 07N18W. The ITCZ extends from 07N22W to 06N34W, then resumes west of a tropical wave to the coast of Guyana. Outside the convection associated with the tropical wave located near 18W/19W, scattered moderate convection is from 07N-09N W of 50W. Gusty winds to 30 Kt are noted within this area of convection. ...DISCUSSION... GULF OF MEXICO... Mosaic Doppler Radar from the SE U.S. shows numerous showers with embedded tstms along the coast of Texas and the NW Gulf as well as over eastern Texas and much of Louisiana. All this convective activity is associated with a stationary frontal boundary and a weak 1012 mb low pressure located over southern Texas. This front will be the focus for heavy rain and local floodings from the Texas Gulf coast to Alabama coast today. These weather conditions are forecast to extend to the Florida Panhandle on Tuesday. Again, areas of fog were observed over the NW Gulf under the influence of a moist and warm SE wind flow. The remainder of the Gulf is under the influence of a weak ridge, anchored by a 1022 mb located over the western Atlantic. The pressure gradient between the ridge and the frontal boundary is resulting in gentle to moderate E-SE winds over the eastern Gulf and moderate to fresh SE winds across the western Gulf, with higher gusts near the tstms. The ridge is forecast to shift southward through early Wednesday as the weak frontal boundary remains along the Northern Gulf Coast while weakening. A late season cold front will enter the NW Gulf early Wednesday followed by fresh northerly winds. CARIBBEAN SEA... Convection has significantly diminished over the SW Caribbean and now scattered moderate convection is mainly noted along the coast of Nicaragua and NE Honduras. Similar convection is south of 10N and east of 80W where the monsoon trough remains. Upper-level diffluence is helping to induce this convective activity, that is forecast to persist over the SW Caribbean and southern Central America for the next several days. A tropical wave is moving across the basin. Please refer to the TROPICAL WAVE section above for details. High pressure located over the western Atlantic near 29N66W combined with the Colombian/Panamanian low is supporting fresh to locally strong trade winds over the south-central Caribbean and the Gulf of Venezuela. These winds are expected to expand across the eastern and central Caribbean on Wednesday as pressure builds again north of the area. Patches of low level moisture, embedded in the trade wind flow, are observed elsewhere across the region. The Saharan Air Layer from UW-CIMSS and visible satellite imagery reveal the presence of african dust over the eastern Caribbean, including the Leeward Islands, Puerto Rico and the Virgin Islands. Some of the islands continue to report haze and dust, reducing somewhat the visibility. ...HISPANIOLA... Daytime heating, local sea breezes and mountain upslope lifting will combine with available moisture to produce scattered showers and isolated thunderstorms mainly during the afternoon and early evening hours during the next two days. A tropical wave moving across the island today and tonight could enhance the shower activity. ...ATLANTIC OCEAN... High pressure prevails across most of the Atlantic Ocean. As previously mentioned, a 1022 mb high is over the western Atlantic near 29N66W while another high pressure center of 1023 mb is near 28N31W. In between, a surface trough remains and extends from 27N52W to 24N61W to 20N63W. Scatterometer data continue to support the presence of this trough. Convection has diminished in association with this feature since yesterday. This trough is a reflection of an upper-level trough forecast to move eastward. The high pressure over the western Atlantic will slide eastward through mid-week as a cold front approaches from the west. For additional information please visit http://www.hurricanes.gov/marine $$ GR