000 AXNT20 KNHC 020605 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 205 AM EDT Sat Sep 2 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 0000 UTC surface analysis and satellite imagery through 0545 UTC. ...SPECIAL FEATURES... Hurricane Irma is centered near 19.1N 40.5W at 02/0300 UTC or about 1220 nm E of the Leeward Islands moving W at 12 kt. Estimated minimum central pressure is 967 mb. Maximum sustained wind speed is 100 kt with gusts to 130 kt. Numerous moderate convection is within from 17N to 20N between 39W and 42W. Scattered moderate is elsewhere from 17N to 21N between 37W and 45W. Irma is expected to remain a powerful hurricane through the weekend. Interests in the northern Leeward Islands should monitor the progress of this system. See the latest NHC Forecast/Advisory under AWIPS/WMO headers MIATCMAT1/WTNT21 KNHC for more details. ...TROPICAL WAVES... A tropical wave is in the E Atlc just W of the Cape Verde Islands. Its axis extends from 15N28W to 07N26W, moving W at 15 kt. The wave is in a region of low vertical wind shear and is underneath middle level diffluent flow. Enhanced IR imagery show some Saharan dry air and dust NE of the wave axis, however the CIRA LPW show abundant low level moisture in the wave environment, which is supporting scattered moderate convection and tstms from 05N to 14N between 26W and 32W. A tropical wave is in the central Atlc, just E of the Lesser Antilles. The wave axis extends from 21N56W to 10N56W, moving W at 5 kt. Even though the wave is in a region of low vertical wind shear, water vapor imagery show dry air subsidence at the middle to upper levels while the CIRA LPW imagery show patches of dry air in the wave environment. No deep convection is observed at this time. A tropical wave is moving across Belize, Honduras, San Salvador into EPAC waters. Its axis extends from 19N87W to 10N88W, moving W at 15 kt. The wave is in a region of moderate vertical wind shear, however abundant moisture in its environment along with upper level diffluence support scattered heavy shower and tstms W of 81W, including the Yucatan Channel. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 13N16W to 12N20W to 06N28W. Scattered to isolated showers are from 05N to 11N between 14W and 20W. Otherwise, see tropical waves section. ...DISCUSSION... GULF OF MEXICO... Water vapor imagery indicates a middle to upper level trough extending from over the Ohio River valley and southern Mississippi River valley to a base over the Bay of Campeche. The troughing supports a stationary front extending across SW Georgia, SE Alabama to 28N88W. South of the upper trough base, a ridge over the Yucatan Peninsula extending over the far NW Caribbean generate diffluence aloft, which is supporting scattered heavy showers and tstms in the SE Gulf S of 28N E of 88W. Diffluence aloft also support scattered showers in the E Bay of Campeche where a surface trough extends from 22N88W to 16N91W. Isolated showers are elsewhere in the SW Gulf. Otherwise, a surface ridge extends across the Florida Peninsula into the central basin, being anchored by a 1017 mb high near 27N87W. This is providing with mostly light anticyclonic flow to the northern half of the Gulf. Moderate NE flow is off the Yucatan Peninsula associated with the surface trough. CARIBBEAN SEA... A tropical wave is moving across northern Central America into the EPAC waters. This wave is underneath upper level diffluent flow that along with abundant moisture in the NW Caribbean waters support scattered heavy showers and tstms W of 81W. Most of this activity is expected to move west of the area by Saturday night. Water vapor imagery show dry air aloft in the remainder basin, which is supporting fair weather conditions. Otherwise, moderate to fresh trades are basin-wide, except for strong winds in the south-central basin along the coast of Colombia. An approaching tropical wave currently with axis along 57W will impact the Lesser Antilles on Saturday with increase cloudiness and a greater chance for isolated showers and tstms. Looking beyond this weekend, Hurricane Irma looms across the central tropical Atlc and is forecast to approach 60W Tuesday night into Wednesday. ...HISPANIOLA... Water vapor imagery show dry air aloft, which continue to support fair weather and clear skies across the island. The overall dry weather pattern is expected to persist through late Saturday. However, a tropical wave will approach the Island early Sunday morning and is forecast to bring scattered to isolated showers to the Island. ATLANTIC OCEAN... Hurricane Irma remains the main concern in the basin. See special features for further details. A middle to upper level trough is progressing over the mid-Atlc and SE CONUS regions and generates divergece aloft across the far western SW North Atlc waters. This environment aloft supports scattered heavy showers and tstms generally N of 25N W of 77W, including interior portions of Florida. Farther east, an upper level low supports a stationary front extending from 30N55W SW to 24N65W. Otherwise, surface ridging prevails elsewhere N of 22N. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos