000 AXNT20 KNHC 261809 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 209 PM EDT Sat Aug 26 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 1700 UTC. ...SPECIAL FEATURES... Tropical Storm Harvey is centered near 29.1N 97.6W at 26/1800 UTC or about 40 nm WNW of Victoria Texas and about 50 nm ESE of San Antonio Texas moving NNW at 2 kt. Estimated minimum central pressure is 987 mb. Maximum sustained wind speed is 60 kt with gusts to 75 kt. Numerous moderate and isolated strong convection is occurring within 60 nm of the center. Scattered moderate and strong convection is seen elsewhere in the E semicircle within 240 nm of the center. See latest Intermediate Public Advisory under AWIPS/WMO headers MIATCPAT4/WTNT34 KNHC and the full Forecast/Advisory under AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC for more details. ...TROPICAL WAVES... A tropical wave extends from 14N28W to 24N22W moving slowly W at around 5 kt. The wave coincides with amplified 700 mb troughing in initial model field wind data. Infrared satellite imagery shows a large area of Saharan dust to the N of the wave to about 30N and W of the wave to about 40W. No significant deep convection is associated with the wave at this time. A tropical wave extends from 11N45W to 17N49W to 22N49W moving W at around 10 kt. The weak low previously analyzed along the wave axis has dissipated. Initial global model guidance indicates weak 700 mb troughing in conjunction with this wave. Infrared satellite imagery shows a large area of Saharan dust to the N and E of this wave and a smaller area of Saharan dust between this wave and 60W. Scattered moderate and isolated strong convection is present within 60 nm either side of a line from 16N47W to 18N51W. A tropical wave extends from 11N93W to 20N91W moving W at 15 to 20 kt. Global model guidance shows modest 700 mb troughing in conjunction with this wave. Convection associated with this wave has diminished over the Bay of Campeche and is shifting westward with the wave into the eastern Pacific. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from 18N22W to 13N33W to 14N48W to 12N52W. The ITCZ continues from 12N52W to 10N61W. Scattered moderate convection is from 08N to 11N between 40W and 51W. ...DISCUSSION... GULF OF MEXICO... The primary concern for the Gulf of Mexico is Hurricane Harvey that has made landfall and continues impacting SE Texas with winds and very heavy rains. The ridging that has been steering Harvey has begun to break down and Harvey is slowing down. This weak steering environment is expected to remain in place for at least the next several days, so Harvey is forecast to remain over or near SE Texas during this time. The SE side of Harvey is expected to remain over water and allow Harvey to continue generating winds and very heavy rains along the Texas and Louisiana Coasts. To the east of Harvey...upper level divergence associated with the ridging supports a 1012 mb low centered NE close to Tampa Bay near 27.5N82.5W. A surface trough extends N-NE from the low to NE of Jacksonville near 31N80W and W from the low into the NW gulf S of Mobile near 28N87W. The low along with the boundaries in place and upper level divergence are generating scattered showers and strong tstms from 24.5N to 27.5N between 80W and 85W. As Harvey impacts the NW Gulf waters and coastal Texas for the next several days...the troughing and weaker low pressure across the eastern Gulf waters and Florida peninsula are expected to maintain unsettled conditions across the region as this system moves NE into the SW North Atlc waters on Sunday night or Monday. CARIBBEAN SEA... Almost all of the deep convection over the Caribbean is confined to the far SW near Panama and Costa rica in the vicinity of the monsoon trough which extends E into northern Colombia from the eastern Pacific. Much of the central and eastern Caribbean are still under dry air aloft and mostly fair conditions at the surface. However...a weak surface trough currently along 61W/62W is crossing the Lesser Antilles into the eastern Caribbean and producing isolated showers near the Virgin islands and Trinidad and Tobago. Fresh to strong winds N of Colombia and over the Gulf of Honduras are expected to subside by Monday as the high pressure ridge to the N weakens. Otherwise, moderate to fresh trades prevail and this overall synoptic pattern is expected to persist through Monday. ...HISPANIOLA... An upper-level low centered just N of the island near 21N78W could trigger isolated afternoon showers and tstms over Hispaniola during the time of maximum daytime heating and instability...along with local sea breeze effects. Otherwise...a relatively dry weather pattern is expected during the next few days. ATLANTIC OCEAN... Upper level ridging and an overall divergent upper level pattern prevails over the SW North Atlc this morning generating scattered showers and tstms N of a line from 31N71W to the coast of Florida near 26N80W. Water vapor imagery also indicates long wave upper level troughing offshore of the eastern CONUS just E of Cape Hatteras with the base of this trough near 34N. The trough supports a nearly stationary front from coastal Georgia and South Carolina near 32N81W along the northern Gulf Coast to SE Texas. An upper level low is centered near 29N48W has induced a weak surface trough from 27N55W to 31N51W. Isolated showers and tstms are occurring N of 27N between 46W and 52W. The remainder of the central and eastern Atlc remains under the influence of a surface ridge anchored by a broad 1028 mb high centered W-NW of the Azores near 40N36W. For additional information please visit http://www.hurricanes.gov/marine $$ McElroy