000 AXNT20 KNHC 062359 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 759 PM EDT Wed Sep 6 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 1800 UTC surface analysis and satellite imagery through 2300 UTC. ...SPECIAL FEATURES... The center of Hurricane Irma, at 07/0000 UTC is near 18.8N 65.4W, or about 30 nm NW of St. Thomas, and about 45 nm ENE of San Juan Puerto Rico. Irma is moving WNW or 295 degrees, at 14 knots. The estimated minimum central pressure is 914 mb. The maximum sustained wind speeds remain 160 kt with gusts to 195 kt. Irma is the strongest hurricane to be in the Atlantic basin outside of the Caribbean Sea and the Gulf of Mexico. Irma has a well defined eye about 25 NM in diameter. Numerous moderate and scattered strong convection is observed in the eastern semicircle within 150 nm and in the western semicircle within 90 nm. Scattered moderate and isolated strong convection is seen elsewhere in the eastern semicircle within 240 nm and in the western semicircle within 150 nm. Please read the latest NHC Intermediate Public Advisory under AWIPS/WMO headers MIATCPAT1/WTNT31 KNHC and, the Forecast/ Advisory under AWIPS/WMO headers MIATCMAT1/WTNT21 KNHC for more details. The center of newly upgraded Hurricane Jose, at 07/2100 UTC is near 13.9N 45.8W, or about 905 NM E of the Lesser Antilles. Jose is moving WNW, 285 degrees, at 15 knots. The estimated minimum central pressure is 994 mb. The maximum sustained wind speeds are now 65 kt with gusts to 80 kt. Numerous moderate and isolated strong convection is present within 60 nm of the center and within 30 nm of 12.5N47.5W. Scattered moderate convection is present elsewhere from 12N to 17N between 44W and 48W. Please read the latest Forecast/Advisory under AWIPS/WMO headers MIATCMAT2/WTNT22 KNHC for more details. The center of newly upgraded Hurricane Katia, at 07/0000 UTC, is in the SW Gulf of Mexico near 21.7N 94.9W, or about 170 nm E of Tampico, Mexico, moving SE or 135 degrees, at 3 knots. The estimated minimum central pressure is 992 mb. The maximum sustained wind speeds are 65 kt with gusts to 80 kt. Numerous moderate and scattered strong convection is found within 30 nm of the center. Scattered moderate and isolated strong convection is taking place elsewhere from 20N to 24N between 90W and 98W. Please read the latest NHC Forecast/Advisory under AWIPS/WMO headers MIATCMAT3/WTNT23 KNHC for more details. ...TROPICAL WAVES... A tropical wave is off the coast of W Africa. Its axis extends from 15N27W to low pres 1012 mb centered near 08N28W to 03N28W, moving W around 15 kt. SSMI TPW imagery shows the wave is embedded in an area of deep layer moisture. The wave is also coincides with well defined troughing at 700 mb. Moderate convection is present from 04N to 06N between 31W and 34W and from 10N to 12N between 32W and 34W. A tropical wave over the western Caribbean has an axis extending from near the western tip of Cuba at 23N84W to just SW of Costa Rica near 09N84W, moving W around 15 kt. TPW satellite imagery indicates this wave has limited moisture to work with, probably as a result of interaction with an upper-level low centered near 15N81W. The wave is collocated with modest troughing at 700 mb in initial model wind fields. There is no significant convection currently associated with this wave. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from Mauritania on the African coast near 19N16W to 17N20W to low pres 1012 mb near 08N28W to 06N32W. Aside from the convection associated with the Atlantic tropical wave, widely scattered moderate convection is present from 05N to 07N between 17W and 21W. ...DISCUSSION... GULF OF MEXICO... Newly upgraded Hurricane Katia is drifting SE over the SW Gulf of Mexico. See the special features section above. Farther N, a cold front extends SW from the Florida Panhandle near 30N85W to 28N91W. Scattered moderate convection is seen along and up to 150 nm SE of the front. In the upper levels, an upper level trough touches the northern Gulf coast from Louisiana to the Florida Panhandle. Otherwise, high pressure dominates the Gulf. Upper level divergence SE of the trough is enhancing diurnal convection Florida and the NE Gulf. Expect Katia to intensify gradually and slowly meander over the SW Gulf for the next two to three days. Also expect increased convection over S Florida and the Straits of Florida over the next 24 hours. CARIBBEAN SEA... Hurricane Irma remains a formidable major hurricane just to the ENE of San Juan Puerto Rico. See Above. A tropical wave is also over the W Caribbean. See above. In addition, the eastern portion of the E Pacific monsoon trough traverses Costa Rica and Panama and intersects the tropical wave. Convection associated with the tropical wave is confined to latitudes over or south of Panama and Costa Rica. In the upper levels, an upper-level trough crosses the Caribbean from eastern Honduras to eastern Cuba. Winds converging in the vicinity of the trough are inhibiting convection over virtually all of the basin. ...HISPANIOLA... Cloudiness and convection associated with Hurricane Irma is rapidly approaching with Hurricane warnings already in effect for N Hispaniola. The core of Irma is expected to miss Hispaniola, but expect windy and rainy weather to affect the island through Friday morning. See Special Features for more details. ATLANTIC OCEAN... Major Hurricane Irma and Hurricane Jose are both over the Atlantic. A tropical wave is also passing over the eastern Atlantic. See above. Scattered moderate and isolated strong convection is occurring over the W Atlantic N of 30N between 69W and 73W due to the cold front approaching the coastlines of Georgia and South Carolina. A 1033 mb high is centered over the eastern Atlantic just N of the Azores near 42N26W. A slightly weaker 1031 mb high is centered over the central Atlantic near 39N46W. The enhanced pressure gradient between ridging on the south side of these highs and low pressure associated with Irma and Jose is generating fresh to locally strong trades from 15N to 23N between 35W and 55W and from 18N to 26N between 55W and 65W. For additional information please visit http://www.hurricanes.gov/marine $$ McElroy