000 AXNT20 KNHC 280005 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 805 PM EDT Sun May 27 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 1800 UTC surface analysis and satellite imagery through 2300 UTC. ...SPECIAL FEATURES... The center of Subtropical Storm Alberto as of 27/2100 UTC, is located near 28.0N 85.2W, or about 145 nautical miles W of Tampa, FL, or about 105 nautical miles S of Apalachicola, FL. The estimated minimum central pressure is 994 mb. The maximum sustained wind speeds are 45 knots with gusts to 55 knots. Alberto is moving NNW, or 345 degrees, 10 knots. Precipitation: isolated to widely scattered moderate and isolated strong rainshowers cover the area that extends from 20N northward between 70W in the Atlantic Ocean and 90W in the Gulf of Mexico. This precipitation covers parts of the NW Caribbean Sea, Cuba and the Bahamas, Florida and the Gulf of Mexico and adjacent waters of the Atlantic Ocean. Alberto is expected to become a tropical storm during the early morning hours of Memorial Day Monday, and then move inland, in the Florida Panhandle, by Monday afternoon. Alberto will weaken after the landfall. Public Advisories about Subtropical Storm Alberto are being listed under the WMO header WTNT31 KNHC, and under the AWIPS header MIATCPAT1. The Forecast/Advisories about Subtropical Storm Alberto are being listed under the WMO header WTNT21 KNHC, and under the AWIPS header MIATCMAT1. ...TROPICAL WAVES... An Atlantic Ocean tropical wave is along 27W/28W from 13N southward, moving W 10 knots. The wave shows up well in lower level precipitable water imagery. Precipitation: isolated moderate rainshowers are from 06N southward between 25W and 30W. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal sections of Guinea near 10N14W, to 06N18W and 03N25W. The ITCZ continues from 02N31W, to the Equator along 43W, to the coastal areas of Brazil near 01S49W. Precipitation: isolated moderate to locally strong rainshowers are within 500 nm to the south of the line 09N13W 07N38W 04N51W. ...DISCUSSION... GULF OF MEXICO... Please read the Special Features section for information about Subtropical Storm Alberto, currently in the eastern Gulf of Mexico. A NW-to-SE oriented upper level trough passes through Louisiana, beyond the Yucatan Channel, into the NW corner of the Caribbean Sea. Scatterometer data has been showing fresh to strong winds over the east Gulf near Alberto, moderate to fresh winds over the central Gulf, and gentle to moderate winds over the western Gulf waters. Wave heights across the basin are ranging from 12-15 ft near Alberto's center, 5-8 ft over the central Gulf and 2-3 ft for the western Gulf waters. Expect for winds and seas to decrease following landfall on Monday. Subtropical Storm Alberto near 28.0N 85.2W 994 mb at 5 PM EDT moving NNW at 10 kt. Maximum sustained winds 45 kt gusts 55 kt. Alberto will move to 29.1N 85.7W Mon morning...inland to 30.4N 86.2W Mon afternoon...and inland to 32.2N 86.6W Tue morning. Winds and seas will start to decrease after the storm moves inland with ridging building in from the Atlantic. A strong trough will impact the southern waters Wed and Thu. CARIBBEAN SEA... Please read the Special Features section for information about Subtropical Storm Alberto, currently in the eastern Gulf of Mexico. A NW-to-SE oriented upper level trough passes through Louisiana, beyond the Yucatan Channel, into the NW corner of the Caribbean Sea. Scatterometer data has been showing moderate to fresh easterly winds across most of the basin except west of 80W, where gentle to moderate southerly winds prevail. Wave heights range between 4-6 ft across the far east and west Caribbean, while 5-7 ft seas will continue between 69W- 74W. Subtropical Storm Alberto in the eastern Gulf of Mexico will continue to move N and away from the NW Caribbean. High pressure in the central Atlantic will maintain fresh to strong trade winds in the central Caribbean through the week. The strongest winds are expected over the S central Caribbean. A strong trough will move from the NW Caribbean to the Yucatan Peninsula Wed through early Fri with associated increasing winds and seas. ATLANTIC OCEAN... Please read the Special Features section for information about Subtropical Storm Alberto, currently in the eastern Gulf of Mexico. The surface pressure gradient between Subtropical Storm Alberto and the Atlantic surface ridge may support increasing wind speeds to near gale-force in the Florida coastal and offshore waters through tonight. A surface ridge extends across the basin, from a 1024 mb high pressure center that is near 31N58W, to a 1029 mb high near 39N25W. Aside from the convection related to Alberto over the west Atlantic west of 75W, the only area with shower activity at this time is east of the Leeward Islands from 16N-19N between 54W-63W due an upper-level trough. A tight pres gradient will persist through Mon night as Subtropical Storm Alberto moves through the eastern Gulf of Mexico, while central Atlantic ridging lingers. Winds will be near gale W of 79W and strong between 77W and 79W through tonight. Conditions will improve Tue as the pres gradient slackens. A cold front or frontal trough may drop into the NE waters Wed night through Thu. For additional information please visit http://www.hurricanes.gov/marine $$ MT