000 AXNT20 KNHC 221802 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Thu Sep 22 2022 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 31N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 1200 UTC surface analysis and satellite imagery through 1740 UTC. ...SPECIAL FEATURES... The center of Major Hurricane Fiona, at 22/1800 UTC, is near 29.7N 69.8W. Fiona also is about 555 km/300 nm to the WSW of Bermuda. Fiona is moving NNE, or 025 degrees, 13 knots. The estimated minimum central pressure is 936 mb. The maximum sustained wind speeds are 115 knots with gusts to 140 knots. Hurricane force winds are within 55 nm of the center in the NE semicircle, within 60 nm of the center in the SE quadrant, within 45 nm of the center in the SW quadrant, and within 45 nm of the center in the NW quadrant. Tropical storm force winds are within 150 nm of the center in the NE quadrant, within 180 nm of the center in the SE quadrant, within 130 nm of the center in the SW quadrant, and within 150 nm of the center in the NW quadrant. The sea heights of 12 feet or greater are within 240 nm of the center in the NE quadrant, within 270 nm of the center in the SE quadrant, within 270 nm of the center in the SW quadrant, and within 240 nm of the center in the NW quadrant. The maximum sea heights are reaching 50 feet. The wind speeds in the forecast waters are ranging from 20 knots to 33 knots within 240 nm of the center, except within 360 nm of the center in the SE quadrant. The sea heights range from 8 feet to 12 feet in mixed swell from 21N northward between 64W and 80W, from the Bahamas eastward. Precipitation: numerous strong is within 200 nm of the center in the NE quadrant. Broken to overcast multilayered clouds, and scattered moderate to strong, are within 480 nm of the center in the NE quadrant. Isolated moderate to locally strong is in the remainder of the Atlantic Ocean from 20N northward from 60W westward. Please, read the latest NHC Public Advisory, at https://www.nhc.noaa.gov/text/MIATCPAT2.shtml, and the Forecast/Advisory, at https://www.nhc.noaa.gov/text/MIATCMAT2.shtml, for more details. The center of Tropical Storm Gaston, at 22/1500 UTC, is near 40.9N 33.8W. Gaston is moving ENE, or 065 degrees, 18 knots. The estimated minimum central pressure is 999 mb. The maximum sustained wind speeds are 55 knots with gusts to 65 knots. Precipitation: scattered moderate to strong is within 180 nm of the center in the NE quadrant. Please, read the latest NHC Public Advisory, at https://www.nhc.noaa.gov/text/MIATCPAT3.shtml, the Forecast/ Advisory, at https://www.nhc.noaa.gov/text/MIATCMAT3.shtml, and the High Seas Forecast at https://ocean.weather.gov/shtml/NFDHSFAT1.php, for more details. A tropical wave is along 65W in the southeastern Caribbean Sea. A 1008 mb low pressure center is near 11.5N along the tropical wave. Precipitation: scattered moderate to widely scattered strong is from 16N southward between 62W and 73W. The environment is forecast to become gradually more favorable in a couple of days, although upper level winds currently are inhibiting development. It is likely for a tropical depression to form in a couple of days. The disturbance is forecast to move west-northwestward through the eastern Caribbean Sea during the next day or two, and be in the central Caribbean Sea this weekend. It is likely for locally heavy rainfall and gusty winds to affect the Windward Islands, northern Venezuela, and the ABC island chain today. It is likely for these impacts to spread to northeastern Colombia later this evening. The chance of formation into a tropical cyclone during the next 48 hours is high. A tropical wave is along 16W near the western coast of Africa. A 1008 mb low pressure center is near 15N along the tropical wave. Precipitation: widely scattered moderate to isolated strong is from 10N to 18N between 12W and 20W. The environmental conditions are forecast to be conducive for some development. It is possible that a tropical depression may form by this weekend. The system is forecast to move northward slowly, between west Africa and the Cabo Verde Islands. The chance of formation into a tropical cyclone during the next 48 hours is medium. Please, refer to the following website, https://www.nhc.noaa.gov/gtwo.php?basin=atlc&fdays=2, for more details. ...TROPICAL WAVES... Please, read the SPECIAL FEATURES section, for information about the tropical waves. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the combination 16W tropical wave, and the 1008 mb low pressure center that is near 15N along the tropical wave, to a second 1008 mb low pressure center that is near 12N35W, to 09N38W. The ITCZ continues from 09N38W to 06N57W, to Guyana near 05N59W. Precipitation: widely scattered moderate to isolated strong is from the monsoon trough/ITCZ southward from 40W eastward. Isolated moderate is from the ITCZ to 17N between 40W and 50W. Precipitation with the 12N35W low pressure center: widely scattered moderate to isolated strong is from 08N to 16N between 30W and 40W. Some slow development of this system is possible during the next several days, despite marginal environmental conditions. The forecast is for this feature to move northwestward or northward, slowly, in the tropical Atlantic Ocean. GULF OF MEXICO... Broad surface anticyclonic wind flow is in the SE U.S.A., and in south Texas, into south central Mexico. A surface trough extends from NE Mexico, to the Yucatan Peninsula, into the NW corner of the Caribbean Sea. The GFS model for 250 mb, for 500 mb, and for 700 mb shows broad cyclonic wind flow/a trough, that covers the areas from the Yucatan Channel into the SW corner of the Gulf of Mexico. Broad upper level anticyclonic wind flow covers the northern half of the Gulf of Mexico, away from the cyclonic wind flow. Precipitation: isolated moderate to locally strong spans the entire area. Gentle to locally moderate N to NE winds are in the northern half, and in the far SW Gulf. Light to gentle winds are elsewhere. The sea heights range from 2 feet to 4 feet. A relatively weak pressure gradient in the Gulf waters will support mainly gentle to locally moderate winds and slight seas through the upcoming weekend. A weak cold front will reach the the NE waters on Fri. On Mon, wind and seas could begin to increase across the Yucatan Channel as a possible tropical cyclone approaches from the NW Caribbean. CARIBBEAN SEA... Please, read the SPECIAL FEATURES section, for more information about the 65W tropical wave, and the 1008 mb low pressure center that is along the tropical wave. The chance of development into a tropical cyclone during the next 48 hours is high. A surface trough extends from the NW Caribbean Sea, beyond the Yucatan Peninsula, to NE Mexico. Precipitation: isolated moderate is from 15N northward from 80W westward. Most of the precipitation covers the areas that are from western Honduras to Belize to the SE Yucatan Peninsula. Light to gentle variable winds, and sea heights that range from 1 foot to 3 feet, are in the remainder of the basin, from 68W westward. The monsoon trough is along 18N80W, through Honduras, and beyond El Salvador, into the eastern Pacific Ocean. Precipitation: widely scattered moderate to isolated strong is from 14N southward from 72W westward. An eastern Caribbean Sea tropical wave is near 65W. A low pressure of 1008 mb is along the wave near 11.5N65W. The environment is forecast to become gradually more favorable in a couple of days, although upper-level winds currently are inhibiting development. It is likely for a tropical depression to form in a couple of days. The disturbance is forecast to move west-northwestward through the eastern Caribbean Sea during the next day or two, and be in the central Caribbean Sea this weekend. ATLANTIC OCEAN... Please, read the SPECIAL FEATURES section, for information about Major HURRICANE FIONA. An upper level trough passes through 31N43W, to a cyclonic circulation center that is near 20N51W, to the coastal border areas of Venezuela and Guyana along 60W. Precipitation: scattered moderate to widely scattered strong is in the coastal plains and the coastal waters between 56W Suriname and 64W Venezuela. Widely scattered moderate to isolated strong is from 09N to 13N between 50W and 60W. A surface ridge extends from a 1025 mb high pressure center that is near 35N27W, through 31N43W, to 25N60W. Isolated moderate to locally strong is from 20N northward between 44W and 60W. This precipitation is downstream from a frontal boundary that is from 30N northward between 50W and 72W. The wind speeds are mainly easterly moderate, with sea heights reaching 6 feet at a maximum. The exception is fresh to locally strong N to NE winds, and the sea heights reaching 8 feet, between the Cabo Verde Islands and W Africa. Hurricane Fiona near 28.6N 70.2W 936 mb at 11 AM EDT moving NNE at 13 kt. Maximum sustained winds 115 kt gusts 140 kt. Fiona will move to 30.7N 68.8W this evening, be N of the area near 34.6N 65.2W Fri morning, 40.6N 61.8W Fri evening, become extratropical and move to 45.5N 61.2W Sat morning. Swells generated by Fiona will continue to spread northwestward across the western Atlantic Ocean toward the mid-Atlantic and northeast coasts of the United States during the next day or so. The swells will also reach Atlantic Canada on Friday. These swells are likely to cause life-threatening surf and rip current conditions. A cold front will drop south into the north waters early on Fri through Sat night, followed by fresh northeast winds and building seas. High pressure will build in behind the cold front. $$ mt/gr