000 AXNT20 KNHC 202323 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Sun Feb 21 2021 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... Caribbean Gale Warning: The combination of strong high pressure building north of the area and the typical low pressure found over northern Colombia will support gale force northeast to east winds near the coast of Colombia beginning on Sun night and continuing through the middle of the upcoming week. Wave heights with these are expected to be in the 7-10 ft. Please read the latest NWS high seas forecast issued at the National Hurricane Center at website: https://www.nhc.noaa.gov/text/MIAHSFAT.shtml for more details. ...MONSOON TROUGH/ITCZ... The monsoon trough axis passes through the coastal sections of Sierra Leone near 08N13W to 07N17W, where latest scatterometer data indicates that it transitions to the ITCZ to 02N30W and to below the equator at 01S44W. Scattered moderate to isolated strong convection is within 180 nm south of the ITCZ between 20W- 26W, and within 60 nm north of the ITCZ between 22W-29W. Scattered moderate convection is within 120 nm north of the ITCZ between 30W-36W, and also well south of the ITCZ within 30 nm of line from 02S25W to 01S29W. GULF OF MEXICO... A 1030 mb high pressure center is analyzed over extreme southwestern Louisiana, while a 1032 mb high is analyzed over southwestern Alabama. Associated strong high pressure has build over the entire basin in the wake of the recent cold front that is presently stationary over the northwestern Caribbean Sea. Latest ASCAT data passes show moderate to fresh northeast winds over the eastern Gulf, and mainly moderate northeast to east winds gentle over the central Gulf. Buoy observations in the western Gulf are reporting moderate to fresh southeast winds there. Wave heights are in the range of 5-7 ft in the eastern Gulf, except for up to 8 ft near the Yucatan Channel and 4-6 ft elsewhere. The present high pressure is controlling the wind regime throughout and keeping the atmosphere stable as dry air has advected over the Gulf behind the cold front. Only scattered to broken low clouds are noted south about 29N. A pocket of overcast low clouds is identified to be in the Bay of Campeche, where scattered showers are possible. As for the forecast: The high pressure area will shift eastward to the Atlantic Ocean on Mon in response to the next cold front to approach the area. This front is forecast to move over the NW Gulf early Mon morning. It will move across the rest of the Gulf through Tue night. Scattered showers and a few thunderstorms may be possible with this front. Beyond the forecast time frame, yet a third cold front may reach the NW Gulf by early on Thu. CARIBBEAN SEA... Please see the Special Features section above for details on a Gale Warning for pulsing gale-force winds off the coast of Colombia. A stationary front extends from west-central Cuba to the Gulf of Honduras at 16N86W. Latest ASCAT data revealed strong to near gale-force northwest winds west of the front and south of 19N to the Gulf of Honduras. Wave heights there are in the range of 6-8 ft. Elsewhere west of the front, the ASCAT pass along with recent buoy data indicate fresh northerly winds over those waters along with wave heights of 7-10 ft in a north swell. Fresh to strong trade winds are noted over the south-central Caribbean elsewhere outside the vicinity of the Colombia, where strong northeast to east winds are present when not pulsing to gale force at night as mentioned above. Wave heights with these winds are in the range of 6-9 ft, but will be lightly higher at night. Moderate trade winds are noted elsewhere over the eastern Caribbean. Patches of low-level moisture, in the form of broken to scattered shallow low-level clouds, are moving quickly westward in the trade wind flow over the areas north of 12N east of 70W, and north of 14N west of 70W. Isolated to scattered showers may be possible with some of these clouds. As for the forecast: The stationary front will weaken tonight and dissipate by Sun evening. High pressure north of the area building in the wake of the front will support fresh to strong northeast winds east of 80W into Mon. ATLANTIC OCEAN... A cold front extends from near 32N66W southwestward to the central Bahamas and to west-central Cuba. Buoy observations over the western Atlantic are reporting fresh to strong north to northeast winds west of the front, except for strong northwest winds between the front and 70W. Wave heights resulting from these winds are in the range of 7-10 ft, but are slightly lower west of 70W. A few ship observations in the area are reporting similar wind speeds like that from the buoys. Latest ASCAT data showed moderate to fresh south to southwest winds ahead of the front north of 26N, with wave heights of 6-8 ft. Latest GOES-16 satellite imagery depicts overcast to broken low and mid-level clouds within 50-60 nm either side of the front. Scattered showers are possible underneath these clouds. Cold-air stratocumulus clouds are observed elsewhere to the northwest of the front suggestive of cold air advection that is filtering in over the northwest part of the area behind the cold front. Available partial ASCAT data passes suggested that an eastern Atlantic anticyclone is located at 27N42W. It was analyzed with a pressure of 1023 mb at 18Z. A ridge axis stretched from it west- southwestward to the central Bahamas. Another ridge axis extends from the anticyclone east- southeastward to just inland the coast of Western Sahara, Africa near 23N15W. The latest ASCAT data confirmed that there are mainly fresh northeast to east trade winds south of the ridge axis between 33W and the Lesser Antilles. Gentle to moderate east to southeast winds are seen in the ASCAT data from 20N-25N between 30W-76W, and gentle to moderate north-northeast winds are over the far eastern Atlantic from 16N-22N between 20W-30W. Light and variable winds are in the vicinity of the 1026 mb anticyclone. Wave heights elsewhere east and southeast of the aforementioned cold front are in the range of 5-7 ft due to mainly an east-southeast swell. Over the far eastern Atlantic, a cold front extends from near 32N14W southwestward to the western part of the Canary Islands and to 24N32W. Fresh northwest to north winds as captured by morning ASCAT pass to be present north of this, while fresh to strong southwest winds were seen in the same ASCAT pass to be present east of the front north of 27N. Altimeter data passes from during the day reveal wave heights in the range of 10-15 ft due to a northwest to north swell east of a line from 32N49W to 24N35W. This swell is forecast to begin to decay through early Sun allowing for these large wave heights to subside to around 8-12 ft through late Sun. As with the forecast regarding the western Atlantic cold front: It will move southeastward across the open Atlantic Ocean tonight through Sun night, then begin to weaken and become stationary along roughly 23N across the central Bahamas through Mon night. High pressure in the wake of the front will support fresh to strong northeast to east winds across the western Atlantic tonight through Mon morning. The next cold front will move off the northeast Florida coast Mon night and reach from Bermuda to the Straits of Florida by mid-week. Strong to gale force southwest winds and building wave heights are expected ahead of the front north of 29N early Tue and through and Tue night. $$ Aguirre