000 AXNT20 KNHC 271202 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Thu May 27 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 31N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 0600 UTC surface analysis and satellite imagery through 1145 UTC. ...TROPICAL WAVES... A far eastern Atlantic tropical wave has its axis along 19W south of 12N. It is moving westward at 15 kt. Enhanced scattered moderate to isolated strong convection is within 180 nm east of the wave from 02N to 03N and also within 120 nm west west of the wave from 01N to 05N. Scattered showers and isolated thunderstorms are elsewhere east of the wave axis from 01N to 08N and east to near 11W. Other scattered showers and isolated thunderstorms are east of the wave from 01N to 05N, east to 07W. Another tropical wave has its axis along 35W from 01N to 10N. It is moving westward near 20 kt. This wave is located under a more stable upper environment that is marked by subsidence and dry sinking air found behind an upper-level trough. Scattered moderate convection within 180 nm east of this wave is confined to the ITCZ from 03N to 05N. Scattered showers and isolated thunderstorms are within 120 nm west of the wave from 03N to 05N. ...MONSOON TROUGH/ITCZ... The monsoon trough remains inland in Africa. The ITCZ is identified from just west of the tropical wave that is 19W, to 04N27W and to just east of the tropical wave that is along 35W. It continues from 05N38W to 05N46W and to the coast of French Guiana near 52W. Increasing scattered moderate to isolated strong convection is within 60 nm either side of the ITCZ between 41W-46W, and within 60 nm north of the ITCZ between 46W- 54W. Similar activity is south of the ITCZ within 30 nm of line from 02N46W to inland the coast of Brazil near 01N52W. GULF OF MEXICO... An upper-level trough stretches from the eastern U.S. southwestward to NE Gulf and continues to near 22N91W. Comparatively drier air due to subsidence aloft is apparent in water vapor satellite imagery northwest of the trough to within 120 nm offshore NE Texas. A sub-tropical jet stream branch cuts across the southernmost section of the upper-level trough. Associated strong southwest winds are advecting scattered to broken high clouds from the eastern Pacific northeastward to across the far southern Gulf. A surface ridge axis extends from a western Atlantic 1023 mb high pressure center near 30N77W westward across north-central Florida, to near 27N90W and southwestward from there to the far SW Gulf. A surface trough is just inland the Yucatan Peninsula northwestward from there to inland central Mexico. Scattered showers and a few thunderstorms are along the coast Mexico between 94W-97W. Overnight ASCAT data revealed moderate to fresh northeast to east winds are within 90 nm of the Yucatan Peninsula coast between 88W-92W. Wave heights are 5 ft or less from 20N to 22N between 91W-93W, also in the central Gulf and in the eastern Bay of Campeche. Wave heights are 2-4 ft elsewhere. As for the forecast: Gentle to moderate east to southeast winds are expected through Sat night as weak high pressure off the NE Florida coast extends westward to SE Texas and gradually weakens. Fresh northeast to east winds will pulse nightly to strong off the Yucatan Peninsula through Sat. A cold front is expected to move across the northern Gulf on Sat night into Sun, then stall across the northern Gulf Sun night. Expect moderate north to northeast winds behind the front. CARIBBEAN SEA... An upper-level low is near noted over the Atlantic near 28N65W, with an associated trough extending from it southwestward to the northeastern Caribbean. No significant deep convection is seen in satellite imagery. The monsoon trough is analyzed from Colombia near 11N74W westward to central Panama and to the border of Costa Rica and Panama near 09N83W, and well into the eastern Pacific Ocean. Scattered showers and thunderstorms are along and near the trough, mainly over Costa Rica and Panama. Debris high level cloudiness from this activity is streaming eastward over the southwestern Caribbean. Isolated showers and thunderstorms moving westward are over this same part of the Caribbean. Isolated showers moving westward with the trade wind flow are over the northeastern Caribbean. Overnight ASCAT data showed fresh to strong northeast to east winds over the central part of the Caribbean south of about 16N and between 71W-78W. Wave heights with these winds are in the 8-10 ft range. Wave heights elsewhere are in the 3-6 ft range, except for higher heights of up to 7 ft in the central Caribbean and up to 6 ft in the Windward Passage. As for the forecast: Fresh to strong trades will prevail across the central portions of the Caribbean through early today as high pressure resides offshore of the NE Florida coast. Winds will diminish significantly through early next week as the high collapses. Fresh winds are expected in the southern Gulf of Honduras and the Windward Passage tonight. ATLANTIC OCEAN An upper-level low is vividly noted near 28N65W, with a trough stretching from it to the northeastern Caribbean Sea. Comparatively drier air in subsidence is apparent in water vapor imagery from 15N to 25N between 64W-80W. One surface trough is analyzed along a position from 31N64W to 27N67W. A second trough is analyzed along 65W from just northeast of Puerto Rico north to near 28N65W. Yet a third trough extends from near 31N52W to 23N55W. A very moist and unstable atmospheric environment around the upper-level low along with upper diffluence is supporting increasing numerous showers and thunderstorms from 24N to 30N between 59W- 64W. Lightning data indicates frequent strikes with this activity. A ridge axis extends from a 1024 mb high pressure center that is near 33N68W, to a 1023 mb high pressure near 30N78W and to across north-central Florida and to the north-central Gulf of Mexico. Overnight ASCAT data indicated fresh to strong northeast winds over the tropical Atlantic waters from 06N to 12N between 45W-53W. Wave heights in the range of 8-10 ft are roughly within about 500 nm to the north of the ITCZ between 40W-57W. As for the forecast: Light winds will prevail north of 24N through today as weak low pressure just east of Bermuda interrupts the Atlantic ridge. Moderate to locally fresh winds will continue across the Bahamas and Greater Antilles through early today. Winds will become gentle to moderate today through Sun as the Atlantic ridge extends from the east-central Atlantic weakly WSW to Florida. Fri night, moderate to fresh southerly winds will develop off the NE Florida coast ahead of a cold front forecast to emerge off the southeastern CONUS early Sun. The cold front will move across northern Florida on Sun before stalling Sun night. $$ Aguirre