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TROPICAL WEATHER DISCUSSION
Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Thu Apr 25 2024 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 1030 UTC.
SPECIAL FEATURES East Atlantic Gale Warning: Low pressure of 1008 mb is centered near 22N37W moving south-southwest. A tight pressure gradient between the low and strong high pressure to the north has induced near gale to gale-force winds of 30-35 kt within about 90 nm of the low in the NW and N quadrants. An ASCAT pass from Wed evening revealed these winds. Seas with these winds are 10 to 13 ft. As the low pressure continues to move south-southwestward early this morning, it will undergo weakening and the culprit tight pressure gradient will relax enough to allow for the gale-force winds to diminish to just below gale force. Seas will remain at 10-13 ft in the NW and N quadrants of the low. The seas will begin to slowly subside later in the morning and into the afternoon. Please read the latest High Seas Forecast issued by the National Hurricane Center at https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details. Heavy Rainfall In Hispaniola: A persistent surface trough extends from near 31N51W southwestward to 25N56W and to 19N64W. To its west, a stationary front extends from 31N60W to 24N66W and to 20N74W. The combination of a moist and unstable environment between these two features and the additional ingredient of a very moist southwest to west flow aloft is favorable for the development of numerous showers and strong thunderstorms over and near Hispaniola this afternoon and early evening. This activity is capable of producing heavy downpours, increasing the chance for flash flooding, especially in hilly terrains and low-lying areas. Please refer to local weather service offices for more details on this event. MONSOON TROUGH/ITCZ The monsoon trough axis passes through the coastal border of Sierra Leone and Liberia southwestward to 02N16W and to the Equator at 20W, where latest scatterometer data indicates the ITCZ begins and continues along the Equator to 30W and to 38W. Scattered moderate to isolated strong convection is seen from 01N to 06N between 20W-25W, and within 60 nm west-southwest of the ITCZ between 37W-39W. Scattered moderate convection is within 60 nm south of the ITCZ between 30W-34W, and within 60 nm of 02N46W. GULF OF MEXICO A 1021 mb high pressure center is analyzed over the NE Gulf near 29N87W. A ridge extends from the high westward to central Texas coast, with associated anticyclonic flow covering the entire basin. An inland Mexico surface trough curves through the Yucatan Peninsula, to the Isthmus of Tehuantepec of southern Mexico, northwestward. Both partial ASCAT data and buoy observations indicate light to gentle winds over the NE Gulf and gentle to moderate winds elsewhere, except for slightly higher winds of fresh speeds over the western Gulf and central Bay of Campeche. Seas are in the 3 to 5 ft range, except for slighter higher seas of 4 to 6 ft over the NW Gulf and west-central Gulf sections. For the forecast, the high pressure of 1021 mb centered over the NE Gulf near 29N87W will maintain light to gentle winds over that part of the Gulf today, and for moderate to fresh southeast winds over most of the western part of the Gulf. The pressure gradient will tighten over the Gulf beginning tonight resulting in increasing east to southeast fresh to strong winds over just about the entire basin through Sun night. Seas will build to 10 ft in the NW Gulf on Sun. Meanwhile, winds will pulse to fresh to strong speeds near the Yucatan Peninsula each evening through the period. CARIBBEAN SEA Please read the Special Features section for details about the potential for heavy rainfall in Hispaniola. Western Atlantic high pressure extends south over the northwestern part of the Caribbean. The pressure gradient between the high pressure and relatively lower pressure in the southern section of the basin is allowing for fresh to strong winds to exist in the south-central Caribbean to along the coast of Colombia and in the Gulf of Venezuela. Fresh northeast winds are in the lee of Cuba, in the Windward Passage and just south of the Dominican Republic. A surface trough extends from the central Atlantic southward to Puerto Rico and to near 16N67W. Isolated showers are possible near the trough. Moderate to fresh trade winds are elsewhere over the basin, except for fresh winds from 11N to 15N between 76W and 80W, south of 15N east of 72W and in the Windward Passage. Seas are in the 4 to 6 ft range, except for slightly lower seas of 3 to 5 ft north of 15N west of 64W and in the Gulf of Honduras. Isolated showers are possible over the central Caribbean. For the forecast, high pressure north of the Greater Antilles is sustaining moderate to fresh trade winds, except for fresh to strong winds in the Windward Passage and in the south-central Caribbean. The gradient associated to the high pressure will maintain fresh to strong winds just north of Colombia, through the Windward Passage, and in the lee of Cuba through this morning. Looking ahead, strengthening of the high pressure beginning late Fri will also force fresh to strong trade winds in the Gulf of Honduras, lee of Cuba, Windward Passage and just south of Hispaniola through early next week. ATLANTIC OCEAN Please read the Special Features section for details about the potential for heavy rainfall in Hispaniola, and for details on soon to end gale-force winds related to low pressure in the eastern Atlantic. A stationary front is analyzed from 31N60W to 24N66W and to near eastern Cuba. A trough extends from just south of the front at 26N63W south to across Puerto Rico. A 1022 mb high center is just southwest of Bermuda near 32N66W. Latest ASCAT data shows moderate to fresh northeast winds south of 24N between 70W and 77W. Fresh northeast winds are in the Windward Passage. The ASCAT data also reveals mainly gentle to moderate winds elsewhere west of 55W, except for light to gentle winds north of 27N and west of the frontal boundary. Satellite imagery shows an area of scattered showers and isolated thunderstorms near the stationary front and northern part of the trough from 25N to 28N between 60W and the front. Small isolated showers and thunderstorms are seen south of about 24N between the trough and 70W. In the eastern Atlantic, a rather large surface trough is east of the Special Features low along a position from near 25N26W southwestward to 17N33W, to 13N38W and to near 10N47W. No significant convection is occurring with this trough, however, an area of increasing numerous showers and thunderstorms is to its northwest from 25N to 31N between 27W and 33W. This activity is due to a rather robust upper trough that extends from an upper- level cyclonic circulation near 30N31W southeastward to 27N30W and southwestward to near 21N34W. Aside from conditions associated directly with the Special Features low, relatively weak high pressure is present over the eastern and central Atlantic. Stronger high pressure ridging is just north of the area. A broad area of fresh to strong northeast to east winds is noted north of 22N and east of 50W. Strong to near gale force northeast winds are closer to the low. An overnight ASCAT pass captured some of these winds. Seas with these winds are in the 9 to 13 ft range. Moderate or weaker winds easterly winds are over the remainder of the basin along with generally moderate seas. For the forecast W of 55W, the aforementioned stationary front is forecast to weaken to a trough by this evening. A cold front is forecast to merge with the trough and progress eastward, reaching from near 31N57W to eastern Cuba early Sat morning, from near 25N55W to Hispaniola early Sun, then stall and weaken into a trough over the far southeastern part late Sun through Mon night. North swell behind the front will build seas over most of the area northeast of the Bahamas by Sun. Strengthening high pressure in the wake of the front will result in fresh to strong north to northeast winds behind the front from late Fri through Sun. By late Sun, these winds are expected to be at mainly fresh speeds south of 29N and west of 60W. At that time, fresh to strong west to northwest winds are expected over the far northeast forecast waters along with building seas. |
