Special Features

Northwestern Gulf of America (Invest AL90): A trough of low pressure located over northeastern Mexico is producing a large area of disorganized showers and thunderstorms. Development is not expected during the next day or so while the trough remains inland. However, the system could re-emerge over the northwestern Gulf of America late Tuesday or Wednesday, and environmental conditions there are marginally conducive for the formation of a short-lived tropical storm on Wednesday into Thursday. Regardless of tropical cyclone formation, interests across southern and eastern Texas and portions of Louisiana and Mississippi should prepare for periods of intense rainfall over the next several days which could produce widespread, life- threatening flash, urban, and river flooding. Gusty winds and coastal flooding are also possible along portions of the northwestern Gulf Coast, and Tropical Storm Watches or Warnings could be required on Tue. Additional information on this system can be found in products issued by your local National Weather Service Forecast Office or NHC Key Messages. This area has a medium chance of tropical cyclone formation in the next 48 hours. Please refer to the latest Tropical Weather Outlook issued by the National Hurricane Center under AWIPS/WMO headers ABNT20 KNHC/TWOAT or at website https: //www. nhc. noaa. gov/text/MIATWOAT. shtml for further details.

Tropical Waves

A tropical wave in the eastern Atlantic is along 22W, south of 18N just east of the Cabo Verde Islands, moving westward at around 10 kt. Scattered moderate convection is observed from 04N to 11N between 13W and 24W.

An Atlantic tropical wave is along 41W, south of 16N, moving westward at around 20 kt. Scattered moderate convection is present from 03N to 09N and between 34W and 41W.

An Atlantic tropical wave is along 57W, south of 18N to Suriname, moving westward at around 20 kt. Scattered moderate isolated strong convection is present from 07N to 10N between 51W and 62W.

A Caribbean tropical wave is along 72W, south of 20N or Hispaniola to portions of far NW Venezuela and eastern Colombia, moving westward at around 15 kt. Scattered showers are seen over the waters south of 16N in the south-central Caribbean with deep convection present and enhanced over portions of Venezuela and Colombia.

Monsoon Trough Itcz

The monsoon trough enters the Atlantic through the coast of Mauritania near 19N16W and continues southwestward to 07N33W. The ITCZ extends from 07N33W to 06N40W and then resumes from 05. 5N42. 5W to 07N55W. In addition to convection described above in the TROPICAL WAVES section, scattered moderate convection is found from 05N to 08N between 45W and 49W.

Gulf Of America

Please refer to the Special Features section above for details on the potential for tropical cyclone formation in the Gulf of America.

Numerous moderate to strong convection is occurring along and near the coasts of NE Mexico, Texas, and SW Louisiana with a frontal boundary inland over Texas and Mexico, as well as multiple surface troughs analyzed inland. The tightening pressure gradient between these troughs and a subtropical ridge stemming from the Atlantic support moderate to locally fresh SE winds and in the W Gulf, as well as in the NE Gulf. Gentle to moderate or weaker winds prevail elsewhere. Seas in the Gulf range from 1-2 E of 90W, except to 4 ft near the Yucatan Channel, and 3-5 ft W of 90W.

For the forecast, a trough with weak low pressure along it is inland northeastern Mexico. It will slowly move northward during the next couple of days. It is then forecast to move northeastward along the Texas coast, and possibly re-emerge over the NW Gulf late Tue or Wed, at which time environmental conditions may be marginally conducive for the formation of a short-lived tropical storm Wed into Thu. Widespread showers and thunderstorms are expected over the NW Gulf through Thu. Otherwise, a tightening pressure gradient over the area will sustain fresh to strong southerly winds over the western Gulf early Wed through late Thu night, and moderate to fresh winds over the eastern Gulf. Winds begin to diminish Fri as high pressure settles in over the eastern Gulf.

Caribbean Sea

Scattered moderate and isolated strong convection are ongoing in the far SW Caribbean, near the East Pacific monsoon trough. The pressure gradient between the Atlantic subtropical ridge and the Colombia Low supports fresh to strong E winds and rough seas across much of the central to SW Caribbean. Moderate to fresh trades and moderate seas prevail in the eastern and NW Caribbean, except locally strong offshore central Honduras. Gentle to moderate trades and moderate seas prevail elsewhere.

For the forecast, the gradient between broad Atlantic high pressure and relatively lower pressures south of the Greater Antilles will sustain a rather extensive area of fresh to strong trade winds in the south-central section of the basin through the forecast period. The highest of the winds and seas are expected off the coast of Colombia. Pulsing winds at fresh to strong speeds are expected in the Gulf of Honduras nightly through Fri. Gentle to moderate winds elsewhere across the northwestern Caribbean will become southeast at fresh to strong speeds Wed through Thu.

Atlantic Ocean

A surface trough is analyzed from 31N42W to 25N55W to 19N64W, with scattered moderate convection seen N of 29N between 35W and 50W. Another surface trough is analyzed N of the Bahamas from 31N76W to 27N79W. Moderate to fresh SW winds are N of 27N and E of the trough to 67W along with 4-6 ft seas. Some scattered showers are found near the trough. Otherwise, ridging extends and dominates from 31N28W to 1024 mb high pressure near 29N34W to 1022 mb high pressure near 26N61W. Winds are mainly moderate or weaker across the remainder of the waters W of 35W, except moderate to fresh S of 22N near Puerto Rico and Hispaniola. Fresh to strong N-NE winds are found offshore Africa from 20N to 31N to the E of 20W. Moderate to locally fresh trades are found from this area to the Lesser Antilles in a belt extending N of the ITCZ where three Atlantic tropical waves are present as described in detail above. Seas of 3-6 ft dominate the open tropical Atlantic waters in mixed NE-E and NW-N swells.

For the forecast west of 55W, broad high pressure over the area will change little through Fri, then begin to weaken Fri night. The related pressure gradient will maintain moderate to locally fresh trade winds south of 22N through Fri, diminishing some in coverage beginning Fri night. Moderate to fresh southwest winds east of northeast Florida to near 74W are ahead of a trough. These winds will expand eastward to near 67W through Wed, as a weak frontal system moves across the southeastern U. S. It is expected to move offshore late Fri night and stall offshore northeast Florida Sat and Sat night. Expect fresh to strong winds each afternoon through late evening across Atlantic waters near Puerto Rico and Hispaniola.

Posted about 1 hour ago by NHC Forecaster Lewitsky