Special Features

Post-Tropical Cyclone Arthur has weakened further overnight, and is now an elongated trough across SE Texas extending into SW Louisiana, and moving NE around 8 kt. Maximum sustained wind speed along the coast is near 30 kt with gusts to 40 kt. Scattered moderate to strong convection continues well SE of the remnants of Arthur, and is across SE Louisiana and the adjacent coastal waters to the south and east and shifting into coastal Mississippi. Seas across the SE Texas and Louisianan coastal waters are estimated at 6 to 10 ft. The remnants of Arthur area expected to be captured by a middle level trough and accelerate off to the northeastward today through Friday. On the forecast track, the remnants of Arthur should move farther inland over southeastern Texas and western Louisiana, early this morning, then cross the southeastern United States Thursday through Friday. While additional weakening is expected as the system moves inland, the remnants of Arthur will continue to produce widespread heavy rains across the southeastern United States during the next few days. Arthur is expected to produce rainfall totals of 5 to 10 inches, with isolated higher totals near 20 inches, through early Friday, from southern and central portions of Louisiana, Mississippi, and Alabama, along with western portions of Georgia and the Florida Panhandle. This could generate dangerous to life- threatening flash flooding.

Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center at website - https: //www. nhc. noaa. gov/text/MIAHSFAT2. shtml and the latest Arthur NHC Forecast/Advisory and Public Advisory at www. hurricanes. gov for more details.

Tropical Waves

An eastern Atlantic tropical wave is along 23W, south of 16N, moving westward at 15-20 kt. Scattered moderate to strong convection is present from 02N to 08. 5N between 17W and 30W.

Another Atlantic tropical wave is along 40W-41W, south of 18N, moving westward at 15 kt. Scattered moderate convection is observed from 02N to 09N and between 34W and 45W.

An eastern Caribbean tropical wave is along 64W, south of 17N, moving westward at 15-20 kt. Scattered showers are seen behind the wave, S of 14N, between 57W and 64W.

A western Caribbean tropical wave is along 83W, south of 18N, moving westward at 15-20 kt. A few clusters of moderate convection are along the monsoon trough there between Colombia and Nicaragua.

Monsoon Trough Itcz

The monsoon trough enters the Atlantic through the coast of Guinea-Bissau near 12N16. 5W and continues southwestward to 06. 5N21W to 06N31W. The ITCZ extends from 06N31W to 04. 5N40W and then from 04N42W to 00. 5N50W. See the TROPICAL WAVES section for details on convection.

Gulf Of America

Please refer to the Special Features section above for details on Post-Tropical Cyclone Arthur impacting portions of the NW and north-central Gulf and adjacent land areas.

Outside of the influence of ex-Arthur, the remainder of the Gulf is dominated by a broad subtropical ridge over the western Atlantic, and extending across Florida and into the eastern Gulf. Fresh to strong southerly winds are generally N of 26W and W of 86W, off the northern Yucatan to 26N. Seas are 6 to 8 ft across most of this area, except 8 to 10 ft offshore of central Louisiana. Elsewhere, moderate to fresh southerly winds and moderate seas to 6 ft prevail.

For the forecast, Atlantic high pressure has begun to build westward across Florida and into the Gulf basin tonight, in the wake of Arthur, and will tighten the pressure gradient through Thu night, to sustain fresh to strong southerly winds over the western and central Gulf, and moderate to fresh winds over the eastern Gulf. Expect rough seas N of 27N and offshore of the Louisiana coast this morning to shift eastward with these winds through Thu night before diminishing. Winds and seas will diminish basin-wide late Fri through the weekend as weak high pressure settles over the eastern Gulf.

Caribbean Sea

The broad subtropical ridge over the western Atlantic extends westward along 27N-28N and across south-central Florida. This pressure pattern is forcing fresh to strong easterly trade winds and moderate to rough seas in the central Caribbean and across the Gulf of Honduras. Moderate easterly winds and 4-7 ft seas are noted elsewhere. A lingering middle-level trough across the central Bahamas and Cuba is supporting lingering scattered moderate convection from the Windward Passage to the NE coasts of Honduras and Nicaragua.

For the forecast, the western Atlantic ridge will remain in place along 27N-28N through the upcoming weekend, while weakening slightly Fri night through Sun, as a frontal system clips the waters off NE Florida. The pressure gradient south of the ridge will sustain fresh to strong trade winds and moderate to rough seas in the south-central Caribbean through the forecast period, with highest winds and seas expected off the coast of Colombia. Pulsing winds at fresh to strong speeds and moderate to rough seas are expected in the Gulf of Honduras nightly through Mon, pulsing briefly to near gale-force Thu night and Fri night. Moderate to fresh E to SE winds are expected elsewhere across the northwestern Caribbean through Mon. Active showers and thunderstorms are expected across SW portions through Sat as an upper-level trough digs into the area.

Atlantic Ocean

The Bermuda-Azores subtropical ridge dominates the tropical Atlantic, and extends along about 27N-28N. The ridge is interruptedby a frontal trough extending into the area from 31N34W to 26N44W. A few showers are along this trough. Moderate to locally fresh easterly winds and seas of 4-7 ft are found south of 23N and west of 35W into the SE Bahamas. In the far east, fresh to strong N to NE winds and seas of 5-8 ft are present from 17N to 24N and east of 27W. Moderate to locally fresh S to SW winds extend from the NW Bahamas N-NE across the waters W of 75W, where seas are 4 ft or less. Elsewhere, fresh or weaker winds and moderate seas are prevalent.

For the forecast west of 55W, the western Atlantic ridge will remain in place along 27N-28N through the upcoming weekend, while weakening slightly Fri night through Sun, as a frontal system clips the waters offshore of NE Florida. The related pressure gradient will maintain moderate to locally fresh trade winds south of 22N through Sun. Moderate to locally fresh SW winds offshore of northeast Florida to near 75W will expand eastward to near 70W through tonight, as a weak frontal system moves across the southeastern U. S. The front is expected to move slowly offshore early Sat and stall offshore NE Florida by Sun, allowing the moderate to fresh SW winds to shift eastward ahead of it across the northern waters. 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 Stripling