Special Features

Tropical Storm Fernand: Tropical Storm Fernand is centered near 29.7N 60.7W at 24/0900 UTC or 260 nm SE of Bermuda, moving NNE at 13 kt. Estimated minimum central pressure is 1010 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Peak seas are currently near 5.0 m, or 16 ft. Numerous moderate convection is noted within 90 nm in the NW semicircle and 30 nm in the SE semicircle of the system. Similar convection is noted from 28.5N to 31N between 58W and 60W. Fernand is moving toward the north- northeast and this motion is expected to continue for the next day or two, followed by a turn to the northeast. On the forecast track, Fernand should move well east of Bermuda and across the open waters of the subtropical North Atlantic. Some strengthening is forecast during the next 48 hours. A weakening trend is expected by Tuesday.

East of the Windward Islands (AL99): During the past several hours, showers and thunderstorms associated with a tropical wave, AL99, located about 390 nautical miles east of the Windward Islands near 12.5N54W have changed little in organization. Numerous moderate convection is noted from 10N to 16N between 54W and 58.5W. Associated winds are currently fresh to strong with seas of 2.5 to 3.0 m, or 8 to 10 ft. This system could become a tropical depression during the next day or two while it moves quickly westward at about 20 to 25 kt, passing through the Windward and Leeward Islands late today or tonight. Regardless of development, locally heavy rainfall and gusty winds are possible across portions of the Windward and Leeward Islands today and Monday. The system is expected to reach the central Caribbean on Tuesday, where conditions are expected to become less favorable for additional development. An Air Force reconnaissance aircraft is scheduled to investigate the system later today, if necessary. There is a medium chance of formation within the next 48 hours and the next 7 days.

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 Fernand NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details.

Tropical Waves

An eastern Atlantic tropical wave is along 26W just west of the Cabo Verde Islands from 22N southward to near 08N. The wave is moving slowly westward around 5 kt. Nearby convection has diminished and is isolated at best.

An central Atlantic tropical wave has been analyzed along 54W, from 21N southward through a 1010 mb low (AL99) near 12.5N54W to French Guiana, moving west at around 20 kt. Refer to the Special Features section above for more details on these features.

A central Caribbean tropical wave is near 73W from 20N in central Haiti southward to near the NW border of Venezuela with Colombia, moving westward around 20 kt. Satellite imagery indicates that the tropical wave envelope is large and extends across most of the eastern and central Caribbean, where widely scattered showers and isolated thunderstorms are evident.

Monsoon Trough/ITCZ

The monsoon trough enters the Atlantic along the coast of Mauritania near 18N16W and extends southwestward to near 10N42W. The ITCZ then extends from 10N42W to 13N51W where it is broken by the tropical wave associated with AL99. The ITCZ then resumes near 11N55.5WW and runs SW to 08.5N60W at the border of Guyana and Venezuela. Other than the convection described with the Special Features and in the Tropical Waves section, scattered moderate is noted from 05N to 12N within 270 nm of the coast of Africa. Similar convection is found on satellite imagery within 120 nm S of the ITCZ between 42W and 50W, and from 08N to 10.5N between 58W and 61W.

The eastern extension of the East Pacific monsoon trough reaches across the far SW Caribbean. Scattered moderate convection is occurring generally S of 15N and W of 76W.

Gulf Of America

A stationary front persists across the northern Gulf Coast, and continues to produce scattered moderate convection across the central and northern Gulf waters north of 23.5N. Moderate to locally fresh E to NE winds are noted north and west of the Yucatan Peninsula into the eastern Bay of Campeche. Otherwise, gentle to moderate anticyclone winds prevail across the rest of the Gulf with a ridge noted along 25N/26N, with 1-3 ft seas, locally higher in the Straits of Florida.

For the forecast, a weak pressure pattern will continue over the Gulf region through the period, maintaining mostly tranquil marine conditions. A stationary front will linger along the northern Gulf coast into the early part of the week supporting numerous showers and scattered thunderstorms mainly N of 22N. Moderate to fresh NE to E winds will develop over the south-central Gulf each afternoon through at least the middle of next week as a trough develops over the Yucatan Peninsula and moves westward at night.

Caribbean Sea

Please see the Special Features and Tropical Waves sections above.

Fresh to strong E winds and seas of 4-7 ft prevail across much of the central Caribbean, due to the moderate pressure gradient in place between higher pressure N of the region and the 1010 Colombia Low. Moderate to fresh trades and 3-6 ft seas prevail in the E Caribbean, Windward Passage, and the Gulf of Honduras, with locally higher seas in the NE and E Atlantic Passages. The remainder of the basin is seeing gentle to moderate or weaker winds and seas of 2-5 ft.

For the forecast, fresh to strong trades and moderate to locally rough seas will return to the south-central Caribbean this evening through Sun as central Atlantic high pressure builds W-SW across the western Atlantic. Fresh to strong winds will then expand across most of central and eastern portions, and the Windward Passage, Sun night through Wed as a strong tropical wave moves through the basin. Locally heavy rainfall, strong gusty winds, and squalls and thunderstorms are expected to accompany this tropical wave across east and central portions Sun evening through late Wed. Fresh to strong E to SE winds will pulse across the Gulf of Honduras at night through Tue. NW to N swell will build across the tropical Atlantic waters and move through the Atlantic Passages tonight through early Mon.

Atlantic Ocean

Please see the SPECIAL FEATURES section above for information on Tropical Storm Fernand and Invest Area AL99. Please see the TROPICAL WAVES section above.

Residual northerly swell from distant Post-Tropical Cyclone Erin continues to affect parts of the western and central Atlantic. 8-11 ft seas, with periods of 14-18 seconds, are analyzed N of 23N between 38W and 74W. Please note the locally different sea state within this area near Tropical Storm Fernand, which is described in the SPECIAL FEATURES section. Off the SE US coast, a warm front lifting north of the discussion waters is leading to widely scattered showers and thunderstorms generally north of 24N and W of 73W. In the deep tropical Atlantic away from the aforementioned features, moderate to locally fresh trades are analyzed from 11N to 20N and west of 50W. Moderate or weaker trades prevail elsewhere across the basin, with 4-7 ft seas in open waters.

For the forecast, Fernand will move to just N of the area at 31.3N 60.1W this afternoon, then continuing away from the area to 33.6N 59.1W Mon morning. Central Atlantic high pressure will then build W-SW and into the NW Bahamas Mon through Wed. Meanwhile, large northerly swell generated by distant extratropical cyclone Erin will continue to affect the W Atlantic waters through the next couple of days. A stationary front will linger off the SE U.S. Coast into the early part of the week with fresh winds SE of it. Fresh to strong winds will pulse N of Hispaniola Mon afternoon through Tue afternoon. Tranquil marine conditions may prevail by the end of next week.

Posted 1 hour, 2 minutes ago by NHC Forecaster Lewitsky