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Gulf
Atlantic
For the North Atlantic, Caribbean Sea and the Gulf of America:
Offshore the East Coast of the United States (Remnants of Arthur): Showers and thunderstorms associated with a trough of low pressure (the remnants of Arthur) are located over the southeastern United States. The system is expected to emerge offshore the east coast of the United States by this afternoon. Environmental conditions then appear to be marginally conducive for some subtropical or tropical development tonight or Saturday as the system moves northeastward at around 20 mph across the Western Atlantic Ocean.
Regardless of development, heavy rainfall with the potential for widespread and life-threatening flash flooding is likely across portions of the Southeast United States during the next day or two. Additional information on the rainfall potential can be found in rainfall forecasts and Excessive Rainfall Outlooks from the Weather Prediction Center online at www.wpc.ncep.noaa.gov. More information on this system, including Gale Warnings, is available in High Seas Forecasts issued by the National Weather Service under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and online at ocean.weather.gov/shtml/NFDHSFAT1.php Formation chance through 48 hours, low, 10 percent. Formation chance through 7 days, low, 10 percent.
Posted 4 hours ago by NHC Forecaster Forecaster Beven
Tropical Waves
An eastern Atlantic tropical wave has its axis near 26.5W, south of 17N, moving westward at around 10-15 kt. Any nearby convection is discussed in the ITCZ/MONSOON TROUGH section below.
Another Atlantic tropical wave has its axis near 47W, south of 17N, moving westward at around 10 kt. Any nearby convection is discussed in the ITCZ/MONSOON TROUGH section below.
An eastern Caribbean tropical wave has its axis near 65W, south of 19N near the Anegada Passage to central Venezuela, moving westward at around 10-15 kt. Scattered moderate convection is seen S of 14N between 62W and 68W.
The western Caribbean tropical wave that was mentioned in the previous discussion is crossing Central America and moving into the Eastern Pacific. Please refer to the Eastern Pacific Tropical Weather Discussion for information on this wave.
Monsoon Trough/ITCZ
The monsoon trough enters the Atlantic off the coast of Africa near 18N16W and extends SW to near 06N28W. The ITCZ extends from 06N28W to 06.5N46W where it becomes ill-defined due to a tropical wave to the west. Numerous moderate to strong convection is seen from 03N to 11N and E of 20W. Scattered moderate convection is occurring from 02N to 10N between 25W and 45W.
Gulf Of America
A ridge extends from subtropical high centered in the Atlantic to across Florida and the Gulf along 26N, with a surface trough emerging off the western Yucatan Peninsula. The pressure gradient between these features is supporting fresh to strong winds across much of the Gulf. Seas are in the 4-7 ft over much of the Gulf, reaching 8 ft off the coast of Louisiana to the western Florida Panhandle.
For the forecast, the western periphery of Atlantic high pressure extends westward across Florida and to the central Gulf. The pressure gradient between the high pressure and relatively lower pressures over Texas and northeastern Mexico will generally support mostly fresh southerly winds over the western and central Gulf, and gentle to moderate anticyclonic winds over the eastern Gulf through Fri. Winds over the western and central Gulf will change little through early Mon, then diminish to gentle to moderate speeds afterward. Winds over the eastern Gulf become light to gentle in speeds beginning Fri night as weak high pressure settles over the eastern Gulf.
Caribbean Sea
Please refer to the Tropical Waves section for details on convection associated with a wave in the eastern Caribbean.
The broad subtropical ridge over the western Atlantic extends westward along 27N-28N and across central Florida. The pressure gradient between the ridge and the Colombian low is supporting fresh to strong winds over the south-central Caribbean and the Gulf of Honduras, where seas are in the 6-8 ft range. Moderate to fresh trades and 4-7 ft seas prevail in the eastern and NW Caribbean. Gentle to moderate winds and seas of 3-6 ft are across the remainder of the Caribbean. Scattered showers and isolated thunderstorms are ongoing in the central Caribbean to the north of the Colombia low.
For the forecast, high pressure over the Atlantic will change little into next week. The pressure gradient between the high pressure and relatively lower pressure to its south will maintain fresh to strong trade winds and moderate to rough seas in the 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 tonight and Fri night. Moderate to fresh east to southeast winds are expected elsewhere from 12N to 18N west of 80W through Mon night.
Atlantic Ocean
A frontal remnant trough extends from 31N30W to 26N44W. No significant convection is seen near the trough. The rest of the discussion waters N of 20N is dominated by high pressure anchored by a 1024 mb subtropical high centered near 27N59W. Moderate to fresh trades and moderate seas prevail across much of the Atlantic S of 20N as well as between the Bahamas and Cuba, with gentle to moderate or weaker E winds and 3-6 ft seas to the N of 20N.
For the forecast west of 55W, high pressure across the basin will begin to shift slightly eastward Fri night as a cold front moves across the southeastern U.S. The front will move offshore northeast Florida during the weekend, then stall and weaken. Fresh to strong southwest winds are expected north of 30N and east to near 72W through Fri night. Moderate to fresh nightly pulsing fresh to strong winds south of 22N will continue into early next week.
Posted 4 hours ago by NHC Forecaster Adams
