Tropical Weather Discussion

SPECIAL FEATURE

Caribbean Gale Warning: The subtropical ridge north of the Caribbean will support gale-force winds off the coast of Colombia through near sunrise this morning, and strong to near- gale force easterly trade winds across the much of the central Caribbean into early Mon, before becoming confined to south of 15N through midweek. Winds will pulse to gale force over the waters north of Colombia tonight. Rough to very rough seas, peaking at 12 to 13 ft, will develop during the times of peak winds.

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

NE Gulf of America (Invest AL91): Recent satellite scatterometer wind data and nearby surface observations indicate that an area of low pressure located over the northeastern Gulf of America is slowly becoming better defined. However, its associated shower and thunderstorm activity remains disorganized and displaced well the southwest and west of the low. This activity may produce gusty winds, frequent lightning and rough seas. Mariners should exercise caution across this area. Regardless, gradual development of this system is forecast, and a tropical depression could form over the next couple of days as the system moves slowly northward or northwestward. Interests along the northern Gulf coast from Florida, Alabama, Mississippi, to Louisiana should monitor the progress of this system as it is expected to bring heavy rain to portions of that region during the next several days. An Air Force Reserve reconnaissance aircraft is scheduled to investigate the system later today, if necessary. This system has a medium chance for tropical cyclone formation during the next 48 hours.

Please refer to the latest TROPICAL WEATHER OUTLOOK issued by the National Hurricane Center at www.hurricanes.gov for more information.

TROPICAL WAVES

A well-defined tropical wave in the eastern Atlantic is now along 34W, south of 19N, based on recent satellite and scatterometer data. The wave is moving westward at 15 to 20 kt. No significant convection is observed near this wave due to dry Saharan air.

An Atlantic tropical wave is along 60W, south of 18N, moving westward at 15 to 20 kt. Scattered moderate convection is near the wave along the ITCZ, from 10N to 12.5N and between 57W and 62W.

MONSOON TROUGH/ITCZ

The monsoon trough enters the Atlantic through the coast of Mauritania near 19N16W and continues southwestward through the Cabo Verde Islands to 15N30W and then to 06.5N42.5W. The ITCZ extends from 06.5N42.5W to 07N58W. Scattered moderate to strong convection is moving off the coast of Africa from 07.5N to 14.5N and E of 18W. Scattered moderate convection is found N of the ITCZ from 06.5N to 09.5N between 41W and 57W.

GULF OF AMERICA

Please refer to the Special Features section for information on a broad low pressure over the eastern Gulf that has a medium chance of tropical cyclone formation during the next 48 hours. A 1012 mb low center is analyzed near 27.5N 85.5W and is nearly stationary. Scattered to locally numerous moderate isolated strong convection is occurring in broken bands from 120 to 300 nm around the periphery of this low, except for the N semicircle. Recent satellite scatterometer wind data showed strong gusty winds to near 30 kt in some of these thunderstorms. Seas are estimated at 2 to 5 ft across this area.

Elsewhere, dry air dominates the remainder of the basin suppressing the development of showers and thunderstorms. A 1018 mb high pressure over the NW Gulf waters supports moderate to fresh NE winds and seas of 2-4 ft in the eastern Bay of Campeche, while light to gentle winds and slight seas prevail elsewhere.

For the forecast, the broad area of low pressure over the eastern Gulf is expected to move slowly north to northwestward over the next couple of days, and could become a tropical depression. Regardless, this system will bring thunderstorms with heavy rainfall and strong gusty winds to the NE Gulf and adjacent portions of the Gulf coast through at least Tue. Away from this system, weak high pressure will dominate, producing gentle to moderate winds and slight to moderate seas through the period.

CARIBBEAN SEA

A Gale Warning remains in effect for the south-central Caribbean near the coast of Colombia until near sunrise. Please refer to the Special Features section for more details.

The 1024 mb subtropical ridge centered near 28.5N59W in the central Atlantic and extends westward to the coast of Florida. The pressure gradient to the south of the ridge is forcing strong to near-gale easterly trade winds across the central Caribbean, with the strongest winds occurring off Colombia. Rough to very rough seas are found in these waters. Moderate to fresh NE-E winds and moderate seas are present in the eastern Caribbean and Windward Passage. Elsewhere, light to gentle winds and slight to moderate seas are prevalent. A few showers and isolated thunderstorms that developed over Panama and Costa Rica have shifted inland, while scattered moderate convection associated with a tropical wave is moving into the southern Windward Islands. Generally dry weather conditions are noted elsewhere.

For the forecast, the pressure gradient between the western Atlantic high pressure ridge oriented along 28N, and the Colombian low will support NE winds pulsing to gale-force across the waters N of Colombia through early this morning. Otherwise, strong to near- gale force trade winds and rough seas will prevail across the much of the central Caribbean into Sun night, before contracting to south of 15N Mon through Thu. East winds will pulse fresh to locally strong each evening through Tue in the Windward Passage.

ATLANTIC OCEAN

A couple of weak surface troughs and an upper level low in the north- central tropical Atlantic combine to generate isolated showers north of 23N and between 37W and 53W. Meanwhile, a broad subtropical ridge centered over the central Atlantic forces fresh to locally strong easterly trade winds off northern Hispaniola as shown in a recent satellite scatterometer data. Elsewhere in the central and western Atlantic, moderate to fresh easterly winds and seas of 4-8 ft are occurring south of 24N and west of 45W, with highest seas to 8 ft E of the Windward Islands.

In the far eastern Atlantic, fresh to locally strong N to NE winds and seas of 4-8 ft are present north of the monsoon trough and east of 25W. In the rest of the basin, moderate or weaker winds and moderate seas prevail within the ridge axis.

For the forecast west of 55W, the western Atlantic subtropical ridge along 28N-29N this morning will weaken and drift northward through early next week as a broad surface trough forms E of 50W. This trough will shift westward and reach 65W by Wed, then move W of 70W and weaken quickly Thu. Moderate to fresh trades will prevail S of 24N through Tue, with gentle winds to the N. Pulsing strong winds are expected during the evenings through Tue N of Hispaniola and in the Windward Passage. Expect increasing winds and seas N of 22N and E of 70W Tue through Wed night as the trough approaches.

SPECIAL FEATURES

Tropical Depression Six-E: centered near 12.1N 110.6W at 19/0900 UTC, moving west-northwest at 12 kt. Estimated minimum central pressure is 1007 mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt. Peak seas are currently around 11 ft or just less than 3.5 m. Numerous moderate to strong convection is noted between 90 nm and 300 nm in the north quadrant, and within 330 nm in the SW semicircle of the depression. The depression is moving toward the west-northwest and this general motion is expected to continue for the next two to three days. Steady to rapid strengthening is forecast during the next few days. The depression is forecast to become a tropical storm later today and become a hurricane by Mon night or Tue. Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center at website - https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml and the latest Six-E NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details.

Tropical Storm Elida: centered near 21.4N 125.2W at 19/0900 UTC, moving north-northwest at 11 kt. Estimated minimum central pressure is 996 mb. Maximum sustained wind speed is 50 kt with gusts to 60 kt. Peak seas are currently around 23 ft or 7 m. Numerous moderate isolated strong convection is noted within 150 nm of the center of Elida. Elida is moving toward the north- northwest. A gradual increase in forward speed is expected over the next couple of days as the system turns northward. Steady weakening is expected during the next couple of days as Elida moves over progressively cooler waters. Elida is forecast to become a remnant low by Mon night and dissipate by late Wed. Swells generated by Elida will affect portions of the west coast of the Baja California Peninsula and southern California through early next week. These swells will likely result in life-threatening surf and rip current conditions. Please consult products from your local weather office. Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center at website - https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml and the latest Elida NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details.

INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH

The monsoon trough extends from 1005 mb low pressure over northern Colombia near 10N75.5W to 10N85W to 08N91W to 10N107W, then resumes SSW of Elida from 14N124W to 08N140W. Scattered to numerous moderate to strong convection is noted from 00N to 11N between 77W and 91W, and within 270 nm SSE of the monsoon trough west of 124W. Scattered moderate convection is noted from 10N to 17.5N between 94W and 101W, from 05N to 13N between 101W and 105W, and from 08.5N to 10.5N between 137W and 140W.

OFFSHORE WATERS WITHIN 250 NM OF MEXICO

Please refer to the Special Features section for details on Tropical Depression Six-E, centered about 647 nautical miles south of the southern tip of Baja California, and on Tropical Storm Elida, centered about 856 nautical miles west of the southern tip of Baja California.

Fresh to strong N to NE winds are in the Gulf of Tehuantepec as confirmed by recent ASCAT-B and ASCAT-C scatterometer passes. Otherwise, rather broad high pressure is over the offshore waters, with moderate or weaker winds. Outer associated rough seas from Elida are near the far outer offshore waters boundary of Baja California and are finally pulling away. Moderate seas dominate elsewhere, with rough seas associated with Tropical Depression Six-E just beyond the outer offshore waters of southwestern Mexico. Seas are slight in the Gulf of California, while winds are moderate to locally fresh in the northern portion. Very active convection is present near the monsoon trough across much of the offshore waters south of 14N, as well as near the coast of Oaxaca and Guerrero with locally higher winds and seas possible near any thunderstorms.

For the forecast, seas generated by Elida will finally subside to less than 8 ft by this afternoon. Meanwhile, Tropical Depression Six-E will strengthen to a tropical storm near 12.5N 112.3W this afternoon, move to 13.2N 114.4W Mon morning, 14.4N 116.2W Mon afternoon, strengthen to a hurricane near 15.5N 117.8W Tue morning, 16.3N 119.3W Tue afternoon, and 16.8N 120.6W Wed morning. Six-E will change little in intensity as it moves to 17.3N 124.2W early Thu. Associated increasing winds and building seas are forecast to impact portions of the waters well offshore southwest Mexico to the Revillagigedo Islands into the early part of the week. Fresh to strong northerly winds will continue to pulse in the Gulf of Tehuantepec through the next several days, with locally rough seas at times. In the Gulf of California, gentle to moderate winds and slight seas will prevail, except for locally fresh winds in the northern Gulf at times. Winds may freshen nearshore Baja California Norte midweek as the gradient temporarily tightens there. Looking ahead, low pressure may develop well south of Mexico during the middle to latter part of next week and increasing winds and seas may impact portions of the outer offshore waters of southern and southwestern Mexico by the end of next week.

...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR...

Fresh to strong northeast to east winds continue across the Papagayo region and downwind to near 09N92W. Moderate to fresh NE winds are near the Gulf of Fonseca. Seas are 6 to 9 ft downstream of Papagayo. Moderate to locally fresh N to NE winds are in the Gulf of Panama. Moderate or weaker winds and moderate seas, primarily in south to southwest swell, dominate the remainder of the offshore waters, except slight seas in the immediate lee of the Galapagos Islands and near shore western Colombia. Very active convection is present near the monsoon trough across much of the offshore waters, with locally higher winds and seas possible near thunderstorms.

For the forecast, fresh to strong NE to E winds and moderate to rough seas will persist across the Papagayo region through early next week, with moderate to fresh NE winds pulsing near the Gulf of Fonseca. Gentle to moderate N winds are expected in the Gulf of Panama with slight to moderate seas. Moderate or weaker winds and moderate seas in SW swell are expected elsewhere, except in the immediate lee of the Galapagos Islands and nearshore western Colombia where slight seas are forecast. Looking ahead, low pressure is forecast to develop well south of Mexico during the middle to latter part of the upcoming week, and increasing winds and seas may impact portions of the outer offshore waters of Guatemala and El Salvador.

REMAINDER OF THE AREA

Please refer to the Special Features section for details on Tropical Depression Six-E, centered about 647 nautical miles south of the southern tip of Baja California, and on Tropical Storm Elida, centered about 856 nautical miles west of the southern tip of Baja California.

Both of the above systems dominate the open waters, as well as another area of disturbed with and associated fresh to strong winds and locally rough seas near 08N97W. Otherwise, broad ridging prevails both west and east of Elida. Winds are mainly moderate or weaker across the remainder of the open waters along with moderate seas, except moderate to locally fresh in the south-central waters south of 04N between 105W and 125W, along with 7 to 9 ft seas there. Very active convection is present near the monsoon trough, concentrated near all three significant features, with locally higher winds and seas possible.

For the forecast, Tropical Storm Elida Elida will move to 22.7N 126.0W this afternoon, 24.8N 126.9W Mon morning, 27.5N 127.5W Mon afternoon, weaken to a remnant low just north of the discussion waters near 30.2N 127.7W Tue morning, 32.9N 127.9W Tue afternoon, and 35.6N 127.9W Wed morning. Elida will dissipate early Thu. Meanwhile, Tropical Depression Six-E will strengthen to a tropical storm near 12.5N 112.3W this afternoon, move to 13.2N 114.4W Mon morning, 14.4N 116.2W Mon afternoon, strengthen to a hurricane near 15.5N 117.8W Tue morning, 16.3N 119.3W Tue afternoon, and 16.8N 120.6W Wed morning. Six-E will change little in intensity as it moves to 17.3N 124.2W early Thu. Associated increasing winds and building seas are forecast to impact portions of the waters well offshore southwest Mexico to the Revillagigedo Islands into the early part of the week. Moderate to fresh winds and locally rough seas over the south-central waters will gradually spread northward in the wake of Elida and the wake of Six-E into the early part of the week. Little change in marine conditions is expected across the remainder of the open waters.

Looking ahead, a broad area of low pressure is forecast to develop well south of Mexico during the middle to latter part of the upcoming week. Environmental conditions appear conducive for development of the system thereafter, and a tropical depression could form while it moves westward to west-northwestward across the eastern and central portions of the eastern Pacific.