Monthly Archives: May 2018

Tropical Cyclone Mekunu Intensifies Over the Arabian Sea

Tropical Cyclone Mekunu intensified over the Arabian Sea on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Tropical Cyclone Mekunu was located at latitude 11.0°N and longitude 55.9°E which put it about 120 miles (195 km) southeast of Socotra Island.  Mekunu was moving toward the northwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 985 mb.

The circulation of Tropical Cyclone Mekunu became much better organized on Tuesday.  A primary rainband wrapped around the center of circulation and eye was evident at the center of circulation on microwave satellite images.  Several bands of showers and thunderstorms developed and began to revolve around the core of Tropical Cyclone Mekunu.  The strongest rainbands were in the western and northern parts of the circulation.  Storms near the core generated upper level divergence which pumped mass away from the tropical cyclone.  Winds to tropical storm force extended out about 95 miles (155 km) from the center of circulation.

Tropical Cyclone Mekunu will move through an environment favorable for intensification during the next several days.  Mekunu will move over water where the Sea Surface Temperature is near 30°C.  It is moving around the western end of an upper level ridge.  The ridge is producing southerly winds which were blowing toward the top of the circulation.  Those winds will generate some vertical shear, but the shear will not be strong enough to prevent intensification.  Tropical Cyclone Mekunu is likely to intensify into the equivalent of a hurricane/typhoon during the next 24 hours.

The upper level ridge was steering Tropical Cyclone Mekunu toward the northwest.  A general motion toward the north-northwest is forecast for the next two to three days.  On its anticipated track Tropical Cyclone Mekunu will approach Socotra Island within 24 hours.  The strongest part of Mekunu will pass over Socotra Island.  It will bring gusty winds and locally heavy rain.  Flash floods could occur.  Tropical Cyclone Mekunu could approach the coast of western Oman and eastern Yemen in about three days.

Tropical Cyclone 02A Develops Over the Arabian Sea

Tropical Cyclone 02A formed over the Arabian Sea on Monday.  At 11:00 p.m. EDT on Monday the center of Tropical Cyclone 02A was located at latitude 9.3°N and longitude 57.1°E which put it about 285 miles (460 km) southeast of Socotra Island.  It was moving toward the northwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 999 mb.

A center of circulation began to consolidate within a broader area of low pressure over the Arabian Sea on Monday.  Thunderstorms formed west and north of the developing center.  There were fewer thunderstorms in the eastern half of the circulation.  Storms west of the center began to organize into several bands and the circulation began to exhibit the characteristics of a tropical cyclone.  Thunderstorms near the core of the circulation began to generate upper level divergence which was pumping mass away from the developing tropical cyclone.  Winds to tropical storm force extended out about 110 miles (175 km) from the center of circulation.

Tropical Cyclone 02A will move through an area favorable for intensification during the next several days.  It will move over water where the Sea Surface Temperature is near 30°C.  An upper level ridge is east of the tropical cyclone.  The ridge is producing southerly winds which are blowing toward of the top of the circulation.  Those winds will generate some vertical wind shear, but the shear will not be strong enough to prevent intensification.  The circulation of Tropical Cyclone 02A will continue to organize on Tuesday.  It will strengthen and it could become the equivalent of a hurricane/typhoon by the middle of the week.

The ridge to the east of Tropical Cyclone 02A is steering the cyclone toward the northwest.  A general motion toward the north-northwest is expected during the next two or three days.  On its anticipated track the center of Tropical Cyclone 02A will pass west of Socotra Island.  It could bring gusty winds and locally heavy rain to that location.  Tropical Cyclone 02A could approach western Oman and eastern Yemen in three or four days.  It could be the equivalent of a hurricane/typhoon at that time.

Tropical Cyclone Sagar Brings Wind and Rain to Djibouti, Western Somalia

Tropical Cyclone Sagar brought wind and rain to Djibouti and Western Somalia on Saturday.  At 11:00 a.m. EDT on Wednesday the center of Tropical Cyclone Sagar was centered at latitude 10.1°N and longitude 43.4°E which put it about 100 miles (165 km) south-southeast of Djibouti City, Djibouti.  Sagar was moving toward the southwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 988 mb.

Tropical Cyclone Sagar made landfall on the coast of northwestern Somalia near Bullaxaar on Saturday.  Sagar was the equivalent of a strong tropical storm at the time of landfall.  It moving south of an upper level ridge which was generating easterly winds which were blowing toward the top of the tropical cyclone.  Those winds were causing some vertical wind shear.  The stronger thunderstorms were occurring west of the center of circulation, which was probably due to the vertical wind shear.

Thunderstorms in the western half of Tropical Cyclone Sagar may have produced wind gusts to near hurricane force when Sagar made landfall on the coast of northwestern Somalia.  The gusts were capable of causing minor wind damage.  Sagar may have generated a storm surge of 4 to 8 feet (1.2 to 2.4 meters) near where the center made landfall.  Tropical Cyclone Sagar was dropping heavy rain on parts of extreme western Somalia and Djibouti.  The heavy rain was capable of producing flash floods.

Tropical Cyclone Sagar has a small circulation and Sagar will likely weaken quickly as moves inland into drier air over eastern Africa.  Even though it will weaken quickly, Sagar could also drop heavy heavy over parts of eastern Ethiopia and flash floods could occur in that region.

Tropical Cyclone Sagar Strengthens Over Western Gulf of Aden

Tropical Cyclone Sagar strengthened over the western Gulf of Aden on Friday.  At 5:00 p.m. EDT on Friday the center of Tropical Cyclone Sagar was located at latitude 11.2°N and longitude 45.0°E which put it about 105 miles (170 km) south of Aden, Yemen.  Sagar was moving toward the west-southwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 986 mb.

A small eye appeared at the center of Tropical Cyclone Sagar on microwave satellite imagery.  The eye was surrounded by a tight ring of thunderstorms and the strongest winds were occurring in the ring of storms.  There was a small break on the southeast side of the ring of storms.  A short, broad band of showers and thunderstorms wrapped around the western and northern sides of the core of the circulation.  A longer, thinner rainband wrapped around the southern and eastern periphery of the circulation.  Storms near the core of Tropical Cyclone Sagar were generating upper level divergence which was pumping mass away from the tropical cyclone.  Winds to tropical storm force extended out about 60 miles (95 km) from the center of circulation.

Tropical Cyclone Sagar will be moving through an environment favorable for intensification for about another 12 to 18 hours.  Sagar will move over water where the Sea Surface Temperature is near 29°C to 30°C.  It is moving south of an upper level ridge.  The ridge is generating easterly winds which are blowing toward the top of the circulation.  Those winds are producing some vertical wind shear.  The shear may be the reason why most of the stronger thunderstorms are in the western half of the circulation.  The shear will inhibit intensification, but it will not be strong enough to prevent further strengthening.  Tropical Cyclone Sagar could become the equivalent of a hurricane/typhoon.  Much drier air is over eastern Africa and the Arabian Peninsula.  When Tropical Cyclone Sagar nears the coast of western Somalia, it will pull some of the drier air into the circulation and that will cause Sagar to start to weaken.

The upper level ridge is steering Tropical Cyclone Sagar toward the west-southwest and that general motion is expected to continue for several more days.  On its anticipated track Tropical Cyclone Sagar could make landfall on the coast of western Somalia in 18 to 24 hours.  Sagar will be capable of causing minor wind damage.  It could produce a storm surge of 4 to 8 feet (1.5 to 2.5 meters) near where the center makes landfall.  The core of Tropical Cyclone Sagar could also drop locally heavy rain over parts of western Somalia and eastern Ethiopia.  Heavy rain could cause flash floods in some locations.

Tropical Cyclone Sagar Strengthens Over Gulf of Aden

Tropical Cyclone Sagar (01A) strengthened over the Gulf of Aden on Thursday.  At 11:00 a.m. EDT on Thursday the center of Tropical Cyclone Sagar was located at latitude 12.8°N and longitude 47.8°E which put it about 210 miles (335 km) east of Aden, Yemen.  Sagar was moving toward the west-southwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 992 mb.

The circulation of Tropical Cyclone Sagar became more organized on Thursday.  An eyelike feature appeared at the center of circulation.  A partial ring of thunderstorms wrapped around the northeast, northwest and southwest quadrants of the incipient eye.  There was a break in the ring of storms southeast of the center.  The strongest winds were occurring in the partial ring.  Additional bands of showers and thunderstorms were occurring north and west of the center of circulation.  Bands south and east of the center consisted primarily of low clouds and showers.  Storms near the center of circulation were generating upper level divergence which was pumping mass away from the tropical cyclone.  Winds to tropical storm force extended out about 70 miles (110 km) from the center of circulation.

Tropical Cyclone Sagar will move through an environment somewhat favorable for intensification during the next 24 to 36 hours.  Sagar will move over water where the Sea Surface Temperature is near 29°C to 30°C.  So, there is plenty of energy in the upper ocean to support intensification.  Sagar is moving south of an upper level ridge.  The ridge is producing easterly winds which are blowing toward the top of the circulation.  Those winds are causing some vertical wind shear and they are part of the reason why the strong storm are occurring mainly in the western half of the circulation.  The wind shear is not strong enough to prevent intensification and Tropical Cyclone Sagar is likely to continue to strengthen during the next 24 hours.  It could strengthen into the equivalent of a hurricane/typhoon.  Much drier air is over the Arabian Peninsula and Somalia.  When Sagar approaches the coast of the Gulf of Aden, it will start to pull drier air into the circulation and that will cause Sagar to weaken.

The upper level ridge is steering Tropical Cyclone Sagar toward the west-southwest and that general motion is expected to continue during the next several days.  On its anticipated track Tropical Cyclone Sagar could be south of Aden in about 36 hours.  Sagar could approach the coast of western Somalia and Djibouti in two or three days.  Tropical Cyclone Sagar will bring gusty winds and it could cause some storm surge at the coast.  The greater risk is for locally heavy rain near the coast of Yemen and over north Somalia.  The rain could be heavy enough to produce flash floods in some locations.

Tropical Cyclone 01A Forms Over the Gulf of Aden

Tropical Cyclone 01A formed over the Gulf of Aden on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Tropical Cyclone 01A was located at latitude 13.0°N and longitude 48.6°E which put it about 265 miles (425 km) east of Aden, Yemen.  It was moving toward the west at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 995 mb.

A distinct low level center of circulation developed in an area of showers and thunderstorms that moved from the Arabian Sea to the Gulf of Aden.  Several bands of stronger thunderstorms formed west of the center of circulation and the strongest winds were occurring in these bands.  Bands in the eastern half of the circulation consisted primarily of low clouds and showers.  The storms west of the center were generating upper level divergence which was pumping mass away from the tropical cyclone.  Winds to tropical storm force extended out about 60 miles (95 km) from the center of circulation.

Tropical Cyclone 01A will move through an environment somewhat favorable for intensification during the next 24 to 36 hours.  It will move over water where the Sea Surface Temperature is near 29°C.  Tropical Cyclone 01A is moving south of an upper level ridge.  The ridge is producing westerly winds which were blowing toward the top of the circulation.  Those winds may be part of the reason why the stronger thunderstorms are occurring on the western side of the center  The winds are causing some vertical wind shear, but the shear is not likely to be strong enough to prevent intensification.  Tropical Cyclone 01A is likely to strengthen as long as it stays over the Gulf of Aden and it could intensify into the equivalent of a hurricane.  Much drier air is over the Arabian Peninsula and over eastern Africa.  Tropical Cyclone 01A will likely weaken when it moves closer to land and starts to pull drier air into the circulation.

The upper level ridge is steering Tropical Cyclone 01A toward the west.  The ridge is forecast to strengthen and to steer the tropical cyclone a little to the south of west during the next several days.  On its anticipated track Tropical Cyclone 01A is expected to remain over the Gulf of Aden for several more days.  Bands of showers and thunderstorms could bring locally heavy rain to coastal portions of Yemen and northern parts of Somalia.

System Could Bring Heavy Rain to Southeast U.S.

A weather system over the southeastern Gulf of Mexico could bring heavy rain to the southeastern U.S. this week.  An upper level low over the eastern Gulf of Mexico could transfer enough kinetic energy down to the lower troposphere to spin up a low at the surface.  Air flowing around the eastern side of the low is contributing to upper level divergence over Florida.  The divergence enhanced rising motion over Florida and rain fell over parts of the southern and central portions of that state.

The weather system is forecast to move slowly northward during the next several days.  The Sea Surface Temperatures in the southeastern Gulf of Mexico are 24°C to 26°C.  There is enough energy in the upper levels of the water to support the formation of a tropical cyclone.  The upper level low will create southerly winds which will cause moderate vertical wind shear.  The shear will inhibit development, although those winds could contribute to upper level divergence to the east of the weather system.  Upper level divergence could allow the surface pressure to decrease and a low pressure system could form at the surface.  The National Hurricane Center (NHC) issued a special Tropical Weather Outlook on Sunday afternoon on the weather system.  NHC indicated the probability was 40% that a tropical or subtropical cyclone could form during the next five days.

Guidance from numerical models suggest that the weather system will move slowly northward over the eastern Gulf of Mexico during the next few days.  Counterclockwise rotation around the low will transport moist air northward on the eastern side of the low.  The moist air combined with upper level divergence will create the potential for locally heavy rainfall over the southeastern U.S.  Heavy rain could result in floods in some locations.

Tropical Depression 04W Forms East of the Northern Marianas

Tropical Depression 04W formed east of the Northern Marianas very late on Friday.  At 11:00 p.m. EDT on Friday the center of Tropical Depression 04W was located at latitude 18.8°N and longitude 148.5°E which put it about 185 miles (300 km) east of Agrihan.  It was moving toward the northwest at 11 m.p.h. (17 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1003 mb.

An area of showers and thunderstorms persisted for much of the past week east of the Northern Marianas.  Several smaller centers of circulation formed within the area of showers and storms, but those centers ran into strong upper level winds and weakened because strong vertical wind shear and they dissipated.  Another center formed on Friday, but the upper level winds were a little weaker and the center persisted.  An upper level trough south of Japan was still producing southwesterly winds which were blowing toward the top of the circulation.  Those winds were producing moderate vertical wind shear, but the center of circulation persisted.  Most of the thunderstorms were occurring in bands east of the center of circulation.  The bands west of the center consisted primarily of low clouds and showers.

Tropical Depression will move through an area marginally favorable for intensification during the next 24 hours.  it will move over water where the Sea Surface Temperatures are near 28°C.  So, there will be enough energy in the upper ocean to support some intensification.  The upper level trough south of Japan will continue to cause moderate vertical wind shear, but the upper level winds could be weak enough to allow for further intensification.  Tropical Depression 04W could strengthen into a tropical storm on Saturday.

Tropical Depression 04W is moving near the southwestern part of a ridge over the North Pacific Ocean.  The ridge is steering the depression toward the northwest and that general motion is expected to continue for another day or two.  On its anticipated track Tropical Depression 04W is expected to pass near the northernmost Mariana Islands.  It could pass near Asuncion Island, the Maug Islands, Supply Reef and Farallon de Pajaros.  Tropical Depression 04W could bring gust winds, locally heavy rain and higher waves to those places.

Tropical Depression 01E Forms Southwest of Baja California

Tropical Depression 01E formed southwest of Baja California on Thursday afternoon.  A distinct low level center of circulation formed inside a larger area of low pressure that was previously designated as Invest 90E.  The National Hurricane Center (NHC) determined that the system possessed sufficient organization and NHC designated it as Tropical Depression 01E.  At 5:00 p.m. EDT on Thursday the center of Tropical Depression 01E was located at latitude 12.4°N and longitude 126.5°W which put it about 1310 miles (2105 km) west-southwest of the southern tip of Baja California.  Tropical Depression 01E was moving toward the west-northwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1007 mb.

Tropical Depression 01E formed in a larger area of low pressure that was moving slowly westward over the Eastern North Pacific Ocean.  More thunderstorms formed near the center of the low pressure system and a distinct low level center became apparent on visible satellite images.  An upper level trough located west of the depression was producing southwesterly winds which are blowing toward the top of the circulation.  Those winds were causing moderate vertical wind shear and the shear was limiting the development of thunderstorms in the western half of the depression.  Most of the stronger thunderstorms were occurring east of the center of circulation.  The bands in the western half of the depression consisted mostly of lower clouds and showers.  Storms east of the center were producing some upper level divergence which was pumping mass away to the east of the depression.

Tropical Depression 01E will move through an environment only marginally favorable for intensification.  It will move over water where the Sea Surface Temperature is near 27°C.  So, there is enough energy in the upper ocean to support intensification.  However, the upper level trough will continue to produce moderate vertical wind shear.  The upper level winds could be strong enough to prevent further intensification.  If the upper level winds slow, then there is a chance the depression could strengthen into a tropical storm during the next day or two.

Tropical Depression 01E is moving south of a subtropical ridge which is steering the depression toward the west-northwest.  The subtropical ridge is forecast to steer the depression in a general westerly direction during the next several days.  On its anticipated track Tropical Depression 01E poses no immediate threat to any land areas.

System to Bring Wind, Rain to Bahamas and South Florida

A complex weather system near the Bahamas is forecast to move westward and it will bring gusty winds and locally heavy rain to parts of the Bahamas and South Florida during the weekend.  The circulation is strongest in the middle and upper troposphere.  An upper level low is centered near the Bahamas.  Showers and thunderstorms are occurring north and east of the upper low.  There is not a distinct center of circulation in the lower troposphere or at the surface.  There is a small upper level ridge to the east of the upper low and the ridge is producing some upper level divergence which is pumping mass away to the east of the system.

The system will move through an environment that is only marginally favorable for the development of a tropical cyclone.  It will move over water where the Sea Surface Temperature is near 26°C.  So, there is potentially enough energy in the upper ocean to support the development of a minimal tropical cyclone.  The upper low and the ridge to the east are southerly winds near the Bahamas and westerly winds southeast of the Bahamas.  Those winds are causing strong vertical wind shear.  The winds are weaker near the center of the upper low, but there are no thunderstorms in that region at the current time.  If a surface low were to develop under the center of the upper low, then there would be the possibility of some slow development.  A second, possible scenario is that a subtropical cyclone develops north and east of the upper low where the showers and thunderstorms are forming.

The National Hurricane Center (NHC) issued a special Tropical Weather Outlook on this system at 10:45 a.m. EDT on Friday.  NHC indicated that “no significant development” is expected and it gives a 0% probability of the formation of a tropical cyclone.

The upper level low is forecast to move south-southwest over the northwestern Caribbean Sea during the next 72 hours.  The surface and lower parts of the system are forecast to move across the Bahamas toward South Florida during the weekend.  Since the showers and thunderstorms are occurring north and east of the upper low, this could bring gusty winds and locally heavy rain to parts of the Bahamas and South Florida during the weekend.  Some of the humid air on the northeastern periphery of the system could be pulled toward the Carolinas ahead of an approaching cold front.  The moist air could enhance rainfall in eastern South Carolina and eastern North Carolina when the cold front moves through those places and lifts the air.