Author Archives: jay_hobgood

Tropical Storm Don Forms East of Windward Islands

Tropical Storm Don formed east of the Windward Islands on Monday.  An Air Force Reserve Hurricane Hunter reconnaissance aircraft found a small, but well defined center of circulation in a cluster of thunderstorms formerly designated Invest 91L.  Based on information from the recon plane, the National Hurricane Center classified the system at Tropical Storm Don.  At 5:00 p.m. EDT on Monday the center of Tropical Storm Don was located at latitude 11.2°N and longitude 52.6°W which put it about 595 miles (955 km) east of Trinidad.  Don was moving toward the west at 17 m.p.h. (28 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 1009 mb.

A Tropical Storm Warning has been issue for Grenada.  Tropical Storm Watches are in effect for Barbados, St. Vincent, the Grenadines and St. Lucia.

The reconnaissance plane found a small, tight center of circulation near the surface.  A thin band of showers and thunderstorms wrapped partially around the western side of the center.  Other thin bands of showers and thunderstorms were occurring north and west of the center.  There were fewer showers and thunderstorms in the eastern half of Tropical Storm Don.  The circulation of Tropical Storm Don is small and winds to tropical storm force only extend out about 25 miles (40 km) from the center of circulation.  Thunderstorms in the band west of the center of circulation were generating some upper level divergence but it was not well developed.

Tropical Storm Don will move through an environment that will be somewhat favorable for intensification during the next several days.  Don will move over water where the Sea Surface Temperature is near 29°C.  An upper level ridge east of Don is generating easterly winds which are blowing over the top of the tropical storm.  Those easterly winds are generating some vertical wind shear and the shear may partly explain why there are fewer showers and thunderstorms in the eastern half of the circulation.  The shear will also inhibit intensification, but Tropical Storm Don could strengthen during the next 24 to 48 hours.

A strong subtropical high over the Atlantic Ocean is steering Tropical Storm Don toward the west and a generally westward motion is expected to continue during the next several days.  On its anticipated track the center of Tropical Storm Don could pass south of Barbados on Tuesday.  Tropical Storm Don could move over the southern Windward Islands on Tuesday night.  Tropical Storm Don could bring gusty winds and locally heavy rain to the southern Windward Islands.  Flash floods could occur in areas of steep terrain, if they receive locally heavy rainfall.

Hurricane Fernanda Slowly Weakens As It Moves West

Hurricane Fernanda weakened slowly as it moved farther west over the Eastern North Pacific Ocean on Sunday.  At 11:00 p.m. EDT on Sunday the center of Hurricane Fernanda was located at latitude 13.0°N and longitude 129.2°W which put it about 1440 miles (2315 km) west-southwest of the southern tip of Baja California.  Fernanda was moving toward the west-northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 140 m.p.h. (220 km/h).  The minimum surface pressure was 960 mb.

Hurricane Fernanda completed at least one eyewall replacement cycle in which an outer eyewall formed around the original eyewall.  Eventually, the inner eyewall dissipated and a larger eye formed inside the outer eyewall.  The eyewall replacement cycle weakened Hurricane Fernanda when the stronger, inner eyewall dissipated.  Although Hurricane Fernanda is weaker, it is still a powerful hurricane.  There is a circular eye at the center of circulation.  A ring of strong thunderstorms still surrounds the eye and the strongest winds are occurring in that ring of storms.  Additional bands of showers and thunderstorms are revolving around the core of the circulation.  Thunderstorms in the core of Hurricane Fernanda are generating strong upper level divergence which are pumping out mass in all directions.

Hurricane Fernanda is moving over water where the Sea Surface Temperature (SST) is near 29°C.  The upper level winds are weak and there is little vertical wind shear.  Fernanda will gradually move over cooler SSTs.  When Fernanda moves over the cooler SSTs, it will extract less energy from the ocean and the hurricane will continue to weaken.  The weakening could occur very gradually because the wind shear is limited.

Hurricane Fernanda is moving south of a subtropical high pressure system which is steering the hurricane toward the west-northwest.  The subtropical high is expected to steer Fernanda toward the west-northwest during the next several days.

Tropical Storm Talas Makes Landfall in Vietnam

Tropical Storm Talas made landfall on the coast of Vietnam on Sunday.  Talas was bringing gusty winds and heavy rainfall to parts of Vietnam, Laos and Thailand.  At 5:00 p.m. EDT on Sunday the center of Tropical Storm Talas was located at latitude18.6°N and longitude 105.5°E which put the center near Vinh, Vietnam.  Talas was moving toward the west at 17 m.p.h. (27 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 984 mb.

Tropical Storm Talas strengthened before it made landfall in Vietnam.  A primary band wrapped around the western and southern sides of the center of circulation.  Thunderstorms formed near the center of Talas as the tropical storm approached the coast of Vietnam.  The strongest winds in Tropical Storm Talas were occurring in thunderstorms over the South China Sea.  Tropical Storm Talas will weaken as it moves farther inland.

Tropical Storm Talas was bringing gusty winds and heavy rain to parts of Vietnam, Laos and Thailand.  Locally heavy rain could cause flooding, which will be the greatest risk as Tropical Storm Talas moves farther inland.

Tropical Storm Talas Forms East of Vietnam

Tropical Storm Talas formed east of Vietnam on Saturday.  At 5:00 p.m. EDT on Saturday the center of Tropical Storm Talas was located at latitude 17.3°N and longitude 110.1°E which put it about 170 miles (270 km) east-northeast of Da Nang, Vietnam.  Talas was moving toward the west at 11 m.p.h. (17 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 996 mb.

A large area of showers and thunderstorms persisted over the South China Sea for the past several days.  A distinct center of circulation began to develop in the northern part of the area of thunderstorms.  The Japan Meteorological Agency classified the system as Tropical Storm Talas on Saturday.

The circulation of Tropical Storm Talas is still organizing.  The center of rotation was near the northwestern edge of the area of thunderstorms.  Additional thunderstorms were beginning to form near the center of circulation.  Several bands of showers and thunderstorms were southwest of the center.  Bands of lighter showers were occurring in the remainder of Tropical Storm Talas.  Thunderstorms forming near the center of circulation were beginning to generate strong upper level divergence which was pumping out mass.

Tropical Storm Talas has about 24 hours to strengthen.  Talas will move over water where the Sea Surface Temperature is near 30°C.  An upper level ridge north of Talas is producing easterly winds which are blowing toward the top of the tropical storm.  There is some vertical wind shear, but the shear appears to have diminished during the past few hours.  Since Tropical Storm Talas will be moving through an environment of very warm water and reduced vertical wind shear, it will likely strengthen during the next 24 hours.

A subtropical ridge north of Talas is steering the tropical storm toward the west and motion a little to the north of due west is forecast.  On its anticipated track the center of Tropical Storm Talas will pass south of Hainan Island.  Tropical Storm Talas will approach the coast of Vietnam near Vinh in about 24 hours.  Tropical Storm Talas will bring gusty winds and locally heavy rain to Central Vietnam when it makes landfall.

Hurricane Fernanda Intensifies Rapidly to Category 4

Hurricane Fernanda intensified rapidly to Category 4 on the Saffir-Simpson Scale on Friday.  At 5:00 p.m. EDT on Friday the center of Hurricane Fernanda was located at latitude 10.7°N and longitude 119.7°W which put it about 1060 miles (1710 km) southwest of the southern tip of Baja California.  Fernanda was moving toward the west at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 130 m.p.h. (215 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 960 mb.

A clear circular eye formed at the center of Hurricane Fernanda.  The eye is surrounded by a ring of very strong thunderstorms and the strongest winds are occurring in the eyewall.  Additional bands of showers and thunderstorms formed outside the core of Fernanda.  There are more bands in the eastern half of the hurricane, but the overall circulation is fairly symmetrical.  The thunderstorms in the core of Fernanda are generating strong upper level divergence which is pumping mass away from the hurricane.

Fernanda is a small hurricane.  Winds to hurricane force only extend out about 25 miles (40 km) from the center of circulation.  Winds to tropical storm force only extend out about 70 miles (110 km) from the center.  The Hurricane Intensity Index (HII) is 25.1.  The Hurricane Size Index (HSI) is 9.0 and the Hurricane Wind Intensity Size Index (HWISI) is 34.1.  The indices indicate that Hurricane Fernanda is somewhat similar in size and strength to Hurricane Charley in 2004 when Charley was approaching the southwest coast of Florida.

Hurricane Fernanda will remain in an environment very favorable for intensification for another 24 to 48 hours.  It will move over water where the Sea Surface Temperature (SST) is near 28.5°C.  The upper level winds are weak and there is little vertical wind shear.  Hurricane Fernanda has a chance to intensify into a Category 5 hurricane on the Saffir-Simpson Scale before it moves into a less favorable environment.  When a hurricane becomes as intense as Hurricane Fernanda is, an outer rainband can wrap around the eye and an eyewall replacement cycle can occur.  If an eyewall replacement cycle occurs in Hurricane Fernanda, then fluctuations in intensity may also happen.  Eventually Fernanda will move over cooler SSTs and the hurricane will start to weaken.

Hurricane Fernanda is moving south of a subtropical ridge and the ridge is steering the hurricane a little south of due west.  A general westward motion is forecast to continue during the next few days.  On its anticipated track Hurricane Fernanda will continue to move farther away from Mexico.  Fernanda could approach Hawaii by the end of next week.

Fernanda Rapidly Intensifies Into a Hurricane

Former Tropical Storm Fernanda rapidly intensified into a hurricane on Thursday.  At 5:00 p.m. EDT on Thursday the center of Hurricane Fernanda was located at latitude 11.2°N and longitude 116.0°W which put it about 900 miles (1450 km) south-southwest of the southern tip of Baja California.  Fernanda was moving toward the west at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (155 km/h).  The minimum surface pressure was 990 mb.

A primary rainband wrapped around the center of circulation and an eye appeared intermittently on visible satellite images on Thursday afternoon.  The improved organization of the inner core of Fernanda allowed it to intensify rapidly into a hurricane.  The distribution of thunderstorms become more symmetrical and circulation exhibited a more circular appearance.  Thunderstorms in the inner core began to generate strong upper level divergence which pumped out mass in all directions.  The divergence of mass allowed the surface pressure to decrease and the wind speeds to increase rapidly.

Hurricane Fernanda will move through an environment that will be favorable for further intensification during the next two days.  Fernanda will move over water where the Sea Surface Temperature (SST) is near 29°C.  An upper level ridge northeast of Fernanda is producing easterly winds which are blowing toward the top of the hurricane.  However, the speed of the upper level winds decreased on Thursday and there is less vertical wind shear.  A combination of a well organized inner core, warm SSTs and reduced vertical wind shear resulted in rapid intensification of Fernanda into a hurricane.  Rapid intensification could continue for another 24 to 36 hours and Fernanda is forecast to become a major hurricane on Friday.

A subtropical ridge to the north of Fernanda is steering the hurricane toward the west and a general westerly motion is expected to continue for several more days.  On its anticipated track Hurricane Fernanda will move farther away from Mexico.

TD 6E Strengthens Into Tropical Storm Fernanda

Tropical Depression Six-E strengthened into Tropical Storm Fernanda on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Fernanda was located at latitude 11.9°N and longitude 113.1°W which put it about 790 miles (1270 km) south-southwest of the southern tip of Baja California.  Fernanda was moving toward the west at 9 m.p.h. (15 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 1004 mb.

Thunderstorms on the western side of the center of Tropical Storm Fernanda increased on Wednesday night.  Several bands of showers of thunderstorms formed in the western half of the circulation, but the distribution of convection remained asymmetrical.  There were few showers and thunderstorms in the eastern half of the circulation.  The thunderstorms in the western half of the were generating upper level divergence which was pumping out mass to the west of Tropical Storm Fernanda.

Tropical Storm Fernanda is currently in an environment that is moderately favorable for intensification.  It is moving over water where the Sea Surface Temperature (SST) is near 29.5°C.  An upper level ridge north of Fernanda is producing easterly winds which are blowing toward the top of the tropical storm.  Those winds are causing moderate vertical wind shear and the shear may be the cause of the asymmetrical distribution of thunderstorms.  Fernanda is likely to move into an area where the upper level winds are weaker and the shear will decrease.  Warm SSTs and less wind shear should allow Tropical Storm Fernanda to intensify into a hurricane later this week.  Once an eye forms, a period of rapid intensification will be possible and Fernanda could eventually become a major hurricane.

A subtropical ridge north of Fernanda is steering the tropical storm westward and a general westerly motion is expected to continue for the next few days.  On its anticipated track Tropical Storm Fernanda will move away from Mexico and it could move into the Central Pacific in a few days.

Tropical Depression Six-E Forms West of Mexico

The Eastern North Pacific basin continues to be active tropically.  Tropical Depression Six-E formed west of Mexico on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Tropical Depression Six-E was located at latitude 12.2°N and longitude 109.9°W which put it about 740 miles (1190 km) south of the southern tip of Baja California.  It was moving toward the west at 12 m.p.h. (19 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.

A center of circulation consolidated within a large area of thunderstorms south of Baja California on Tuesday.  A primary band of showers and thunderstorms wrapped around the western and southern sides of the center of circulation.  Additional bands of showers and thunderstorms were beginning to form north and west of the center.  There were not many showers and storms in the eastern half of the circulation.  The thunderstorms near the core of the circulation were beginning generate upper level divergence which was pumping away from depression.

Tropical Depression Six-E will move through an environment that will be favorable for intensification.  It will move over water where the Sea Surface Temperature (SST) is near 29°C.  Tropical Depression Six-E is near the western end of an upper level ridge and the upper level winds are relatively weak.  Warm SSTs and little vertical wind shear should allow the depression to strengthen during the next several days.  Tropical Depression Six-E is likely to become a tropical storm on Wednesday and it could become a hurricane later this week.

Tropical Depression Six-E is moving south of a subtropical ridge which is steering the depression toward the west.  The subtropical ridge is expected to continue to steer the depression toward the west during the next few days.  On its anticipated track the depression is expected to move away from the coast of Mexico.

Eugene Becomes a Hurricane Southwest of Baja California

Tropical Storm Eugene strengthened rapidly into a hurricane on Saturday as it moved southwest of Baja California.  At 11:00 p.m. EDT on Saturday the center of Hurricane Eugene was located at latitude 14.4°N and longitude 113.5°W which put it about 630 miles (1020 km) south-southwest of the southern tip of Baja California.  Eugene was moving toward the northwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (155 km/h).  The minimum surface pressure was 990 mb.

A primary raindband wrapped around the center of Hurricane Eugene on Saturday and an eye formed at the center of circulation.  The eye had a diameter of 30 miles (50 km).  Additional bands of showers and thunderstorms were revolving around the core of the circulation.  Thunderstorms were generating well developed upper level divergence which was pumping mass away in all directions.  The circulation of Hurricane Eugene was symmetrical and well organized.

Hurricane Eugene was moving over water where the Sea Surface Temperature (SST) was near 29°C.  Eugene was underneath the western end of an upper level ridge.  The ridge was producing southerly winds which were blowing toward the top of the hurricane, but the vertical wind shear was not very strong.  Eugene is likely to intensify on Sunday.  It will gradually move over cooler SSTs and Hurricane Eugene will move over water where the water is cooler than 26°C on Monday.  When Eugene reaches the cooler SSTs, it will begin a steady weakening trend.

Hurricane Eugene is moving around the western end of a subtropical ridge which is steering it toward the northwest.  Eugene is expected to continue to move toward the northwest during the next several days.  On its anticipated track Hurricane Eugene will move parallel to the west coast of Baja California.

Tropical Storm Eugene Forms South of Baja California

A distinct center of circulation consolidated within a broader area of low pressure south of Baja California on Friday and the National Hurricane Center classified the system as Tropical Storm Eugene.  At 5:00 p.m. EDT on Friday the center of Tropical Storm Eugene was located at latitude 11.9°N and longitude 111.2°W which put it about 765 miles (1230 km) south of the southern tip of Baja California.  Eugene 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 1006 mb.

The circulation of Tropical Storm Eugene is large and there are numerous bands of showers and thunderstorms rotating around the center of circulation.  A primary rainband is wrapping around the southern and eastern sides of the center and the strongest winds are occurring northeast of the center of circulation.  The circulation is circular and symmetrical.  Thunderstorms around the core of Eugene are beginning to generate upper level divergence which is pumping out mass in all directions.

Tropical Storm Eugene will move through an environment that is favorable for intensification.  Eugene will move over water where the Sea Surface Temperature is near 29°C.  The upper level winds over Tropical Storm Eugene are relatively weak and there is not a lot of vertical wind shear.  The circulation of Tropical Storm Eugene will continue to consolidate and it is likely to intensify during the weekend.  It is likely to become a hurricane and it could intensify rapidly if an eye forms.

Tropical Storm Eugene is moving near the western end of a subtropical ridge which is steering it toward the northwest.  A generally northwesterly motion is expected to continue during the next few days.  On its anticipated track Tropical Storm Eugene would move parallel to the west coast of Baja California and the center would remain west of the coast.