Author Archives: jay_hobgood

Low Pressure Develops East of the Bahamas

An area of low pressure developed east of the Bahamas and the system was designated as Invest 90L on Sunday afternoon.  At 5:00 p.m. EDT on Sunday the center of Invest 90L was located at latitude 24.0°N and longitude 71.0°W which put it about 260 miles (420 km) east of the Bahamas.  Invest 90L was moving toward the northwest 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 1009 mb.

The circulation of Invest 90L consists of a large asymmetrical low pressure system.  Most of the showers and thunderstorms are occurring northeast of the center of circulation.  Those showers and thunderstorms are being generated by convergence of winds from a large high pressure system over the north Atlantic Ocean into the area of low pressure.  A swirl of low clouds has emerged on the southwestern side of the low, but it is unclear if this is the actual center of circulation or is just a transient mesoscale feature.  A strong pressure gradient between the high pressure system and the low is producing an area of winds to tropical storm force northeast of the center of the low.  The winds are weaker in other parts of the circulation.

Invest 90L is in an environment that is mostly unfavorable for tropical cyclones.  It is moving over water where the Sea Surface Temperature is near 25°C.  So, there is less energy in the upper ocean to support tropical development.  An upper level trough over the southeastern U.S. is producing strong southwesterly winds which are blowing across the top of Invest 90L.  Those winds are producing strong vertical wind shear.  Marginal Sea Surface Temperatures and strong vertical wind shear make the classical development of a tropical cyclone unlikely.  However, the temperature in the upper troposphere is also cold and there may be enough instability in the atmosphere to produce thunderstorms.  If the wind shear decrease, then more thunderstorms could develop closer to the center of circulation and a subtropical cyclone could form.

The high over the north Atlantic is blocking northward movement of Invest 90L and the high is steering it toward the northwest.  A general northwesterly motion is expected to continue for another day or so.  Eventually the high will move off to the east and Invest 90L will start to move toward the northeast.  On its anticipated track Invest 90L will stay east of the U.S. and the Bahamas.  Invest 90L could pass close to Bermuda and it has the potential to bring gusty winds.

Tropical Cyclone Debbie Moves Toward Queensland and Strengthens

Tropical Cyclone Debbie moved toward Queensland and strengthened on Saturday.  At 11:00 p.m. EDT on Saturday the center of Tropical Cyclone Debbie was located at latitude 18.2°S and longitude 151.2°E which put it about 295 miles (475 km) east-northeast of Townsville, Australia.  Debbie was moving toward the west-southwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 95 m.p.h. (155 km/h).  The minimum surface pressure was 982 mb.

The circulation of Tropical Cyclone Debbie continued to become better organized on Saturday.  A primary rainband wrapped around the southern and western sides of the center of circulation.  An eyewall appeared to be forming but there were breaks on the east side of the incipient eyewall.  Additional bands of showers and thunderstorms were revolving around the core of the circulation.  The thunderstorms were generating upper level divergence which was pumping mass out in all directions.  The circulation is very symmetrical and winds to tropical storm force extend out about 190 miles (305 km) from the center.

Tropical Cyclone Debbie will be moving through an environment that is very favorable for intensification during the next 24 hours.  Debbie will move moving over water where the Sea Surface Temperature is near 29°C.  The upper level winds are weak and there is little vertical wind shear.  Tropical Cyclone Debbie will continue to intensify and it could intensify rapidly once a complete eyewall surrounds the center of circulation.  Tropical Cyclone Debbie will become the equivalent of a hurricane/typhoon on Sunday and it could strengthen into the equivalent of a major hurricane before it reaches the coast of Queensland.

Tropical Cyclone Debbie is moving around the eastern end of a ridge centered over northern Australia.  The ridge is steering Debbie toward the west-southwest and that general motion is expected to continue during the next several days.  On its anticipated track the center of Tropical Cyclone Debbie could approach the coast of Queensland in 36 hours.  Tropical Cyclone Debbie could make landfall between Mackay and Rollingstone.  The greatest probability currently is for a landfall between Bowen and Townsville near Ayr.

Tropical Cyclone Debbie will bring destructive winds, storm surge and heavy rain to the coast of Queensland in about 36 hours.

Tropical Cyclone Debbie Develops East of Queensland

The low level circulation of a tropical low east of Queensland continued to organize on Friday and the Australian Bureau of Meteorology designated the system as Tropical Cyclone Debbie early on Saturday.  At 11:00 p.m. EDT on Friday the center of Tropical Cyclone Debbie was located at latitude 17.4°S and longitude 151.9°E which put it about 360 miles (580 km) east-northeast of Townsville, Australia.  Debbie was moving toward the southwest at 6 m.p.h. (9 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 low level circulation of Tropical Cyclone Debbie continued to consolidate around the center of circulation on Friday.  Numerous bands of thunderstorms were revolving around the center of circulation and an eye-like feature appeared on satellite imagery at various times.  The structure of the circulation was fairly symmetrical, although there were more bands of showers and thunderstorms in the eastern half of Debbie.  Thunderstorms near the core of the circulation were generating upper level divergence, which was pumping out mass in all directions.

Tropical Cyclone Debbie is moving through an environment that is very favorable for intensification.  Debbie is moving over water where the Sea Surface Temperature is near 30°C.  The upper level winds are very weak and there is almost no vertical wind shear.  Tropical Cyclone Debbie should continue to intensify and it could intensify very rapidly once a well developed inner core forms around an eye.  Tropical Cyclone Debbie could strengthen into the equivalent of a major hurricane in two or three days.

A subtropical ridge over northern Australia is steering Tropical Cyclone Debbie toward the southwest and a general southwesterly or west-southwesterly motion is expected to continue for the next two or three days.  On its anticipated track Tropical Cyclone Debbie could approach the coast of Queensland near Townsville in about 72 hours.  Debbie could be the equivalent of a major hurricane when it approaches the coast.

Tropical Low Forms Northeast of Queensland

A Tropical Low organized quickly northeast of Queensland over the Coral Sea on Thursday.  At 11:00 p.m. EDT on Thursday the center of the Tropical Low was located at latitude 16.1°S and longitude 151.4°E which put it about 370 miles (600 km) northeast of Townsville, Australia.  The Tropical Low as moving toward the south at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1005 mb.

The low level circulation of the Tropical Low organized quickly on Thursday.  Numerous bands of showers and thunderstorms formed and they began to wrap around a center of circulation.  The distribution of showers and thunderstorms was relatively symmetrical, although there are a few more storms in the eastern half of the circulation.  Storms closer to the center started to generate upper level divergence.

The Tropical Low is in an environment that is very favorable for intensification.  The low is over water where the Sea Surface Temperature is near 30°C.  The upper level winds are light and there is very little vertical wind shear.  The Tropical Low is likely to continue to organize quickly in the favorable environment and it will likely become a named tropical cyclone on Friday.  Once thunderstorms consolidate around the center of circulation, a period of rapid intensification may occur.

The Tropical Low is currently being steered to the south and that motion could continue for another 12 to 24 hours.  A strengthening subtropical ridge is forecast to turn the Tropical Low toward the west in about 24 hours.  On its anticipated track the Tropical Low could approach the coast of Queensland in about three days.

Tropical Cyclone Caleb Forms Over South Indian Ocean

Tropical Cyclone Caleb formed over the South Indian Ocean on Thursday.  At 8:00 a.m. EDT on Thursday the center of Tropical Cyclone Caleb was located at latitude 13.0°S and longitude 100.7°E which put it about 255 miles (410 km) east-southeast of Cocos Island.  Caleb was moving toward the south-southeast at 6 m.p.h. (9 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 995 mb.

Although there is a well defined low level circulation in Tropical Cyclone Caleb, the distribution of thunderstorms is asymmetrical.  The strongest thunderstorms are occurring in the northwestern quadrant of the circulation and they are in the primary rainband.  Those thunderstorms contain the strongest winds.  There are few thunderstorms in the other parts of the circulation, although there are some bands of lower clouds and showers in those regions.  The thunderstorms in the primary rainband are generating upper level divergence which is pumping out mass to the west of Tropical Cyclone Caleb.

Tropical Cyclone Caleb is in an environment that is marginal for intensification.  Caleb is moving over water where the Sea Surface Temperature is near 28°C.  So, there is enough energy in the upper ocean to support intensification.  However, an upper level ridge located southeast of Caleb is producing easterly winds which are blowing across the top of the tropical cyclone.  The easterly winds are generating moderate vertical wind shear and the shear is probably the reason why most of the thunderstorms are occurring in the northwestern quadrant of the circulation.  The moderate shear will inhibit intensification, but some strengthening may be possible if the upper level winds abate.

A ridge to the east of Caleb is steering the tropical cyclone toward the south-southeast and that general motion is expected to continue for another day or two.  Eventually, a second ridge is forecast to strengthen and steer Tropical Caleb back toward the northwest.

Tropical Cyclone Enawo Hits Madagascar

Powerful Tropical Cyclone Enawo made landfall on the coast of northeastern Madagascar near Ambohitralanana on Tuesday.  Tropical Cyclone Enawo was the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale when it made landfall.  At 10:00 p.m. EST on Tuesday the center of Tropical Cyclone Enawo was located near latitude 15.5°S and longitude 49.2°E which put it near Mandritsara, Madagascar.  Enawo was moving toward the southwest at 7 m.p.h. (11 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 980 mb.

Even though the center has been over land for more than 12 hours the circulation of Tropical Cyclone Enawo is still very well organized.  The structure is very symmetrical and there are multiple bands of thunderstorms revolving around the center of circulation.  The strongest winds are occurring in the portions of the rainbands that are over the Indian Ocean.  The circulation of Tropical Cyclone Ewano is still very large and winds to tropical storm force extend out about 200 miles (320 km) from the center.  Thunderstorms near the core of the circulation are generating upper level divergence which is pumping out mass in all directions.

The circulation of Tropical Cyclone Enawo will continue to weaken on Wednesday because the center is over land.  However, the atmospheric environment is favorable for a tropical cyclone.  The upper level winds are weak and there is very little vertical wind shear.  The lack of wind shear will cause the circulation of Tropical Cyclone Enawo to spin down more slowly and it is likely to persist for several more days.

Tropical Cyclone Enawo is moving around the western end of a subtropical high pressure system which is steering the tropical cyclone toward the southwest.  Tropical Cyclone Enawo is likely to turn more toward the south on Wednesday as it reaches the western end of the subtropical high.  On its anticipated track Tropical Cyclone Enawo will move over the center of Madagascar and it could pass near Antananarivo in 24 to 36 hours.  Tropical Cyclone Enawo is producing very heavy rainfall and flash flooding is a serious risk in areas of steep terrain.

Powerful Tropical Cyclone Enawo Nears Madagascar

Powerful Tropical Cyclone Enawo neared Madagascar late on Monday.  At 11:00 p.m. EST on Monday the center of Tropical Cyclone Enawo was located at latitude 14.7°S and longitude 51.1°E which put it about 140 miles (225 km) northeast of Mananara, Madagascar.  Enawo was moving toward the west-southwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 145 m.p.h. (230 km/h) and there were wind gusts to 175 m.p.h. (285 km/h).  The minimum surface pressure was 931 mb.

Tropical Cyclone Enawo intensified rapidly on Monday and it is now the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.  The circulation of Tropical Cyclone Enawo is very well organized.  There is an circular eye with a diameter of 30 miles (50 km) at the center of the circulation.  The eye is surround by a ring of strong thunderstorms and the strongest winds are occurring in the eyewall.  The remainder of the circulation is symmetrical and additional well formed bands of thunderstorms are revolving around the core of the circulation.  Winds to hurricane force extend out about 70 miles (110 km) from the center.  Winds to tropical storm force extend out about 220 miles (350 km) from the center.

The Hurricane Intensity Index (HII) for Tropical Cyclone Enawo is 29.9.  The Hurricane Size Index (HSI) is 25.0 and the Hurricane Wind Intensity Size Index (HWISI) is 54.9.  The indices indicate that Tropical Cyclone Enawo is capable of causing significant widespread wind damage.  Tropical Cyclone Enawo is as intense as Hurricane Katrina was just before it made landfall in the coast of Mississippi in 2005.  Enawo is a little smaller than Hurricane Katrina was when Katrina was moving across the Gulf of Mexico in 2005.

Tropical Cyclone Enawo is moving through a very favorable environment.  Enawo is moving over water where the Sea Surface Temperature is near 29°C.  The upper level winds are weak and there is little vertical wind shear.  Tropical Cyclone Enawo is likely to maintain its intensity until it reaches the coast of Madagascar in a few hours.  Enawo will weaken after the center moves inland.

A subtropical ridge is steering Tropical Cyclone Enawo a little to the south of due west and that general motion is expected to continue for another 12 to 24 hours.  Tropical Cyclone Enawo will move near the western end of the subtropical ridge in another day or so and it will start to move more toward the south when it nears the end of the ridge.  On its anticipated track Tropical Cyclone Enawo will make landfall on the northeast coast of Madagascar near Ambohitralanana in a few hours.

Tropical Cyclone Enawo is a dangerous storm.  It is capable of causing widespread significant wind damage when it moves over eastern Madagascar.  The strong winds will also drive water toward the coast and Tropical Cyclone Enawo will generate a significant storm surge near where the center makes landfall.  Enawo will produce very heavy rain and significant inland flooding could occur if rainfall exceeds the capacity of rivers and streams.

Tropical Cyclone Enawo Moves Toward Madagascar and Strengthens

Tropical Cyclone Enawo moved toward Madagascar and strengthened on Sunday.  At 10:00 p.m. EST on Sunday the center of Tropical Cyclone Enawo was located at latitude 14.0°S and longitude 54.1°E which put it about 340 miles (550 km) east-northeast of Mananara, Madagascar.  Enawo was moving toward the west at 7 m.p.h.  The maximum sustained wind speed was 105 m.p.h. (170 km/h) and there were wind gusts to 125 m.p.h. (205 km/h).  The minimum surface pressure was 961 mb.

The circulation of Tropical Cyclone Enawo is very well organized.  A circular eye is at the center of circulation.  The eye is surrounded by a ring of thunderstorms.  Additional bands of showers and thunderstorms are revolving around the core of the circulation.  The circulation is very symmetrical although there are more thunderstorms in the northwestern quadrant of the circulation.  Thunderstorms in the core of the circulation are generating upper level divergence which is pumping mass away from the tropical cyclone.

The size of the circulation of Tropical Cyclone Enawo increased on Sunday.  Winds to hurricane force extend out about 30 miles (50 km) from the center of circulation.  Winds to tropical storm force extend out about 250 miles (400 km) from the center.  The Hurricane Intensity Index (HII) for Tropical Cyclone Enawo is 17.8.  The Hurricane Size Index (HSI) is 17.8 and the Hurricane Wind Intensity Size Index (HWISI) is 35.6.  These indices indicated that Tropical Cyclone Enawo is capable of causing serious wind damage on a regional scale.

Tropical Cyclone Enawo will continue to move through an favorable environment.  It will move over water where the Sea Surface Temperature is near 29°C.  The upper level winds are weak and there is little vertical wind shear.  Tropical Cyclone Enawo will continue to intensify during the next 24 hours and it could become the equivalent of a major hurricane.

A subtropical ridge is steering Tropical Cyclone Enawo toward the west and a general west or west-southwest motion is expected to continue during the next several days.  On its anticipated track Tropical Cyclone Enawo will approach the coast of Madagascar in about 36 hours.  Enawo will be capable of causing serious wind damage.  It will also generate a storm surge along the coast.  Tropical Cyclone Enawo will produce very heavy rain and a potential for flooding over eastern and southern Madagascar.

Tropical Cyclone Blanche Strengthens Near Coast of Western Australia

Tropical Cyclone Blanche strengthened on Sunday as it moved over the Timor Sea toward the coast of Western Australia.  At 7:00 p.m. EST on Sunday the center of Tropical Cyclone Blanche was located at latitude 14.0°S and longitude 128.2°E which put it about 100 miles (165 km) north of Wyndham, Australia.  Blanche was moving toward the southwest at 11 m.p.h. (17 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 988 mb.

The inner core of Tropical Cyclone Blanche became more organized on Sunday.  A band of thunderstorms wrapped about two thirds of the way around the southern and western portions of the center.  The band has the appearance of a partial eyewall.  The strongest winds are occurring in the band near the center.  The thunderstorms are generating upper level divergence which is pumping out mass to the west and southeast of the Tropical Cyclone Blanche.  The upper level divergence allowed the surface pressure to decrease and the wind speed to increase.

Tropical Cyclone Blanche will be over the Timor Sea for a few more hours.  It will be in an environment that is favorable for intensification during that time.  Blanche will move over water where the Sea Surface Temperature is near 29°C.  An upper level ridge east of Blanche is producing northerly winds which are blowing toward the tropical cyclone.  The winds are causing moderate vertical wind shear, but the shear was not strong enough to prevent intensification on Sunday.  Tropical Cyclone Blanche could intensify a little more before it makes landfall.

A subtropical ridge is steering Tropical Cyclone Blanche toward the southwest and that general motion is expected to continue.  On its anticipated track Tropical Cyclone Blanche will make landfall on the coast of Western Australia northwest of Wyndham in a few hours.  Blanche will bring gusty winds and some storm surge to the coast.  It will cause locally heavy rain and the potential for flooding as it moves inland.

Tropical Cyclone Enawo Intensifies Into Equivalent of a Hurricane

Tropical Cyclone Enawo intensified into the equivalent of a hurricane/typhoon on Saturday.  At 10:00 p.m. EST on Saturday the center of Tropical Cyclone Enawo was located at latitude 13.9°S and longitude 56.3°E which put it about 475 miles (765 km) north of St. Denis, La Reunion.  Enawo was moving toward the south at 2 m.p.h. (3 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 979 mb.

A primary rainband wrapped around the center of circulation and there was evidence of an eye on microwave satellite imagery.  A broken ring of thunderstorms surrounded the eye.  Additional bands of thunderstorms were rotating around the core of the circulation.  Thunderstorms near the center of circulation were generating upper level divergence which was pumping out mass in all directions.  The circulation of Tropical Cyclone Enawo is relatively small and winds to tropical storm force only extended out about 100 miles (160 km) from the center.

Tropical Cyclone Enawo will move through an environment very favorable for intensification during the next several days.  It will move over water where the Sea Surface Temperature is near 30°C.  The upper level winds are weak and there is little vertical wind shear.  Tropical Cyclone Enawo will continue to intensify and it could intensify rapidly for a time.  Tropical Cyclone Enawo is likely to become the equivalent of a major hurricane within 48 hours.

Tropical Cyclone Enawo was in an area where the steering currents were weak and it did not move much on Saturday.  A subtropical ridge east of Enawo is forecast to strengthen and extend westward.  When the ridge strengthens, it is expected to steer Tropical Cyclone Enawo toward the west-southwest.  On its anticipated track Tropical Cyclone Enawo could approach the coast of northeast Madagascar in 48 to 72 hours.  It could be a strong, dangerous tropical cyclone at that time.