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Low Pressure System Forms Over Southwest Gulf of Mexico

A surface low pressure system formed over the southwestern Gulf of Mexico on Wednesday.  At 8:00 p.m. EDT on Wednesday the center of the low pressure system was located at latitude 20.8°N and longitude 95.4°W which put it about 70 miles (110 km) east-southeast of Nautla, Mexico.  The low was moving toward the north 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 1009 mb.

The northern end of a trough of low pressure moved over the Bay of Campeche on Wednesday and a surface low formed when the trough moved over the southwestern Gulf of Mexico.  More thunderstorms developed near the center of the low pressure system.  Divergence from a surface high pressure system over the U.S. was converging with the northern periphery of the circulation around the surface low and a band of showers and thunderstorms was occurring over the west central Gulf of Mexico.  Storms near the center of the low were starting to generate some upper level divergence.

The low pressure system will move through an environment that will be favorable for intensification during the next 24 to 36 hours.  The low will move over water where the Sea Surface Temperature is near 29°C.  It will move under an upper level ridge where the winds are weak and divergent.  The low could intensify slowly if it gets better organized on Thursday.  The National Hurricane Center is indicating that there is a 60% probability of formation of either a tropical or subtropical storm.  A reconnaissance plane has been tentatively tasked to investigate the low pressure system on Thursday afternoon.

The upper level ridge over the surface low pressure system will steer the low toward the northeast during the next several days.  On its anticipated track the low could approach the northeastern coast of the Gulf of Mexico on Friday.  The low will bring gusty winds and locally heavy rain.  The winds will generate higher waves and there could be a storm surge of 3 to 6 feet (1 to 2 meters).

Tropical Low Pressure System Will Drop Heavy Rain on Southern Mexico

A tropical low pressure system designated Potential Tropical Cyclone Seventeen-E by the National Hurricane Center will drop heavy rain on parts of southern Mexico.  At 11:00 p.m. EDT on Tuesday the center of Potential Tropical Cyclone Seventeen-E was located at latitude 13.7°N and longitude 93.4°W which put it about 210 miles (340 km) southeast of Salina Cruz, Mexico.  It was moving toward the west-northwest at 10 m.p.h. (16 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 was1005 mb.

The government of Mexico issued a Tropical Storm Watch for the portion of the coast from Barra de Tonala to Puerto Escondido.

A large low pressure system moved slowly from the western Caribbean Sea into the extreme Eastern North Pacific Ocean west of Guatemala during the past few days.  The low pressure system dropped heavy rain over parts of Nicaragua, Honduras, El Salvador, Guatemala and Belize.  Several smaller centers of circulation developed within the larger low pressure system on Tuesday.  More thunderstorms developed around one of the smaller centers west of Guatemala on Tuesday evening and the sustained wind speed increased to 35 m.p.h. (55 km/h).  Some bands of showers and thunderstorms were beginning to develop around the low pressure system.  A potential primary rainband appeared to be wrapping around the western and southern portions of the center of circulation.

The low pressure system will move through an environment favorable for some intensification on Wednesday.  The low will move over water where the Sea Surface Temperature is near 29.5°C.  An upper level high over the eastern Gulf of Mexico will produce northeasterly winds which will blow toward the top of the low pressure system.  Those winds will cause some vertical wind shear which will inhibit intensification.  The low pressure system will be close to the coast of Mexico, which will also limit intensification.  The low pressure system could intensify while the center is over the warm water.  It is forecast to become a tropical storm on Wednesday, which is why the Tropical Storm Watch was issued.

A high pressure system over the eastern Gulf of Mexico and northwestern Caribbean Sea will steer Potential Tropical Cyclone Seventeen-E toward the northwest during the next several days.  On its anticipated track the low pressure system could make landfall on the coast of Mexico between Barra de Tonala and Puerto Escondido within 24 hours.  It will bring gusty winds to that portion of the coast.  The low pressure system will drop heavy rain on parts of Chiapas and Oaxaca.  It could cause flash floods in some locations.

Tropical Depression Fifteen Forms Southeast of Cabo Verde Islands

Tropical Depression Fifteen formed southeast of the Cabo Verde Islands on Monday.  At 5:00 p.m. EDT on Monday the center of Tropical Depression Fifteen was located at latitude 13.2°N and longitude 20.2°W which put it about 320 miles (515 km) southeast of the Cabo Verde Islands.  The depression was moving toward the northwest at 8 m.p.h. (13 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 1006 mb.

A large, well developed low pressure system embedded in the northern end of a tropical wave moved over the Atlantic Ocean west of North Africa on Monday.  Bands of showers and thunderstorms began to strengthen when the low moved over water and the National Hurricane Center designated the system as Tropical Depression Fifteen.  Bands of showers and thunderstorms were revolving around the center of the depression.  Storms closer to the center were generating upper level divergence which was pumping mass away from Tropical Depression Fifteen.  The circulation around the depression was quite large.  The diameter of the low level circulation was about 500 miles (800 km).

Tropical Depression Fifteen will move through an environment favorable for intensification during the next 24 to 48 hours.  The depression will move over water where the Sea Surface Temperature is near 28°C.  It will move under the western end of an upper level ridge centered over North Africa.  The upper level winds will be weak and there will be little vertical wind shear during the next day or two.  Tropical Depression Fifteen is likely to strengthen into Tropical Storm Nestor.

The ridge over North Africa will steer Tropical Depression Fifteen toward the northwest during the next several days.  On its anticipated track the center of the depression could reach the Cabo Verde Islands within 24 hours.  Since the depression is forecast to strengthen into a tropical storm watches and/or warnings could be issued.

Elsewhere over the Atlantic Ocean, Tropical Storm Melissa completed a transition to an extratropical cyclone on Monday.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Melissa was located at latitude 41.0°N and longitude 51.4°W which put it about 405 miles (650 km) south-southeast of Cape Race, Newfoundland.  Melissa was moving toward the east at 23 m.p.h. (37 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 1004 mb.

Tropical Storm Ema Forms Southwest of Hawaii

Tropical Storm Ema formed southwest of Hawaii on Saturday.  At 5:00 p.m. EDT on Saturday the center of Tropical Storm Ema was located at latitude 21.1°N and longitude 163.9°W which put it about 245 miles (395 km) southeast of French Frigate Shoals.  Ema was moving toward the northwest at 13 m.p.h. (20 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 1003 mb.

A Tropical Storm Watch has been issued for the Papahanaumokuakea Marine National Monument from Nihoa to French Frigate Shoals to Maro Reef.

A distinct low level center of circulation formed in a small area of low pressure southwest of Hawaii on Saturday morning and the Central Pacific Hurricane Center designated the system as Tropical Storm Ema.  The circulation around Tropical Storm Ema was very small.  Winds to tropical storm force extended out 45 miles (75 km) from the center of circulation.  Several short bands of showers and thunderstorms developed around the center of Ema.  Storms near the center began to generate upper level divergence which pumped mass away from the tropical storm.

Tropical Storm Ema will move through an environment marginally favorable for intensification during the next 12 to 24 hours.  Ema will move over water where the Sea Surface Temperature is near 28°C.  An upper level trough west of Hawaii will produce southerly winds which will blow toward the top of the circulation.  Those winds will cause moderate vertical wind shear which inhibit the intensification of Tropical Storm Ema.  Ema could strengthen a little during the next 12 to 24 hours.  The upper level trough will produce stronger southwesterly winds on Sunday and the wind shear will increase.  Stronger wind shear will weaken Tropical Storm Ema in a day or so.  The upper level winds could blow the top half of Ema north of the low level circulation and the tropical storm could weaken very quickly if that happens.

The upper level trough will steer Tropical Storm Ema toward the north during the next 12 hours or so.  If the wind shear separates the upper and lower parts of the tropical storm, the low level center will be steered by winds closer to the surface.  Clockwise flow around a subtropical high pressure system centered northeast of Hawaii could steer Tropical Storm Ema more toward the northwest later on Sunday.

Typhoon Hagibis Brings Wind and Rain to Honshu

Typhoon Hagibis brought wind and rain to Honshu on Saturday.  At 11:00 a.m. EDT on Saturday the center of Typhoon Hagibis was located at latitude 36.6°N and longitude 140.8°E which put it about 50 miles south of Iwaki, Japan.  Hagibis was moving toward the north-northeast at 25 m.p.h. (40 km/h).  The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 105 m.p.h. (165 km/h).  The minimum surface pressure was 969 mb.

The center of Typhoon Hagibis made landfall on the coast of Honshu on the Izu Peninsula southeast of Tokyo on Saturday.  The center of Hagibis moved quickly across the Tokyo metropolitan area toward Mito, Japan.  Typhoon Hagibis brought strong winds to coastal areas of Honshu.  A weather station at Tokyo International Airport in Haneda measured a sustained wind speed of 77 m.p.h. (124 km/h).  Rainbands on the northern side of Hagibis dropped heavy rain over the Tokyo metropolitan area.  Rainfall rates at some weather stations approached an inch (0.3 meters) per hour.  Flash floods occurred as the water from heavy rain ran off.  The rain also caused landslides on some steeper slopes.  Conditions will improve around Honshu as Typhoon Hagibis moves quickly away from Japan.  The heavy rain will end soon and the wind speed will gradually decrease.

Typhoon Hagibis Aims at Tokyo

Typhoon Hagibis was aimed at Tokyo on Friday afternoon.  At 5:00 p.m. EDT on Friday the center of Typhoon Hagibis was located at latitude 31.5°N and longitude 137.4°E which put it about 345 miles (555 km) south-southwest of Tokyo, Japan.  Hagibis was moving toward the north at 11 m.p.h. (17 km/h).  The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 150 m.p.h. (240km/h).  The minimum surface pressure was 949 mb.

Typhoon Hagibis was weakening slowly as it shifted onto a course toward Tokyo.  An eye was no longer visible on satellites images.  The ring of strong thunderstorms around the center of Hagibis was weaker in the southern half of the ring.  Most of the stronger thunderstorms were occurring in bands in the northern half of Typhoon Hagibis.  Bands in the southern half of Hagibis consisted primarily of showers and lower clouds.  An upper level trough over eastern Asia was producing southwesterly winds which were causing moderate vertical wind shear.   In addition, Typhoon Hagibis appeared to be pulling drier air into the southern half of the circulation.  The combination of wind shear and drier seemed to have weakened the southern half of the typhoon.

Even though it had weakened, Typhoon Hagibis remained a dangerous typhoon.  Winds to typhoon force extended out 60 miles (95 km) from the center of circulation.  Winds to tropical storm force extended out about 190 miles (305 km) from the center.  The Hurricane Intensity Index (HII) for Hagibis was 22.1  The Hurricane Size Index (HSI) was 21.5 and the Hurricane Wind Intensity Size Index (HWISI) was 43.6.  Typhoon Hagibis was capable of causing major damage.

The upper level trough over eastern Asia will steer Typhoon Hagibis toward the northeast during the next several days.  On its anticipated track Typhoon Hagibis could approach the coast of Honshu southeast of Tokyo in 12 to 18 hours.  Hagibis will continue to weaken as it moves toward Tokyo, but it will still be a typhoon when it reaches the region around Tokyo  Typhoon Hagibis will bring damaging winds to the Tokyo metropolitan area.  Bands of showers and thunderstorms on the northern side of Hagibis are already dropping rain over portions of Honshu southeast of Tokyo.  The rain will continue for another 12 to 24 hours in many locations.  Locally heavy rain will cause flash floods in some parts of Honshu.

Subtropical Storm Melissa Develops off Northeast U.S. Coast

Subtropical Storm Melissa developed off the northeast coast of the U.S. on Friday.  At 11:00 a.m. EDT on Friday the center of Subtropical Storm Melissa was located at latitude 38.5°N and longitude 69.6°W which put it about 190 miles (300 km) south of Nantucket, Massachusetts.  Melissa was moving toward the south-southwest at 3 m.p.h. (5 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 995 mb.

More thunderstorms developed near the center of a large low pressure system off the northeast coast of the U.S. on Friday morning and the National Hurricane Center designated the system as Subtropical Storm Melissa.  Melissa initially began as an extratropical cyclone along a slow moving cold front off the east coast of the U.S earlier this week.  The cold front moved east of the surface low pressure system and the surface low stalled underneath an upper level trough.  More showers and thunderstorms began to develop in bands and the low pressure system started to look more subtropical.

The circulation around Melissa was characteristic of a subtropical storm.  There was a well defined center of circulation visible on satellite images.  However, many of the stronger thunderstorms were occurring in a band that wrapped around the northern portion of the circulation.  Bands in the other parts of the circulation consisted primarily of showers and lower clouds.  The circulation was drawing cooler, drier air into the western and southern parts of the subtropical storm.  The wind field around Subtropical Storm Melissa was large and asymmetrical.  Winds to tropical storm force extended out 350 miles (565 km) from the center in the northeastern part of Melissa.  Tropical storm force winds only extended out 100 miles (160 km) to the southeast of the center of circulation.

The intensity of Subtropical Storm Melissa may not change much during the next 12 to 24 hours.  Melissa will remain under the middle of the upper level trough during the rest of Friday.  The winds are weak in the middle of the trough and there will not be much vertical wind shear.  Subtropical Storm Melissa will be over water where the Sea Surface Temperature is near 24°C.  So, there will not be a lot of energy in the upper ocean to support intensification.  The upper level trough will move eastward on Saturday and westerly winds will blow toward the top of Melissa.  The westerly winds will cause significant vertical wind shear, which will start to weaken Subtropical Storm Melissa.

Since the winds are weak in the middle of the upper level trough, Subtropical Storm Melissa is unlikely to move much during the rest of Friday.  Stronger westerly winds will steer Melissa to the east during the weekend.  On its anticipated track Subtropical Storm Melissa is forecast to move away from the U.S. during the weekend.  The large circulation around Melissa will generate large waves which will affect the south coast of New England and the Mid-Atlantic states.  Coastal flooding could occur in some locations.

Large Typhoon Hagibis Threatens Honshu

Large Typhoon Hagibis threatened Honshu on Thursday night.  At 11:00 p.m. EDT on Thursday the center of Typhoon Hagibis was located at latitude 27.9°N and longitude 137.8°E which put it about 555 miles (895 km) south-southwest of Tokyo, Japan.  Hagibis was moving toward the north-northwest at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 140 m.p.h. (220 km/h) and there were wind gusts to 165 m.p.h. (265 km/h).  The minimum surface pressure was 933 mb.

Powerful Typhoon Hagibis weakened slowly on Thursday.  There was still a circular eye at the center of Hagibis and the eye was surrounded by a ring of strong thunderstorms.  The strongest winds were in the ring of thunderstorms, but the wind speed decreased slowly during Thursday.  Bands of showers and thunderstorms were revolving around the core of Typhoon Hagibis.  Storms near the core were generating strong upper level divergence which was pumping mass away from the typhoon.

Although the circulation around Typhoon Hagibis weakened slowly on Thursday, it remained a large typhoon.  Winds to typhoon force extended out 80 miles (130 km) from the center of circulation.  Winds to tropical storm force extended out 345 miles (545 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Hagibis was 28.3.  The Hurricane Size Index (HSI) was 28.6 and the Hurricane Wind Intensity Size Index (HWISI) was 56.9,  Hagibis was capable of causing widespread significant damage.

Typhoon Hagibis will continue to weaken slowly on Friday.  Hagibis will move over water where the Sea Surface Temperature is near 28°C.  An upper level trough over eastern Asia will move toward Typhoon Hagibis.  The upper level trough will produce southwesterly winds which will blow toward the top of Hagibis.  The wind shear caused by those winds will create increasing vertical wind shear.  Increased wind shear will cause Typhoon Hagibis to weaken a little more quickly in 12 to 24 hours.

Typhoon Hagibis will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean on Friday.  The high will steer Hagibis toward the north during the next 12 to 24 hours.  The upper level trough over eastern Asia will steer Typhoon Hagibis toward the northeast in about 24 hours.  On its anticipated track Typhoon Hagibis could reach the coast of Honshu near Tokyo in less than 36 hours.  Hagibis will still be a typhoon when it reaches Tokyo.  It will bring strong winds and heavy rain to the part of Honshu around Tokyo.  Heavy rain is likely to cause flash floods in some locations.

Powerful Typhoon Hagibis Continues Toward Honshu

Powerful Typhoon Hagibis continue to move toward Honshu on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Typhoon Hagibis was located at latitude 23.7°N and longitude 139.5°E which put it about 140 miles (225 km) west-southwest of Iwo To.  Hagibis was moving toward the north at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 195 m.p.h. (315 km/h).  The minimum surface pressure was 918 mb.

Typhoon Hagibis continued to have a powerful, large circulation on Wednesday.  A circular eye with a diameter of 25 miles (40 km) was at the center of circulation.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Typhoon Hagibis.  The rainbands in the northwestern quadrant of Hagibis were a little weaker than the bands in other parts of the typhoon.  Some drier air may have been being pulled into the the northwestern quadrant of the circulation.  Storms around the core of the typhoon continue to generate strong upper level divergence.

The strength of the winds around Typhoon Hagibis exhibited more asymmetry on Wednesday.  Winds to typhoon force extended out 150 miles (240 km) from the center of circulation in the northeastern part of Hagibis.  Winds to typhoon force were occurring within 100 miles (160 km) of the center in the other parts of Typhoon Hagibis.  Winds to tropical storm force extended out 370 miles (565 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Hagibis was 35.0.  The Hurricane Size Index (HSI) was 39.9 and he Hurricane Wind Intensity Size Index (HWISI) was 74.9.  Typhoon Hagibis was capable of causing extensive catastrophic damage.

Typhoon Habigis will continue to move through an environment capable of supporting strong  typhoons, but Hagibis is likely to start to weaken on Thursday.  Typhoon Hagibis will move over water where the Sea Surface Temperature is near 29°C, but that is slightly cooler than the water Hagibis has been over.  Typhoon Hagibis will move through a region where the upper level winds are weak during the next 24 hours.  There will be little vertical wind shear on Thursday, and so Hagibis will likely weaken slowly.  Typhoon Hagibis will move closer to upper level westerly winds in the middle latitudes on Friday.  When Hagibis gets closer to the stronger upper level winds, vertical wind shear will increase and the typhoon will weaken more quickly.  The large circulation around Typhoon Hagibis will slow the rate of weakening even when the wind shear increases.

Typhoon Hagibis will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean during the next 24 hours.  The high will steer Hagibis toward the north on Thursday.  Typhoon Hagibis will move toward the northeast on Friday when it reaches the upper level westerly winds.  On its anticipated track the center of Typhoon Hagibis will move west of Iwo To during the next 24 hours.  Hagibis will bring winds to tropical storm force to Iwo To and there is a chance that the winds could reach typhoon force at times.  Rainbands on the eastern side of the typhoon will drop heavy rain on Iwo To.  Typhoon Hagibis could approach the coast of Honshu near Tokyo in a little over 48 hours.  Hagibis will still be a typhoon when it approaches Tokyo.  It will bring strong winds and heavy rain to parts of Honshu.  Typhoon Hagibis could also produce winds to tropical storm force on Shikoku.

Large Powerful Typhoon Hagibis Turns Toward Japan

Large powerful Typhoon Hagibis turned toward Japan on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Typhoon Hagibis was located at latitude 20.2°N and longitude 140.1°E which put it about 350 miles (565 km) south of Iwo To.  Hagibis was moving toward the northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 195 m.p.h. (315 km/h).  The minimum surface pressure was 915 mb.

Typhoon Hagibis appeared to complete an eyewall replacement cycle on Tuesday.  The original tiny pinhole eye was no longer visible on satellite imagery.  A larger circular eye with a diameter of 24 miles (39 km) was at the center of Hagibis.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Typhoon Hagibis.  Storms around the core were generating strong upper level divergence which was pumping mass away from the typhoon in all directions.

Completion of the eyewall replacement cycle increased the size of the circulation around Typhoon Hagibis.  Winds to typhoon force extended out 115 miles (185 km) from the center of circulation.  Winds to tropical storm force extended out 350 miles (565 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Hagibis was 35.0.  The Hurricane Size Index (HSI) was 38.1 and the Hurricane Wind Intensity Size Index (HWISI) was 73.1.  Hagibis was capable of causing extensive catastrophic damage.

Typhoon Hagibis will move through an environment capable of supporting intense typhoons during the next 24 to 36 hours.  Hagibis will move over water where the Sea Surface Temperature is near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Typhoon Hagibis will move closer to the upper level westerly winds in the middle latitudes in two or three days.  Those winds will cause more vertical wind shear and Hagibis will weaken when the shear increases.

Typhoon Hagibis will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean.  The high will steer Hagibis toward the north-northwest during the next 48 hours.  The upper level westerly winds will steer Typhoon Hagibis quickly toward the northeast later this week.  On its anticipated track the center of Typhoon Hagibis could approach the coast of Honshu near Tokyo in 72 to 84 hours.  Hagibis could bring strong winds and heavy rain to Tokyo.  The large circulation around Typhoon Hagibis will mean that much of central Honshu could experience gusty winds and winds to tropical storm force could affect parts of Kyushu and Shikoku.