Monthly Archives: September 2024

Typhoon Krathon Intensifies to Equivalent of Cat. 4 Hurricane

Typhoon Krathon intensified to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale on Monday as it passed just south of Taiwan.  At 5:00 p.m. EDT on Monday the center of Typhoon Krathon was located at latitude 20.7°N and longitude 119.9°E which put the center about 135 miles (220 km) south-southwest of Kaohsiung, Taiwan.  Krathon was moving toward the west at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 150 m.p.h. (240 km/h) and there were wind gusts to 185 m.p.h. (295 km/h).  The minimum surface pressure was 927 mb.

Typhoon Krathon continued to intensify Monday.  It is now the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.  A circular eye with a diameter of 30 miles (50 km) is present at the center of Krathon’s circulation.  The eye is surrounded by a ring of thunderstorms and the strongest winds are occurring in that ring of storms.  Numerous bands of showers and thunderstorms are revolving around the core of Typhoon Krathon.  Storms near the core generated strong upper level divergence that pumped mass away from the typhoon.

The circulation around Typhoon Krathon is symmetrical.  Winds to typhoon force extend out 80 miles (130 km) from the center of Krathon’s circulation.  Winds to tropical storm force extend out 200 miles (320 km) from the center of Typhoon Krathon.

The Hurricane Intensity Index (HII) for Typhoon Krathon is 31.6.  The Hurricane Size Index (HSI) is 24.1 and the Hurricane Wind Intensity Size Index (HWISI) is 55.7.  Typhoon Krathon is similar in intensity to Hurricane Laura when Jeanne hit Louisiana in 2020.  Krathon is bigger than Laura was.

Typhoon Krathon will move through an environment favorable for intensification during the next 24 hours.  Krathon will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the axis of an upper level ridge south of Japan.  The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear.  Even though Typhoon Krathon will be in an environment favorable for intensification, Krathon may not intensify.  Images from the Taiwan Central Weather Agency’s radar indicate that concentric eyewalls may be forming at the center of Krathon’s circulation.  If concentric eyewalls do form, then an eyewall replacement cycle would cause Typhoon Krathon to weaken during the next 24 hours.

Typhoon Krathon will move around the southwestern part of a high pressure system south of Japan.  The high pressure system will steer Krathon slowly toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Krathon will move southwest of Taiwan.  An upper level trough over southern China will start to steer Krathon toward the northeast on Wednesday.  The center of Krathon could make landfall on Taiwan near Kaohsiung.

Typhoon Krathon will be a large, powerful storm when it hits Taiwan.  Krathon will bring strong winds and heavy rain to Taiwan.  Heavy rain will cause flash floods in some locations.  Typhoon Krathon could also cause a storm surge of up to 13 feet (4 meters) on the coast of southwestern Taiwan.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Jebi strengthened south of Japan.  At 5:00 p.m. EDT on Monday the center of Tropical Storm Jebi was located at latitude 31.7°N and longitude 141.3°E which put the center about 320 miles (520 km) south-southeast of Tokyo, Japan.  Jebi was moving toward the north at 17 m.p.h. (28 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.

Tropical Storm Kirk Forms Over the Eastern Atlantic

Tropical Storm Kirk formed over the eastern Atlantic Ocean west of the Cabo Verde Islands on Monday morning.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Kirk was located at latitude 13.5°N and longitude 34.8°W which put the center about 740 miles (1195 km) west of the Cabo Verde Islands.  Kirk was moving toward the west at 12 m.p.h. (19 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 1001 mb.

A low pressure system over the eastern Atlantic Ocean west of the Cabo Verde Islands strengthened on Monday morning and the U.S. National Hurricane Center designated the system as Tropical Storm Kirk.  The circulation around Tropical Storm Kirk exhibited more organization on Monday.  The inner end of a rainband wrapped around the center of Kirk’s circulation.  Storms near the center of KIrk’s circulation generated upper level divergence that pumped mass away from the tropical storm.  Even though Tropical Storm Kirk exhibited more organization, the distribution of thunderstorms was asymmetrical.  Thunderstorms were occurring in bands in southern and eastern parts of Kirk’s circulation.  Bands in the northern parts of Tropical Storm Kirk consisted primarily of showers and lower clouds.

The distribution of winds speeds around Tropical Storm Kirk was fairly symmetrical.  Winds to tropical storm force extended out 115 miles (185 km) from the center of Kirk’s circulation.

Tropical Storm Kirk will move through an environment favorable for intensification during the next 24 hours.  Kirk will move over water where the Sea Surface Temperatures are near 29°C. It will move under the middle of an upper level ridge over the eastern Atlantic Ocean.  The winds are weak near the middle of the upper level ridge and there will be little vertical wind shear.  Tropical Storm Kirk will intensify during the next 24 hours.  Kirk is likely to strengthen to a hurricane on Tuesday.

Tropical Storm Kirk will move around of a subtropical high pressure system over the Atlantic Ocean.  The high pressure system will steer Kirk toward the west during the next 24 hours.  On its anticipated track, Tropical Storm Kirk will move farther away from the Cabo Verde Islands.

Elsewhere over the Atlantic Ocean, Tropical Storm Isaac was making a transition to an extratropical cyclone north-northwest of the Azores and Tropical Depression Joyce was spinning east-northeast of the northern Leeward Islands.

At 11:00 a.m. EDT on Monday the center of Tropical Storm Isaac was located at latitude 44.8°N and longitude 29.1°W which put the center about 480 miles (775 km) north-northwest of the Azores.  Isaac was moving toward the east-northeast at 17 m.p.h. (28 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 983 mb.

At 11:00 a.m. EDT on Monday the center of Tropical Depression Joyce was located at latitude 22.4°N and longitude 49.3°W which put the center about 940 miles (1510 km) east-northeast of the Northern Leeward Islands.  Joyce was moving toward the north at 2 m.p.h. (3 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.

Typhoon Krathon Rapidly Intensifies to Equivalent of a Major Hurricane

Typhoon Krathon rapidly intensified to the equivalent of a major hurricane on Sunday.  At 5:00 p.m. EDT on Sunday the center of Typhoon Krathon was located at latitude 20.1°N and longitude 122.0°E which put the center about 200 miles (320 km) southeast of Kaohsiung, Taiwan.  Krathon was moving toward the west-northwest 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. (240 km/h).  The minimum surface pressure was 950 mb.

Typhoon Krathon rapidly intensified to the equivalent of a major hurricane over the Western North Pacific Ocean south of Taiwan on Sunday.  A large circular eye with a diameter of 50 miles (80 km) was at the center of Krathon’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Typhoon Krathon.  Storms near the core of Krathon’s circulation generated upper level divergence that pumped large quatities of mass mass away from the typhoon.  The removal of large amounts of mass caused the surface pressure to decrease rapidly.

The size of the circulation around Typhoon Krathon increased as it intensified.  Winds to typhoon force extended out 60 miles (95 km) from the center of Krathon’s circulation.  Winds to tropical storm force extended out 265 miles (425 km) from the center of Typhoon Krathon.

The Hurricane Intensity Index (HII) for Typhoon Krathon was 22.1.  The Hurricane Size Index (HSI) was 23.1 and the Hurricane Wind Intensity Size Index (HWISI) was 45.2.  Typhoon Krathon was similar in size and intensity to Hurricane Jeanne when Jeanne hit southeast Florida in 2004.

Typhoon Krathon will move through an environment favorable for intensification during the next 24 hours.  Krathon will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the axis of an upper level ridge south of Japan. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear, Typhoon Krathon will intensify during the next 24 hours.  Krathon could continue to intensify rapidly during the next few hours.  Typhoon Krathon is likely strengthen to a the equivalent of a major hurricane.

Typhoon Krathon will move around the southwestern part of a high pressure system south of Japan.  The high pressure system will steer Krathon toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Krathon will move closer to Taiwan.  The center Krathon’s circulation will approach the southern end of Taiwan in 36 hours. Typhoon Krathon is will be the equivalent of a major hurricane when it approaches Taiwan.  Bands in the northern side of Krathon’s circulation will begin to bring wind and rain to Taiwan on Monday.

Elsewhere over the Western North Pacific Ocean, the center of Tropical Storm Jebi passed just to the west of Iwo To.  At 5:00 p.m. EDT on Sunday the center of Tropical Storm Jebi was located at latitude 25.8°N and longitude 140.7°E which put the center about 50 miles (80 km) west-northwest of Iwo To.  Jebi was moving toward the north at 6 m.p.h. (10 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 993 mb.

Krathon Rapidly Intensifies to a Typhoon

Former Tropical Storm Krathon rapidly intensified to a typhoon over the Western North Pacific Ocean south of Taiwan on Sunday morning.  At 5:00 a.m. EDT on Sunday the center of Typhoon Krathon was located at latitude 19.3°N and longitude 123.7°E which put the center about 330 miles (530 km) south-southeast of Taipei, Taiwan.  Krathon was moving toward the northwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 105 m.p.h. (165 km/h).  The minimum surface pressure was 973 mb.

Former Typhoon Krathon rapidly intensified to a typhoon south of Taiwan on Sunday.  A circular eye formed at the center of Krathon’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Typhoon Krathon.  Storms near the core of Krathon’s circulation generated upper level divergence that pumped large quatities of mass mass away from the typhoon.  The removal of large amounts of mass caused the surface pressure to decrease rapidly.

The size of the circulation around Typhoon Krathon increased as it intensified.  Winds to typhoon force extended out 60 miles (95 km) in the eastern side of Krathon’s circulation.  Winds to tropical storm force extended out 165 miles (265 km) from the center of Typhoon Krathon.

Typhoon Krathon will move through an environment favorable for intensification during the next 24 hours.  Krathon will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the axis of an upper level ridge south of Japan.  The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear,  Tropical Storm Krathon will intensify during the next 24 hours.  Krathon could continue to intensify rapidly today.  Typhoon Krathon is likely strengthen to a the equivalent of a major hurricane.

Typhoon Krathon will move around the southwestern part of a high pressure system south of Japan.  The high pressure system will steer Krathon toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Krathon will move closer to Taiwan.  The center Krathon’s circulation will approach the southern end of Taiwan in 48 hours.  Typhoon Krathon is will be the equivalent of a major hurricane when it approaches Taiwan.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Jebi brought wind and rain to Iwo To.  At 5:00 a.m. EDT on Sunday the center of Tropical Storm Jebi was located at latitude 24.4°N and longitude 141.0°E which put the center about 40 miles (65 km) south of Iwo To.  Jebi was moving toward the north-northwest at 15 m.p.h. (24 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.

Tropical Storm Krathon Forms Southeast of Taiwan

Tropical Storm Krathon formed over the Western North Pacific Ocean southeast of Taiwan on Saturday.  At 11:00 a.m. EDT on Saturday the center of Tropical Storm Krathon was located at latitude 18.6°N and longitude 125.1°E which put the center about 480 miles (775 km) south-southeast of Taipei, Taiwan.  Krathon was moving toward the west at 4 m.p.h. (6 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.

A low pressure system over the Western North Pacific Ocean southeast of Taiwan strengthened on Saturday and the Japan Meteorological Agency designated the system as Tropical Storm Krathon.  The circulation around Tropical Storm Krathon was organizing quickly on Saturday.  The inner end of a rainband wrapped around the eastern and northern sides of the center of Krathon’s circulation.  Other bands of showers and thunderstorms were revolving around the center of Tropical Storm Krathon.  Storms near the center of Krathon’s circulation generated upper level divergence that pumped mas away from the tropical storm.

The circulation around Tropical Storm Krathon was increasing size as Krathon strengthened.  Winds to tropical storm force extended out 125 miles (200 km) from the center of Krathon’s circulation.

Tropical Storm Krathon will move through an environment favorable for intensification.  Krathon will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the axis of an upper level ridge south of Japan.  The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear,  Tropical Storm Krathon will intensify during the next 24 hours.  Krathon could strengthen to a typhoon on Sunday.

Tropical Storm Krathon will move around the southwestern part of a high pressure system south of Japan.  The high pressure system will steer Krathon toward the northwest during the next 24 hours.  On its anticipated track, Tropical Storm Krathon will move closer to Taiwan.

Elsewhere over the Western North Pacific Ocean, Tropical Depression Jebi was moving closer to Iwo To.  At 11:00 a.m. EDT on Saturday the center of Tropical Storm Jebi was located at latitude 21.7°N and longitude 142.3°E which put the center about 275 miles (445 km) south-southeast of Iwo To.  Jebi was moving toward the north-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 1000 mb.

Hurricane Isaac Strengthens to Cat. 2 West of the Azores

Hurricane Isaac strengthened to Category 2 on the Saffir-Simpson Scale over the North Atlantic Ocean west of the Azores on Saturday.  At 11:00 a.m. EDT on Saturday the center of Hurricane Isaac was located at latitude 40.2°N and longitude 39.7°W which put the center about 695 miles (1120 km) west-northwest of the Azores.  Isaac was moving toward the east-northeast at 20 m.p.h. (32 km/h).  The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there were wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 968 mb.

Even though Hurricane Isaac was at latitude 40°N, it intensified to a Category 2 hurricane on the Saffir-Simpson Scale on Saturday morning.  A circular eye was present at the center of Isaac’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Hurricane Isaac.  Storms near the core of Isaac generated upper level divergence that pumped mass away from the hurricane.

The circulation around Hurricane Isaac was reasonably symmetrical given it high latitude.  Winds to hurricane force extended out 45 miles (75 km) from the center of Isaac’s circulation.  Winds to tropical storm force extended out 200 miles (320 km) from the center of Hurricane Isaac.

Hurricane Isaac will move through an environment unfavorable for intensification during the next 24 hours.  Isaac will move over water where the Sea Surface Temperatures are near 24°C.  It will move under the eastern side of an upper level trough that is southeast of Greenland.  The upper level trough will produce strong southwesterly winds that will blow toward the top of Isaac’s circulation.  Those winds will cause the vertical wind shear to increase.  The combination of cooler water and stronger vertical wind shear will cause Hurricane Isaac to weaken during the next 24 hours.

The upper level trough southeast of Greenland will steer Hurricane Isaac toward the east-northeast during the next 24 hours.  On its anticipated track, Hurricane Isaac will pass northwest of the Azores on Sunday.

Elsewhere, the circulation of former Hurricane Helene was spinning down south of the Ohio River and Tropical Storm Joyce was churning east of the Northern Leeward Islands.

At 11:00 a.m. EDT on Saturday the center of Tropical Depression Helene was located at latitude 36.6°N and longitude 86.4°W which put the center about 50 miles (80 km) northwest of Nashville, Tennessee.  Helene was moving toward the east at 3 m.p.h. (5 km/h).  The maximum sustained wind speed was 15 m.p.h. (25 km/h) and there were wind gusts to 25 m.p.h. (40 km/h).  The minimum surface pressure was 968 mb.

At 11:00 a.m. EDT on Saturday the center of Tropical Storm Joyce was located at latitude 20.0°N and longitude 46.0°W which put the center about 1120 miles (1805 km) east of the Northern Leeward Islands.  Joyce was moving toward the northwest at 10 m.p.h. (16 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 1004 mb.

Tropical Storm John Makes Landfall in Mexico Again

Tropical Storm John made landfall on the west coast of Mexico again on Friday.  At 2:00 p.m. EDT on Friday the center of Tropical Storm John was located at latitude 18.3°N and longitude 103.2°W which put the center about 90 miles (145 km) southeast of Manzanillo, Mexico.  John was moving toward the northwest at 3 m.p.h. (5 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 996 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Punta Maldonado to Manzanillo, Mexico.

The center of Tropical Storm John moved back over the west coast of Mexico between Lazaro Cardenas and Manzanillo on Friday afternoon.  The maximum sustained wind speed in Tropical Storm John at the time of landfall was 60 m.p.h. (95 km/h).

The strongest winds were occurring in the southeastern portion of Tropical Storm John.  Winds to tropical storm force extended out 160 miles (260 km) in the southeastern quadrant of Tropical Storm John.  Winds to tropical storm force only extended out 70 miles (110 km) in the other parts of John’s circulation.

Tropical Storm John will move around the southwestern part of a high pressure system over Mexico.  The high pressure system will steer John slowly toward the northwest during the next 24 hours.  On its anticipated track, Tropical Storm John will continue to grind slowly along the west coast of Mexico.

Tropical Storm John will drop heavy rain over parts of Colima, Jalisco, and Michoacan.  Heavy rain is likely to cause flash floods in some locations.

Tropical Storm Helene Brings Heavy Rain and Floods to Southeast U.S.

Tropical Storm Helene brought heavy rain and floods to parts of the southeast U.S. on Friday.  At 11:00 a.m. EDT on Friday the center of Tropical Storm Helene was located at latitude 35.1°N and longitude 83.8°W which put the center about 30 miles (50 km) southwest of Bryson City, North Carolina.  Helene was moving toward the north at 32 m.p.h. (52 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 975 mb.

A Tropical Storm Warning is in effect for the portion of the coast from Savannah River, Georgia to Little River Inlet, South Carolina.

Tropical Storm Warnings were also in effect for inland locations in South Carolina, eastern Georgia, western North Carolina and eastern Tennessee. 

Even though former Hurricane Helene weakened to a tropical storm as it moved over the southeastern U.S. on Friday, Helene still was dropping very heavy rain.  Heavy rain fell over parts of Georgia, South Carolina, western North Carolina, eastern Tennessee, and western Virginia.  The heavy rain caused rivers and streams to rise quickly in those areas and numerous flash flood and flood warnings were issued.

The Catawba River at Pleasant Gardens, North Carolina was at Record Flood level.  The Saluda River at Greenville, South Carolina was at Major Flood level.  The French Broad River at Blantyre, North Carolina was at Record Flood level.  The Pigeon River at Canton, North Carolina was at Record Flood level.  The Pigeon River at Newport, Tennessee was at Major Flood level.  The Swannanoa River at Biltmore, North Carolina was at Record Flood level.  Numerous other rivers and streams in the region were also flooding.  Many roads were impassible.

Over four million customers in Florida, Georgia, South Carolina and North Carolina were experiencing electricity outages.

Tropical Storm Helene will move around the eastern side of an upper level low over the middle Mississippi River Valley.  The upper level low will steer Helene toward the north during the next 24 hours.  The circulation around Tropical Storm Helene will gradually merge with the circulation around the upper level low.

Tropical Storm Helene will continue to drop heavy rain on the southern Appalachians.  the heavy rain is likely to cause additional flash floods.  Helene will also bring gusty winds as far north as southern and central Ohio on Friday afternoon and evening.

Elsewhere over the Atlantic Ocean, former Tropical Storm Isaac intensified to a hurricane west of the Azores and Tropical Storm Joyce formed east of the Northern Leeward Islands.

At 11:00 a.m. EDT on Friday the center of Hurricane Isaac was located at latitude 37.4°N and longitude 46.8°W which put the center about 1080 miles (1740 km) west of the Azores.  Isaac was moving toward the east-northeast at 18 m.p.h. (30 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 981 mb.

At 11:00 a.m. EDT on Friday the center of Tropical Storm Joyce was located at latitude 18.1°N and longitude 42.9°W which put the center about 1325 miles (2130 km) east of the Northern Leeward Islands.  Joyce was moving toward the northwest at 13 m.p.h. (20 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.

Tropical Storm Jebi Forms West of the Northern Marianas

Tropical Storm Jebi formed west of the Northern Marianas on Friday.  At 11:00 a.m. EDT on Friday the center of Tropical Storm Jebi was located at latitude 18.7°N and longitude 144.6°E which put the center about 60 miles (95 km) west-northwest of Agrihan. Jebi was moving toward the north-northwest at 4 m.p.h. (6 km/h).  The maximum sustained wind speed was 45 m.p.h. (65 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1001 mb.

A low pressure system west of the Northern Marianas strengthened on Friday and the Japan Meteorological Agency designated the system as Tropical Storm Jebi.  The circulation around Tropical Storm Jebi was poorly organized.  Thunderstorms were occurring in the southeastern quadrant of Jebi’s circulation.  There were no thunderstorms near the center of Tropical Storm Jebi.  Bands in the other parts of Jebi’s circulation consisted primarily of showers and lower clouds.

Tropical Storm Jebi will move through an environment somewhat favorable for intensification during the next 24 hours.  Jebi will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southeastern part of an upper level ridge south of Japan.  The upper level ridge will produce northeasterly winds that will blow toward the top of Jebi’s circulation.  Those winds will cause moderate vertical wind shear.  The wind shear will inhibit intensification.  Tropical Storm Jebi could intensify a little during the next 24 hours, if the wind shear does not get any stronger.

Tropical Storm Jebi will move around the western side of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Jebi toward the northwest during the next 24 hours.  On its anticipated track, Tropical Storm Jebi will move slowly away from the Northern Marianas.  Jebi could approach Iwo To in 36 hours.

Elsewhere over the Western North Pacific Ocean, Tropical Depression 20W formed south-southeast of Taiwan.  At 11:00 a.m. EDT on Friday the center of Tropical Depression 20W was located at latitude 19.6°N and longitude 125.8°E which put the center about 430 miles (690 km) south-southeast of Taipei, Taiwan.  The tropical depression was moving toward the southwest at 7 m.p.h. (11 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 1001 mb.

Hurricane Helene Makes Landfall in North Florida

The center of Hurricane Helene officially made landfall in North Florida on Thursday night.  The center of Helene crossed the coast of Florida near the mouth of the Aucilla River west-southwest of Perry.  At 11:00 p.m. EDT on Thursday the center of Hurricane Helene was located at latitude 29.9°N and longitude 83.9°W which put the center about 40 miles (65 km) southeast of Tallahassee, Florida and about 10 miles (15 km) west-southwest of Perry.  Helene was moving toward the north-northeast at 24 m.p.h. (39 km/h).  The maximum sustained wind speed was 140 m.p.h. (225 km/h) and there were wind gusts to 165 m.p.h. (265 km/h).  The minimum surface pressure was 938 mb.

A Hurricane Warning is in effect for the portion of the coast from Anclote River to Mexico Beach, Florida.

A Hurricane Watch is in effect for the portion of the coast from Anclote River to Englewood, Florida.  The Hurricane Watch includes Tampa Bay.

A Tropical Storm Warning is in effect for the portion of the coast from Anclote River to Flamingo, Florida.  The Tropical Storm Warning includes Tampa Bay.  A Tropical Storm Warning is in effect for the Lower and Middle Florida Keys west of Channel 5 Bridge.  A Tropical Storm Warning is in effect for the Dry Tortugas.  A Tropical Storm Warning is in effect for the portion of the coast from Mexico Beach to the Okaloosa/Walton County Line, Florida.  A Tropical Storm Warning is in effect for the portion of the coast from Flamingo, Florida to Little River Inlet, South Carolina.  A Tropical Storm Warning is in effect for Lake Okeechobee. 

Hurricane Helene intensified to Category 4 on the Saffir-Simpson Scale before it made landfall on the coast of Florida.  A circular eye with a diameter of 32 miles (52 km) was at the center of Helene’s circulation. The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the center of Hurricane Helene. Storms near the center of Helene generated strong upper level divergence that pumped large quantities of mass away from the hurricane. The removal of large quantities of mass was causing the surface pressure to decrease.

The circulation around Hurricane Helene was large. Winds to hurricane force extended out 60 miles (95 km) from the center of Helene’s circulation. Winds to tropical storm force extended out 310 miles (500 km) in the eastern side of Hurricane Helene.  Winds to tropical storm force extended out 140 miles (225 km) in the western side of Helene’s circulation.

The Hurricane Intensity Index (HII) is 28.3. The Hurricane Size Index (HSI) is 21.2 and the Hurricane Wind Intensity Size Index (HWISI) 49.5.  Hurricane Helene is stronger than Hurricane Irma was when Irma hit southwest Florida in 2017.  However, Helene is not quite as big as Irma was.

Hurricane Helene will move around the eastern side of an upper level trough over the Mississippi River Valley.  The upper level trough will steer Helene quickly toward the north during the next 24 hours.  On its anticipated track, Hurricane Helene will move across Georgia on Friday.

Hurricane Warnings are in effect for parts of northern Florida, southeastern Alabama and southwestern Georgia.  The Hurricane Warnings include Tallahassee, Florida and Macon, Georgia.

Tropical Storm Warnings are in effect for the Florida Peninsula, northwest Florida eastern Alabama, northern and eastern Georgia, all of South Carolina, southwestern North Carolina, and southeastern Tennessee.  The Tropical Storm Warnings include Atlanta, Georgia and Charleston, South Carolina.

Hurricane Helene will weaken gradually as it moves farther inland.  Hurricane Helene will bring strong winds and heavy rain to Georgia on Friday.  Heavy rain will also fall over the southern Appalachians.  Heavy rain is likely to cause flash floods.

Flood Watches are in effect for Florida, eastern Alabama, Georgia, western South Carolina, western North Carolina and eastern Tennessee.

Hurricane Helene will continue to cause a storm surge along the west coast of Florida during the next few hours.

A Storm Surge Warning is in effect for the portion of the coast from Mexico Beach to Flamingo, Florida.  The Storm Surge Warning includes Tampa Bay and Charlotte Harbor.