Hurricane Simon Stalls Just West of Mexico

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Hurricane Simon stalled just west of Mexico on Monday afternoon.  At 5:00 p.m. EDT on Monday the center of Hurricane Simon was located at latitude 20.2°N and longitude 106.8°W which put the center about 75 miles (120 km) west of Cabo Corrientes, Mexico.  Simon was moving toward the west-northwest at 3 m.p.h. (5 km/h).  The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h).  The minimum surface pressure was 969 mb.

A Hurricane Warning is in effect for Las Islas Marias.

A Hurricane Watch is in effect for the portion of the coast from Cabo Corrientes to Bahia Tempehuaya, Mexico.  The Hurricane Watch includes Puerto Vallarta.

Hurricane Simon weakened gradually as it stalled on Monday.

Even though Hurricane Simon weakened on Monday, a very small circular eye was still present at the center of Simon’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 Simon’s circulation.  Storms near the core of Simon generated upper level divergence that pumped mass away from the hurricane.  The removal of mass in the upper levels was less than the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure increased on Monday.

The circulation around Hurricane Simon was very small.  Winds to hurricane force extended out 15 miles (25 km) from the center of Simon’s circulation.  Winds to tropical storm force extended out 45 miles (75 km) from the center of Hurricane Simon.

The Hurricane Intensity Index (HII) for Hurricane Simon is 16.5.  The Hurricane Size Index (HSI) is 4.4 and the Hurricane Wind Intensity Size Index (HWISI) is 20.9.  Hurricane Simon is similar in intensity to Hurricane Idalia when Idalia hit Florida in 2023.  Simon is smaller than Idalia was.

Hurricane Simon will move through an environment marginally favorable for intensification during the next 24 hours.  Simon will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge that is over Mexico and the Eastern North Pacific Ocean.  The upper level ridge winds are weak near the middle of the ridge and there will be little vertical wind shear.  However, Hurricane Simon will pull some drier air that is over Mexico into its circulation because Simon will remain very close to Mexico.  The drier air will inhibit the formation of new thunderstorms in the eastern and northern parts of Simon’s circulation.  Hurricane Simon is likely to continue to weaken gradually on Tuesday because of the effects of the drier air.  Simon could intensify on Wednesday when it is little farther away from the coast of Mexico.

Hurricane Simon will move around the western part of a high pressure system that is over Mexico.  The high pressure system will steer Simon slowly toward the northwest during the next 24 hours.  On its anticipated track, the core of Hurricane Simon will pass west of the Islas Marias on Tuesday night.

The core of Hurricane Simon will pass west of Las Islas Marias on Tuesday night.  Simon will bring strong winds and heavy rain to those islands on Tuesday and Wednesday.  Flash floods are likely to occur in some locations.  Hurricane Simon could cause a storm surge of up to 10 feet (3 meters) along parts of coast of Las Islas Marias.

Typhoon Koguma Weakens

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Typhoon Koguma weakened on Sunday as it moved over the Western North Pacific Ocean southeast of Japan.  At 11:00 p.m. EDT on Sunday the center of Typhoon Koguma was located at latitude 29.0°N and longitude 147.6°E which put the center about 655 miles (1060 km) southeast of Tokyo, Japan.  Koguma was moving toward the north at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 115 m.p.h. (1850 km/h) and there were wind gusts to 145 m.p.h. (235 km/h).  The minimum surface pressure was 954 mb.

Typhoon Koguma weakened on Sunday, but the structure of Koguma was still intact.  A large circular eye with a diameter of 45 miles (75 km) was at the center of Koguma’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 revolved around the center of Koguma’s circulation.  Storms near the center of Koguma generated upper level divergence that pumped mass away from the typhoon.  The removal of mass in the upper levels was less than the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure increased on Sunday.

The distribution of wind speeds in Typhoon Koguma was fairly symmetrical.  Winds to typhoon force extended out 65 miles (105 km) from the center of Koguma’s circulation.  Winds to tropical storm force extended out 130 miles (210 km) from the center of Typhoon Koguma.

The Hurricane Intensity Index (HII) for Typhoon Koguma is 20.6. The Hurricane Size Index (HSI) is 19.6 and the Hurricane Wind Intensity Size Index (HWISI) is 40.2. Typhoon Koguma is similar in intensity to Hurricane Rita when Rita hit southwest Louisiana in 2005.  Koguma is not as large as Rita was.

Typhoon Koguma will move through an environment that will be unfavorable for intensification during the next 24 hours.  Koguma will move over water where the Sea Surface Temperatures are near 26°C.  It will move under the eastern side of an upper level trough that is over Japan.  The upper level trough will produce southwesterly winds that will blow toward the top of Koguma’s circulation.  Those winds will cause moderate vertical wind shear.  Moderate vertical wind shear and cooler Sea Surface Temperature will cause Typhoon Koguma to continue to weaken on Monday.

The upper level trough over Japan will steer Typhoon Koguma toward the northeast during the next 24 hours.  On its anticipated track, Typhoon Koguma will stay far to the east of Japan.

Hurricane Simon Stays Just West of Mexico

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The core of Hurricane Simon stayed just to the west of the west coast of Mexico on Sunday.  At 5:00 p.m. EDT on Sunday the center of Hurricane Simon was located at latitude 19.6°N and longitude 105.8°W which put the center about 55 miles (90 km) south of Cabo Corrientes, Mexico.   Simon was moving toward the north-northwest at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 947 mb.

A Hurricane Warning is in effect for the portion of the coast from Punta San Telmo to El Roblito, Mexico.  The Hurricane Warning includes Manzanillo and Puerto Vallarta.

A Hurricane Warning is in effect for Las Islas Marias.

A Hurricane Watch is in effect for the portion of the coast from El Roblito to Tempehuaya, Mexico.

Hurricane Simon was a Category 4 hurricane on the Saffir-Simpson Scale on Sunday afternoon.

A circular eye with a diameter of 10 miles (16 km) was at the center of Hurricane Simon.  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 Simon’s circulation.  Storms near the core of Simon generated upper level divergence that pumped mass away from the hurricane.  The removal of mass in the upper levels was less than the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure increased on Sunday.

The circulation around Hurricane Simon was very small.  Winds to hurricane force extended out 25 miles (40 km) from the center of Simon’s circulation.  Winds to tropical storm force extended out 60 miles (95 km) from the center of Hurricane Simon.

The Hurricane Intensity Index (HII) for Hurricane Simon is 25.1.  The Hurricane Size Index (HSI) is 8.2 and the Hurricane Wind Intensity Size Index (HWISI) is 33.3. Hurricane Simon is similar in intensity to Hurricane Harvey when Harvey hit Texas in 2017.  Simon is smaller than Harvey was.

Hurricane Simon will move through an environment somewhat favorable for intensification during the next 24 hours.  Simon will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge that is over Mexico and the Eastern North Pacific Ocean.  The upper level ridge winds are weak near the middle of the ridge and there will be little vertical wind shear.  However, Hurricane Simon is likely to pull some drier air that is over Mexico into its circulation because Simon will remain very close to Mexico.  The drier air will inhibit the formation of new thunderstorms in the eastern and northern parts of Simon’s circulation.  Hurricane Simon is likely to weaken on Monday because of the effects of the drier air.

Hurricane Simon will move around the western part of a high pressure system that is over Mexico.  The high pressure system will steer Simon toward the north-northwest during the next 24 hours.  On its anticipated track, the core of Hurricane Simon will remain just to the west of Mexico on Monday.  The center of Simon’s circulation will pass just to the west of Cabo Corrientes on Sunday night.  The core of Hurricane Simon will be near Las Islas Marias on Monday afternoon.

Bands in the eastern side of Hurricane Simon will continue to bring strong winds and locally heavy rain to the west coast of Mexico.  The strongest winds and heaviest rains will occur in Colima, Jalisco and Nayarit.  Heavy rain is likely to cause flash floods in some locations.

The core of Hurricane Simon will pass near Las Islas Marias on Monday afternoon.  Simon will bring strong winds and heavy rain to those islands.  Flash floods are likely to occur in some locations.  Hurricane Simon could cause a storm surge of up to 13 feet (4 meters) along parts of coast of Las Islas Marias.

Typhoon Koguma Spins East of Iwo To

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Typhoon Koguma was spinning over the Western North Pacific Ocean east of Iwo To on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Typhoon Koguma was located at latitude 24.9°N and longitude 148.0°E which put the center about 435 miles (700 km) east of Iwo To.  Koguma was moving toward the northwest at 11 m.p.h. (17 km/h).  The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 944 mb.

Typhoon Koguma intensified on Saturday.  Koguma was the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.  A circular eye with a diameter of 23 miles (37 km) was at the center of Typhoon Koguma.  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 revolved around the center of Koguma’s circulation.  Storms near the center of Koguma generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease on Saturday.

The distribution of wind speeds in Typhoon Koguma was fairly symmetrical.  Winds to typhoon force extended out 65 miles (105 km) from the center of Koguma’s circulation.  Winds to tropical storm force extended out 150 miles (240 km) from the center of Typhoon Koguma.

The Hurricane Intensity Index (HII) for Typhoon Koguma is 25.1.  The Hurricane Size Index (HSI) is 19.9 and the Hurricane Wind Intensity Size Index (HWISI) is 45.0.  Typhoon Koguma is similar in intensity in intensity to Hurricane Harvey when Harvey hit Texas in 2017.  Koguma is larger than Harvey was.

Typhoon Koguma will move into an environment that will become unfavorable for intensification during the next 24 hours.  Koguma will move over water where the Sea Surface Temperatures are near 28°C.  It will move under the upper level western winds in the middle latitudes.  The vertical wind shear will increase when Koguma moves under those upper level westerly winds.  Typhoon Koguma will start to weaken when the vertical wind shear increases.

Typhoon Koguma will move around the southwestern part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Koguma toward the north during the next 24 hours.  On its anticipated track, Typhoon Koguma willmove away from Iwo To on Sunday.

Hurricane Simon Nears Western Mexico

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Powerful Hurricane Simon was nearing the west coast of Mexico on Saturday afternoon.  At 5:00 p.m. EDT on Saturday the center of Hurricane Simon was located at latitude 17.6°N and longitude 104.8°W which put the center about 100 miles (160 km) south-southwest of Manzanillo, Mexico.   Simon was moving toward the north 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 175 m.p.h. (280 km/h).  The minimum surface pressure was 932 mb.

A Hurricane Warning is in effect for the portion of the coast from Punta San Telmo to El Roblito, Mexico.  The Hurricane Warning includes Manzanillo and Puerto Vallarta.

A Hurricane Warning is in effect for Las Islas Marias.

A Tropical Storm Watch is in effect for the portion of the coast from Punta San Telmo to Lazaro Cardenas, Mexico.

Hurricane Simon intensified to Category 4 on the Saffir-Simpson Scale on Saturday.

The inner end of a rainband wrapped around the existing eye and eyewall on Saturday.  Concentric eyewalls were at the center of Hurricane Simon.  The inner eyewall had a diameter of 14 miles (22 km).  The outer eyewall had a diameter of 40 miles (65 km).

Bands of showers and thunderstorms were revolving around the core of Simon’s circulation.  Storms near the core of Simon generated upper level divergence that pumped mass away from the hurricane.  The removal of mass caused the surface pressure to decrease.

The circulation around Hurricane Simon was small.  Winds to hurricane force extended out 25 miles (40 km) from the center of Simon’s circulation.  Winds to tropical storm force extended out 90 miles (145 km) from the center of Hurricane Simon.

The Hurricane Intensity Index (HII) for Hurricane Simon is 31.6.  The Hurricane Size Index (HSI) is 8.5 and the Hurricane Wind Intensity Size Index (HWISI) is 40.1.  Hurricane Simon is bigger and stronger than Hurricane Charley was when Charley hit southwest Florida in 2004.

Hurricane Simon will move through an environment favorable for intensification during the next 12 hours.  Simon will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge that is over Mexico and the Eastern North Pacific Ocean.  The upper level ridge winds are weak near the middle of the ridge and there will be little vertical wind shear.  Hurricane Simon could weaken during the next few hours if an eyewall replacement cycle occurs, even though Simon is in a favorable environment.

Hurricane Simon will move around the western part of a high pressure system that is over Mexico.  The high pressure system will steer Simon toward the north during the next 24 hours. On its anticipated track, the center of Hurricane Simon will be near Manzanillo on Sunday morning.

Hurricane Simon will be a major hurricane when it hits the west coast of Mexico.  Simon will bring strong winds and locally heavy rain to the west coast of Mexico.  The strongest winds and heaviest rains will occur in Colima, Jalisco and Nayarit.  Heavy rain is likely to cause flash floods in some locations.  Hurricane Simon could cause a storm surge of up to 16 feet (5 meters) along parts of the west coast of Mexico.

Elsewhere over the Eastern North Pacific Ocean, Tropical Storm Rachel was moving quickly toward northern Baja California.

At 5:00 p.m. EDT on Saturday the center of Tropical Storm Rachel was located at latitude 27.0°N and longitude 118.3°W which put the center about 255 miles (415 km) southwest of Punta Baja, Mexico.  Rachel was moving toward the north-northeast at 30 m.p.h. (48 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 989 mb.

A Tropical Storm Warning is in effect for the portion of the coast from Punta Eugenia, Mexico to the Mexico/U.S. border.

A Tropical Storm Warning is in effect for the portion of the coast from Isla San Luis to Puerto Penasco, Mexico.

A Tropical Storm Watch is in effect for the portion of the coast from the U.S./Mexico border to the San Diego County/Orange County line in California.

A Tropical Storm Watch is in effect for the portion of the coast from Isla San Luis to Bahia de Los Angeles, Mexico.

A Tropical Storm Watch is in effect for the portion of the coast from Puerto Libertad to Puerto Penasco, Mexico.

Simon Intensifies to a Major Hurricane

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Hurricane Simon intensified to a major hurricane as it moved over the Eastern North Pacific Ocean south of Mexico on Friday.

At 11:00 p.m. EDT on Friday the center of Hurricane Simon was located at latitude 16.8°N and longitude 104.6°W which put the center about 155 miles (250 km) south of Manzanillo, Mexico.   Simon was moving toward the north at 7 m.p.h. (11 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. (225 km/h).  The minimum surface pressure was 952 mb.

A Hurricane Warning is in effect for the portion of the coast from Punta San Telmo to Punta Mita, Mexico.  The Hurricane Warning includes Manzanillo and Puerto Vallarta.

A Hurricane Watch is in effect for the portion of the coast from Punta Mita to El Roblito, Mexico.

A Hurricane Watch is in effect for Las Islas Marias.

A Tropical Storm Watch is in effect for the portion of the coast from Punta San Telmo to Lazaro Cardenas, Mexico.

Hurricane Simon intensified to a major hurricane on Friday.

A very small eye formed at the center of Hurricane Simon.  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 Simon’s circulation.  Storms near the center of Simon generated upper level divergence that pumped mass away from the hurricane.  The removal of mass caused the surface pressure to decrease.

The circulation around Hurricane Simon was small.  Winds to hurricane force extended out 20 miles (30 km) from the center of Simon’s circulation.  Winds to tropical storm force extended out 80 miles (130 km) from the center of Hurricane Simon.

The Hurricane Intensity Index (HII) for Hurricane Simon is 22.1.  The Hurricane Size Index (HSI) is 6.1 and the Hurricane Wind Intensity Size Index (HWISI) is 28.2.

Hurricane Simon will move through an environment favorable for intensification during the next 24 hours.  Simon will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge that is over Mexico and the Eastern North Pacific Ocean.  The upper level ridge winds are weak near the middle of the ridge and there will be little vertical wind shear.  Hurricane Simon will intensify during the next 24 hours.  Simon could intensify rapidly at times.  Hurricane Simon could strengthen to a Category 5 hurricane on Saturday.

Hurricane Simon will move around the western part of a high pressure system that is over Mexico.  The high pressure system will steer Simon toward the north during the next 24 hours.  Hurricane Simon will approach the west coast of Mexico between Manzanillo and Cabo Corrientes on Saturday.

Hurricane Simon is likely to be a major hurricane when it hits the west coast of Mexico.  Simon will bring strong winds and locally heavy rain to the west coast of Mexico.  The strongest winds and heaviest rains will occur in Jalisco and Nayarit.  Heavy rain is likely to cause flash floods in some locations.  Hurricane Simon could cause a storm surge of up to 16 feet (5 meters) along parts of the west coast of Mexico.

Elsewhere over the Eastern North Pacific Ocean, Tropical Storm Rachel started to move toward Baja California.  Tropical Storm Watches and Tropical Storm Warnings were issued for parts of southern California, the northern part of Baja California and northwestern Mexico.

At 11:00 p.m. EDT on Friday the center of Tropical Storm Rachel was located at latitude 23.8°N and longitude 123.3°W which put the center about 720 miles (1160 km) south-southwest of San Diego, California.  Rachel was moving toward the northeast 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 995 mb.

A Tropical Storm Warning is in effect for the portion of the coast from San Jose de Las Palomas, Mexico to the Mexico/U.S. border.

A Tropical Storm Warning is in effect for the portion of the coast from Isla San Luis to Puerto Penasco, Mexico.

A Tropical Storm Watch is in effect for the portion of the coast from the U.S./Mexico border to the San Diego County/Orange County line in California.

A Tropical Storm Watch is in effect for the portion of the coast from Isla San Luis to Bahia de Los Angeles, Mexico.

A Tropical Storm Watch is in effect for the portion of the coast from Puerto Libertad to Puerto Penasco, Mexico.

Hurricane Isaias Hits Northwest Florida

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Hurricane Isaias hit Northwest Florida on Friday evening.  At 11:00 p.m. EDT on Friday the center of Hurricane Isaias was located at latitude 30.8°N and longitude 86.5°W which put the center about 45 miles (75 km) east-northeast of Pensacola, Florida.  Isaias was moving toward the north at 20 m.p.h. (32 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 982 mb.

A Hurricane Warning is in effect for the portion of the coast from the Mississippi/Alabama border to the Bay County/Gulf County line in Florida.

A Tropical Storm Warning is in effect for the portion of the coast from the Bay County/Gulf County line to the Aucilla River in Florida.

The center of Hurricane Isaias made landfall near Destin, Florida on Friday evening.

Hurricane Isaias was a Category 2 hurricane on the Saffir-Simpson Scale at the time of landfall.  The maximum sustained wind speed was 105 m.p.h. (165 km/h) when the center of Isaias made landfall.  The Hurricane Intensity Index (HII) was 17.8.  The Hurricane Size Index (HSI) was 14.6 and the Hurricane Wind Intensity Size Index (HWISI) was 32.4.

An upper level low that is over Mississippi will steer Hurricane Isaias toward the north during the next 24 hours.  On its anticipated track, Hurricane Isaias will move inland over Alabama on Saturday.

Hurricane Isaias will continue to bring strong winds to northwest Florida during the next few hours.  Even though Hurricane Isaias will weaken to a tropical storm by Saturday morning, Isaias will bring strong winds and heavy rain to Alabama on Saturday.

Flood Watches are in effect for parts of Alabama.

There are reports of over 400,000 customers without electricity in Florida.  There are also reports of over 200,000 customers without electricity in Alabama.

There are also reports of flooding due to a storm surge along parts of the coast of Northwest Florida.

Typhoon Koguma Intensifies to Equivalent of a Major Hurricane

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Typhoon Koguma intensified to the equivalent of a major hurricane east of the Northern Marianas on Friday.  At 11:00 a.m. EDT on Friday the center of Typhoon Koguma was located at latitude 20.5°N and longitude 153.5°E which put the center about 640 miles (1035 km) east-northeast of Saipan.  Koguma was moving toward the west-northwest at 17 m.p.h. (28 km/h).  The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 145 m.p.h. (235 km/h).  The minimum surface pressure was 961 mb.

Typhoon Koguma intensified to the equivalent of a major hurricane on Friday as it was completing an eyewall replacement cycle.  A new larger eye was forming at the center of Koguma’s circulation.  Bands of showers and thunderstorms were revolving around the center of Typhoon Koguma.  Storms near the center of Koguma generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

Even though Typhoon Koguma was completing an eyewall replacement cycle, the circulation around Koguma was still small for a typhoon over the Western North Pacific Ocean.  Winds to typhoon force extended out 45 miles (75 km) from the center of Koguma’s circulation.  Winds to tropical storm force extended out 105 miles (165 km) from the center of Typhoon Koguma.

The Hurricane Intensity Index (HII) for Typhoon Koguma is 20.6.  The Hurricane Size Index (HSI) is 16.2 and the Hurricane Wind Intensity Size Index (HWISI) is 36.8.  Typhoon Koguma is similar in size and intensity to Hurricane Delta when Delta hit Louisiana in 2020.

Typhoon Koguma will move through an environment that will be favorable for intensification during the next 24 hours.  Koguma will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southwestern part of an upper level ridge that is over the Central North Pacific Ocean.  The upper level ridge will produce southeasterly winds that will blow toward the top of Koguma’s circulation.  Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification.  Typhoon Koguma will intensify during the next 24 hours.

Typhoon Koguma will move around the southwestern part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Koguma toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Koguma will pass northeast of the Northern Marianas.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Nolo continued to weaken gradually far to the southeast of Japan.

At 11:00 a.m. EDT on Friday the center of Tropical Storm Nolo was located at latitude 29.7°N and longitude 147.6°E which put the center about 635 miles (1025 km) southeast of Tokyo, Japan.  Nolo was moving toward the northwest at 13 m.p.h. (21 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 991 mb.

Isaias Intensifies to a Major Hurricane

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Hurricane Isaias intensified to a major hurricane early on Friday as it moved toward the northern Gulf Coast.  At 8:20 a.m. EDT on Friday the center of Hurricane Isaias was located at latitude 27.0°N and longitude 87.6°W which put the center about 240 miles (390 km) south of Pensacola, Florida.  Isaias was moving toward the north-northeast at 15 m.p.h. (24 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. (225 km/h).  The minimum surface pressure was 959 mb.

A Hurricane Warning is in effect for the portion of the coast from Ocean Springs, Mississippi to the Bay County/ Gulf County line in Florida.  The Hurricane Warning includes Mobile, Alabama and Pensacola, Florida.

A Tropical Storm Warning is in effect for the portion of the coast from the Jefferson Parish/Plaquemines Parish line in Louisiana to Ocean Springs, Mississippi.

A Tropical Storm Warning is in effect for the portion of the coast from the Bay County/Gulf County Line to Aucilla River, Florida.

Aircraft reconnaissance found that Hurricane Isaias had intensified to a major hurricane on Friday morning.

A circular eye with a diameter of 25 miles (40 km) was at the center of Hurricane Isaias.  Bands of showers and thunderstorms were revolving around the center of Isaias’ circulation.  Storms near the center of Isaias generated upper level divergence that pumped mass away from the tropical storm.  The removal of mass caused the surface pressure to decrease.

The size of the circulation around Hurricane Isaias increased on Thursday night.  Winds to hurricane force extended out 30 miles (50 km) from the center of Isaias’ circulation.  Winds to tropical storm force extended out 185 miles (295 km) from the center of Hurricane Isaias.

The Hurricane Intensity Index (HII) for Hurricane Isaias is 22.1.  The Hurricane Size Index (HSI) is 12.0 and the Hurricane Wind Intensity Size Index (HWISI) is 34.1.  Hurricane Isaias is similar in size and intensity to Hurricane Dennis when Dennis hit Northwest Florida in 2005.

Hurricane Isaias will move through an environment that will be somewhat favorable for intensification during the next 12 hours.  Isaias will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the southeastern part of an upper level trough that is over Texas.  The upper level trough will produce southwesterly winds that will blow toward the top of Isaias’ circulation.  Those winds will cause moderate vertical wind shear, but the wind shear may not be enough to prevent intensification.  Hurricane Isaias could intensify during the next 12 hours.

The upper level trough over Texas will steer Isaias toward the north during the next 24 hours. On its anticipated track, Isaias will make landfall on the northern Gulf Coast near Pensacola, Florida on Friday night.

Hurricane Isaias will bring strong winds and locally heavy rain to the northern Gulf Coast.  Heavy rain could cause flash floods in some locations.  Isaias will be capable of causing major damage.  Widespread electricity outages are likely.

Flood Watches are in effect for parts of southern Mississippi, southern Alabama, and Northwest Florida.

Isaias could cause a storm surge of up to 13 feet (4 meters) along portions of the northern Gulf Coast.

A Storm Surge Warning is in effect for the portion of the coast from the Mouth of the Mississippi River to Suwannee River, Florida.

Simon Strengthens to a Hurricane

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Former Tropical Storm Simon strengthened to a hurricane on Thursday evening as it moved over the Eastern North Pacific Ocean south of Mexico.  At 11:00 p.m. EDT on Thursday the center of Hurricane Simon was located at latitude 15.6°N and longitude 104.6°W which put the center about 235 miles (380 km) south of Manzanillo, Mexico.  Simon was moving toward the west-northwest at 6 m.p.h. (10 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 985 mb.

A Hurricane Warning is in effect for the portion of the coast from Punta San Telmo to Punta Mita, Mexico.

A Tropical Storm Watch is in effect for the portion of the coast from Punta San Telmo to Lazaro Cardenas, Mexico.

Former Tropical Storm Simon strengthened to a hurricane on Friday evening.

Tall thunderstorms formed near the center of Hurricane Simon.  Bands of showers and thunderstorms were revolving around the center of Simon’s circulation.  Storms near the center of Simon generated upper level divergence that pumped mass away from the hurricane.  The removal of mass caused the surface pressure to decrease.

The circulation around Hurricane Simon was small.  The strongest winds were occurring in the northeastern part of Simon’s circulation.  Winds to hurricane force extended out 20 miles in the northeastern quadrant of Simon.  Winds to tropical storm force extended out 90 miles (145 km) from the center of Hurricane Simon.

Hurricane Simon will move through an environment favorable for intensification during the next 24 hours.  Simon will move over water where the Sea Surface Temperatures are near 30°C. It will move under the middle of an upper level ridge that is over Mexico and the Eastern North Pacific Ocean.  The upper level ridge winds are weak near the middle of the ridge and there will be little vertical wind shear.  Hurricane Simon will intensify during the next 24 hours.  Simon could intensify rapidly at times.  Hurricane Simon could strengthen to a major hurricane on Friday.

Hurricane Simon will move around the western part of a high pressure system that is over Mexico.  The high pressure system will steer Simon toward the north during the next 24 hours. Hurricane Simon will approach the west coast of Mexico on Saturday.

Hurricane Simon is likely to be a major hurricane when it hits the west coast of Mexico.  Simon will bring strong winds and locally heavy rain to the west coast of Mexico.  The strongest winds and heaviest rains will occur in Jalisco and Nayarit.  Heavy rain is likely to cause flash floods in some locations.  Hurricane Simon could cause a storm surge of up to 13 feet (4 meters) along parts of the west coast of Mexico.

Elsewhere over the Eastern North Pacific Ocean, Tropical Storm Rachel continued to weaken gradually west of Baja California.

At 11:00 p.m. EDT on Thursday the center of Tropical Storm Rachel was located at latitude 22.6°N and longitude 125.5°W which put the center about 995 miles (1600 km) west of the southern tip of Baja California.  Rachel was moving toward the west-northwest at 6 m.p.h. (10 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 990 mb.