Hurricane Hermine Making Landfall in North Florida

After intensifying into a hurricane on Thursday, Hurricane Hermine is making landfall near St. Marks, Florida.  At midnight EDT the center of Hurricane Hermine was located at latitude 29.8°N and longitude 84.2°W which put it about 20 miles (30 km) south of St. Marks, Florida.  Hermine was moving toward the north-northeast at 14 m.p.h. (22 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 984 mb.

A Hurricane Warning is in effect from Suwannee River to Mexico Beach, Florida.  A Hurricane Watch is in effect from Anclote River to Suwannee River and from Mexico Beach to the Walton County/Bay County line.  A Tropical Storm Warning is in effect from Englewood to Suwannee River and from Mexico Beach to the Walton County/Bay County line.  A Tropical Storm Warning is also in effect from the Flagler County/Volusia County line to Duck, North Carolina including Pamlico and Albemarle Sounds.  A Tropical Storm Watch is in effect from Duck, North Carolina to Sandy Hook, New Jersey including the Chesapeake Bay from Smith Point southward and southern Delaware Bay.

The circulation of Hurricane Hermine organized quickly on Thursday.  It developed an eye with a mostly complete eyewall.  Spiral rainbands developed with strong winds in the eastern half of the circulation.  Upper level divergence to the east of Hermine pumped out mass and allowed the surface pressure to decrease.  The circulation is still asymmetrical with most of the stronger winds east of the center, but it looks a lot more typical of hurricanes that move toward the northern coast of the Gulf of Mexico.

Hurricane Hermine will weaken after it makes landfall.  It could interact with a cold front moving into the southeastern U.S.  It is possible that Hermine could develop a hybrid structure that is part tropical and part extratropical.  Hermine could have winds to tropical storm force as it passes over the Mid-Atlantic coast.  The stronger winds are likely to be out over the Atlantic Ocean and winds should be weaker farther inland.

An upper level trough is steering Hurricane Hermine toward the north-northeast and a general northeasterly motion is expected to continue for another 36 hours.  Later in the weekend a surface high pressure system could move north of Hermine and stall its progress.  Hermine could be stationary for a time.  On its anticipated track center of Hermine is likely to pass east of Tallahassee, Florida.  The center could pass north of Savannah, Georgia before coming near Charleston, South Carolina.  Hermine is likely to move near Cape Hatteras, North Carolina and out into the Atlantic Ocean.

Hurricane Hermine is capable of causing regional minor wind damage.  It is likely to cause widespread power outages.  The coast of the northeastern Gulf of Mexico is susceptible to storm surges and high water will effect that area overnight.  Locally heavy rainfall will create the potential for flooding.  When rainbands move ashore, wind shear could spin up tornadoes.  As Hermine moves near the Mid-Atlantic coast, easterly winds could cause water rises.

The Hurricane Intensity Index (HII) for Hurricane Hermine is 11.5.  The Hurricane Size Index (HSI) is 14.0.  The Hurricane Wind Intensity SIze Index (HWISI) is 25.5.  These indices are very similar to the ones for Hurricane Isaac before it hit the coast of Louisiana n 2012.  The HII for Isaac was 11.5.  Its HSI was 16.7 and its HWISI was 28.2.  This means that Hurricane Hermine is as strong and just smaller than Hurricane Isaac was just before it made landfall.  Hurricane Isaac did hit a more populated and more built up region.  Hurricane Isaac did 970 million dollars worth of insured damage.  It caused 407 million dollars to be paid out for flood insurance.  It is estimated that Hurricane Isaac caused 2.35 billion dollars worth of damage in the U.S.

Typhoon Namtheun Heads for Southern Japan

Typhoon Namtheun spun up quickly on Thursday and moved steadily toward Kyushu in southern Japan.  At 11:00 p.m. EDT on Thursday the center of Typhoon Namtheun was located at latitude 26.6°N and longitude 130.8°E which put it about 335 miles (540 km) south of Kagoshima, Japan.  Namtheun was moving toward the north at 7 m.p.h. (11 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 975 mb.

Typhoon Namtheun developed quickly from a low pressure system along a surface trough.  Namtheun has a small but very well organized circulation.  It has a tiny pinhole eye surrounded by a ring of strong thunderstorms.  Several other rainbands are spiraling around the ring of strong thunderstorms.  The thunderstorms are generating upper level divergence which is pumping out mass in all directions.  The upper level divergence is slightly less to the west of the center of circulation.

Typhoon Namtheun is in an environment favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 30°C.  Although there is a large upper level trough over eastern Asia which contains strong southwesterly winds, Typhoon Namtheun developed east of those strong winds.  It is in an area where the upper level winds are weaker and there is little vertical wind shear.  Namtheun is likely to intensify more during the next day or two.  However, Namtheun’s small circulation means that it will respond very rapidly to positive or negative changes in its surrounding environment.

A ridge to the east of Namtheun is steering the typhoon toward the north and that general motion is expected to continue for several more days.  On its anticipated track Typhoon Namtheun could be very near the southern tip of Kyushu within 48 hours.  It could bring strong winds and heavy rain to parts of southern Japan.

Hurricane Watch Issued for Hawaii as Hurricane Lester Moves Closer

As Hurricane Lester moved steadily closer to Hawaii on Thursday, a Hurricane Watch was issued for Hawaii County and Maui County including Maui, Molokai, Lanai and Kahoolawe.

At 8:00 p.m. EDT on Thursday the center of Hurricane Lester was located at latitude 18.5°N and longitude 145.4°W which put it about 640 miles (1030 km) east of Hilo, Hawaii.  Lester was moving toward the west at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 145 m.p.h. (235 km/h).  The minimum surface pressure was 960 mb.

The symmetrical circulation of Hurricane Lester is very well organized.  There is a circular eye with a diameter of 25 miles (40 km).  A ring of strong thunderstorms completely surrounds the eye.  Multiple spiral rainbands are rotating around periphery of the circulation.  Hurricane Lester is generating strong upper level divergence which is pumping mass out in all directions.

Hurricane Lester is currently moving through a favorable environment.  It is over water where the Sea Surface Temperature is near 27°C.  The upper level winds are light and there is little vertical wind shear.  Hurricane Lester will be moving over some of the same water that Hurricane Madeline passed over a few days ago.  If Madeline stirred any cooler water to the surface, it could cause Hurricane Lester to weaken.  When Hurricane Lester gets closer to Hawaii an upper level trough will produce stronger upper level southwesterly winds and the wind shear will increase.  Lester should weaken as it gets closer to Hawaii.

A subtropical ridge has been steering Hurricane Lester toward the west.  The western end of the ridge is expected to weaken and that will cause Lester to move more toward the west-northwest.  On its anticipate track Hurricane Lester could approach Hawaii on Saturday morning.

Tropical Storm Hermine Strengthens, Hurricane Warning Issued

Tropical Storm Hermine strengthened on Wednesday evening and a Hurricane Warning was issued for a portion of the northern Florida coast.  A Hurricane Warning was in effect for the portion of the coast from Suwannee River to Mexico Beach, Florida.  A Hurricane Watch and a Tropical Storm Warning was in effect for the portions of the coast from Anclote River to Suwannee River and from Mexico Beach to Destin, Florida.  The Tropical Storm Watch was extended farther up the Mid-Atlantic coast.  The Tropical Storm Watch was in effect for the portion of the coast from Marineland, Florida to South Santee River, South Carolina.

At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Hermine was located at latitude 25.8°N and longitude 87.0°W which put it about 295 miles (475 km) south-southwest of Apalachicola, Florida.  Hermine was moving toward the north-northeast at 10 m.p.h. (16 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 998 mb.

The circulation of Tropical Storm Hermine became better organized on Wednesday, but it is still not really well organized.  A tighter center of circulation developed.  However, the wind field is still asymmetrical.  The stronger winds are mainly east of the center and the winds are weaker in the western half of the circulation.  An area of strong thunderstorms developed near the center and another cluster of thunderstorms persisted southwest of the center.  There are not many thunderstorms northwest of the center.  There are some spiral rainbands, but they are fragmented.

Tropical Storm Hermine is in an environment that is favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 30°C.  The upper level flow pattern is enhancing the divergence of mass to the northeast of Hermine.  The enhanced upper level divergence pumped out enough mass to allow the surface pressure to decrease by a few millibars on Wednesday evening.  Tropical Storm Hermine is expected to continue to intensify on Thursday and it should become a hurricane before it makes landfall on Thursday night.

The upper level ridge that was blocking a northward motion of Hermine has weakened.  So, the tropical storm has begun to more toward the north-northeast.  An upper level trough is expected to steer Hermine a little faster toward the northeast on Thursday.  On its anticipated track Hermine could make landfall somewhere between Apalachicola and Tarpon Springs, Florida on Thursday night.  After it moves across northeast Florida, Hermine could move near the coast of Carolinas on Friday.

Hermine is likely to be a hurricane when it makes landfall on Thursday night.  The core of the circulation which will contain the highest winds is likely to be fairly small and Hermine is likely to cause localized minor wind damage.  There will undoubtedly be power outages.  The coastline around the northeastern Gulf of Mexico is vulnerable to storm surges and Hermine will also produce a storm surge which could range up to 7 to 8 feet (2 to 2.5 meters) near where the center crosses the coast.  The storm surge will be less farther away from where the center makes landfall.  In addition Hermine will generate locally heavy rain which could cause fresh water flooding.  Directional wind shear associated with rainbands moving inland could spin up tornadoes in the eastern half of Hermine.

Large Hurricane Gaston Prompts Tropical Storm Watch for Azores

Large Hurricane Gaston starting moving more quickly toward the northeast on Wednesday and it prompted a Tropical Storm Watch for some of the Azores.  The Tropical Storm Watch includes Flores, Corvo, Faial, Pico Gracsiosa, Sao Jorge and Terceira in the Azores.

At 8:00 p.m. EDT on Wednesday the center of Hurricane Gaston was located at latitude 35.6°N and longitude 46.5°W which put it about 1000 miles (1610 km) west of Faial in the Azores.  Gaston was  moving toward the northeast at 18 m.p.h. (30 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 969 mb.

Hurricane Gaston has a large circular eye with a diameter of 35 miles (55 km).  The eye is surrounded by a nearly complete eyewall, although the eyewall is thinner in the southwestern quadrant.  Winds to hurricane force extend out about 45 miles (70 km) from the center.  Hurricane Gaston has characteristics of an annular hurricane and the surrounding rainbands are mainly comprised of showers and shallow clouds.  The upper level divergence is inhibited over the southwestern past of the circulation, but divergence is still occurring north and east of the center.

Hurricane Gaston will be moving through an environment that will become increasingly unfavorable.  It is currently over water where the Sea Surface Temperature (SST) is near 27.5°C, but it will be moving over cooler SST during the next few days.  An upper level trough is producing southwesterly winds which are causing vertical wind shear.  The strength of the upper level winds is expected to increase.  The combination of cooler SSTs and more wind shear will weaken Gaston during the next few days.

Hurricane Gaston is being steering toward the northeast by the westerly flow in the middle latitudes.  That general motion is expected to continue.  On its anticipated track Hurricane Gaston could reach the western Azores within 48 hours.  It is expected to weaken below hurricane intensity by that time.  Because of its large size, Gaston could bring wind and rain to many of the Azores.

Hurricane Warning for Hawaii as Madeline Moves Closer

The Central Pacific Hurricane Center issued a Hurricane Warning for Hawaii County (i.e. the Big Island of Hawaii) as Hurricane Madeline moved steadily closer on Tuesday.  A Tropical Storm Watch has been issued for Maui County including Maui, Molokai and Lanai.

At 11:00 p.m. EDT on Tuesday the center of Hurricane Madeline was located at latitude 19.3°N and longitude 150.3°W which put it about 315 miles (505 km) east of Hilo, Hawaii.  Madeline was moving toward the west at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 130 m.p.h. (210 km/h).  The minimum surface pressure was 972 mb.

A subtropical ridge has been steering Hurricane Madeline toward the west.  The ridge is expected to strengthen and steer Madeline more toward the west-southwest for the next day or two.  On its anticipated track Hurricane Madeline could approach the island of Hawaii in about 30 hours.

An upper level trough north of Hawaii has been producing westerly winds which are causing vertical wind shear.  The westerly winds are restricting the upper level divergence to the west of Hurricane Madeline.  However, thunderstorms in the core of the hurricane have strengthened periodically and reduced the impact of the wind shear.  The shear is expected to continue and Hurricane Madeline is forecast to slowly weaken.  However, Madeline is moving over water where the Sea Surface Temperature is near 27°C, and it could move over warmer water if it moves toward the west-southwest.

Madeline is expected to be a hurricane when it moves past the island of Hawaii.  On its anticipated track the greatest threat would be to the southern half of the island.  Madeline is a compact hurricane and winds to hurricane force only extend out about 25 miles (40 km) from the center.  Hurricane Madeline will be capable of causing localized serious wind damage.  It may also produce heavy rain and flash flooding, especially where the wind blows up the slopes.

Tropical Depression Nine Causes Hurricane Watch for Part of Florida

Although Tropical Depression Nine did not strengthen on Tuesday afternoon, guidance from numerical models suggested it could be stronger when it eventually reaches the coast of Florida.  As a result, the National Hurricane Center at 5:00 p.m. EDT issued a Hurricane Watch for the portion of the Florida coast from Anclote River to Indian Pass.  A Tropical Storm Watch was issued for the portion of the coast from Indian Pass to the Walton County/Bay County line.

At 5:00 p.m. EDT on Tuesday the center of Tropical Depression Nine was located at latitude 24.4°N and longitude 87.3°W which put it about 345 miles (555 km) west of Key West, Florida.  It was moving toward the northwest at 5 m.p.h. (8 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. (70 km/h).  The minimum surface pressure was 1004 mb.

The circulation of Tropical Depression Nine is not currently well organized.  The surface center is located northwest of an apparent mid-level center.  Upper level divergence is not well developed.  The development of thunderstorms has been cyclical during the past several days.  Clusters of thunderstorms developed south and east of the center and then they weaken.  A few hours later more thunderstorms would develop, persist for a few hours and weaken again.  It appears that new thunderstorms are developing northeast and southwest of the surface center which would be a change from the previous pattern.

The vertical structure of Tropical Depression Nine has been out of sync.  As mentioned above, the surface center was northwest of the mid-level center.  Both the surface and mid-level centers have been located on the western edge of a larger upper level high.  Clockwise flow around the upper high has been creating vertical wind shear, which has prevented the development of a vertically coherent structure in the depression.  Despite the effect of the wind shear and the lack of a coherent vertical structure, the surface center has managed to persist and become a little more organized each day.

Tropical Depression Nine is moving through an environment that is currently marginal for intensification.  It is moving over water where the Sea Surface Temperature is near 31°C.  So, there is plenty of energy in the upper ocean.  The vertical wind shear mentioned previously is the primary factor inhibiting intensification.  However, as Tropical Depression Nine moves north, if is forecast to move into an area where the upper level winds are not as strong.  If that happens, then the depression will strengthen.  As the depression becomes more organized, the rate of intensification could increase and the depression could become a hurricane over the northeastern Gulf of Mexico.

An upper level ridge over the southeastern U.S. has been blocking the northward movement of Tropical Depression Nine.  An upper level trough approaching from the west is expected to weaken the ridge.  As the ridge weakens, The depression will be able to move north.  Eventually in a couple of days, the upper level trough is expected to steer the depression more toward the northeast.  On its anticipated track the depression could be approaching the northeastern Gulf Coast by Thursday afternoon.

The northeastern Gulf Coast is very susceptible to storm surges and a surge is the greatest risk.  Locally heavy rain could cause some flooding, and there could be some minor wind damage.

Typhoon Lionrock Nearing Landfall in Japan

An upper level low is pulling Typhoon Lionrock toward a landfall in northern Japan.  At 8:00 p.m. EDT on Monday the center of Typhoon Lionrock was located at latitude 36.1°N and longitude 142.5°E which put it about 150 miles (240 km) south-southeast of Sendai, Japan.  Lionrock was moving toward the north-northwest at 24 m.p.h. (39 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 965 mb.

An upper level low west of Japan was pulling Typhoon Lionrock back toward the west-northwest.  At its current track and speed Typhoon Lionrock would make landfall on the northeastern coast of Honshu near Sendai in about six hours.

The structure of Typhoon Lionrock is changing as a result of cooler Sea Surface Temperatures and more vertical wind shear.  Lionrock is making a transition of a tropical cyclone to an extratropical cyclone.  The circulation is becoming more elongated and the typhoon is pulling cooler drier air into the western half of the circulation.  The wind field will tend to expand as the typhoon becomes extratropical.

Typhoon Lionrock will be capable of producing minor wind damage along its path.  It could also cause locally heavy rainfall and flash floods over northern Honshu.  It will pass over some of the same areas recently affected by Typhoon Mindulle.

Major Hurricanes Madeline and Lester Moving Toward Hawaii

Hurricanes Madeline and Lester intensified quickly on Monday into Major Hurricanes as they moved toward Hawaii.  The approach of Hurricane Madeline prompted the Central Pacific Hurricane Center to issue a Hurricane Watch for Hawaii County.  Both hurricanes have the potential to affect the weather around Hawaii during the next few days.

At 5:00 p.m. EDT on Monday the center of Hurricane Madeline was located at latitude 18.6°N and longitude 145.5°W which put it about 630 miles (1015 km) east of Hilo, Hawaii.  Madeline was moving toward the west-northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 135 m.p.h. (220 km/h).  That made Hurricane Madeline the equivalent of a Category 3 hurricane on the Saffir-Simpson Scale.  The minimum surface pressure was 966 mb.

At 5:00 p.m. EDT on Monday the center of Hurricane Lester was located at latitude 18.0°N and longitude 130.5°W which put it about 1375 miles (2210 km) west of the southern tip of Baja California.  Lester was moving toward the west at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 130 m.p.h. (215 km/h) and there were wind gusts to 150 m.p.h. (240 km/h).  That made Hurricane Lester a Category 4 hurricane on the Saffir-Simpson Scale.  The minimum surface pressure was 951 mb.

Both Hurricanes Madeline and Lester are relatively compact hurricanes and the winds to hurricane force only extend out about 30 miles (50 km) from the center of circulation.  In Hurricane Madeline the Hurricane Intensity Index (HII) is 20.6.  The Hurricane Size Index (HSI) is 11.4 and the Hurricane Wind Intensity Size Index (HWISI) is 32.0.  Hurricane Lester is stronger, but slightly smaller.  The HII for Hurricane Lester is 25.1, while HSI is 10.3 and HWISI is 35.4.

Both hurricanes have well formed symmetrical eyes surrounded by rings of tall thunderstorms.  Each is producing well developed upper level divergence which is pumping out mass in all directions.  Hurricane Madeline has more spiral rainbands, and Hurricane Lester shows some indications that the structure might be assuming more of the shape of an annular hurricane.

Hurricanes Madeline and Lester responded to a favorable environment by intensifying rapidly on Monday.  The maximum sustained wind speed in Hurricane Madeline increased from 65 m.p.h. (105 km/h) to 115 m.p.h. (185 km/h) during the past 24 hours.  The maximum sustained wind speed in Hurricane Lester increased from 85 m.p.h. (140 km/h) to 130 m.p.h. (215 km/h) during the past 24 hours.

Hurricanes Madeline and Lester will remain in a favorable environment during the short term.  They are moving over water where the Sea Surface Temperatures (SSTs) are near 27.5°C.  The upper level winds are light and there is little vertical wind shear.  Thus, both hurricanes could maintain their intensity for another 12 to 24 hours.  When the hurricanes move closer to Hawaii, they will move over slightly cooler SSTs.  In addition, an upper level trough approaching from the northwest could increase the vertical wind shear later this week.  Hurricane Lester may also move over some cooler water mixed to the surface by Hurricane Madeline.

A subtropical ridge is steering Hurricanes Madeline and Lester toward the west and that general motion is expected to continue for the next several days.  On its anticipated track Hurricane Madeline could approach Hawaii in a couple of days.  Hurricane Lester could approach Hawaii in about five days.

 

Tropical Depression Eight Prompts Tropical Storm Warning for North Carolina

The approach of Tropical Depression Eight and the potential for intensification prompted the National Hurricane Center to issue a Tropical Storm Warning for the portion of the coast from Cape Lookout to Oregon Inlet, North Carolina including Pamlico Sound.

At 5:00 p.m. EDT on Monday the center of Tropical Depression Eight was located at latitude 33.6°N and longitude 74.0°W which put it about 140 miles (225 km) southeast of Cape Hatteras, North Carolina.  It was moving toward the northwest at 6 m.p.h. (10 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. (70 km/h).  The minimum surface pressure was 1011 mb.

Vertical wind shear disrupted the circulation of Tropical Depression Eight earlier today, but more thunderstorms developed northwest of the center of circulation during the afternoon.  The circulation is still not well organized, but there are indications on radar that it could be developing a tighter center.  An upper level low centered near Savannah, Georgia is producing southerly winds which are causing the moderate vertical wind shear over the depression.  The upper level winds are blocking upper level divergence to the south of Tropical Depression Eight, but there are some sign that upper level divergence could be occurring to the northeast.

Tropical Depression Eight could move into an area marginally more favorable for intensification.  As it gets farther from the upper level low, the winds aloft will decrease.  The depression is moving near the Gulf Stream and the Sea Surface Temperatures are near 29.5°C.  If thunderstorms persist near the center of circulation and a more coherent vertical structure develops, the the depression could strengthen into a tropical storm.

The upper low is steering Tropical Depression toward the northwest and that general motion is expected to continue for another day or so.  When the depression reaches latitude 35°N, westerly winds will begin to steer it off toward the northeast.  On its anticipated track Tropical Depression Eight could be very near Cape Hatteras in 24 to 36 hours.

Although Tropical Depression Eight will bring some stronger winds, locally heavy rain, rip currents, higher waves and beach erosion are greater risks.