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.

Large Typhoon Lionrock Moves Closer to Japan

Large Typhoon Lionrock moved closer to Japan on Sunday.  At 11:00 p.m. EDT on Sunday the center of Typhoon Lionrock was located at latitude 31.1°N and longitude 142.1°W which put it about 385 miles (620 km) south-southeast of Tokyo, Japan.  Lionrock was moving toward the northeast at 19 m.p.h. (31 km/h).  The maximum sustained wind speed was 110 m.p.h. (180 km/h) and there were wind gusts to 130 m.p.h. (210 km/h).  The minimum surface pressure was 952 mb.

Typhoon Lionrock retains a large symmetrical circulation.  Winds to typhoon force extend out about 40 miles (65 km) from the center.  Microwave satellite images suggest that there could be two eyewalls.  The inner eyewall is weaker on the western side and the larger outer eyewall has fewer thunderstorms on the northwestern side.  Other spiral bands are rotating around outside the outer eyewall.  Thunderstorms near the core of the circulation are generating upper level divergence which is pumping out mass primarily to the east of the typhoon.

The environment around Typhoon Lionrock would be marginally favorable for intensification.  Lionrock is moving over water where the Sea Surface Temperature (SSTs) is near 28°C.  An upper level trough west of Lionrock is generating southwesterly winds which are affecting the upper level divergence on the western side of the typhoon.  However, the vertical wind shear is not too significant.  On the other hand, concentric eyewalls often produce weakening as the inner eye wall dissipates and the stronger winds occur in the outer eyewall.  So, Lionrock could maintain a steady intensity or weaken slowly during the next 24 hours.  After that time is will move over cooler SSTs and it could weaken more.

The upper level trough is steering Typhoon Lionrock toward the northeast and that general motion is expect to continue for another 24 hours.  After that time, the upper trough will turn Lionrock back toward the northwest.  On its anticipated track Typhoon Lionrock will make landfall on northeast Honshu north of Tokyo in about 36 hours.  It could cause some wind damage.  Heavy rainfall and flash floods will also pose serious risks since Lionrock will move over some of the same areas affected by Typhoon Mindulle.

Tropical Depressions Form South of Key West & Southeast of Cape Hatteras

Two tropical depressions formed near the U.S. on Sunday.  Tropical Depression Nine formed south of Key West, Florida and Tropical Depression Eight formed southeast of Cape Hatteras, North Carolina.  Both depressions could have an impact on the U.S., but Tropical Depression Nine could pose a greater risk to the southeastern U.S.

At 5:00 p.m. EDT on Sunday the center of Tropical Depression Nine was located at latitude 23.7°N and longitude 81.7°W which put it about 60 miles (95 km) south of Key West, Florida.  It was moving toward the west at 9 m.p.h. (15 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 1009 mb.

At 5:00 p.m. EDT on Sunday the center of Tropical Depression Eight was located at latitude 31.8°N and longitude 70.9°W which put it about 355 miles (570 km) southeast of Cape Hatteras, North Carolina.  It was moving toward the west at 9 m.p.h. (15 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 1010 mb.

The circulation of Tropical Depression Nine is still organizing.  A NOAA plane found a distinct center of circulation, but most of the stronger thunderstorms are south and east of the center.  There is a broader counterclockwise rotation with numerous showers and thunderstorms indicated by the National Weather Service radar in Key West.  An upper level low east of Florida is contributing to easterly winds that are blowing across the northern side of the depression.  The vertical wind shear is inhibiting the development of thunderstorms north and west of the center.

The circulation of Tropical Depression Eight was more well organized earlier today.  Strong easterly winds from the same upper level low that is affecting Tropical Depression Nine are creating significant vertical wind shear.  Those winds and the shear they caused blew the upper portion of the depression’s circulation west of the low level center of circulation.  The low level circulation is presently exposed as seen on visible satellite imagery and by an Air Force Reserve Hurricane Hunter aircraft.

The intensity forecast for Tropical Depression Nine is challenging because it is moving through a complex environment.  The depression is moving over water where the Sea Surface Temperature is near 31°C.  So, there is plenty of energy in the upper ocean.  However, as mentioned above, an upper low is causing vertical wind shear which will inhibit intensification.  Tropical Depression Nine could move into a region where there is less shear when it moves over the Gulf of Mexico.  Tropical Depression Nine has a good chance to intensify into a tropical storm, but it is unclear if it could become a hurricane before it reaches the coast.

There is also significant uncertainty in the track forecast for Tropical Depression Nine.  A ridge over the southeastern U.S. is steering the depression toward the west and that general motion should continue for several more days.  The ridge is forecast to weaken during the middle of the week and that should allow Tropical Depression Nine to turn toward the north.  The timing of that turn and how sharp it will be are still uncertain.

The upper low is expected to continue to generate wind shear over Tropical Depression Eight.  If the upper levels winds remain as strong as they are now, the depression will slowly weaken.  If the upper level winds weaken, then Tropical Depression Eight could strengthen into a minimal tropical storm.  The upper level low is steering the depression west and that general motion is expected to continue in the short term.  The depression could stall just off the coast of North Carolina.

Tropical Depression Nine could intensify and bring wind and rain to the Gulf Coast later this week.  The Gulf Coast is also vulnerable to storm surges.  Given the uncertainty in both the track and intensity, interests along the coast should monitor official sources of information for updates on Tropical Depression Nine.  The primary effects of Tropical Depression Eight are likely to be higher than normal surf, rip currents and some beach erosion along the North Carolina coast.  People along the Mid-Atlantic coast should pay attention to the depression in case the forecast changes.

Gaston Regains Hurricane Intensity East of Bermuda

Gaston intensified back into a hurricane east if Bermuda on Saturday.  At 11:00 p.m. EDT on Saturday the center of Hurricane Gaston was located at latitude 29.6°N and longitude 54.2°W which put it about 655 miles (1055) km east-southeast of Bermuda.  Gaston was moving toward the northwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 85 m.p.h. (140 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 980 mb.

The circulation of Hurricane Gaston is as well organized as it has ever been.  Gaston has a well formed circular eye surrounded by a ring of thunderstorms.  Multiple spiral rainbands are rotating around the circulation.  Upper level outflow channels to the southwest and east are enhancing upper level divergence and allowing the surface pressure to decrease.

Hurricane Gaston has moved into an environment that is favorable for further intensification.  If it moving over water where the Sea Surface Temperature is near 29°C.  An upper level low northeast of Puerto Rico and an upper level low southeast of Gaston are partially responsible for the two upper level outflow channels.  The upper level winds are weaker in between the two upper level lows and the vertical shear is less than it has been in recent days.  Gaston is likely to intensify further and it could become the first Major Hurricane of the 2016 Atlantic hurricane season.

The steering currents between the two upper lows are weaker and Hurricane Gaston has been moving more slowly toward the northwest.  Gaston is expected to move slowly northward for another day or two.  An upper level trough is likely to begin to steer the hurricane toward the east in 48 to 72 hours.  On its anticipated track Hurricane Gaston should pass well to the east of Bermuda.

Tropical Storm Madeline Forms East of Hawaii

A cluster of thunderstorms between Hawaii and Mexico developed enough organization on Friday night that the National Hurricane Center designated the system as Tropical Storm Madeline.  At 11:00 p.m. EDT on Friday the center of Tropical Storm Madeline was located at latitude 13.9°N and longitude 137.4°W which put it about 1235 miles (1990 km) east-southeast of Hilo, Hawaii.  Madeline was moving toward the west-northwest at 12 m.p.h. (19 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.

The circulation of Tropical Storm Madeline is still organizing.  A primary spiral band wraps around the western side of the circulation.  There are additional spiral bands of the thunderstorms in the southern part of the tropical storm.  The thunderstorms in the primary rainband are generating upper level divergence which it pumping mass out primarily to the west of tropical storm Madeline.

Tropical Storm Madeline is moving through an environment that is favorable for intensification.  It is moving over water where the Sea Surface Temperature (SST) is near 29°C.  The upper level winds are light and there is not much vertical wind shear.  Tropical Storm Madeline is expected to intensify steadily and it could become a hurricane by the end of the weekend.  In a few days Madeline will move over cooler SSTs and into an area where the is more vertical wind shear.  When that happens, Madeline will start to weaken.

A subtropical high is steering Tropical Storm Madeline toward the west-northwest and a general west-northwest or westerly motion is expected to continue during the next few days.  On its anticipated track Madeline could approach the Hawaiian Islands in about five days.

Typhoon Lionrock Turns in the Direction of Japan

After meandering southeast of Okinawa for several days Typhoon Lionrock started moving northeast toward Japan on Friday.  At 5:00 p.m. EDT on Friday the center of Typhoon Lionrock was located at latitude 23.7°N and longitude 133.0°E which put it about 920 miles (1485 km) south-southwest of Tokyo, Japan.  Lionrockk was moving toward the northeast at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 105 m.p.h. (170 km/h) and there were wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 953 mb.

Typhoon Lionrock is very well organized.  It has a circular eye surrounded by a ring of strong thunderstorms.  Additional well formed spiral bands are rotating around outside the core of Lionrock.  Thunderstorms in the eyewall and spiral bands are generating upper level divergence which are pumping out mass in all directions.  The upper level divergence is inhibited a little on the far northern edge of the circulation by northerly winds impinging on Typhoon Lionrock.  Even so, there is enough upper level divergence to compensate for the strong inflow of mass near the surface and Typhoon Lionrock has been in a nearly steady state during recent hours.

Typhoon Lionrock is moving through an environment that should allow for it to maintain its intensity during the next severall days.  It is moving over water where the Sea Surface Temperature (SST) is near 30°C.  An upper level high over China is generating northerly winds which are effecting the extreme northern edge of the outflow from Lionrock.  However, the vertical wind shear is not very strong and it should have a minimal effect on the intensity of the typhoon in the short term.  Eventually, Typhoon Lionrock will move over cooler SSTs and into a region where the upper level winds are stronger and it will start to weaken before it reaches Japan.

Typhoon Lionrock is moving around the western end of a subtropical ridge and that ridge is beginning to steer it toward the northeast.  That general motion is expected to continue for the next several days.  Eventually Lionrock is forecast to turn more toward the northwest.  On its anticipated track Typhoon Lionrock could approach the eastern coast of Honshu in three or four days.  Lionrock could still be a typhoon at that time.

If Lionrock makes landfall in Honshu as a typhoon it will be strong enough to cause some wind damage.  In addition, Typhoon Lionrock could move over some of the same areas affected by Typhoon Mindulle.  Heavy rain caused by Lionrock could create the potential for additional flash flooding and mudslides.

Tropical Storm Lester Forms West of Mexico

Tropical Storm Lester became the 12th named tropical storm to form over the Eastern North Pacific Ocean during 2016 on Thursday.  At 5:00 p.m. EDT on Thursday the center of Tropical Storm Lester was located at latitude 16.9°N and longitude 113.4°W which put it about 470 miles (760 km) south-southwest of the southern tip of Baja California.  Lester was moving toward the west-northwest 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 1000 mb.

Tropical Storm Lester formed when a distinct center of circulation developed within a tropical wave.  The core of the tropical storm is still consolidating.  There are thunderstorms near the center of circulation and there are spiral bands rotating around the core of Tropical Storm Lester.  The thunderstorms near the center are generating upper level divergence which is pumping away may to the south of the tropical storm.  There are hints of the possible formation of an eye on some satellite images.

Tropical Storm Lester is moving through an environment that is generally favorable for intensification.  It is moving over water where the Sea Surface Temperature is around 30°C.  An upper level ridge northwest of Lester is generating northerly winds which are blowing across the top of the tropical storm.  The northerly winds are producing some vertical wind shear, but the shear is only slowing the intensification process.  Tropical Storm Lester is expected to continue to intensify and it could become a hurricane.

A subtropical ridge is steering Tropical Storm Lester toward the west-northwest and that general motion is expected to continue.  On its anticipated track Tropical Storm Lester will move farther away from Mexico and it currently poses no threat to land.

Lionrock Becomes a Typhoon East of Okinawa

Tropical Storm Lionrock intensified into a typhoon east of Okinawa on Tuesday.  At 8:00 p.m. EDT on Tuesday the center of Typhoon Lionrock was located at latitude 25.3°N and longitude 132.8°E which put it about 340 miles (550 km) east-southeast of Okinawa.  Lionrock was moving toward the south-southwest at 11 m.p.h. (17 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 965 mb.

Lionrock is a fairly small typhoon.  Winds to tropical storm force only extend out about 150 miles (240 km) from the center.  The circulation of Typhoon Lionrock is very well organized.  A small distinct eye is visible on satellite imagery.  The eye is surrounded by a ring of strong thunderstorms.  Additional spiral rainbands are rotating around the core of Lionrock.  The thunderstorms around the eye are generating upper level divergence which is pumping out mass in all directions.

Typhoon Lionrock is in an environment that is favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 30.5°C.  The upper level winds are weak and there is little vertical wind shear.  A small typhoon like Lionrock can intensify very quickly and it appears to be doing so.

An upper level ridge over China is steering Typhoon Lionrock slowly toward the south-southwest and that general motion is expected to continue for another day or two.  Lionrock could move into an area where the steering winds are weak and it could stall for a period of time.  Eventually, an upper level trough is expected to approach the area from the west and begin to pull Lionrock toward the north.

Tropical Storm Gaston Forms Southwest of the Cape Verde Islands

A center of circulation quickly organized within a tropical wave on Monday night and the National Hurricane Center designated the system as Tropical Storm Gaston.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Gaston was located at latitude 12.6°N and longitude 30.7°W which put it about 450 miles (725 km) west-southwest of the Cape Verde Islands.  Gaston was moving toward the west-northwest at 18 m.p.h. (30 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 1005 mb.

The circulation consolidated rapidly around the center of Tropical Storm Gaston on Monday.  Several spiral bands of thunderstorms formed close to the center and additional bands formed farther from the center.  The thunderstorms near the center began to generate upper level divergence, which pumped mass away from the center.

Tropical Storm Gaston is moving through an environment that is favorable for intensification.  It is over water where the Sea Surface Temperature is near 28°C.  The upper level winds are light and there is little vertical wind shear.  Gaston is likely continue to intensify steadily during the next several days and it is expected to become a hurricane.  Once a tightly organized core consolidates completely, Gaston could undergo a period of more rapid intensification.

A subtropical ridge is steering Tropical Storm Gaston toward the west-northwest and that general motion is expected to continue for a day or so.  The ridge is expected to weaken northwest of Gaston, and the tropical storm is expected to turn more toward the north during the middle of the week.  Gaston could be moving out into the Central Atlantic Ocean by the end of the week.