Tag Archives: Hawaii

Hurricane Lester Passing North of Hawaii

Hurricane Lester passed north of Hawaii on Saturday.  All Hurricane Watches were cancelled, although the surf on the north coasts of the islands should be increased by the waves generated by Hurricane Lester.  At 5:00 p.m. EDT on Saturday the center of Hurricane Lester was located at latitude 22.4°N and longitude 155.4°W which put it about 175 miles (285 km) east-northeast of Honolulu, Hawaii.  Lester was moving toward the west-northwest at 17 m.p.h. (28 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 985 mb.

Hurricane Lester weakened slowly on Saturday as it moved north of the Hawaiian Islands.  An upper level trough northwest of Lester produced southwesterly winds that blew across the top of the hurricane.  The vertical wind shear tilted the circulation toward the northeast with height.  The wind shear also inhibited the upper level divergence to the south of the center of Lester.  Less upper level divergence meant that the hurricane could not pump out as much mass and the surface pressure slowly rose.

Hurricane Lester is moving through an environment that is likely to weaken it further.  Lester is moving over water where the Sea Surface Temperature (SST) is 27°C.  So, there is enough energy to support the hurricane.  However, the upper level trough will continue to create vertical wind shear and the shear will continue to weaken Hurricane Lester.

Hurricane Lester is moving around the western end of a subtropical ridge which is steering toward the west-northwest.  That general motion is expected to continue for several more days.  When Hurricane Lester gets farther north the westerlies in the middle latitudes will turn it toward the northeast.  On its anticipated track Hurricane Lester will stay north of the Hawaiian Islands.

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.

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.

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 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.

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.

Tropical Storm Kay Forms South of Baja California

A distinct center of circulation consolidated within a cluster of thunderstorms south of Baja California and the National Hurricane Center designated the system as Tropical Storm Kay.  At 5:00 a.m. EDT on Friday the center of Tropical Storm Kay was located at latitude 18.4°N and longitude 110.9°W which put it about 315 miles (510 km) south-southwest of the southern tip of Baja California.  Kay was moving toward the northwest at 7 m.p.h. (11 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 of Tropical Storm Kay is only moderately well organized.  Most of the stronger thunderstorms are occurring in a band that wraps around the western side of the circulation.  There are also scattered thunderstorms in broken bands around the tropical storm, but much of the convection is occurring in the western half of Kay.  The thunderstorms in the primary rainband are generating some upper level divergence which is moving air to the west of the Tropical Storm Kay.

Tropical Storm Kay is moving through an environment that is marginally favorable for intensification in the short term.  Kay is moving over water where the Sea Surface Temperature (SST) is near 29°C.  An upper level ridge to the north of Kay is generating northeasterly winds which are blowing across the top of the tropical storm.  The moderate vertical wind shear is inhibiting intensification and it is also contributing to the asymmetrical distribution of thunderstorms.  The effect of the warm SSTs could allow for some additional intensification during the next 24 hours.  Tropical Storm Kay will be moving over cooler SSTs during the weekend and the effect of the effect of the cooler water with less energy will weaken the storm.

Tropical Storm Kay is moving around the western end of a subtropical ridge and that is steering the storm toward the northwest.  That general motion is expected to continue for another 24 to 48 hours.  When Tropical Storm Kay moves over cooler SSTs, the thunderstorms will weaken and the circulation will become shallower.  The shallower circulation will be steered by the winds closer to the surface, which are expected to turn Tropical Storm Kay more toward the west in a couple of days.  On its anticipated track Tropical Storm Kay will pass west of Baja California.

Weaker Tropical Storm Darby Makes Landfall on Big Island of Hawaii

A weakened Tropical Storm Darby made landfall on the southern end of the Big Island of Hawaii on Saturday.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Darby was located at latitude 19.3°N and longitude 155.8°W which put it about 195 miles (310 km) southeast of Honolulu, Hawaii.  Darby was moving toward the west at 10 m.p.h. (16 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 Warnings are in effect for Oahu, Hawaii County, Maui County including Maui, Molokai, Lanai and Kahoolawe, and Kauai County including Kauai and Niihau.

Air Force Reserve Hurricane Hunters investigated Tropical Storm Darby on Saturday and documented its weaker, less well organized structure.  Darby does not have a well formed inner core and the center of low pressure is broad and diffuse.  Most of the rain and thunderstorms are occurring south of the center of circulation.  The remnant of the primary spiral band consists of a short arc of thunderstorms southeast of the center of circulation.  There are few showers in the northern part of the circulation.

Tropical Storm Darby is moving toward water where the Sea Surface Temperature is near 28°C.  However, the center is moving over the Big Island of Hawaii, which will further disrupt the circulation.  Drier, more stable air is north of Darby and that will limit the potential for further convection.  If Darby retains sufficient organization after it moves back over water, it could continue as a tropical storm for another day or so.  However, if passage over land completely destroys the inner core, then Darby could dissipate during the next several days.

Tropical Storm Darby is nearing the western end of a subtropical ridge that has been steering toward the west.  When Darby reaches the end of the ridge, it is expected to turn more toward the northwest, which is why tropical storm warnings are in effect for a number of the Hawaiian Islands.   Locally heavy rain and the potential for flash flooding are the primary threats from Tropical Storm Darby.

Tropical Storm Darby Closes In on Hawaii

Tropical Storm Darby moved closer to Hawaii on Friday and the Tropical Storm Watches were upgraded to Tropical Storm Warnings.  At 11:00 p.m. EDT on Friday the center of Tropical Storm Darby was located at latitude 18.7°N and longitude 152.1°W which put it about 205 miles (335 km) east-southeast of Hilo, Hawaii.  Darby was moving toward the west at 12 m.p.h. (19 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 1000 mb.

Tropical Storm Warnings are in effect for Hawaii County and Maui County including Maui, Molokai, Lanai and Kahoolawe,  A Tropical Storm Watch has been issued for Maui.

An Air Force Reserve Hurricane Hunter reconnaissance aircraft investigated Tropical Storm Darby on Friday and provided data from inside the tropical storm.  Darby has an asymmetrical structure.  A primary rainband wraps around the western side of the tropical storm and most of the thunderstorms are west of the center of circulation.  An upper level ridge west of Hawaii is generating northeasterly winds which are blowing over the top of Tropical Storm Darby.  The vertical wind shear caused by the upper level ridge is contributing to the asymmetrical structure of the circulation.  The thunderstorms in the primary rainband are generating some upper level divergence.  Most of the stronger winds are occurring in the northern half of the circulation.

Darby is moving through an environment that is marginal for intensification.  It is moving over water where the Sea Surface Temperature (SST) is near 27.5°C.  However, the vertical wind shear is inhibiting the upper level divergence to the northeast.  The effects of warm SSTs and moderate upper level divergence appear to be offsetting each other and the intensity of Tropical Storm Darby did not change much on Friday.  As Darby moves farther west, the SSTs will start to decrease and the vertical wind shear will increase.  The more hostile environment is expected to cause Darby to weaken during the next few days.

A subtropical ridge north of Darby is steering the tropical storm toward the west.  Darby is moving near the western end of the ridge and it is expected to turn more toward the northwest during the weekend.  On its expected track Tropical Storm Darby is forecast to move near the Big Island of Hawaii on Saturday.  If Darby makes the expected turn toward the northwest, it could affect much of Hawaii.

Tropical Storm Darby will bring strong winds and higher than normal surf to Hawaii.  However, the greatest risk will be caused by winds flowing up slopes, which will produce locally heavy rain and the chance for flash floods.

Tropical Storm Darby Moves Closer to Hawaii and Watches Issued

Tropical Storm Darby moved closed to Hawaii on Thursday and Tropical Storm Watches were issued for some of the islands.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Darby was located at latitude 18.9°N and longitude 147.5°W which put it about 500 miles (800 km) east of Hilo, Hawaii.  Darby was moving toward the west at 13 m.p.h. (20 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 997 mb.

A Tropical Storm Watch has been issued for Hawaii County and Maui County including the islands of Maui, Molokai, Lanai, and Kahoolawe.

Tropical Storm Darby is maintaining its structure.  A primary rainband wraps around the north and west sides of the center of circulation.  Strong thunderstorms continue to develop close to the center of circulation.  Those thunderstorms are producing upper level divergence.  Darby is a small tropical storm.  Winds to tropical storm force extend out about 100 miles (160 km) on the north side of the circulation, but they only extend out about 50 miles (80 km) to south of the center.

Tropical Storm Darby is moving through an environment that is marginal for intensification.  It is moving over water where the Sea Surface Temperature (SST) is near 27°C.  So, there is enough energy in the upper ocean to support a tropical cyclones.  However, an upper level ridge centered west of Hawaii is generating northeasterly winds which are blowing over the western half of the circulation.  The moderate vertical wind shear is inhibiting intensification.  Darby maintained its intensity on Thursday as the positive and negative environmental factors effectively balanced each other out.  Darby could continue to maintain its intensity for several more days until it moves over cooler SSTs and into a region of stronger vertical wind shear.

A subtropical ridge north of Darby is steering the tropical storm toward the west.  That general motion is forecast to continue for another 36 hours.  On its anticipated track Tropical Storm Darby could approach the Big Island of Hawaii in about 36 hours.  It could bring tropical storm force winds to that island.  In addition Darby could cause heavy rain and flash flooding in locations where the wind blows up the slopes on the islands.