Tag Archives: Hawaii

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.

Tropical Storm Estelle Forms As Hurricane Darby Nears Peak Intensity

Tropical Storm Estelle developed late Friday over the Eastern North Pacific as Hurricane Darby neared its peak intensity farther west.  At 11:00 p.m. EDT on Friday the center of Tropical Storm Estelle was located at latitude 15.2°N and longitude 108.3°W which put it about 370 miles (600 km) southwest of Manzanillo, Mexico.  Estelle was moving toward the west-northwest at 12 m.p.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.  Estelle is the fifth tropical storm to form over the Eastern North Pacific during the month of July.

Meanwhile, about 950 miles west of Estelle, Hurricane Darby neared its peak intensity.  At 11:00 p.m. EDT on Friday the center of Hurricane Darby was located at latitude 17.3°N and longitude 122.1°W which put it about 880 miles (1415 km) west-southwest of the southern tip of Baja California.  Darby was moving toward the west-northwest at 9 m.p.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 972 mb.

The large circulation around Tropical Storm Estelle is still organizing.  A primary rainband is wrapping around the western side of the center.  Several spiral bands of thunderstorms are forming farther away from the core of the tropical storm.  Storms near the center are beginning to produce upper level divergence, but it is not currently well developed.

The environment around Estelle is favorable for gradual intensification.  Estelle is moving over water where the Sea Surface Temperature is near 29°C.  An upper level ridge north of Estelle is generating easterly winds which are blowing over the top of the tropical storm.  There is enough vertical wind shear to slow the rate of intensification, but the shear is probably not strong enough to keep Estelle from intensifying.  Storms like Estelle with large initial circulations can intensify slowly as a tighter core develops within the larger circulation.

Hurricane Darby is a well formed mature hurricane.  It has a well developed eye surrounded by a narrow ring of strong thunderstorms.  Several spiral bands are rotating around the core of Darby.  The thunderstorms near the center of circulation are generating upper level divergence which is pumping out mass in all directions.

Hurricane Darby is probably close to its peak intensity.  It is moving over water where the Sea Surface Temperature is near 27°C and Darby will be moving over cooler water during the next few days.  There is not much vertical wind shear, and Darby may have a chance to intensify during the next 12 to 24 hours.  However, Darby will reach cooler water in about a day and then the hurricane will being to weaken.

A subtropical ridge located north of Hurricane Darby and Tropical Storm Estelle is expected to steer both cyclones toward the west during the next few days.

Tropical Storm Darby Intensifies as Hurricane Celia Weakens

Tropical Storm Darby intensified on Tuesday as it moved in the trail of weakening Hurricane Celia.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Darby was located at latitude 15.4°N and longitude 110.4°W which put it about 520 miles (835 km) south of the southern tip of Baja California.  Darby was moving toward the west at 10 m.p.h. (16 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.

Farther west Hurricane Celia continued to weaken slowly on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Hurricane Celia was located at latitude 18.0°N and longitude 110.4°W which put it about 1360 miles (2190 km) west of the southern tip of Baja California.  Celia was moving toward the northwest at 12 m.p.h. (19 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 986 mb.

More thunderstorms developed near the center of Tropical Storm Darby on Tuesday.  However, most of the stronger thunderstorms were southwest of the center of circulation.  An upper level ridge near the west coast of Mexico was producing northeasterly winds which are blowing over the top of the tropical storm.  The vertical wind shear caused the asymmetric distribution of convection.  Despite the vertical wind shear the circulation in the lower levels was well developed.

Tropical Storm Darby is over water where the Sea Surface Temperature is near 30°C and Darby is expected to intensify into a hurricane.

Hurricane Celia is moving over water where the Sea Surface Temperature is near 25°C.  Since the hurricane is extracting less energy from the ocean, the thunderstorms are not as tall and Celia is slowly weakening.  The hurricane is in an area where the vertical wind shear is minimal and so the weakening trend is likely to occur at a slower rate than normal.

A subtropical ridge north of the Celia and Darby is steering the two tropical storms toward the west and that general motion is expected to continue for the next few days.

Hurricane Celia Develops West of Mexico

The next in a series of tropical systems over the Eastern North Pacific Ocean developed into Hurricane Celia on Sunday.  At 11:00 p.m. EDT on Sunday the center of Hurricane Celia was located at latitude 15.0°N and longitude 123.5°W which put it about 1040 miles (1675 km) west-southwest of the southern tip of Baja California.  Celia was moving toward the west at 13 m.p.h. (20 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 988 mb.

The circulation of Hurricane Celia is well developed.  A primary spiral band loops around the center of circulation and a small eye is apparent intermittently on satellite imagery.  The strongest winds are occurring within 20 miles (30 km) of the center of circulation.  Although there are numerous thunderstorms in the core of Hurricane Celia, they are not as tall as one might expect.  It could be that slightly cooler water was mixed to the surface by Hurricane Blas and the cooler water is causing the thunderstorms to reach their Equilibrium Level at a lower height.  In spite of the shorter thunderstorms, the circulation is generating upper level divergence in all directions.

The environment is favorable for intensification.  Hurricane Celia is moving over water where the Sea Surface Temperature (SST) is near 28°C.  The winds in the upper levels are weak and there is not much vertical wind shear.  Celia could intensify while is remains over warmer SSTs.  The hurricane will start to move over cooler SSTs in about another 24 hours, which will contribute to a less favorable environment.

A subtropical high pressure system north of Celia is steering the hurricane toward the west and that general motion is expected to continue during the next few days.  On its anticipated track Hurricane Celia will continue to move farther away from Mexico.

Blas Strengthens to Cat. 4 Hurricane

Hurricane Blas strengthened rapidly Tuesday to a Category 4 hurricane on the Saffir-Simpson Scale.  At 11:00 p.m. EDT on Thursday the center of Hurricane Blas was located at latitude 14.4°N and longitude 121.7°W which put it about 970 miles (1560 km) west-southwest of the southern tip of Baja California.  Blas was moving toward the west at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 140 m.p.h. (220 km/h) and there were wind gusts to 170 m.p.h. (275 km/h).  The minimum surface pressure was 947 mb.

The Hurricane Intensity Index (HII) for Blas was 28.2.  The Hurricane Size Index (HSI) was 12.2 and the Hurricane Wind Intensity Size Index (HWISI) was 40.4.

The circulation of Hurricane Blas is fairly symmetrical and well organized, although many of the stronger thunderstorms are occurring in the southeastern quadrant.  Blas has a clear eye which is surrounded by a ring of strong thunderstorms.  Those storms generated upper level divergence which pumped out a lot of mass in all directions and allowed the pressure to decrease rapidly on Tuesday.

Hurricane Blas is in an environment that is favorable for strong hurricanes.  It is moving over water where the Sea Surface Temperature is near 29°C.  The winds in the upper levels are light and there is not much vertical wind shear.  Hurricane Blas could get stronger on Wednesday.  However, eyewall replacement cycles sometimes occur in strong hurricanes.  When an eyewall replacement cycle occurs, it can bring an end to a period of intensification.

A ridge of high pressure located north of Blas is steering the hurricane toward the west and that motion is expected to continue for several more days.  Hurricane Blas continues to move farther away from Mexico.

Blas Intensifies Into a Hurricane

Tropical Storm Blas intensified into the first Eastern North Pacific hurricane of 2016 on Monday.  At 5:00 p.m. EDT on Monday the center of Hurricane Blas was located at latitude 13.7°N and longitude 115.7°W which put it about 740 miles (1190 km) southwest of the southern tip of Baja California.  Blas was moving toward the west-northwest at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were gusts  to 90 m.p.h. (145 km/h).  The minimum surface pressure was 994 mb.

The Hurricane Intensity Index (HII) for Blas was 10.4.  The Hurricane Size Index (HSI) was 6.1.  The Hurricane Wind Intensity Size Index (HWISI) was 16.5.

The large circulation of Hurricane Blas is still organizing.  A primary rainband wrapped around the center of circulation and an eye may be forming in the center of Blas.  Additional bands of thunderstorms are spiraling around the core of Hurricane Blas.  The thunderstorms near the center of circulation are generating upper level divergence which is pumping out mass.  Despite the improved organization the wind field around Hurricane Blas is asymmetrical.  Winds to hurricane force are occurring primarily in the eastern half of the circulation.  The strongest winds extend out about 25 miles (40 km) east of the center of Hurricane Blas.  Winds to tropical storm force extend out about 150 miles (240 km) east of the center, but only about 80 miles (130 km) west of the center.

Hurricane Blas is in an environment that is favorable for further intensification.  It is moving over water where the Sea Surface Temperature is near 29°C.  An upper level ridge north of Blas is generating some northeasterly winds which are blowing over the top of the circulation.  The vertical wind shear is moderate.  It is slowing the rate of intensification, but the shear is unlikely to prevent Hurricane Blas from intensifying during the next several days.  Blas does have a chance to become a major hurricane later this week.

A ridge of high pressure is steering Hurricane Blas toward the west-northwest and that general motion is expect to continue for several more days.  Hurricane Blas is moving farther away from Mexico.

Tropical Storm Blas Forms West of Mexico

After having no tropical storms during the first month and a half of the Eastern North Pacific hurricane season, Blas became the second tropical storm to form in the past two days.  At 11:00 p.m. EDT on Sunday the center of Tropical Storm Blas was located at latitude 12.4°N and longitude 112.2°W which put it about 740 miles (1190 km) south-southwest of the southern tip of Baja California.  Blas was moving toward the west-northwest 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 1001 mb.

The circulation of Tropical Storm Blas organized quickly on Sunday.  A primary rainband wrapped around the western and southern portions of the center of circulation.  Additional rainbands spiraled around the core of the storm.  The intensity of the thunderstorms weakened for a few hours, but storms east of the center of the circulation are intensifying again.  Winds to tropical storm force extend out about 70 miles (115 km) from the center of circulation.

An upper level ridge northeast of Blas is causing some northeasterly winds to blow over the top of the tropical storm.  The winds are responsible for vertical wind shear and they are inhibiting upper level divergence to the east of the circulation.  Tropical Storm Blas is moving over water where the Sea Surface Temperature is near 29°C.  In spite of the vertical wind shear the environment is favorable for intensification and Blas could become a hurricane on Monday.

A ridge of high pressure north of Blas is steering the tropical storm toward the west-northwest and that general motion is expected to continue for the next several days.  Tropical Storm Blas is moving away from Mexico.