Tag Archives: Tropical Storm Darby

Tropical Storm Estelle Forms South of Mexico

Tropical Storm Estelle formed over the Eastern North Pacific Ocean south of Mexico on Friday night. At 11:00 p.m. EDT on Friday the center of Tropical Storm Estelle was located at latitude 13.2°N and longitude 102.0°W which put it about 290 miles (470 km) south-southwest of Acapulco, Mexico. Estelle was moving toward the northwest at 10 m.p.h. (16 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1006 mb.

An area of low pressure over the Eastern North Pacific Ocean south of Mexico strengthened on Friday night and the National Hurricane Center designated the system as Tropical Storm Estelle. The circulation around Estelle exhibited more organization. More thunderstorms developed near the center of Tropical Storm Estelle. Storms near the center of circulation generated upper level divergence that pumped mass away from the tropical storm. Bands of showers and thunderstorms were revolving around the center of Estelle’s circulation. Winds to tropical storm force extended out 45 miles (75 km) in the northeastern quadrant of Tropical Storm Estelle. The wind in the other parts of Estelle’s circulation were blowing at less than tropical storm force.

Tropical Storm Estelle will move through an environment favorable for intensification during the next 36 hours. Estelle will move over water where the Sea Surface Temperatures are near 28˚C. It will move under an upper level ridge near the west coast of Mexico. The upper level winds are weak in the ridge and there will be little vertical wind shear. Tropical Storm Estelle will intensify during the next 36 hours and it could strengthen to a hurricane.

Tropical Storm Estelle will move around the southern side of a high pressure system over Mexico. The high pressure system will steer Estelle toward the west-northwest during the next 36 hours. On its anticipated track Tropical Storm Estelle will move away from the west coast of Mexico.

Elsewhere, Tropical Storm Darby weakened east-southeast of Hawaii. At 11:00 p.m. EDT on Friday the center of Tropical Storm Darby was located at latitude 17.7°N and longitude 149.4°W which put it about 400 miles (640 km) east-southeast of Hilo, Hawaii. Darby was moving toward the west at 20 m.p.h. (32 km/h). The maximum sustained wind speed was 45 m.p.h. (75 km/h) and and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 1006 mb.

Tropical Storm Darby Forms South of Baja California

Tropical Storm Darby formed over the Eastern North Pacific Ocean south of Baja California on Saturday. At 11:00 p.m. EDT on Saturday the center of Tropical Storm Darby was located at latitude 14.3°N and longitude 114.9°W which put it about 680 miles (1090 km) south-southwest of the southern tip of Baja California. Darby was moving toward the west at 17 m.p.h. (28 km/h). The maximum sustained wind speed was 45 m.p.h. (75 km/h) and and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 1004 mb.

A well defined low pressure system formed in a tropical wave located south of Baja California on Saturday and the National Hurricane Center designated the system as Tropical Storm Darby. A small, well defined center of circulation was evident on visible and infrared satellite images. Bands of showers and thunderstorms were revolving around the center of Darby. Storms near the center generated upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 35 miles (55 km) from the center of circulation.

Tropical Storm Darby will move through an environment favorable for intensification during the next 48 hours. Darby will move over water where the Sea Surface Temperatures are near 28˚C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. Tropical Storm Darby will intensify during the 48 hours and it could strengthen to a hurricane.

Tropical Storm Darby will move around the southern side of a high pressure system over the Eastern North Pacific Ocean. The high pressure system will steer Darby toward the west during the next 48 hours. On its anticipated track Tropical Storm Darby will move farther away from Baja California.

Elsewhere over the Eastern North Pacific Ocean, the National Hurricane Center designated former Tropical Storm Bonnie as a Post Tropical Cyclone. At 5:00 p.m. EDT on Saturday the center of former Tropical Storm Bonnie was located at latitude 19.5°N and longitude 129.4°W which put it about 1275 miles (2055 km) west of the southern tip of Baja California. Bonnie was moving toward the west at 21 m.p.h. (33 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1009 mb.

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 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.