Monthly Archives: October 2018

Possible Tropical Development Near Yucatan Peninsula

A tropical cyclone could develop near the Yucatan peninsula during the next few days.  At 2:00 p.m. EDT on Friday the center of Invest 91L was located at latitude 16.0°N and longitude 84.3°W which put it about 400 miles (640 km) southeast of Cancun, Mexico.  It was moving toward the northwest at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1007 mb.

A broad area of low pressure is over the western Caribbean Sea, Central America and the adjacent waters of the Eastern North Pacific Ocean.  Several smaller, mesoscale centers of rotation appear to be revolving around the larger low pressure system.  One of the mesoscale centers is over the Eastern North Pacific Ocean just west of the coast of Central America.  One or two other mesoscale centers appear to be over the western Caribbean Sea near Honduras.  The low level circulation is not currently well organized.  It is broad and diffuse.  Thunderstorms are clustered around the mesoscale centers, but large scale rainbands have not formed.

Westerly winds in the upper levels are are blowing over the top of the system.  Those winds are creating moderate vertical wind shear which is inhibiting the development of the low pressure system.  The upper level winds are forecast to weaken during the next few days and the wind shear will diminish.  The Sea Surface Temperature of the water in the northwestern Caribbean Sea and Gulf of Mexico is near 30°C.  The broad low pressure system could slowly organize during the next two to three days.  The National Hurricane Center is indicating that there is a 70% probability of formation of a tropical cyclone near the Yucatan peninsula or over the southern Gulf of Mexico during the next five days.  A reconnaissance plane is scheduled to investigate the low pressure system on Sunday, if necessary.

The broad low is southwest of a subtropical high pressure system over the Atlantic Ocean.  The high is expected to steer the low toward the northwest during the weekend.  On its anticipated track the low will move over the northwestern Caribbean Sea during the next several days.  it could move into the Gulf of Mexico on Monday.

Elsewhere over the Atlantic Ocean, Tropical Storm Leslie continued to meander northeast of Bermuda.  At 11:00 a.m. EDT on Friday the center of Tropical Storm Leslie was located at latitude 36.2°N and longitude 58.4°W which put it about 455 miles (730 km) northeast of Bermuda.  Leslie was moving toward the north-northwest at 9 m.p.h. (15 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 986 mb.

Typhoon Kong-rey Brings Wind and Rain to Okinawa

Typhoon Kong-rey was bringing wind and rain to Okinawa on Wednesday night.  At 11:00 p.m. EDT on Wednesday the center of Typhoon Kong-rey was located at latitude 23.6°N and longitude 127.3°W which put it about 230 miles (375 km) south of Okinawa.  Kong-rey was moving toward the northwest at 10 m.p.h. (16 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 964 mb.

Typhoon Kongrey weakened steadily during Wednesday.  The eye became less distinct on satellite imagery.  The ring of strong thunderstorms around the eye broke and stronger thunderstorms were only occurring to the east of the eye.  It appeared that Typhoon Kong-rey was pulling cooler, drier air into the western half of the circulation and that air was wrapping around the southern half of the typhoon.  Kong-rey may have also moved over some cooler water that was mixed to the surface by Typhoon Trami last week.

The circulation around Typhoon Kong-rey was still large.  Winds to typhoon force extended out about 70 miles (110 km) from the center of circulation.  Winds to tropical storm force extended out about 230 miles (375 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Kong-rey was 11.5.  The Hurricane Size Index (HSI) was 24.7 and the Hurricane Wind Intensity Size Index (HWISI) was 36.2.

Typhoon Kong-rey will move around the western end of a subtropical ridge over the Western North Pacific Ocean.  The ridge will steer Kong-rey toward the north during the next 24 to 36 hours.  Typhoon Kong-rey will turn more toward the northeast in about 36 hours.

The outer rainbands on the northern side of Typhoon Kong-rey are already over Okinawa.  Kong-rey will drop heavy rain and it will produce gusty winds over Okinawa and the Ryukyu Islands on Thursday.  The wind and rain will hinder efforts to recover from damage caused by Typhoon Trami.  Typhoon Kong-rey could be southeast of Kyushu in about 36 hours and it could be near South Korea in about 48 hours.  The soil in much of Japan is already near saturation and more heavy rain could cause flash flooding.  Typhoon Kong-rey could also hinder recovery efforts in Kyushu, Shikoku and Honshu.

Major Hurricane Sergio Churns Southwest of Baja California

Major Hurricane Sergio churned southwest of Baja California.  At 5:00 p.m. EDT on Wednesday the center of Hurricane Sergio was located at latitude 13.3°N and longitude 117.9°W which put it about 845 miles (1360 km) southwest of the southern tip of Baja California.  Sergio was moving toward the northwest at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 125 m.p.h. (200 km/h) and there were wind gusts to 145 m.p.h. (230 km/h).  The minimum surface pressure was 955 mb.

Hurricane Sergio is a well organized hurricane.  There is a circular eye at the center of circulation.  A ring of strong thunderstorms surrounds the eye and the strongest winds are occurring in that ring of storms.  Several bands of showers and thunderstorms are revolving around the core of Hurricane Sergio.  Storms near the core are generating strong upper level divergence which is pumping mass away in all directions from the hurricane.

Winds to hurricane force extend out about 45 miles (75 km) from the center of Hurricane Sergio.  Winds to tropical storm force extend out about 150 miles (240 km) from the center of circulation.  The Hurricane intensity Index (HII) for Hurricane Sergio is 23.6.  The Hurrricane Size Index (HSI) is 15.1 and the Hurricane Wind Intensity Size Index (HWISI) is 38.7.

Hurricane Sergio will remain in an environment capable of supporting a major hurricane for several more days.  Sergio will move over water where the Sea Surface Temperature is near 28°C.  It will move through an area where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Sergio could strengthen to Category 4 on the Saffir-Simpson Scale.  Hurricane Sergio will move over cooler water in a couple of days and it is likely to weaken when that occurs.

Hurricane Sergio will move south of a subtropical ridge over the Eastern North Pacific Ocean.  The ridge will steer Sergio toward the northwest during the next day or so.  The ridge is forecast to strengthen on Friday and it will steer Sergio more toward the west when that happens.  On its expected track Hurricane Sergio will move gradually farther away from Baja California.

Leslie Strengthens Into a Hurricane East of Bermuda

Former Tropical Storm Leslie strengthened into a hurricane east of Bermuda on Wednesday morning.  At 11:00 a.m. EDT on Wednesday the center of Hurricane Leslie was located at latitude 29.5°N and longitude 56.8°W which put it about 510 miles (825 km) east-southeast of Bermuda.  Leslie was nearly stationary.  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 975 mb.

After being designated as a subtropical storm, Hurricane Leslie made a transition to an extratropical cyclone and then back to a subtropical storm.  Leslie eventually moved over warmer water and the structure changed to that of a tropical storm, which intensified slowly until it reached hurricane intensity earlier this morning.  It is gradually exhibiting the classical appearance and structure of a hurricane.

There is a circular eye at the center of circulation.  A nearly complete ring of thunderstorms surrounds the eye and the strongest winds are occurring in that ring of storms.  Several bands of showers and thunderstorms are revolving around the core of Hurricane Leslie.  Storms near the core are generating upper level divergence which is pumping mass away from the hurricane, which is causing the surface pressure to decrease.  Winds to hurricane force extend out about 35 miles (55 km) from the center of circulation.  Winds to tropical storm force extend out about 230 miles (370 km) from the center.

Hurricane Leslie will remain in an environment favorable for intensification for another day or two.  Leslie will remain over water where the Sea Surface Temperature is near 27.5°C.  it will be in a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Leslie is likely to get a little stronger during the next day or so.  Leslie will move over cooler water later this week and it will start to weaken when that happens.

Hurricane Leslie has been in an area where the steering winds were weak which is why it has meandered east of Bermuda during the past few days.  A subtropical ridge southeast of Leslie will strengthen during the next day or two and the ridge will start to steer the hurricane toward the north.  On its anticipated track Hurricane Leslie will move farther away from Bermuda later this week.

Typhoon Kong-rey Quickly Strengthens Into Equivalent of Cat. 5 Hurricane

Typhoon Kong-rey quickly strengthened into the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale on Monday.  At 11:00 p.m. EDT on Monday the center of Typhoon Kong-rey was located at latitude 17.9°N and longitude 137.3°E which put it about 690 miles (1110 km) southeast of Okinawa.  Kong-rey was moving toward the west-northwest at 11 m.p.h. (17 km/h).  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 195 m.p.h. (315 km/h).  The minimum surface pressure was 910 mb.

The circulation of Typhoon Kong-rey was very organized and symmetrical.  There was a circular eye at the center of Kong-rey.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Several bands of showers and thunderstorms were revolving around the core of Typhoon Kong-rey.  Storms near the core were generating strong upper level divergence which was pumping mass away from the typhoon in all directions.

Kong-rey is a large typhoon.  Winds to typhoon force extend out about 75 miles (120 km) from the center of circulation.  Winds to tropical storm force extend out about 240 miles (390 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Kong-rey is 35.0.  The Hurricane Size Index (HSI) is 26.8 and the Hurricane Wind Intensity Size Index (HWISI) is 61.8.  Typhoon Kong-rey is capable of causing widespread catastrophic damage.

Typhoon Kong-rey will remain in an environment very favorable for strong typhoons for another 24 to 36 hours.  Kong-rey will move over water where the Sea Surface Temperature is near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  If a rainband wraps around the existing eye and eyewall, then an eyewall replacement cycle could cause Typhoon Kong-rey to weaken.  An upper level trough near Taiwan will produce southwesterly winds which will cause the vertical wind shear to increase in a couple of days.  Kong-rey will weaken more steadily when the wind shear increases.

Typhoon Kong-rey will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean.  The high will steer Kong-rey toward the northwest for several more days.  On its anticipated track Typhoon Kong-rey could approach the Rykyu Islands in 48 to 60 hours.  It will still be a typhoon at that time.  If Typhoon Kong-rey brings strong winds and heavy rain, it will hamper the recovery from Typhoon Trami which hit the Ryukyu Islands a few days ago.

Hurricane Walaka Rapidly Intensifies to Category 5

Hurricane Walaka rapidly intensified to Category 5 on the Saffir-Simpson Scale on Monday.  At 11:00 p.m. EDT on Monday the center of Hurricane Walaka was located at latitude 13.2°N and longitude 169.8°W which put it about 240 miles (390 km) south of Johnston Atoll.  Walaka was moving toward the northwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 195 m.p.h. (315 km/h).  The minimum surface pressure was 920 mb.

A Hurricane Warning is in effect for Johnston Atoll.  A Hurricane Watch is in effect for the Papahanaumokuakea Marine National Monument from Nihoa to French Frigate Shoals to Maro Reef.

The circulation of Hurricane Walaka is very well organized,  There is a circular eye at the center of Walaka.  The eye is surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Several bands of showers and thunderstorms were revolving around the core of Hurricane Walaka.  Storms near the core were generating strong upper level divergence which was pumping mass away from the hurricane in all directions.

Winds to hurricane force extended out about 50 miles (80 km) from the center of Hurricane Walaka.  Winds to tropical storm force extended out about 185 miles (300 km) from the center of circulation.  The Hurricane Intensity Index (HII) for Hurricane Walaka was 35.0.  The Hurricane Size Index (HSI) was 16.4 and the Hurricane Wind Intensity Size Index (HWISI) was 51.4.

Hurricane Walaka will remain in an environment very favorable for strong hurricanes for several more days.  Walaka will move over water where the Sea Surface Temperature is near 30°C.  It will move through a region where the upper level winds will be weak and there will be little vertical wind shear.  If a rainband wraps around the existing eye and eyewall, then an eyewall replacement cycle could cause Hurricane Walaka to weaken.  In several days Walaka will move into an area where the upper level winds are stronger and the vertical wind shear will increase.  Hurricane Walaka will weaken more quickly when the shear increases.

Hurricane Walaka is moving around the western end of a subtropical high pressure system.  The high pressure system will steer Walaka toward the north during the next several days.  On its anticipated track Hurricane Walaka will pass near Johnston Atoll on Tuesday.

Tropical Storm Rosa Nears Baja California

Tropical Storm Rosa moved nearer to Baja California on Monday morning.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Rosa was located at latitude 27.5°N and longitude 116.5°W which put it about 90 miles (145 km) west-southwest of Punta Eugenia, Mexico.  Rosa was moving toward the north-northeast at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1000 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Punta Abreojos to Cabo San Quintin, Mexico.  A Tropical Storm Watch was in effect for the portion of the coast from Bahia de los Angeles to San Felipe, Mexico.

Tropical Storm Rosa was weakening as it approached the coast of Baja California.  Rosa was moving over water where the Sea Surface Temperature was near 23°C.  An upper level low west of California was producing southwesterly winds which were blowing toward the top of the circulation.  Those winds were causing significant vertical wind shear.  The effects of cool water and vertical shear were causing most of the stronger thunderstorms to occur northeast of the center of circulation.  Bands south and west of the center consisted primarily of showers and lower clouds.

The center of Tropical Storm Rosa will reach northern Baja California in a few hours.  Rosa will bring some gusty winds when when it reaches the coast, but the greater risk is locally heavy rainfall.  Rosa could drop several inches of rain and flash floods could occur.  The lower level part of Rosa’s circulation will weaken when it crosses Baja California.  However, the upper low west of California will steer the middle and upper parts of Tropical Storm Rosa over the Southwestern U.S.  Rosa, or its remnants, could drop locally heavy rain over that region during the next several days.  Flash Flood Watches have been issued for southeastern California, eastern Nevada, western Arizona, and much of Utah.

Elsewhere over the Eastern North Pacific, Tropical Storm Sergio was strengthening slowly south of Baja California.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Sergio was located at latitude 11.5°N and longitude 109.5°W which put it about 790 miles (1275 km) south of the southern tip of Baja California.  Sergio was moving toward the west at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 995 mb.