Monthly Archives: September 2019

Tropical Storm Karen Drops Heavy Rain on Puerto Rico and the Virgin Islands

Tropical Storm Karen dropped heavy rain on parts of Puerto Rico and the Virgin Islands on Tuesday.  At 2:00 p.m. EDT on Tuesday the center of Tropical Storm Karen was located at latitude 17.5°N and longitude 66.0°W which put it about 65 miles (105 km) south of San Juan Puerto Rico.  Karen was moving toward the north at 8 m.p.h. (13 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 1005 mb.

Tropical Storm Warnings were in effect for Puerto Rico including Vieques and Culebra, the U.S. Virgin Islands and the British Virgin Islands.

The circulation around Tropical Storm Karen exhibited more organization on Tuesday afternoon.  A new low level center of circulation formed a little farther to the west near a cluster of stronger thunderstorms.  The minimum surface pressure decreased by several millibars.  More thunderstorms formed near the center of circulation and in bands revolving around the center.  Storms near the newly reformed center of circulation were generating more upper level divergence which was pumping mass away from the tropical storm.  The removal of mass was what allowed the surface pressure to decrease.  Winds to tropical storm force extended out about 80 miles (130 km) from the center of circulation.

Tropical Storm Karen will move through an environment favorable for intensification during the next 24 to 48 hours.  Karen will move over water where the Sea Surface Temperature is near 29°C.  Karen has moved under the middle of an upper level ridge over the eastern Caribbean Sea where the upper level winds are weaker.  There will be less vertical wind shear during the next day or two.  The environment around Tropical Storm Karen will support intensification.  However, the center of Karen will pass over Puerto Rico during the next 24 hours.  The mountains in Puerto Rico will disrupt the circulation in the lower levels and Tropical Storm Karen will weaken when it passes over those mountains.  Karen will likely strengthen again when it moves north of Puerto Rico.

Tropical Storm Karen will move around the western end of a subtropical high pressure system over the Atlantic Ocean.  The high will steer Karen toward the north during the next day or two.  On its anticipated track Tropical Storm Karen will move across Puerto Rico during the next 24 hours.  Karen will drop heavy rain on parts of Puerto Rico, the U.S. Virgin Islands and the British Virgin Islands.  Prolonged heavy rain will create a high risk for flash floods in those areas.

Elsewhere over the Atlantic Ocean, Tropical Storm Jerry was moving slowly toward Bermuda and Tropical Storm Lorenzo was strengthening west of the Cabo Verde Islands.  At 2:00 p.m. EDT the center of Tropical Storm Jerry was located at latitude 30.9°N and longitude 69.1°W which put it about 270 miles (435 km) west-southwest of Bermuda.  Jerry was moving toward the north-northeast at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 992 mb.  A Tropical Storm Warning was in effect for Bermuda.

At 11:00 a.m. EDT on Tuesday the center of Tropical Storm Lorenzo was located at latitude 12.4°N and longitude 29.3°W which put it about 270 miles (435 km) west-southwest of the Cabo Verde Islands.  Lorenzo was moving toward the west-northwest at 16 m.p.h. (26 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

Tropical Cyclone Hikaa Rapidly Intensifies to Equivalent of Hurricane/Typhoon East of Oman

Tropical Cyclone Hikaa rapidly intensified into the equivalent of a hurricane/typhoon over the northern Arabian Sea east of Oman on Monday.  At 5:00 p.m. EDT on Monday the center of Tropical Cyclone Hikaa was located at latitude 20.2°N and longitude 61.7°E which put it about 225 miles (365 km) east of Masirah Island.  Hikaa 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 100 m.p.h. (160 km/h).  The minimum surface pressure was 975mb.

Tropical Storm Hikaa intensified from the equivalent of a minimal tropical storm into the equivalent of a hurricane/typhoon in 24 hours.  A small eye developed quickly at the center of circulation.  A ring of strong thunderstorms surrounded the eye and the strongest winds were occurring in that ring of storms.  The circulation around Tropical Cyclone Hikaa was very small.  Winds to hurricane/typhoon force extended out about 15  miles (25 km) from the center of circulation.  Winds to tropical storm force only extended out 45 miles (75 km) from the center.

Tropical Cyclone Hikaa may have reached its peak intensity.  Hikaa will move over water where the Sea Surface Temperature is near 27°C.  So, there will be enough energy in the upper ocean to support intensification.  However, the atmospheric conditions will become less favorable.  An upper level ridge over southwestern Asia will produce easterly winds which will cause moderate vertical wind shear.  In addition, the circulation around Tropical Cyclone Hikaa will begin to draw drier air from eastern Africa into the circulation on Tuesday.  Since Hikaa is so small, the tropical cyclone could weaken quickly if the environment becomes less favorable.

The ridge over southwestern Asia will steer Tropical Cyclone Hikaa toward the west.  On its anticipated track Hikaa could approach the coast of Oman near Masirah Island in less than 18 hours.  Tropical Cyclone Hikaa will bring gusty winds and locally heavy rain to the central coast of Oman near Masirah Island.  Heavy rain could cause isolated flash floods.

Tropical Storm Karen Develops Near Windward Islands

Tropical Storm Karen developed near the Windward Islands on Sunday morning.  At 8:00 a.m. EDT on Sunday the center of Tropical Storm Karen was located at latitude 11.9°N and longitude 60.9°W which put it about 55 miles (90 km) east-southeast of Grenada.  Karen was moving toward the west-northwest at 9 m.p.h. (15 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.

Tropical Storm Warnings were in effect for Trinidad and Tobago, Grenada, and for St. Vincent and the Grenadines.

A center of circulation developed in an area of thunderstorms east of the axis of a strong tropical wave near the Windward Islands on Sunday morning and the National Hurricane Center designated the system as Tropical Storm Karen.  The strongest thunderstorms were forming in bands south and west of the center of circulation.  Bands north and west of the center consisted primarily of showers and lower clouds.   Winds to tropical storm force extended out about 125 miles (200 km) on the eastern side of the tropical storm.

An upper level trough northeast of the Lesser Antilles was producing strong westerly winds which were blowing across the northern side of Tropical Storm Karen.  An upper level ridge over the Caribbean Sea was producing strong northeasterly winds which were blowing across the western part of Karen.  The upper level winds were causing moderate vertical wind shear which was inhibiting the development of thunderstorms in those parts of Tropical Storm Karen.  The center of circulation developed in a region between the stronger upper level westerly and northeasterly winds.  Most of the thunderstorms were forming in that area where the upper level winds were not as strong.

Tropical Storm Karen will move through an environment that will be only marginally favorable for intensification during the next day or two.  Karen will move over water where the Sea Surface Temperature  is near 29°C.  However, the upper level trough and upper level ridge will continue to cause moderate vertical wind shear.  If Tropical Storm Karen remains in the zone where the upper level winds are not as strong, it could strengthen.  However, if Karen moves under stronger upper level winds, it could weaken to a depression.  Tropical Storm Karen is forecast to move closer to the center of the upper level ridge in two or three days.  If that happens, then the upper level winds will be weaker and Karen could intensify.

Tropical Storm Karen will move around the western end of a subtropical high pressure system over the Atlantic Ocean.  The high will steer Karen toward the west-northwest during the next 12 hours.  Karen will move more toward the north when reaches the end of the ridge.  On its anticipated track Tropical Storm Karen will move across the Windward Islands on Sunday.  Karen will bring gusty winds and locally heavy rain.  Flash floods are likely.  Tropical Storm Karen could approach Puerto Rico and the Virgin Islands on Tuesday.  Tropical Storm Watches are likely to be issued for those islands.

Elsewhere over the Atlantic Ocean Tropical Storm Jerry was spinning south of Bermuda.  At 5:00 a.m. EDT on Sunday the center of Tropical Storm Jerry was located at latitude 25.0°N and longitude 66.9°W which put it about 520 miles (835 km) south-southwest of Bermuda.  Jerry was moving toward the north-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 1002 mb.

Strong Tropical Wave Brings Wind and Rain to Windward Islands

A strong tropical wave was bringing wind and rain to the Windward Islands.  At 8:00 p.m. EDT on Saturday the center of the tropical wave was located at latitude 11.9°N and longitude 59.5°W which put it about 75 miles (120 km) northeast of Tobago.  The wave was moving toward the west at 20 m.p.h. (32 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. (75 km/h).  The minimum surface pressure was 1009 mb.

The axis of the tropical wave stretched from near Barbados to just east of Trinidad and Tobago.  More thunderstorms developed near the axis of the wave on Saturday night and there were indications that a center of circulation could be forming northeast of Trinidad and Tobago.  There were winds to near tropical storm force.  The National Hurricane Center issued a special Tropical Weather Outlook on Saturday night and indicated that tropical storm watches and warnings might need to be issued on Sunday.  The wave is forecast to move over the Windward Islands and into the eastern Caribbean Sea on Sunday.

Elsewhere over the Atlantic Ocean, Tropical Storm Jerry was located north of Puerto Rico.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Jerry was location at latitude 24.1°N and longitude 66.3°W which put it about 575 miles (925 km) south of Bermuda.  Jerry was moving toward the northwest at 15 m.p.h. (24 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 1002 mb.

Tropical Storm Lorena Brings Rain to Northwestern Mexico

Tropical Storm Lorena brought rain to parts of northwestern Mexico on Saturday night.  At 11:00 p.m. EDT on Saturday was located at latitude 27.6°N and longitude 111.2°W which put it about 35 miles (55 km/h) southwest of Guaymas, Mexico.  Lorena was moving toward the north 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 gust to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1002 mb.  A Tropical Storm Warning was in effect for the portion of the coast from Huatabampito to Puerto Libertad, Mexico.

Former Hurricane Lorena weakened on Saturday as it moved northward across the Gulf of California.  The inner core of Lorena was disrupted on Saturday morning when the eye moved near the southern tip of Baja California.  An upper level trough over the southwestern U.S. produced strong southwesterly winds which caused moderate vertical wind shear.  The wind shear inhibited the development of new thunderstorms while Tropical Storm Lorena moved over the warm water in the Gulf of California.  By Saturday night the strongest thunderstorms were occurring just to the northeast of the center circulation.

Tropical Storm Lorena will make landfall on the west coast of Mexico near Guaymas on Saturday night.  Lorena will move northward over Sonora toward Hermosillo after it make landfall.  Tropical Storm Lorena is a small storm and it will weaken rapidly when it moves inland.  Lorena will drop locally heavy rain over parts of Sonora.  The locally heavy rain could cause flash floods in some locations.

Tapah Strengthens to a Typhoon Southwest of Japan

Former Tropical Storm Tapah strengthened into a typhoon southwest of Japan on Saturday.  At 11:00 a.m. EDT on Saturday the center of Typhoon Tapah was located at latitude 29.2°N and longitude 125.9°E which put it about 380 miles (610 km) southwest of Nagasaki, Japan.  Tapah was moving toward the north 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 972 mb.

The circulation around Typhoon Tapah was very large.  Winds to tropical storm force extended out 250 miles (400 km) from the center of circulation.  There was a large eye with a diameter of 60 miles (95 km) at the center of Typhoon Tapah.  The eye was surrounded by a broken ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the large eye of Tapah.  It appeared on satellite imagery as if some drier air might be wrapping around the southeastern side of the circulation.

Typhoon Tapah will move through an environment that could allow it to maintain its current intensity for another 12 to 24 hours.  Tapah will move over water where the Sea Surface Temperature is near 28°C.  An upper level trough over eastern Asia will produce southwesterly winds which will cause some vertical wind shear, but the shear may not be strong enough to weaken Tapah today.  Typhoon Tapah will move under stronger upper level westerly winds in the middle latitudes on Sunday and the increase in wind shear will weaken the typhoon.  Stronger wind shear and cooler Sea Surface Temperatures will cause Typhoon Tapah to begin a transition into an extratropical cyclone on Sunday.

Typhoon Tapah will move around the western end of a subtropical ridge over the Western North Pacific Ocean during the next 12 to 18 hours.  The ridge will steer Tapah toward the north during that time period.  The stronger westerly winds in the middle latitudes will turn Tapah toward the northeast on Sunday.  On its anticipated track the center of Typhoon Tapah will be west of Kyushu in about 12 to 18 hours.  The center of Tapah could pass between South Korea and Japan on Sunday and then it will move over the Sea of Japan.  Because it has such a large circulation Typhoon Tapah could bring gusty winds and locally heavy rain to parts of Kyushu, Honshu and South Korea.

Hurricane Lorena Near Cabo San Lucas

Hurricane Lorena moved near Cabo San Lucas, Mexico on Friday afternoon.  At 5:00 p.m. EDT on Friday the center of Hurricane Lorena was located at latitude 23.2°N and longitude 109.3°W which put it about 45 miles (75 km) northeast of Cabo San Lucas, Mexico.  Lorena was nearly stationary.  The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 987 mb.

A Hurricane Warning was in effect for the portion of the coast from La Paz to Puerto Cortes, Mexico.  A Hurricane Watch was in effect for the portion of the coast from La Paz to Santa Rosalia.  Tropical Storm Warnings were in effect from Puerto Cortes to Cabo San Lazaro and from La Paz to Santa Rosalia.  Tropical Storm Watches were in effect from Topolobampo to Guaymas and from Cabo San Lazaro to Puerto San Andresito.

The circulation around Hurricane Lorena strengthened quickly when it reached the very warm water at the southern end of the Gulf of Calfiornia.  A small circular eye developed at the center of circulation.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the compact inner core of Hurricane Lorena.  Winds to hurricane force extended out 15 miles (25 km) from the center of circulation.  Winds to tropical storm force extended out 45 miles (75 km) from the center.

The future intensity of Hurricane Lorena will depend entirely on its track.  If Hurricane Lorena moves over Baja California, it will weaken quickly when it moves over the mountains.  However, if the small circulation around Lorena remains over the very warm water in the Gulf of California, then the hurricane could strengthen further.  The numerical models have been trending toward keeping Hurricane Lorena over water for a longer period of time, but the center of the hurricane is very close to the southern end of Baja California.

Hurricane Lorena moved into a region where the steering currents are weak, which is why Lorena is nearly stationary.  The southern end of a trough over the western U.S. will try to steer Hurricane Lorena toward the north-northeast.  However, mountains in Baja California sometimes block westerly winds in the lower levels.  A slightly larger circulation around Tropical Storm Mario could pull Hurricane Lorena toward the west.  The future track of Hurricane Lorena is highly uncertain.  Hurricane Lorena could move over Baja California or it could move farther north into the Gulf of California.

The center of Tropical Storm Mario was located at latitude 18.0°N and longitude 110.0°W which put it about 340 miles (545 km) south of the southern tip of Baja California.  Mario was moving toward the north at 3 m.p.h. (5 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 992 mb.  The future of Tropical Storm Mario will depend on how much its circulation interacts with the circulation around Hurricane Lorena.  Mario is currently about 350 miles (565 km) south of Hurricane Lorena.

Hurricane Jerry Passing North of Leeward Islands

Hurricane Jerry was passing north of the Leeward Islands on Friday afternoon.  At 5:00 p.m. EDT on Friday the center of Hurricane Jerry was located at latitude 19.6°N and longitude 62.0°W which put it about 120 miles (195 km) northeast of Anguilla.  Jerry was moving toward the west-northwest at 18 m.p.h. (30 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 991 mb.

Tropical Storm Watches were in effect for St. Maarten, St. Martin and St. Barthelemy.

Hurricane Jerry weakened during much of Friday, but it began to exhibited greater organization again late in the afternoon.  Thunderstorms weakened around the core of Jerry and in the rainbands on Friday morning.  The lack of stronger thunderstorms to transport stronger winds to the surface caused the circulation around the hurricane to weaken.  Northwesterly winds blowing around the eastern side of an upper level ridge over the Caribbean Sea caused more vertical wind shear.  The circulation may have also draw some drier air into the western half of the circulation.  Stronger thunderstorms began to redevelop near the center of circulation late in the afternoon.  Thunderstorms also began to form in a band on the western side of Hurricane Jerry.  The circulation around Jerry was small.  Winds to hurricane force extended out 20 miles (30 km) from the center of circulation.  Winds to tropical storm force extended out about 90 miles (145 km) from the center.

Hurricane Jerry will move through an environment somewhat favorable for intensification during the weekend.  Jerry will move over water where the Sea Surface Temperature is near 28°C.  It will move near the eastern side of an upper level ridge and the ridge will cause some vertical wind shear.  If the shear is greater, the Hurricane Jerry could weaken to a tropical storm.  If the shear is less then Hurricane Jerry could intensify.  It is possible that the wind speed in Hurricane Jerry will fluctuate during the weekend as the strength of the upper level wind changes.

Hurricane Jerry will move south of a subtropical high pressure system over the Atlantic Ocean.  The high will steer Jerry toward the west-northwest during the next 12 to 24 hours.  A portion of the high is forecast to weaken during the weekend and if that happens, then Hurricane Jerry could move northward.  On its anticipated track Hurricane Jerry will pass north of the Leeward Islands and Puerto Rico.

Tropical Storm Lorena Moves Toward Baja California

Tropical Storm Lorena moved toward Baja California on Thursday night after brushing the west coast of Mexico earlier in the day.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Lorena was located at latitude 22.3°N and longitude 107.7°W which put it about 145 miles (235 km) east-southeast of Cabo San Lucas, Mexico.  Lorena was moving toward the northwest at 10 m.p.h. (16 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 994 mb.

A Hurricane Warning was in effect for the portion of the coast from La Paz to Puerto Cortes, Mexico.  A Hurricane Watch was in effect from La Paz to San Evaristo, Mexico.  Tropical Storm Watches were in effect from San Evaristo to Loreto and from Puerto Cortes to Puerto San Evaristo.

When the center of former Hurricane Lorena passed near the west coast of Mexico, the eastern part of the circulation passes over mountains.  The mountains disrupted the flow of air and some drier air was pulled into the hurricane.  The disruption and drier air weakened the inner core of the circulation and caused Lorena to weaken to a tropical storm.  The inner core was beginning to redevelop on Thursday evening.  More thunderstorms were forming near the center of circulation and other thunderstorms were occurring in bands in the eastern half of the circulation.  Winds to tropical storm force extended out about 70 miles (110 km) from the center of circulation.

Tropical Storm Lorena will move through an environment favorable for intensification on Friday.  Lorena will move over water where the Sea Surface Temperature is near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Tropical Storm Lorena is likely to strengthen back into a hurricane on Friday.

Tropical Storm Lorena will move around the western part of a ridge of high pressure over Mexico.  The ridge will steer Lorena toward the northwest.  The circulation of Tropical Storm Lorena will interact with the circulation of Tropical Storm Mario which is southwest of Lorena.  It looked like Lorena was pulling Mario toward the northeast on Thursday night.  However, it is possible that Mario could tug Lorena more toward the west on Friday.  On its anticipated track Tropical Storm Lorena will approach the southern tip of Baja California on Friday afternoon.  Lorena is likely to be a hurricane at that time.

Elsewhere over the Eastern North Pacific Ocean, Tropical Storm Mario was southwest of Lorena and Tropical Storm Kiko was between Baja California and Hawaii.  At 11:00 p.m. EDT the center of Tropical Storm Mario was located at latitude 17.6°N and longitude 110.2°W which put it about 265 miles (590 km) south of the southern tip of Baja California.  Mario was moving toward the northeast 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 995 mb.

At 11:00 p.m. EDT on Thursday the center of Tropical Storm Kiko was located at latitude 16.6°N and longitude 129.6°W which put it about 1350 miles (2175 km) west-southwest of the southern tip of Baja California.  Kiko was moving toward the northwest at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 1002 mb.

Tropical Storm Tapah Develops East of Taiwan

Tropical Storm Tapah developed east of Taiwan on Thursday.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Tapah was located at latitude 23.3°N and longitude 126.5°E which put it about 150 miles (245 km) east-southeast of Ishigaki, Japan.  Tapah was moving toward the west at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 965 mb.

A distinct low level center of circulation formed on the northern side of an area of thunderstorms east of Taiwan on Thursday and the Japan Meteorological Agency designated the system as Tropical Storm Tapah.  The distribution of thunderstorms around Tapah was asymmetrical.  Most of the thunderstorms  were occurring in bands in the southern half of the circulation.  Bands in the northern half of the tropical storm consisted primarily of showers and lower clouds.  Storm on the southern side of the center began to generate upper level divergence which pumped mass away from the tropical storm.  The circulation around Tropical Storm Tapah was very large.  Winds to tropical storm force extended out about 250 miles (400 km) from the center of circulation.

Tropical Storm Tapah will move through an environment favorable for intensification during the next several days.  Tapah will move over water where the Sea Surface Temperature is near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Some drier air north of Tropical Storm Tapah could inhibit the development of bands of thunderstorms on the northern side of the circulation.  Tropical Storm Tapah is likely to intensify and it could strengthen into a typhoon during the weekend.

Tropical Storm Tapah will move around the western end of a subtropical ridge over the Western North Pacific Ocean.  The ridge will steer Tapah more toward the northwest on Friday.  Tapah will move more toward the north when it rounds the western end of the ridge.  On its anticipated track Tropical Storm Tapah could move over the southern Ryukyu Islands in about 12 hours.  The center of Tapah could pass west of Okinawa in about 24 hours.