Monthly Archives: July 2018

Tropical Storm Beryl Weakens East of the Lesser Antilles

Tropical Storm Beryl weakened on Saturday as it move closer to the Lesser Antilles.  At 11:00 p.m. EDT on Saturday the center of circulation was located at latitude 13.1°N and longitude 54.3°W which put it about 495 miles (795 km) east-southeast of the Lesser Antilles.  Beryl was moving toward the west-northwest at 18 m.p.h. (30 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 Dominica and Guadeloupe.  Tropical Storm Watches were in effect for Saba, St. Eustatius, St. Maarten, Martinique, St. Martin, St. Barthelemy, Barbados and St. Lucia.

Tropical Storm Beryl moved into a region where the easterly winds in the lower level were stronger and the increased vertical wind shear started to blow the lower part of the circulation to the west of the upper part of Beryl.  It also seemed to move into an area of drier air, which caused most of the stronger thunderstorms to weaken.  There was still a well organized circulation in the lower levels, but it weakened on Saturday.  More thunderstorms developed near the center of circulation and on the eastern side of Tropical Storm Beryl in recent hours.  If those storms persist then Beryl could strengthen again, but if they dissipate quickly, then the tropical storm could weaken again on Sunday.

Tropical Storm Beryl will move through an environment that contains factors that are favorable for intensification and other factors that are unfavorable.  Beryl will move over water where the Sea Surface Temperature is near 27°C.  It will move through an area where the lower level winds are stronger and so there will be more vertical wind shear.  There will be areas of moister air within a larger area of drier air.  If the recently developed thunderstorms persist on Sunday, then the Beryl could strengthen again.  However, if the storms dissipate in a few hours, then Tropical Storm Beryl could weaken further.  The small size of the circulation means that rapid changes in intensity can occur.

Tropical Storm Beryl was moving south of the subtropical high over the Atlantic Ocean.  The high was steering Beryl toward the west-northwest and that general motion is forecast to continue for the next several days.  On its anticipated track Tropical Storm Beryl could reach the Lesser Antilles on Sunday night.  There is a lot of uncertainty about how strong Beryl may be when it reaches those islands.

Elsewhere over the Atlantic Ocean Tropical Depression Three spun south of Cape Hatteras.  At 11:00 p.m. EDT on Saturday the center of Tropical Depression Three was located at latitude 32.9°N and longitude 75.1°W which put it about 160 miles (260 km) south of Cape Hatteras, North Carolina.  It was nearly stationary.  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 1014 mb.

Powerful Typhoon Maria Spins East of Taiwan

Powerful Typhoon Maria spun east of Taiwan on Saturday.  At 11:00 p.m. EDT on Saturday the center of Typhoon Maria was located at latitude 19.4°N and longitude 138.3°E which put it about 950 miles (1530 km) east-southeast of Okinawa.  Maria was moving toward the northwest at 13 m.p.h. (10 km/h).  The maximum sustained wind speed was 150 m.p.h. (240 km/h) and there were wind gusts to 185 m.p.h. (295 km/h).  The minimum surface pressure was 925 mb.

Typhoon Maria appeared to complete an eyewall replacement cycle on Saturday.  The completion of the cycle resulted in a  larger circulation.   There was an eye which had a diameter of 24 miles (38 km).  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 the circulation.  The rainbands northwest in the northwestern quadrant of Typhoon Maria were a little weaker than the bands in the other parts of the circulation.  Storms in the core of Maria were generating upper level divergence which was pumping mass away to the northeast of the typhoon.

Winds to typhoon force extended out about 70 miles (110 km/h) from the center of circulation.  Winds to tropical storm force extended out about 200 miles (320 km) from the center.  The Hurricane Intensity Index (HII) for Maria was 37.9.  The Hurricane Size Index (HSI) was 24.5 and the Hurricane Wind Intensity Size Index (HWISI) was 62.4.

Typhoon Maria will move through an environment mostly favorable for powerful typhoons on Sunday.   Maria will move over water where the Sea Surface Temperature is near 30°C.  It will move through an environment where the upper level winds are weak and there will be little vertical wind shear.  There appears to be some sinking motion and drier air northwest of Maria and that may be the reason why the rainbands were weaker in that part of the typhoon.  The drier air could inhibit further strengthening.  Typhoon Maria is likely to remain strong for another 24 to 48 hours.

Typhoon Maria was moving around the southern portion of a subtropical ridge over the Western North Pacific.  The ridge was steering Maria toward the northwest.  The ridge is forecast to strengthen and it will steer Typhoon Maria more toward the west-northwest.  On its anticipated track Typhoon Maria could approach the southern Ryukyu Islands in about 48 hours.  Maria could be near the northern end of Taiwan in about 60 hours.

Hurricane Beryl Prompts Watches for Lesser Antilles, TD 3 Forms Southeast of Carolinas

The potential approach of Hurricane Beryl prompted the issuance of Watches for some of the Lesser Antilles on Friday afternoon, while at the same time Tropical Depression Three formed southeast of the Carolinas.  At 5:00 p.m. EDT on Friday the center of Hurricane Beryl was located at latitude 10.6°N and longitude 47.8°W which put it about 965 miles (1555 km) east-southeast of the Leeward Islands.  Beryl was moving toward the west at 15 m.p.h. (24 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 994 mb.

A Hurricane Watch has been issued for Dominica.  Tropical Storm Watches have been issued for Martinique, Guadeloupe, St. Martin and St. Barthelemy.

The circulation of Hurricane Beryl remains very small.  The pinhole is no longer visible on satellite imagery, although strong thunderstorms continue to develop near the center of circulation.  Short narrow bands or showers and thunderstorms are revolving around the core of Hurricane Beryl.  Winds to hurricane force only extend out about 10 miles (15 km) from the center of circulation.  Winds to tropical storm force extend out about 40 miles (65 km) from the center.

Hurricane Beryl will move through an environment favorable for intensification during the next 24 hours.  Beryl will move over water where the Sea Surface Temperature is near 27°C.  It is moving south of an upper level ridge.  The ridge is producing easterly winds which are blowing toward the top of the circulation.  However, the wind speeds are similar at all levels and there is currently little vertical wind shear.  Tropical Storm Beryl could intensify on Saturday, but the circulation is so small that any increase in wind shear could cause rapid weakening.

The subtropical ridge over the Atlantic Ocean is north of Hurricane Beryl and the ridge has been steering Beryl toward the west.  A motion more toward the west-northwest is forecast during the weekend.  On its anticipated track Hurricane Beryl will approach the Lesser Antilles later on Sunday.  That is the reason why the Watches were issued for some of those islands.  Beryl could still be a hurricane when it gets to the Lesser Antilles, but there is a lot of uncertainty about the intensity forecast because the hurricane is so small.

Elsewhere over the Atlantic Ocean, the National Hurricane Center designated an area of low pressure southeast of the coast of the Carolinas as Tropical Depression Three.  At 5:00 p.m. EDT on Friday the center of Tropical Depression Three was located at latitude 32.2°N and longitude 73.8°W which put it about 230 miles (370 km) south-southeast of Cape Hatteras, North Carolina.  It was moving toward the north-northwest at 5 m.p.h. (8 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 1016 mb.  Tropical Depression Three is forecast to meander off the coast of the Carolinas during the weekend.  It could strengthen into a tropical storm and there is a chance it could intensify into a hurricane next week.

Beryl Strengthens to a Hurricane East of the Lesser Antilles

Former Tropical Storm Beryl strengthened into a hurricane east of the Lesser Antilles on Friday morning.  At 11:00 a.m. EDT on Friday the center of Hurricane Beryl was located at latitude 10.7°N and longitude 46.5°W which put it about 1045 miles (1685 km) east-southeast of the Lesser Antilles.  Beryl was moving toward the west at 15 m.p.h. (24 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 994 mb.

The circulation of Hurricane Beryl remains very small.  There is an eye with a diameter of 6 miles (9 km) at the center of circulation.  The eye is surrounded by a ring of strong thunderstorms and the hurricane force winds are occurring in this ring of storms.  Several short, narrow bands of showers and thunderstorms are revolving around the core of the circulation.  Storms near the core are generating upper level divergence which is pumping mass away from the hurricane.  Winds to hurricane force only extend out about 10 miles (15 km) from the center of circulation.  Winds to tropical storm force only extend out about 40 miles (65 km) from the center.

Hurricane Beryl will move through an environment favorable for intensification during the next 24 to 48 hours.  Beryl will move over water where the Sea Surface Temperature is near 27°C.  It is moving south of an upper level ridge.  The ridge is producing easterly winds which are blowing toward the top of the circulation.  However, the wind speeds are similar at all levels and there will be little vertical wind shear.  Hurricane Beryl is likely to intensify during the next day or so.  There is less mass in motion in a very small hurricane and so it can intensify quickly, but a small hurricane can also weaken quickly if vertical wind shear increases.

Hurricane Beryl is moving south of the subtropical high pressure system over the Atlantic Ocean and the high is steering Beryl toward the west.  A general motion toward the west-northwest is forecast for the next several days.  On its anticipated track Hurricane Beryl could approach the Lesser Antilles later on Sunday.  Beryl could be a hurricane when it nears the Lesser Antilles and watches and warnings may be issued later on Friday or on Saturday.

Typhoon Maria Rapidly Intensifies to Equivalent of Cat. 5 Hurricane

Typhoon Maria rapidly intensified into the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale on Thursday night.  At 11:00 p.m. EDT on Thursday the center of Typhoon Maria was located at latitude 16.2°N and longitude 141.9°E which put it about 250 miles (405 km) northwest of Guam.  Maria 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 918 mb.

Typhoon Maria continued to intensify rapidly on Thursday night and it reached the equivalent of Category 5 on the Saffir-Simpson Scale.  Maria is a strong, well organized typhoon.  There is a small circular eye at the center of circulation.  The eye is surrounded by a ring of strong thunderstorms and the strongest winds were occurring that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Typhoon Maria.  Storms in the core were generating strong upper level divergence which was pumping large amounts of mass away from the typhoon.  The rapid removal of mass allowed the surface pressure to decrease quickly and the wind speeds to increase rapidly.

Winds to typhoon/hurricane force extended out about 45 miles (75 km) from the center of circulation.  Winds to tropical storm force extended out about 155 miles (250 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Maria was 43.5.  The Hurricane Size Index (HSI) was 17.8 and the Hurricane Wind  Intensity Size Index (HWISI) was 51.3.

Typhoon Maria will move through an environment favorable for strong tropical cyclones for another day or two.  Maria will move over water where the Sea Surface Temperature is near 30°C.  It will move through an area where the upper level winds are weak and there will be little vertical wind shear.  Typhoon Maria could intensify further on Friday.  However, a rainband could wrap around the existing eye and eyewall.  If that occurs, then an eyewall replacement cycle will begin.  Maria would weaken while the inner eyewall dissipates.  The typhoon could strengthen again if the outer eyewall contracts around the center of circulation.

Typhoon Maria was moving south of a subtropical ridge which was steering Maria toward the northwest.  The northwesterly motion is expected to continue for another 24 to 48 hours.  After that time the ridge is forecast to strengthen and steer Maria more toward the west-northwest.  on its anticipated track Typhoon Maria could approach Okinawa and the Ryukyu Islands in about four days.  Maris is likely to be a powerful typhoon at that time.

Typhoon Maria Rapidly Intensifies Into Equivalent of Major Hurricane

Typhoon Maria rapidly intensified Thursday into the equivalent of a major hurricane as it moved west of the Mariana Islands.  At 5:00 p.m. EDT on Thursday the center of Typhoon Maria was located at latitude 15.7°N and longitude 142.1°E which put it about 210 miles (340 km) northwest of Guam.  Maria was moving toward the northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 125 m.p.h. (205 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 950 mb.

After striking Guam as a tropical storm on Wednesday Maria rapidly intensified into a strong typhoon on Thursday.  A circular eye was evident on satellite imagery.  The eye was surrounded by a ring of strong thunderstorms.  Several bands of showers and thunderstorms were revolving around the core of the circulation.  Storm in the core were generating strong upper level divergence which was pumping mass away from the typhoon in all directions.  Winds to typhoon force extended out about 35 miles (55 km) from the center of circulation.  Winds to tropical storm force extended out about 155 miles (250 km) from the center.

The Hurricane Intensity Index (HII) for Typhoon Maria was 23.6.  The Hurricane Size Index (HSI) was 14.1 and the Hurricane Wind Intensity Size Index (HWISI) was 37.7.

Typhoon Maria will continue to move through an environment favorable for intensification for another day or two.  Maria will move over water where the Sea Surface Temperature is near 30°C.  It will move through a region of weaker winds between an upper level low to the west and an upper level low to the east.  There will be little vertical wind shear.  Typhoon Maria is likely to intensify more on Friday and it could become the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale.  An eyewall replacement cycle could occur if one of the rainbands wraps around existing eye and eyewall.  If an eyewall replacement cycle starts, it will cause Typhoon Maria to weaken at least temporarily.

Typhoon Maria was moving south of a subtropical ridge over the Western North Pacific Ocean.  The ridge was steering Maria toward the northwest.  A general motion toward the northwest is expected to continue for another day or two.  The ridge is forecast to strengthen after that time and it will steer Typhoon Maria more toward the west-northwest.  On its anticipated track Maria will pass south of Iwo To.  Typhoon Maria could approach Okinawa and the Ryukyu Islands in four or five days.

TD 2 Quickly Strengthens Into Tropical Storm Beryl

Tropical Depression 2 which was designated earlier on Thursday quickly strengthened into Tropical Storm Beryl.  At 5:00 p.m. EDT on Thursday the center of Tropical Storm Beryl was located at latitude 10.3°N and longitude 42.8°W which put it about 1295 miles (2080 km) east-southeast of the Lesser Antilles.  Beryl was moving toward the west at 16 m.p.h. (26 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 1004 mb.

The circulation of very small Tropical Storm Beryl organized very quickly on Thursday afternoon.  There was evidence of a tiny eye on some microwave satellite images.  A small tight ring of thunderstorms surrounded the center of circulation and the strongest winds were occurring in that ring of storms.  Several short bands of thunderstorms were revolving around the core of the circulation.  Winds to tropical storm force only extended out 35 miles (55 km) from the center of circulation.  Storms near the core of Beryl were generating upper level divergence which was pumping mass away from the tropical storm.

Tropical Storm Beryl will move through an environment somewhat favorable for intensification during the next day or two.  Beryl will move over water where the Sea Surface Temperature is near 26.5°C.  There is cooler water north of the expected track of Beryl, which would limit intensification if the tropical storm wobbles toward the north.  An upper level ridge north of Tropical Storm Beryl will generate easterly winds which will blow toward the top of the circulation.  The wind speed is similar at all level and the vertical wind shear will be modest.  Small tropical cyclones can intensify or weaken rapidly.  Beryl is likely strengthen on Friday and it could intensify into a hurricane.

Tropical Storm Beryl was moving south of the subtropical high over the Atlantic Ocean.  The high was steering Beryl toward the west.  A general motion toward the west-northwest is forecast during the next two to three days.  On its anticipated track Tropical Storm Beryl could be east of the Lesser Antilles on Sunday.

Tropical Depression Two Forms East of the Lesser Antilles

Tropical Depression Two formed east of the Lesser Antilles on Thursday morning.  At 11:00 a.m. EDT on Thursday the center of Tropical Depression Two was located at latitude 10.2°N and longitude 41.4°W which put it about 1385 miles (2230 km) east-southeast of the Lesser Antilles.  It was moving toward the west at 16 m.p.h. (26 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.

A distinct area of low pressure developed in the northern end of a tropical wave on Thursday and the National Hurricane Center designated the system as Tropical Depression Two.  The circulation of the depression was quite small.  Several short bands of showers and thunderstorms were revolving around the center of circulation.  Storms near the center were beginning to generate upper level divergence which was pumping mass away from the depression.

Tropical Depression Two will move through an environment somewhat favorable for intensification.  It will move over water where the Sea Surface Temperature is near 26.5°C.  However, there is cooler water to the north of the anticipated track and the depression will not intensify if it moves over the cooler water.  An upper level ridge north of the tropical depression will produce easterly winds which will blow toward the top of the circulation.  The wind speeds will be similar at all levels and there will be little vertical wind shear.  Tropical Depression Two is forecast to strengthen into a tropical storm during the next day or two.

Tropical Depression Two was moving around the southern side of the subtropical ridge over the Atlantic Ocean and the ridge was steering the depression toward the west.  The ridge is forecast to steer the depression toward the west-northwest during the next two or three days.  On its anticipated track Tropical Depression Two could be east of the Lesser Antilles on Sunday.

Strengthening Tropical Storm Maria Brings Wind and Rain to Guam

Tropical Storm Maria strengthened quickly on Wednesday and it brought gusty winds and heavy rain to Guam.  The weather station at Andersen Air Force Base on Guam reported sustained winds to 44 m.p.h. (71 km/h) and wind gusts to 72 m.p.h. (116 km/h).  At 5:00 p.m. EDT on Wednesday the center of Tropical Storm Maria was located at latitude 13.9°N and longitude 144.7°E which put it about 5 miles (10 km/h) south of Andersen Air Force Base.  Maria was moving toward the north-northwest at 11 m.p.h. (17 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 987 mb.  Tropical Storm Warnings remained in effect for Guam and Rota.  Tropical Storm Watches were in effect for Saipan and Tinian.

The circulation of Tropical Storm Maria organized quickly on Wednesday.  A tight center of circulation contracted at the center of Maria.  A partial ring of thunderstorms formed on the east side of the center.  Numerous bands of showers and thunderstorms were revolving around the core of the circulation.  Storms around the core generated well developed upper level divergence which pumped mass away in all directions from the tropical storm.  Winds to tropical storm force extended out about 95 miles (155 km) from the center of circulation.

Tropical Storm Maria will move through an environment very favorable for intensification.  Maria will move over water where the Sea Surface Temperature is near 30°C.  Tropical Storm Maria will move under the western portion of an upper level ridge where the upper level winds are weak.  There will little vertical wind shear.  Upper level lows east and west of the ridge will enhance the upper level divergence.  Tropical Storm Maria will strengthen into a typhoon on Thursday.  Maria could intensify rapidly and it is likely to become the equivalent of a major hurricane.

Tropical Storm Maria was moving around the western end of a subtropical ridge which was steering Maria toward the north-northwest.  The ridge is forecast to steer Maria toward the northwest during the next few days.  On its anticipated track Tropical Storm Maria will move away from the Marianas and toward the Ryukyu Islands.  Tropical Storm Maria will continue to cause gusty winds and drop locally heavy rain on the southern Marianas for a few more hours.  Conditions will improve on Thursday when Maria moves away the Marianas.

Tropical Storm Maria Prompts Warning for Guam

Tropical Depression 10W strengthened into Tropical Storm Maria on Wednesday and a Tropical Storm Warning was issued for Guam.  At 5:00 a.m. EDT on Wednesday the center of Tropical Storm Maria was located at latitude 12.7°N and longitude 145.9°E which put it about 95 miles (155 km) southeast of Guam.  Maria was moving toward the north-northwest at 8 m.p.h. (13 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 1000 mb.  Tropical Storm Warnings were in effect for Guam and Rota.  Tropical Storm Watches were in effect for Saipan and Tinian.

The center of circulation in former Tropical Depression 10W became more well organized on Wednesday and the Japan Meteorological Agency designated the system as Tropical Storm Maria.  The circulation was still increasing in organization.  There was a distinct low level center of circulation.  Numerous bands of showers and thunderstorms were revolving around the center of circulation.  Storms near the center were generating upper level divergence which was pumping mass away from the tropical storm.

Tropical Storm Maria will move through an environment very favorable for intensification during the next few days.  Maria will move over water where the Sea Surface Temperature is near 30°C.  Tropical Storm Maria will move under the western end of an upper level ridge that is between two upper level lows which are east and west of the ridge.  The upper level winds will be relatively weak and there will be little vertical wind shear.  The combination of the ridge and two upper level lows will increase the upper level divergence.  Tropical Storm Maria will continue to strengthen.  Maria will become a typhoon later this week.  It could intensify rapidly once an eye forms and the inner core is well developed.

Tropical Storm Maria is moving around the western end of a subtropical ridge which is steering Maria toward the north-northwest.  On its anticipated track the center of Tropical Storm Maria will move near Guam and Rota later today.  A general motion toward the northwest is forecast for the next several days.  Maria could move in the direction of the Ryukyu Islands at the end of the week.

Tropical Storm Maria will bring gusty winds and heavy rain to the southern Mariana Islands.  The strongest winds and heaviest rain will affect Guam and Rota.  Gusty winds and heavy rain will also affect Saipan and Tinian.  Heavy rain could produce flash floods.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Prapiroon was moving over the Sea of Japan.  Prapiroon was bringing wind and rain to the northern Islands of Japan including Hokkaido and Honshu.  At 5:00 a.m. EDT on Wednesday the center of Tropical Storm Prapiroon was located at latitude 39.6°N and longitude 135.6°E which put it about 360 miles (585 km) west-southwest of Misawa, Japan.  Prapiroon was moving toward the northeast at 25 m.p.h. (40 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were winds gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 987 mb.