Monthly Archives: August 2019

Tropical Depression Five Forms East of Lesser Antilles

Tropical Depression Five formed east of the Lesser Antilles on Saturday morning.  At 11:00 a.m. EDT on Saturday the center of Tropical Depression Five was located at latitude 10.4°N and longitude 47.9°W which put it about 805 miles (1300 km) east-southeast of Barbados.  It was moving toward the west at 12 m.p.h. (19 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 1010 mb.

Data from satellites indicated that there was a closed circulation around an area of low pressure east of the Lesser Antilles on Saturday morning and the National Hurricane Center designated the system as Tropical Depression Five.  The circulation around Tropical Depression Five was still organizing.  Many of the stronger thunderstorms were occurring in bands west of the center of circulation.  Bands in the eastern half of the circulation consisted primarily of showers and lower clouds.  The circulation around Tropical Depression Five was relatively small.

Tropical Depression Five will move through an environment favorable for slow intensification.  It will move over water where the Sea Surface Temperature is near 28°C.  The depression will move south of an upper level ridge over the western north Atlantic Ocean.  The ridge will produce easterly winds which will cause some vertical wind shear.  There will be some drier air just to the north of the depression.  If the depression pulls some of the drier air into the circulation, that could also interrupt intensification.  The combination of some wind shear and intrusions of drier air will limit the rate at which Tropical Depression Five strengthens.  The depression is forecast to strengthen into a tropical storm.

Tropical Depression Five will move south of a subtropical high pressure system over the Atlantic Ocean.  The high will steer the depression toward the west-northwest during the next few days.  On its anticipated track Tropical Depression Five could approach the Lesser Antilles on Monday night or Tuesday.  The depression could be a tropical storm by that time.

Tropical Storm Bailu Brings Wind and Rain to Taiwan

Tropical Storm Bailu brought wind and rain to Taiwan early on Saturday.  At 5:00 a.m. EDT on Saturday the center of Tropical Storm Bailu was located at latitude 22.6°N and longitude 120.2°E which put it about 50 miles (80 km) northwest of Hengchun, Taiwan.  Bailu 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 986 mb.

The broad center of Tropical Storm Bailu moved across southern Taiwan early on Saturday.  Bailu produced winds to tropical storm force over parts of Taiwan, but its greater effect was heavy rain.  Since Tropical Storm Bailu passed near the southern end of Taiwan, its counterclockwise rotation produced easterly winds over much of Taiwan.  Those winds pushed air up the mountains, which enhanced rising motion and caused heavy rain to fall over eastern Taiwan.  Estimates of rainfall from radars indicated that up to one foot (300 mm) of rain could have fallen over southeastern Taiwan.  That much rain is likely to have caused flash floods in some locations.

Tropical Storm Bailu will continue to move southwest of a subtropical ridge over the Western North Pacific Ocean.  The ridge will continue to steer Bailu toward the northwest.  On its anticipated track the center of Tropical Storm Bailu will make landfall on the east coast of China between Xiamen and Shantou in about 12 hours.  Bailu will bring gusty winds and locally heavy rain to parts of eastern China.  Heavy rain could also produce flash floods in some locations.

Tropical Storm Bailu on Track Toward Taiwan

Tropical Storm Bailu remained on a track toward Taiwan on Thursday night.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Bailu was located at latitude 19.0°N and longitude 125.6°E which put it about 385 miles (615 km) east-southeast of Hengchun, Taiwan.  Bailu was moving toward the northwest at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 990 mb.

The circulation around Tropical Storm Bailu was large.  Winds to tropical storm force extended out about 170 miles (280 km) from the center of circulation.  Many of the stronger thunderstorms in Bailu were occurring in bands in the southern half of the circulation.  Bands in the northern half of the circulation consisted primarily of showers and lower clouds.  Tropical Storm Bailu was moving south of an upper level ridge.  The ridge was causing sinking motion to the north of Bailu which appeared to be limiting the development of taller thunderstorms in the northern half of the circulation.

Aside from the sinking motion north of Tropical Storm Bailu, it will move through an environment favorable for intensification.  Bailu 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 not too strong and there will not be a lot of vertical wind shear.  Tropical Storm Bailu could intensify on Friday if more thunderstorms develop around the center of circulation.  There is a chance that Bailu could strengthen into a typhoon.

Tropical Storm Bailu will move around the southwestern part of a subtropical ridge over the Western North Pacific Ocean.  The ridge will steer Bailu toward the northwest.  On its anticipated track Tropical Storm Bailu could approach southern Taiwan in about 24 hours.  Bailu could be a typhoon by that time.  It will bring gusty winds and locally heavy rain to Taiwan.  The locally heavy rain could cause flash floods in some locations.

Tropical Storm Ivo Forms South of Baja California

Tropical Storm Ivo formed south of Baja California on Wednesday.  At 5:00 p.m. EDT on Wednesday the center of Tropical Storm Ivo was located at latitude 15.8°N and longitude 109.5°W which put it about 490 miles (790 km) south of the southern tip of Baja California.  Ivo was moving toward the west-northwest at 20 m.p.h. (32 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 1004 mb.

A distinct low level center of circulation developed in a low pressure system south of Baja California on Wednesday and the National Hurricane Center designated the system as Tropical Storm Ivo.  A band of thunderstorms wrapped around the western and southern parts of the center of circulation and satellite sensors indicated that winds to tropical storm force were occurring in the band.  Other bands of thunderstorms developed in the western half of Tropical Storm Ivo.  Bands in the eastern half of the circulation consisted primarily of showers and lower clouds.  Thunderstorms near the center of Ivo began to generate upper level divergence which was pumping mass away from the tropical storm.

Tropical Storm Ivo will move through an environment favorable for intensification during the next 36 to 48 hours.  Ivo will move over water where the Sea Surface Temperature is near 29°C.  It will move south of an upper level ridge that stretches from west of California to northern Mexico.  The ridge will produce easterly winds which will blow toward the top of the circulation.  Those winds will cause some vertical wind shear, which could slow the rate at which Tropical Storm Ivo intensifies. However, the shear will not be strong enough to prevent intensification and Ivo could strengthen into a hurricane within 36 hours.  Tropical Storm Ivo will start to move over cooler water when it moves west of Baja California and that will cause it to weaken during the weekend.

The ridge will steer Tropical Storm Ivo toward the northwest during the next several days.  On its anticipated track Tropical Storm Ivo will move west of Baja California.  The primary impact of Ivo will be to generate waves which will reach the west coast of Baja California and southern California.

Tropical Storm Bailu Forms East of Luzon

Tropical Storm Bailu formed east of Luzon on Wednesday.  At 5:00 a.m. EDT on Wednesday the center of Tropical Storm Bailu was located at latitude 15.4°N and longitude 131.6°E which put it about 930 miles (1500 km) southeast of Taipei, Taiwan.  Bailu was moving toward the 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 998 mb.

A low pressure system east of northern Luzon strengthened on Wednesday and the Japan Meteorological Agency designated the system as Tropical Storm Bailu.  The circulation around Bailu was gradually exhibiting greater organization.  Bands of showers and thunderstorms were forming and the bands were starting to revolve around the center of the tropical storm.  There were more thunderstorms in the bands on the western side of Tropical Storm Bailu.  Storms near the center of circulation were beginning to generate upper level divergence which was pumping mass away from Bailu.

Tropical Storm Bailu will move through an environment favorable for intensification during the next two to three days.  Bailu will move over water where the Sea Surface Temperature is near 28.5°C.  It will move southeast of an upper level ridge that extends from eastern Asia over the Western North Pacific Ocean.  The ridge will produce northeasterly winds which will blow toward the top of the circulation.  Those winds will cause some vertical wind shear, but the shear will not be strong enough to prevent intensification.  Tropical Storm Bailu will intensify during the next several days and it could strengthen into a typhoon.

Tropical Storm Bailu will move south of a subtropical ridge over the Western North Pacific Ocean.  The ridge will steer Bailu in a northwesterly direction.  On its anticipated track Tropical Storm Bailu could approach Taiwan in about 72 hours.  Bailu could be a typhoon by that time.  Bands on the western side of Tropical Storm Bailu could drop locally heavy rain over parts of northern Luzon.  Flash floods could occur in some locations.

Tropical Storm Chantal Forms Southeast of Nova Scotia

Tropical Storm Chantal formed southeast of Nova Scotia on Tuesday night.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Chantal was located at latitude 40.2°N and longitude 56.2°W which put it about 485 miles (780 km) southeast of Halifax, Nova Scotia.  Chantal was moving toward the east at 22 m.p.h. (35 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 1010 mb.

A small low pressure system that was near the coast of the Carolinas during the weekend began to exhibit tropical characteristics on Tuesday night and the National Hurricane Center designated the system as Tropical Storm Chantal.  Thunderstorms developed closer to the center of circulation when the low moved near the Gulf Stream and the strongest winds were occurring closer to the center.  Although the circulation around Chantal looked more tropical, the distribution of thunderstorms was still asymmetrical.  Many of the stronger storms were occurring in the eastern half of the circulation.  Bands in the western half of the circulation consisted primarily of showers and lower clouds.  Tropical Storm Chantal was far enough north that it was in the region of westerly winds in the upper levels.  Those winds were causing moderate vertical wind shear and they were the primary reason for the asymmetrical distribution of thunderstorms.

Tropical Storm Chantal will move through an environment only marginally favorable for intensification during the next several days.  Chantal will move over water where the Sea Surface Temperature is near 25°C.  It will continue to be in a region of moderate westerly winds in the upper levels, which will cause vertical wind shear.  Tropical Storm Chantal could intensify slowly if the upper level winds do not get any stronger.  However, Chantal could weaken if the upper level winds do get stronger.

Tropical Storm Chantal will move around the northern end of a ridge in the middle troposphere over the Atlantic Ocean.  The ridge will steer Chantal toward the east during the next 24 hours.  Chantal could move more toward the southeast on Thursday when it nears the western end of the ridge.  On its anticipated track Tropical Storm Chantal is forecast to make a slow loop in the middle of the Atlantic Ocean.

Tropical Storm Krosa Brings Wind and Rain to Southwest Japan

Large Tropical Storm Krosa brought wind and rain to parts of southwestern Japan on Wednesday night.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Krosa was located at latitude 33.2°N and longitude 132.9°E which put it about 20 miles (30 km) south-southwest of Uwajima, Japan.  Krosa was moving toward the north at 13 m.p.h. (20 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 975 mb.

The center of large Tropical Storm Krosa was near the southwestern coast of Shikoku on Wednesday night.  The strongest winds were blowing in rainbands that were east of the center of circulation.  Winds to tropical storm force extended out about 260 miles (420 km) from the center of circulation.  The wind was weaker in the western half of Krosa.

Heavy rain was falling on the south facing slopes of Shikoku where the wind was blowing up the slopes.  Heavy rain was also falling on south facing slopes in Wakayama, Mie, Nara and Shiga prefectures in Honshu.  Prolonged heavy rainfall could cause flash floods in some locations.

Tropical Storm Krosa is forecast to move north-northeast across Shikoku and southwestern Honshu.  Krosa will weaken when it moves over land, but it will continue to drop heavy rain over parts of southwestern Japan on Thursday.  A weaker Tropical Storm Krosa is forecast to move over the Sea of Japan later on Thursday.

Large Tropical Storm Krosa Moves Toward Southwest Japan;

Large Tropical Storm Krosa moved toward southwestern Japan on Tuesday.  At 5:00 p.m. EDT on Tuesday the center of Tropical Storm Krosa was located at latitude 28.7°N and longitude 133.4°E which put it about 330 miles (530 km) south of Kochi, Japan.  Krosa was moving toward the northwest at 8 m.p.h. (13 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 965.

The circulation around Tropical Storm Krosa was large.  Krosa has a broad center of circulation which spanned almost 120 miles (195 km).  Several bands of showers and thunderstorms appeared to be consolidating into a broken ring around the broad center.  The strongest winds were occurring in the broken ring.  Other bands of showers and thunderstorms were revolving around the broad center of circulation.  Winds to tropical storm force extended out about 265 miles (425 km) from the center of circulation.

Tropical Storm Krosa will move through an environment favorable for intensification during the next 12 to 24 hours.  Krosa will move over water where the Sea Surface Temperature is near 28.5°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Tropical Storm Krosa is under an upper level ridge which is enhancing the upper level divergence.  However, the large, broad center of circulation will limit the rate of any intensification.  Krosa could strengthen into a typhoon before it reaches southwestern Japan.

Tropical Storm Krosa is moving around the western end of a subtropical ridge over the Western North Pacific Ocean.  Krosa will move more toward the north when it reaches the western end of the ridge.  On its anticipated track Tropical Storm Krosa could reach southwestern Japan within 18 to 24 hours.  Krosa could be a typhoon by that time.  Tropical Storm Krosa will bring gusty winds and heavy rain to parts of Kyushu, Shikoku, and western Honshu.  Heavy rain is likely to cause flooding in some location, especially in areas with steeper slopes.

Tropical Storm Henriette Forms Southwest of Baja California

Tropical Storm Henriette formed southwest of Baja California on Monday.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Henriette was located at latitude 19.7°N and longitude 112.2°W which put it about 265 miles (430 km) southwest of the southern tip of Baja California.  Henriette was moving toward the west-northwest at 12 m.p.h. (19 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 distribution of thunderstorms around Tropical Storm Henriette was highly asymmetrical.  Most of the thunderstorms were occurring southwest of the center of circulation.  Bands in other parts of the circulation consisted primarily of showers and lower clouds.  Tropical Storm Henriette was south of a narrow upper level ridge.  The ridge was producing northeasterly winds which were blowing across the top of Henriette.  Those winds were causing strong vertical wind shear and they were the cause of the asymmetrical distribution of thunderstorms.

Tropical Storm Henriette will be moving through a region that will be mostly unfavorable for intensification.  Henriette will move over water where the Sea Surface Temperature is near 28.5°C.  So, there will be sufficient energy in the upper ocean to support intensification.  However, the upper level ridge will continue to cause strong vertical wind shear which will prevent intensification.  Tropical Storm Henriette is likely to weaken in a day or two when it moves over colder water.

Tropical Storm Henriette will move south of a subtropical ridge over the Eastern North Pacific Ocean.  The ridge will steer Henriette toward the west-northwest during the next several days.  On its anticipated track Tropical Storm Henriette will move farther away from Baja California.

Tropical Storm Krosa Moves Toward Japan

Tropical Storm Krosa moved toward Japan on Sunday after stalling south of Iwo To for several days.  At 11:00 p.m. EDT on Sunday the center of Tropical Storm Krosa was located at latitude 24.7°N and longitude 137.5°E which put it about 255 miles (410 km) west of Iwo To.  Krosa was moving toward the west-northwest at 9 m.p.h. (15 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 965 mb.

Tropical Storm Krosa mixed significant amounts of cooler water to the surface during the days when it was nearly stationary south of Iwo To.  The cooler ware contained less energy and the atmosphere became more stable.  Thunderstorms around the core of the circulation dissipated and the storms in many of the rainbands also weakened.  Some thunderstorms persisted in outer rainbands.  Even though the maximum wind speed decreased, the size of the circulation increased.  Winds to tropical storm force extended out about 280 miles (455 km) from the center of circulation.

Tropical Storm Krosa will move through an environment favorable for intensification during the next several days.  Krosa will move over water where the Sea Surface Temperature is near 29°C after it gets away from the cooler water mixed to the surface.  It will move through a region where there will not be a lot of vertical wind shear.  Tropical Storm Krosa will intensify slowly at first because it lacks a strong inner core.  If more thunderstorms develop near the center of circulation, then Krosa could strengthen more quickly.  It is possible that thunderstorms do not form at  the center of circulation and if that happens, Krosa could develop into a typhoon with a very large eye at the center.

Tropical Storm Krosa will move around the western end of a subtropical ridge over the Western North Pacific Ocean.  The ridge will steer Krosa toward the northwest during the next two or three days.  On its anticipated track Tropical Storm Krosa could approach southwestern Japan within 72 hours.  Krosa is likely to be a large typhoon by that time.

Elsewhere of over the Western North Pacific Ocean, Tropical Storm Lekima continue to bring wind and rain to parts of northeastern China.  At 11:00 p.m. EDT on Sunday the center of Tropical Storm Lekima was located at latitude 37.8°N and longitude 119.6°E which put it about 150 miles (240 km) south-southeast of Tangshan, China.  Lekima was moving toward the north- northwest at 12 m.p.h. (19 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 985 mb.