Monthly Archives: July 2019

Tropical Storm Wipha Forms South of Macau

Tropical Storm Wipha formed south of Macau late on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Wipha was located at latitude 18.8°N and longitude 112.6°E which put it about 175 miles (285 km) south of Macau.  Wipha was moving toward the northwest at 6 m.p.h. (10 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 994 mb.

The circulation around Tropical Storm Wipha was large, but Wipha did not have a well formed inner core.  Winds to tropical storm force extended out about 200 miles (320 km) from the center of circulation.  However, there were no strong thunderstorms near the center.  Stronger thunderstorms were occurring in bands well to the south and east of the center of circulation.  Bands northwest of the center consisted primarily of showers and lower clouds.

The large lower level circulation of Tropical Storm Wipha was just to the southeast of an upper low over the northwestern part of the South China Sea.  The upper low was circulating some drier air over the northwestern part of Wipha.  It was also causing some vertical wind shear.  The drier air and wind shear were inhibiting the formation of thunderstorms in the northwestern part of Tropical Storm Wipha.

Tropical Storm Wipha will move through an environment somewhat favorable for intensification during the next 24 hours.  Wipha will move over water where the Sea Surface Temperature is near 30°C.  The upper low will continue to inhibit the strengthening of Tropical Storm Wipha.  If thunderstorms begin to develop near the center of Wipha, then the tropical storm could strengthen.

Tropical Storm Wipha will move around the southwestern part of a subtropical ridge over the Western North Pacific Ocean.  The ridge will steer Wipha toward the northwest during the next 24 hours.  On its anticipated track the center of Tropical Storm Wipha will be near the northern part of Hainan Island and the south coast of China in 18 to 24 hours.  Wipha could move more toward the west when it reaches the Gulf of Tongking.  Although Tropical Storm Wipha will bring gusty winds to southern China and northern Vietnam, locally heavy rain and the potential for floods will be greater risks.

Erick Rapidly Intensifies Into Major Hurricane

Erick rapidly intensified into a major hurricane over the the Central Pacific Ocean during Monday night.  At 11:00 a.m. EDT on Tuesday the center of Hurricane Erick was located at latitude 13.4°N and longitude 142.8°W which put it about 920 miles (1485 km) east-southeast of Hilo, Hawaii.  Erick was moving toward the west at 17 m.p.h. (28 km/h).  The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 140 m.p.h. (225 km/h).  The minimum surface pressure was 966 mb.

The core of Hurricane Erick intensified rapidly during the overnight hours.  The eye became more circular and distinct on infrared satellite images.  The diameter of the eye was about 12 miles (19 km) on Tuesday morning.  Thunderstorms in the ring around the eye grew taller and the wind speed around the eye increased quickly.  Storms around the core of Erick generated strong upper level divergence which pumped mass away from the hurricane.  Multiple bands of showers and thunderstorms were revolving around the core of the circulation.

The circulation around Hurricane Erick was relatively small.  Winds to hurricane force were occurring within 25 miles (40 km) of the center of circulation.  Winds to tropical storm force extended out about 100 miles (160 km) of the center.  The Hurricane Intensity Index (HII) for Hurricane Erick was 20.6.  The Hurricane Size Index (HSI) was 8.2 and the Hurricane Wind Intensity Size Index (HWISI) was 28.8.

Hurricane Erick will remain in an environment favorable for intensification for about another 24 hours.  Erick will move over water where the Sea Surface Temperature is near 28°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear during the next day or so.  Hurricane Erick will approach an upper level trough east of Hawaii on Wednesday.  The trough will produce stronger southwesterly winds which will cause the vertical wind shear to increase.  Hurricane Erick will start to weaken when the wind shear increases.

Hurricane Erick will move south of a subtropical high pressure system over the Eastern and Central North Pacific Ocean.  The high will steer Erick toward the west during the next several days.  On its anticipated track Hurricane Erick could be south of Hawaii on Thursday night.

Elsewhere, Tropical Storm Flossie was nearing hurricane strength over the Eastern North Pacific Ocean.  At 11:00 a.m. EDT on Tuesday the center of Tropical Storm Flossie was located at latitude 12.2°N and longitude 120.5°W which put it about 1015 mile (1635 km) southwest of the southern tip of Baja California.  Flossie was moving toward the west at 15 m.p.h. (24 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 999 mb.

Hurricane Erik and Tropical Storm Flossie Strengthen

Hurricane Erick and Tropical Storm Flossie both moved westward and strengthened over the Eastern North Pacific Ocean on Monday.  At 11:00 p.m. EDT on Monday the center of Hurricane Erick was located at latitude 12.7°N and longitude 140.0°W which put it about 1110 miles (1790 km) east-southeast of Hilo, Hawaii.  Erick was moving west at 18 m.p.h. (30 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 990 mb.

The circulation around Hurricane Erick exhibited greater organization on Monday.  A small eye developed at the center of circulation.  The eye was surround by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms,  Winds to hurricane force extended out about 20 miles (30 km) from the center of circulation.  Bands of showers and thunderstorms were revolving around the core of Hurricane Erick.  Storms near the core were generating upper level divergence which was pumping mass away from the hurricane.  Winds to tropical storm force extended out about 70 miles (110 km) from the center.

Hurricane Erick will move through an environment favorable for intensification during the next 48 hours.  Erick will move over water where the Sea Surface Temperature is near 28°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Erick will intensify during the next two days and it could strengthen into a major hurricane.  Eventually, Erick will approach an upper level trough east of Hawaii and the vertical wind shear will increase.

Hurricane Erick will move south of a subtropical high pressure system over the Eastern North Pacific Ocean.  The high will steer Erick toward the west. On its anticipated track Hurricane Erick could be southeast of Hawaii on Thursday.

Elsewhere over the Eastern North Pacific Ocean, Tropical Storm Flossie was also intensifying.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Flossie was located at latitude 12.3°N and longitude 117.8°W which put it about 895 miles (1445 km) southwest of the southern tip of Baja California.  Flossie was moving toward the west at 17 m.p.h. (28 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 1001 mb.  Tropical Storm Flossie is also forecast to move westward and strengthen.

Tropical Storm Erick Forms Over Eastern North Pacific

Tropical Storm Erick formed over the Eastern North Pacific Ocean on Saturday.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Erick was located at latitude 11.9°N and longitude 126.8°W which put it about 1955 miles (3145 km) east-southeast of Hilo, Hawaii.  Erick was moving toward the west at 17 m.p.h. (28 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.

More thunderstorms developed near the center of a low pressure system over the Eastern North Pacific Ocean and the National Hurricane Center designated the system as Tropical Storm Erick.  The circulation around Erick was still organizing.  A small cluster of thunderstorms formed near the center of circulation and the strongest winds were occurring in that cluster.  Winds to tropical storm force extended out about 25 miles (40 km) from the center of circulation.  Bands of showers and thunderstorms were developing and the bands were beginning to revolve around the center of Tropical Storm Erick.  Storms near the center of circulation were starting to generate upper level divergence which was pumping mass away from the tropical storm.

Tropical Storm Erick will move through an environment favorable for intensification during the next 48 to 72 hours.  Erick will move over water where the Sea Surface Temperature is near 27.5°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Tropical Storm Erick will strengthen and it could become a hurricane within 48 hours.  Erick could intensify more rapidly if an eye and eyewall form.

Tropical Storm Erick will move south of a subtropical high pressure system over the Eastern North Pacific Ocean.  The subtropical high will steer Erick toward the west-northwest during the next few days.  On its anticipated track Tropical Storm Erick could be southeast of Hawaii in four or five days.

Tropical Storm Nari Drops Heavy Rain on Honshu

Tropical Storm Nari dropped locally heavy rain and producing gusty winds on Honshu on Friday night.  At 11:00 p.m. EDT on Friday the center of Tropical Storm Nari was located at latitude 35.2°N and longitude 137.0°E which put it about 10 miles (15 km) east of Nagoya, Japan.  Nari was moving toward the north-northeast at 15 m.p.h. (24 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 Nari was dropping locally heavy rain over parts of central Honshu.  The heaviest rain was falling in bands located in the western half of the circulation.  Heavier rain was falling in the area between Nagoya, Osaka and Kyoto.  Bands of heavier rain were also falling north of Nagoya.  Most of the bands in the eastern half of Tropical Storm Nari consisted primarily lighter showers and lower clouds.  The heavier rain could produce flash flooding in some locations.

Tropical Storm Nari will move more toward the east-northeast on Saturday.  The center of Nari is forecast to pass north of Tokyo.  Tropical Storm Nari will continue to drop locally heavy rain over central and eastern Honshu when it moves over those locations.

Tropical Storm Nari Develops South of Japan

Tropical Storm Nari developed south of Japan on Thursday night.  The Japan Meteorological Agency designated a low pressure system south of Honshu as Tropical Storm Nari when the maximum sustained wind speed reached 40 m.p.h. (65 km/h).  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Nari was located at latitude 30.2°N and longitude 136.9°E which put it about 350 miles (565 km) south of Nagoya, Japan.  Nari was moving toward the north at 14 m.p.h. (22 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.

The circulation around Tropical Storm Nari exhibited more of a hybrid structure than the structure of a pure tropical cyclone.  Tropical Storm Nari developed when an upper level low pressure system stalled south of the Japan.  A surface circulation formed beneath the upper low and then more thunderstorms formed closer to the center of circulation.  The original upper level low was located southwest of the surface low on Thursday night.  The upper level low was producing southwesterly winds which were blowing across the surface low.  Those winds were creating vertical wind shear.  The circulation around Tropical Storm Nari showed evidence of the effect of that wind shear.  The stronger thunderstorms were in a band that curved around north and west of the center of circulation.  Bands south and east of the center consisted primarily of showers and lower clouds.  The wind field around Tropical Storm Nari was also asymmetric.  Winds to tropical storm force extended out about 115 miles (185 km) to the east of the center of circulation, but only extended out about 60 miles (95 km) to the west of the center.

Tropical Storm Nari will move through an environment only marginally favorable for intensification.  Nari will move over water where the Sea Surface Temperature is near 28°C.  The upper low will continue to cause vertical wind shear, which will inhibit intensification.  The upper low will also pull some drier air around the southern side of the circulation.  Nari could strengthen a little during the next 24 hours if more thunderstorms develop closer to the center of circulation.  Tropical Storm Nari will move under stronger westerly winds in about a day or so.  Those winds will cause more vertical wind shear and they should prevent further intensification.

Tropical Storm Nari will be steered by the interaction of the upper low and a subtropical ridge over the western North Pacific Ocean.  Those two features are likely to steer Nari toward the north during the next 24 hours.  On its anticipated track Tropical Storm Nari could approach the coast of Honshu near Nagoya in about 24 hours.  Nari will move more toward the east when it reaches the stronger westerly winds in a day or so.  Tropical Storm Nari could bring gusty winds and locally heavy rain to central Honshu on Saturday.

Tropical Storm Dalila Develops Southwest of Baja California

Tropical Storm Dalila developed southwest of Baja California on Tuesday morning.  More thunderstorms formed to the south of the center of former Tropical Depression Five-E and the circulation produced wind speeds to tropical storm force.  At 11:00 a.m. EDT on Tuesday the center of Tropical Storm Dalila was located at latitude 18.7°N and longitude 117.7°W which put it about 580 miles (935 km) west-southwest of the southern tip of Baja California.  Dalila 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 1006 mb.

Although Tropical Storm Dalila did have a definite low level center of circulation, the center was relatively broad.  In addition, most of the stronger thunderstorms were occurring south of the center of circulation.  Bands in other parts of the tropical storm consisted primarily of showers and lower clouds.  Dalila was moving southwest of a large upper level high pressure system over the western U.S. and Mexico.  Clockwise flow around the high was producing northeasterly winds which were blowing toward the top of Tropical Storm Dalila.  Those winds were causing moderate vertical wind shear and they were a major reason for the asymmetrical distribution of thunderstorms in the southern part of the tropical storm.

Tropical Storm Dalila will move into an environment that will become increasingly unfavorable for intensification.  The upper level high will continue to produce wind shear which will inhibit strengthening.  Dalila is currently over water where the Sea Surface Temperature is near 26°C, but it will move over colder water during the next several days.  Dalila could maintain tropical storm intensity for another 12 to 24 hours, but it is likely to weaken during the next several days.

Tropical Storm Dalila will continue to move around the southwestern part of the upper level high over the western U.S. and Mexico.  The high will steer Dalila toward the northwest during the next 12 to 24 hours.  When the remaining stronger thunderstorms weaken, Tropical Storm Dalila will be steered by winds at lower levels in the atmosphere and those winds should steer it more toward the west.  On its anticipated track Tropical Storm Dalila will weaken while it moves farther over the Eastern North Pacific Ocean.

Tropical Depression Three Forms East of Florida

Tropical Depression Three formed east of Florida on Monday.  More thunderstorms developed near the center of a small low pressure system over the Northwestern Bahamas on Monday afternoon and the National Hurricane Center (NHC) designated the system as Tropical Depression Three.  At 5:00 p.m. EDT on Monday the center of Tropical Depression Three was located at latitude 25.6°N and longitude 78.6°W which put it about 120 miles (195 km) southeast of West Palm Beach, Florida.  The depression was moving toward the northwest at 13 m.p.h. (20 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 1013 mb.

More thunderstorms developed around the center of a small low pressure system that was embedded in the northern end of a tropical wave over the Bahamas on Monday.  Most of the thunderstorms were forming in bands on the eastern side of the circulation.  Based on data from satellites NHC determined that a closed circulation had formed at the surface.  There were fewer thunderstorms in the western half of the circulation.  Storms in the eastern half of the depression were exhibiting upper level divergence to the north and east.

Tropical Depression Three will move through an environment somewhat favorable for intensification during the next 24 hours.  The depression will move over water where the Sea Surface Temperature is near 29°C.  It will be in under the western side of an upper level ridge.  The ridge could enhance upper level divergence on Tuesday.  The wind aloft will be relatively weak, although a thin upper trough near the east coast of the U.S. will produce southwesterly 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.  The surface pressure is relatively high and that could slow any intensification.  A larger upper level trough will develop over the eastern U.S. on Tuesday and the trough will produce stronger southwesterly winds.  Those winds will create much more shear on Wednesday.

Tropical Depression Three will move around the western end of a subtropical high pressure system over the western Atlantic Ocean.  The high will steer the depression toward the northwest during the next 12 hours.  Tropical Depression Three is likely to more more toward the north later on Tuesday when it reaches the western end of the ridge.  On its anticipated track the center of Tropical Depression Three could be near the southeast coast of Florida in about 12 hours.  The center is not currently forecast to make landfall, but the depression could bring squally weather and an increased chance for rain to the southeast coast of the U.S. during the next several days.

Tropical Storm Danas Speeds Toward South Korea

Tropical Storm Danas sped toward South Korea on Friday as it moved quickly north-northeast over the East China Sea.  At 11:00 a.m. EDT on Friday the center of Tropical Storm Danas was located at latitude 32.3°N and longitude 125.1°E which put it about 190 miles (305 km) south-southwest of Mopko, South Korea.  Danas was moving toward the north-northeast at 19 m.p.h. (30 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 987 mb.

The distribution of thunderstorms around Tropical Storm Danas remained asymmetrical on Friday.  The strongest thunderstorms were occurring in bands well to the east of the center of circulation.  Bands closer to the center and on the western side of the circulation consisted primarily of showers and lower clouds.  An upper level trough over eastern China was producing southwesterly winds which were blowing toward the top of the circulation.  Those winds were causing moderate vertical wind shear and they were the reason for the asymmetrical distribution of thunderstorms.  The wind field also exhibited the effects of the wind shear.  Winds to tropical storm force extended out about 200 miles (320 km) from the center of Danas on the eastern side of the circulation, but only extended out about 120 miles (195 km) on the western side of the tropical storm.

Tropical Storm Danas will remain in an environment only marginally favorable for intensification until it makes landfall in South Korea.  Danas will move over water where the Sea Surface Temperature is near 30°C.  The upper level trough over eastern China will continue to cause moderate vertical wind shear.  Tropical Storm Danas could intensify a little during the next 12 hours, but it will weaken after the center moves over South Korea.

Tropical Storm Danas will move around the western end of a subtropical ridge over the western North Pacific Ocean.  The ridge and the upper level trough will interact to steer Danas rapidly toward the north-northeast.  On its anticipated track the center of Tropical Storm Danas will make landfall on the southwestern coast of South Korea in about 12 hours.  Danas will bring gusty winds and locally heavy rain to South Korea on Saturday.  The heaviest rain will fall over the southeastern half of South Korea.  Locally heavy rain in that region could cause flash floods.  The outer rainbands of Tropical Storm Danas could also drop locally heavy rain over western Kyushu.

Tropical Storm Danas Nears Southern Ryukyu Islands

Tropical Storm Danas moved near the southern Ryukyu Islands late on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Danas was located at latitude 23.9°N and longitude 124.1°E which put it about 30 miles (50 km) south of Ishigaki, Japan.  Danas was moving toward the north at 21 m.p.h. (34 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 990 mb.

The circulation around Tropical Storm Danas exhibited a little more organization on Wednesday.  More thunderstorms formed near the center of circulation and several bands of showers and thunderstorms formed in the eastern half of the circulation.  The bands north and west of the center consisted primarily of showers and lower clouds.  Storms near the center began to generate upper level divergence which pumped mass away to the northeast of the tropical storm.  Winds to tropical storm force extended out about 125 miles (200 km) from the center of circulation.

Tropical Storm Danas will move into an environment somewhat favorable for intensification.  Danas will move over water where the Sea Surface Temperature is near 30°C.  A small upper level low near Taiwan will produce southwesterly winds which blow toward the top of the circulation around Tropical Storm Danas.  Those winds were the reason why the stronger rainbands were in the eastern half of the circulation.  Those winds will cause moderate vertical wind shear, which will inhibit intensification.  However, the shear will have less of an effect since Danas will move in the same direction as the upper level winds.  Tropical Storm Danas is likely to intensify during the next 24 hours and there is a chance it could strengthen into a typhoon.

Tropical Storm Danas will move around the western end of a subtropical ridge over the western North Pacific Ocean.  The ridge will steer Danas toward the north-northeast.  On its anticipated track Tropical Storm Danas will move through the southern Ryukyu Islands during the next few hours.  Danas will bring gusty winds and locally heavy rain when it passes over those islands.  Tropical Storm Danas will move over the East China Sea toward southwestern Japan and South Korea during the next several days.