Monthly Archives: June 2020

Tropical Depression Four-E Forms Southwest of Baja California

Tropical Depression Four-E formed just southwest of Baja California on Monday night.  At 11:00 p.m. EDT on Monday the center of Tropical Depression Four-E was located at latitude 20.5°N and longitude 112.6°W which put it about 240 miles (385 km) southwest of the southern tip of Baja California.  The depression was moving toward the northwest at 7 m.p.h. (11 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 1004 mb.

The circulation around a low pressure system southwest of Baja California exhibited more organization on Monday night and the National Hurricane Center designated the system as Tropical Depression Four-E.  The distribution of thunderstorms around the depression was asymmetrical.  A band of stronger thunderstorms wrapped around the northern side of the center of circulation.  The strongest winds were occurring in that band of storms.  Bands in other parts of the depression consisted of primarily of showers and lower clouds.

Tropical Depression Four-E will move into an environment mostly unfavorable for intensification.  The depression will move over water where the Sea Surface Temperature is near 24.5°C.  An upper level trough over the western U.S. and an upper level ridge over Mexico will produce southwesterly winds which will blow toward the top of the depression.  Those winds will cause moderate vertical wind shear.  The colder water and moderate shear will prevent the potential for significant intensification.  The depression could maintain its intensity during the next six to twelve hours but it is likely to weaken later on Tuesday.

Tropical Depression Four-E will move around the western end of a ridge of high pressure over Mexico.  The ridge will steer the depression slowly toward the northwest.   On its anticipated track Tropical Depression Four-E will pass west of Baja California.

Tropical Storm Boris Develops East-Southeast of Hawaii

Tropical Storm Boris developed east-southeast of Hawaii on Thursday afternoon.  At 5:00 p.m. EDT on Thursday the center of Tropical Storm Boris was located at latitude 11.2°N and longitude 137.1°W which put it about 1330 miles (2145 km) east-southeast of Hilo, Hawaii.  Boris 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.

More thunderstorms developed Thursday afternoon near a low pressure system southeast of Hawaii that was previously designated as Tropical Depression Three-E.  A scatterometer on board a satellite detected winds to 40 m.p.h. (65 km) near the center of the low pressure system and the National Hurricane Center designated the system as Tropical Storm Boris.  A band of showers and thunderstorms wrapped around the southern and eastern sides of the center of circulation and the strongest winds were occurring in that band of storms.  A few other short bands of showers and thunderstorms developed in the eastern half of Boris.  Bands in the western half of the circulation consisted primarily of showers and lower clouds.  Winds to tropical storm force extended out about 50 miles from the center of circulation.

Tropical Storm Boris will move through an environment marginally favorable for intensification during the next 12 to 24 hours.  Boris will move over water where the Sea Surface Temperature is near 26.5°C.  A large upper level trough between Hawaii and the West Coast of the U.S. will produce southwesterly winds which will blow toward the top of the circulation.  Those winds will cause moderate vertical wind shear and the shear will limit intensification.  In addition, there is drier air north and west of Tropical Storm Boris.  Boris could intensify during the next 12 hours in spite of the moderate vertical wind shear and drier air.  However, Tropical Storm Boris will move into a region where the upper level winds are stronger during the weekend.  When the vertical wind shear increases, Boris will weaken.

Tropical Storm Boris will move south of a subtropical high pressure system over the Eastern North Pacific Ocean.  The will steer Boris toward the west-northwest during the next 24 hours.  When Tropical Storm Boris weakens during the weekend, it will be steered by winds closer to the surface.  Those winds will steer Boris toward the west.  On its anticipated track the weakening Tropical Storm Boris will pass southeast of Hawaii.

Tropical Storm Dolly Develops Southwest of Newfoundland

Tropical Storm Dolly developed southwest of Newfoundland on Tuesday.  At 1:00 p.m. EDT on Tuesday the center of Tropical Storm Dolly was located at latitude 39.4°N and longitude 61.9°W which put it about 660 miles (1065 km) southwest of Cape Race, Newfoundland.  Dolly was moving toward the east-northeast at 13 m.p.h. (20 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. (5 km/h).  The minimum surface pressure was 1002 mb.

Former Subtropical Depression Four strengthened on Tuesday and its structure continued to make a transition to a more tropical cyclone like appearance.  A band of showers and thunderstorms wrapped closely around the southern side of the center of circulation.  The strongest winds were occurring in that band.  Other bands of showers and thunderstorms were revolving around the center of circulation.  A scatterometer on board a satellite estimated that there were winds above tropical storm force and the National Hurricane Center designated the system as Tropical Storm Dolly.  The winds to tropical storm force extended out 65 miles (105 km) on the southern side of Dolly.  The winds in the other parts of the circulation were generally blowing at less than tropical storm force.

Tropical Storm Dolly will move through an environment that could be favorable for intensification during the next 6 to 12 hours.  Dolly will move near the northern part of the Gulf Stream where the water is near 26°C.  It will move around the southeastern part of a weakening upper level low.  The upper low will produce some vertical wind shear, but the shear will not be strong enough to prevent intensification during the next 6 to 12 hours.  Tropical Storm Dolly is likely to move north of the Gulf Stream on Wednesday.  When Dolly moves over colder water it will start to weaken.

Tropical Storm Dolly will move around the southeastern side of the upper low during the next few hours.  The upper low will weaken on Wednesday and both the upper low and Dolly will be steered toward the northeast by a larger upper level trough over eastern North America.  On its anticipated track Tropical Storm Dolly could bring gusty winds and rain to southeastern Newfoundland on Wednesday night and Thursday.

Subtropical Depression Four Forms Southeast of Cape Cod

Subtropical Depression Four developed southeast of Cape Cod, Massachusetts on Monday afternoon.  At 5:00 p.m. EDT on Monday the center of Subtropical Depression Four was located at latitude 38.2°N and longitude 65.7°W which put it about 310 miles (495 km) southeast of Cape Cod, Massachusetts.  The depression was moving toward the east-northeast at 9 m.p.h. (15 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 structure of a previously non-tropical low pressure system southeast of Cape Cod evolved into a more symmetrical circular shape on Monday.  Bands of showers and thunderstorms revolved more closely around the center of the low.  The low pressure system exhibited a more tropical like structure on visible satellite imagery.  However, the National Hurricane Center (NHC) observed that the surface low was under an upper low which meant the system had a cold core in the upper troposphere.  So, NHC designated the system as Subtropical Depression Four when it initiated advisories on Monday afternoon.

The circulation around Subtropical Depression Four had a hybrid structure with a tropical like appearance in the lower levels and a non-tropical cold core in the upper levels.  The depression will move through an environment favorable for intensification during the next 12 to 18 hours.  The core of the depression will move near the northern part of the Gulf Stream where the Sea Surface Temperature is near 26°C.  It will move near the south side of the core of the upper low where the winds are weaker.  Those winds will cause some vertical wind shear, but the shear will not be too strong during the next 12 hours.  The depression could strengthen into a subtropical storm.  There is a chance that the circulation could develop a warm core in the upper levels if the depression stays near the Gulf Stream.  The warm water in the Gulf Stream and the cold air in the upper troposphere will enhance instability which will contribute to the development of thunderstorms.  If thunderstorms release enough latent energy in the upper troposphere, then a warm core could form and the system could make an additional transition into a tropical storm.

Subtropical Depression Four is likely to move in tandem with the upper low during the next day or two.  The upper low will move toward the east-northeast on Tuesday and then it will move more toward the northeast on Wednesday.  On its anticipated track Subtropical Depression Four will move away from the northeast U.S.  The depression will remain south of Nova Scotia, but it could pass near southeastern Newfoundland on Thursday.

Weakening Tropical Depression Nuri Makes Landfall West of Hong Kong

A weakening Tropical Depression Nuri made landfall on the coast of China west of Hong Kong on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Tropical Depression Nuri was located at latitude 22.2°N and longitude 111.5°E which put it about 170 miles (280 km) west of Hong Kong.  Nuri was moving toward the northwest at 18 m.p.h. (29 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 1001 mb.

Former Tropical Storm Nuri weakened to a tropical depression as it approached the coast of China on Saturday night.  An upper level ridge centered over China produced northeasterly winds which blew toward the top of former Tropical Storm Nuri.  Those winds caused moderate vertical wind shear and they blew the tops off thunderstorms in the eastern half of Nuri.  The wind shear blocked upper level divergence to the east of the tropical storm and the surface pressure increased.  The wind speed decreased and Nuri was downgraded to a tropical depression as it neared the coast of China.

Tropical Depression Nuri moved around the southwestern part of a subtropical high pressure system over the Western North Pacific Ocean.  The high steered Nuri toward the northwest.  Tropical Depression Nuri made landfall on the coast of China west of Hong Kong.  The center of Nuri crossed the coast between Dianbai and Yangjiang.  The circulation around Tropical Depression Nuri will continue to weaken as it moves farther inland.  Nuri will bring some heavy rain showers to parts of southeastern China before it dissipates.

Tropical Storm Nuri Develops of South China Sea

Tropical Storm Nuri developed over the South China Sea on Friday.  At 5:00 p.m. EDT on Friday the center of Tropical Storm Nuri was located at latitude 18.1°N and longitude 116.4°E which put it about 360 miles (580 km) south-southeast of Hong Kong.  Nuri 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 998 mb.

The wind speed around former Tropical Depression 02W increased on Friday and the Japan Meteorological Agency designated the system as Tropical Storm Nuri.  The distribution of thunderstorms around Nuri was asymmetrical.  The strongest thunderstorms were occurring in bands in the southern and western parts of the circulation.  Bands in the eastern and northern portions of Tropical Storm Nuri consisted primarily of showers and lower clouds.  Thunderstorms near the center of Nuri began to generate upper level divergence which pumped mass away from the tropical storm.

Tropical Storm Nuri will move through an environment somewhat favorable for intensification during the next 24 hours.  Nuri will move over water where the Sea Surface Temperature is near 30°C.  It will move under the southwestern part of an upper level ridge centered over eastern China.  The ridge will produce northeasterly winds which will blow toward the top of the circulation.  Those winds will cause some vertical wind shear and the shear will inhibit intensification.  The wind shear could also cause the distribution of thunderstorms to remain asymmetrical.  Tropical Storm Nuri is likely to get stronger during the next 24 hours in spite of the vertical wind shear.

Tropical Storm Nuri will move around the southwestern part of a subtropical high pressure system over the Western North Pacific Ocean.  The high will steer Nuri toward the northwest during the next 24 to 36 hours.  On its anticipated track the center of Tropical Storm Nuri will approach the coast of China southwest of Hong Kong in about 24 hours.  Nuri will drop locally heavy rain over parts of southeastern China.

Tropical Depression Develops West of Luzon

A tropical depression developed west of Luzon on Thursday night.  At 11:00 p.m. EDT on Thursday the center of Tropical Depression 02W was located at latitude 16.3°N and longitude 119.2°E which put it about 135 miles (215 km) northwest of Manila, Philippines.  The depression was moving toward the west-northwest at 14 m.p.h. (22 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 1002 mb.

An area of low pressure moved west of Luzon on Thursday night and several weather agencies classified the system as a tropical depression.  The circulation around Tropical Depression 02W was not well organized.  There were a number of fragmented bands of showers and thunderstorms revolving around the center of the depression.  The strongest thunderstorms were in bands west and north of the center.  Bands east of the center of circulation were still over the Philippines and those bands consisted primarily of showers and lower clouds.

Tropical Depression 02W will move through an environment favorable for intensification during the next 24 to 36 hours.  The depression will move over water where the Sea Surface Temperature is near 30.5°C.  It will move under the southwestern portion of an upper level ridge centered northeast of Taiwan.  The ridge will produce easterly winds which will blow toward the top of the depression.  Those winds will cause some vertical wind shear and the shear will inhibit intensification.  Tropical Depression 02W is likely to intensify into a tropical storm during the next 24 hours in spite of the vertical wind shear.

Tropical Depression 02W will move around the southwestern end of a subtropical high pressure system over the Western North Pacific Ocean.  The high will steer the depression toward the northwest during the next 36 to 48 hours.  On its anticipated track Tropical Depression 02W will approach the coast of China west of Hong Kong in about 48 hours.  It will likely be a tropical storm at that time.

Tropical Depression Cristobal Brings Rain to Lower Mississippi River Valley

Tropical Depression Cristobal brought rain to the lower Mississippi River Valley on Monday.  At 11:00 p.m. EDT on Monday the center of Tropical Depression Cristobal was located at latitude 34.8°N and longitude 92.8°W which put it about 10 miles (15 km) west of Little Rock, Arkansas.  Cristobal was moving toward the north-northwest at 17 m.p.h. (28 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 994 mb.

Tropical Depression Cristobal moved northward across Louisiana and Arkansas on Monday.  Steadier rain fell in the northern part of the circulation around Cristobal.  Diverging air from a surface high pressure system east of the Great Lakes converged with the circulation around the northern side of Tropical Depression Cristobal to produce rising motion.  The rising motion produced the steadier rain.  Thunderstorms in bands in the southern and eastern parts of Cristobal dropped locally heavy rain over parts of Louisiana, Mississippi and Alabama.  Jackson, Mississippi received 2.49 inches (6.3 cm) of rain.  Little Rock, Arkansas received 1.49 inches (3.8 cm) of rain.

Tropical Depression Cristobal will move around the western side of a high pressure system.  The high will steer Cristobal toward the north during the next several days.  The circulation around Tropical Depression Cristobal retained tropical characteristics on Monday night.  Radiosonde data from Little Rock and Jackson, Mississippi showed that there was still a warm core in the middle troposphere.  Cristobal is forecast to make a gradual transition to an extratropical cyclone during the next 24 to 36 hours.  The circulation could strengthen during the extratropical transition and a Gale Warning has been issued for Lake Michigan.  Flood Watches were also in effect for locations from Mississippi to Wisconsin.

Tropical Storm Cristobal Causes Storm Surge on Gulf Coast

Tropical Storm Cristobal caused a storm surge on the Gulf Coast on Sunday.  At 11:00 p.m. EDT on Sunday the center of Tropical Storm Cristobal was located at latitude 30.3°N and longitude 90.2°W which put it about 20 miles (30 km) north-northwest of New Orleans, Louisiana.  Cristobal was moving toward the north-northwest at 10 m.p.h. (16 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 993 mb.

A Tropical Storm Warning remained in effect for the portion of the coast from Morgan City, Louisiana to the Okaloosa/Walton County Line in Florida.

The large circulation around Tropical Storm Cristobal blew water toward the northern coast of the Gulf of Mexico on Sunday.  The wind produced a rise in the water level from northwest Florida to southeast Louisiana.  The highest storm surges occurred along the coast of Mississippi and southeast Louisiana.  The water level reached 7.47 feet (2.28 m) at the Waveland Yacht Club in Mississippi.  The storm surge was 7.62 feet (2.32 m) at Shell Beach in Louisiana.  The storm surge covered coastal roads in Grand Isle, Louisiana and Biloxi, Mississippi.

The broad center of Tropical Storm Cristobal passed across the Lower Mississippi River delta on Sunday afternoon before it moved over New Orleans.  Cristobal began to weaken slowly as it moved inland.  Winds to tropical storm force were still occurring in the southeastern part of the circulation which was still over the Gulf of Mexico.  Most of the rain was falling in bands on the northern side of Tropical Storm Cristobal.  Locally heavy rain fell over Northwest Florida, Southwest Alabama, Southern Mississippi and Southeastern Louisiana.

Tropical Storm Cristobal will move around the western end of a subtropical high pressure system over the western Atlantic Ocean.  The high will steer Cristobal toward the north during the next several days.  On its anticipated track Tropical Storm Cristobal will move over Louisiana and Arkansas on Monday.  Cristobal will continue to weaken slowly as it moves farther inland.  Tropical Storm Cristobal will drop locally heavy rain over parts of Mississippi, eastern Louisiana, Arkansas and Missouri.  Flood Watches have been issued for some of those areas.

Large Tropical Storm Cristobal Churns Toward Louisiana

Large Tropical Storm Cristobal churned toward the coast of Louisiana on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Cristobal was located at latitude 26.2°N and longitude 90.2°W which put it about 200 miles (320 km) south of Grand Isle, Louisiana.  Cristobal was moving toward the north at 12 m.p.h. (19 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 993 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Intracoastal City, Louisiana to the Okaloosa/Walton County Line in Florida including Lake Pontchartrain and Lake Maurepas.

The circulation around Tropical Storm Cristobal continued to be very large.  Winds to tropical storm force extended out 250 miles (400 km) to the east of the center of Cristobal.  A thunderstorm in a rainband on the eastern periphery of the circulation around Tropical Storm Cristobal produced a tornado near Orlando, Florida.  Winds to tropical storm force extended out 160 miles (260 km) in the western half of the circulation.  The winds were blowing at less than tropical storm force near the center of circulation.  The center passed just to the west of NOAA buoy 42001 on Saturday evening.  The buoy measured a surface pressure of 29.34 inches (993.8 mb).  More thunderstorms appeared to be forming north and south of the center of circulation on Saturday night.

Tropical Storm Cristobal will move through an environment favorable for intensification during the next 12 to 18 hours.  Cristobal will move over water where the Sea Surface Temperature is near 27°C.  It will move under the western side of an upper level ridge.  The ridge will produce southerly winds which will blow toward the top of the circulation.  Those winds will cause some vertical wind shear but the the shear will not be great enough to prevent intensification.  Tropical Storm Cristobal will strengthen on Sunday.  If thunderstorms consolidate around the center of circulation, then there is a chance that Cristobal could strengthen into a hurricane.

Tropical Storm Cristobal will move around the western end of a subtropical high pressure system on Sunday.  The high will steer Cristobal toward the north.  A ridge in the middle troposphere will move north of Tropical Storm Cristobal later on Sunday.  The ridge will turn Cristobal toward the north-northwest.  On its anticipated track Tropical Storm Cristobal will approach the coast of Louisiana on Sunday afternoon.  The center of Cristobal could make landfall between Grand Isle and Morgan City.

Tropical Storm Cristobal will bring gusty winds to Northwest Florida, Southwest Alabama, Southern Mississippi and Southeastern Louisiana.  Those winds will push water toward the coast.  A storm surge of 1 to 4 feet (0.3 to 1.3 meters) will be possible.  The water level could rise 3 to 6 feet (1 to 2 meters) in parts of southeastern Louisiana.  Areas outside of levee protection systems could go under water.  Tropical Storm Cristobal will drop heavy rain over parts of southern Mississippi and Southeastern Louisiana.  Flash Flood Watches have been issued for those regions.