Tag Archives: AL04

Potential Tropical Cyclone Four Brings Rain to Northeast Mexico

A tropical wave designated as Potential Tropical Cyclone Four brought rain to northeastern Mexico on Saturday night. At 11:00 p.m. EDT on Saturday the center of Potential Tropical Cyclone Four was located at latitude 25.3°N and longitude 97.9°W which put it about 60 miles (95 km) southwest of the Mouth of the Rio Grande River. Potential Tropical Cyclone Four was moving toward the northwest at 13 m.p.h. (20 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.

A tropical wave designated as Potential Tropical Cyclone Four moved inland over northeastern Mexico during Saturday night. A center of circulation never formed in the lower levels of the of the tropical wave and so it never developed into a tropical depression or a tropical storm. The tropical wave will move northwest over the Lower Rio Grande Valley on Sunday. Thunderstorms in the tropical wave could drop locally heavy rain over northeastern Mexico and South Texas. Some places could receive 3 to 5 inches (75 to 125 mm) of rain. The heavy rain could cause flash floods in some locations.

Potential Tropical Cyclone Four Prompts Tropical Storm Warnings for Texas and Mexico

A weather system over the southwestern Gulf of Mexico was designated as Potential Tropical Cyclone Four on Friday afternoon and Tropical Storm Warnings were issued for portions of the coasts of Texas and Mexico. At 5:00 p.m. EDT on Friday the center of Potential Tropical Cyclone Four was located at latitude 20.7°N and longitude 94.5°W which put it about 400 miles (640 km) south-southeast of the Mouth of the Rio Grande River. Potential Tropical Cyclone Four was moving toward the 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 1009 mb.

A Tropical Cyclone Warning was issued for the portion of the coast from Port Mansfield, Texas to Boca de Catan, Mexico.

A weather system over the southwestern Gulf of Mexico exhibited more organization on Friday. However, observations from a U.S. Air Force Reserve Hurricane Hunter plane on Friday afternoon indicated that there was not a well defined center of low level circulation in the weather system. The National Hurricane Center designated the system as Potential Tropical Cyclone Four in order to issue a Tropical Storm Warning for the coast of South Texas. The government of Mexico also issued a Tropical Storm Warning for the northern coast of Mexico.

More thunderstorms developed in Potential Tropical Cyclone Four on Friday afternoon. Some of the thunderstorms in the eastern half of the circulation appeared to be organizing into bands. The thunderstorms in Potential Tropical Cyclone Four began to generate upper level divergence that pumped mass away from the weather system.

Potential Tropical Cyclone Four will move through an environment favorable for intensification during the next 18 hours. Potential Tropical Cyclone Four will move over water where the Sea Surface Temperatures are 30˚C. It will move under an upper level ridge over the southwestern Gulf of Mexico. The upper level winds are weak in that region and there will be little vertical wind shear. Potential Tropical Cyclone Four is likely to intensify during the next 18 hours. A well defined low level center of circulation will have to develop in order for the system to become a tropical storm.

Potential Tropical Cyclone Four will move around the southwestern part of a subtropical high pressure system that extends over the Gulf of Mexico. The high pressure system will steer Potential Tropical Cyclone Four toward the northwest during the next 24 hours. On its anticipated track Potential Tropical Cyclone Four will make landfall south of Brownsville, Texas during Saturday night. It will bring locally heavy rain and gusty winds to South Texas and northern Mexico. Locally heavy rain could cause flash floods in some locations.

Tropical Storm Danny Makes Landfall in South Carolina

Tropical Storm Danny made landfall on the coast of South Carolina on Monday evening. Danny weakened to a tropical depression after the center moved over land. At 11:00 p.m. EDT on Monday the center of Tropical Depression Danny was located at latitude 32.6°N and longitude 81.5°W which put it about 50 miles (80 km) west-northwest of Beaufort, South Carolina. Danny was moving toward the west-northwest at 15 m.p.h. (24 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 1013 mb.

The center of Tropical Storm Danny made landfall near Hilton Head, South Carolina at approximately 7:30 p.m. EDT on Monday. Danny produced gusty winds along the coast of South Carolina. Bands on the western side of Tropical Storm Danny dropped locally heavy rain over the area around Savannah, Georgia. Showers and thunderstorms then moved over central Georgia.

Tropical Depression Danny will move west-northwest during the next 12 hours. On its anticipated track the center of Danny will move over eastern and central Georgia on Tuesday. Tropical Depression Danny will continue to weaken as it moves farther inland. Danny will drop locally heavy rain over parts of Georgia on Tuesday.

Tropical Depression Four Strengthens to Tropical Storm Danny

Former Tropical Depression Four strengthened to Tropical Storm Danny near the coast of South Carolina on Monday afternoon. At 3:00 p.m. EDT on Monday the center of Tropical Storm Danny was located at latitude 32.2°N and longitude 79.7°W which put it about 45 miles (75 km) south-southeast of Charleston, South Carolina. Danny was moving toward the west-northwest at 16 m.p.h. (26 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 1014 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Edisto Beach to South Santee River, South Carolina. The Tropical Storm Warning included Charleston.

Based on data from weather radar and a reconnaissance plane, the National Hurricane Center determined that former Tropical Depression Four had strengthened to Tropical Storm Danny on Monday afternoon. Thunderstorms formed near the center of Danny, when the center moved over the warmer water in the Gulf Stream. Downdrafts in the thunderstorms transported stronger winds to the surface and former Tropical Depression Four intensified into Tropical Storm Danny. The thunderstorms were occurring in the western half of Danny. Bands in the eastern half of the tropical storm consisted primarily of showers and lower clouds

Tropical Storm Danny will move through an environment that is slightly favorable for intensification during the next few hours. Danny will move over water where the Sea Surface Temperatures are near 27°C. An upper level low centered over Northwest Florida will produce easterly winds that will blow toward the top of the tropical storm. Those winds will cause vertical wind shear that will inhibit intensification. However, the shear does not appear to be strong enough to prevent intensification. Tropical Storm Danny could get a little stronger during the next few hours.

Tropical Storm Danny will move south of a high pressure system over the western Atlantic Ocean during the next 24 hours. The high will steer Danny toward the west-northwest. On its anticipated track the center of Tropical Storm Danny could make landfall near Edisto Beach, South Carolina on Monday night. Danny will produce gusty winds along the coast of South Carolina. It could also drop locally heavy rain over parts of southern South Carolina and extreme eastern Georgia.

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Tropical Depression Four Forms, Tropical Storm Warning for South Carolina

Tropical Depression Four formed on Monday morning and the National Hurricane Center issued a Tropical Storm Warning for a portion of the coast of South Carolina. At 11:00 a.m. EDT on Monday the center of Tropical Depression Four was located at latitude 31.9°N and longitude 78.3°W which put it about 110 miles (175 km) east-southeast of Charleston, South Carolina. Tropical Depression Four was moving toward the west-northwest 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 1013 mb.

A Tropical Storm Warning was issued for the portion of the coast from Edisto Beach to South Santee River, South Carolina. The Tropical Storm Warning included Charleston.

The National Hurricane Center designated a low pressure system off the coast of South Carolina as Tropical Depression Four on Monday morning. Bands of showers and lower clouds were revolving around the center of Tropical Depression Four. Thunderstorms were occurring in bands on the far western side of the circulation around the depression. An upper low was centered over northern Florida on Monday morning. The upper low was producing easterly winds that were blowing across the top of the tropical depression. The easterly winds were causing moderate vertical wind shear and the wind shear was blowing the tops off clouds in many of the bands closer to the center of the depression

Tropical Depression Four will move through an environment that is only slightly favorable for intensification during the next 12 hours. The depression will move over water where the Sea Surface Temperatures are near 27°C. The upper level low will continue to cause vertical wind shear that will inhibit the formation of thunderstorms near the center of Tropical Depression Four. If the wind shear decreases, then there is a chance Tropical Depression Four could strengthen to a tropical storm later on Monday.

Tropical Depression Four will move south of a high pressure system over the western Atlantic Ocean during the next 24 hours. The high will steer the depression toward the west-northwest. On its anticipated track the center of Tropical Depression Four could make landfall near Edisto Beach, South Carolina on Monday night. The depression will produce gusty winds along the coast of South Carolina. It could also drop locally heavy rain over parts of southern South Carolina and extreme eastern Georgia.

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.

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.

Debby Makes a Transition to a Tropical Storm

Former Subtropical Storm Debby made a transition to a tropical storm on Wednesday.  At 11:00 a.m. EDT on Wednesday the center of Tropical Storm Debby was located at latitude 41.2°N and longitude 48.3°W which put it about 1150 miles (1855 km) west-northwest of the Azores.  Debby was moving toward the northeast at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1003 mb.

The structure of former Subtropical Storm Debby changed on Wednesday and it exhibited the characteristics of a tropical storm.  More thunderstorms formed around the center of circulation and those thunderstorms rose higher into the atmosphere.  Additional bands of showers and thunderstorms developed and revolved around the core of the circulation.  Storms near the core began to generate upper level divergence.  The strongest winds occurred closer to the center of circulation.  The National Hurricane Center designated Debby as a tropical storm based on information from satellites.

Tropical Storm Debby will move into an environment unfavorable for a tropical storm during the next 24 to 48 hours.   Debby was over water where the Sea Surface Temperature was near 26°C, but it will soon move over much cooler water.  It will start to weaken when it moves over the cooler water.  It could take several days for the circulation around Tropical Storm Debby to spin down.

Tropical Storm Debby will be steered toward the northeast as it moves between an upper level trough to the west and an upper level ridge to the east.  On its anticipated track Tropical Storm Debby will move between the Azores and Greenland.

Subtropical Storm Debby Forms West of the Azores

Subtropical Storm Debby formed over the North Atlantic Ocean west of the Azores on Tuesday morning.  At 11:00 a.m. EDT on Tuesday the center of Subtropical Storm Debby was located at latitude 38.9°N and longitude 48.5°W which put it about 1160 miles (1870 km) west of the Azores.  Debby was moving toward the north at 16 m.p.h. (26 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 1008 mb.

A surface low pressure system revolved around the western side of an upper level low over the North Atlantic Ocean during the past few days.  More bands of showers and thunderstorms developed around the surface low on Tuesday morning and its circulation become more circular.  The National Hurricane Center designated the low pressure system as Subtropical Storm Debby based on satellite imagery.  The strongest winds were occurring in a rainband that wrapped around the northern side of the circulation.  Bands south of the center of circulation consisted primarily of showers and lower clouds.

Subtropical Storm Debby will move through an environment somewhat favorable for intensification during the next 24 hours.  Debby will move over water where the Sea Surface Temperature is between 26°C and 27°C.  Subtropical Storm Debby will move between an upper level trough to its west and an upper level ridge to its east.  The trough and ridge will produce southeasterly winds which will cause moderate vertical wind shear.  Subtropical Storm Debby could strengthen during the next 24 hours.  Debby will move over much colder water in about 36 hours and then it will weaken.

The upper level ridge and trough will steer Subtropical Storm Debby in a mainly northerly direction.  On its anticipated track Subtropical Storm Debby will remain west of the Azores.