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Tropical Storm Barry Strengthens South of Louisiana

Tropical Storm Barry strengthened south of Louisiana on Friday morning.  Hurricane Hunters flying into Barry found that the maximum sustained wind speed had increased to 65 m.p.h. (105 km/h).  At 11:00 a.m. EDT on Friday the center of Tropical Storm Barry was located at latitude 28.2°N and longitude 90.4°W which put it about 115 miles (185 km) south-southeast of Morgan City, Louisiana.  Barry was moving toward the west-northwest at 5 m.p.h. (8 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 998 mb.

A Hurricane Warning is in effect for the portion of the coast from Intracoastal City to Grand Isle, Louisiana. Hurricane Watches have been issued for the portions of the coast from the Mouth of the Mississippi River to Grand Isle, Louisiana and from Intracoastal City to Cameron, Louisiana. Tropical Storm Warnings are in effect for the portions of the coast from the Mouth of the Pearl River to Grand Isle, Louisiana and from Intracoastal City to Cameron, Louisiana. A Tropical Storm Watch has been issued for the portion of the coast from the Mouth of the Pearl River to the Mississippi/Alabama border. A Tropical Storm Warning is in effect for Lake Pontchartrain, Lake Maurepas and New Orleans.

The circulation around Tropical Storm Barry exhibited greater organization on Friday morning.  Thunderstorms developed in a band around the southern side of the center of circulation.  More thunderstorms also formed in bands that stretched around the western, southern and eastern sides of the circulation.  Bands in the northern portion of the circulation consisted primarily of showers and lower clouds, although there were some thunderstorms in the parts of those bands over land.  Winds to tropical storm force extended out about 170 miles (280 km) from the center of circulation.  Storms just south of the center were generating upper level divergence which was pumping mass away to the west of Tropical Storm Barry.  The removal of mass allowed the surface pressure to decrease and it was down to 998 mb on Friday morning.

Tropical Storm Barry will move through an environment that is some what favorable for intensification.  Barry will move south of a narrow upper level ridge that stretches from east Texas to south Alabama.  The ridge will produce northeasterly winds which will cause some vertical wind shear.  The shear is one of the reasons why there are fewer thunderstorms in the northern part of the circulation.  Reconnaissance aircraft reported that the middle level center was a little to the south of the surface center.  The tilt of the circulation with height is also the result of the vertical wind shear.  However, the shear will not be strong enough to prevent intensification.  Tropical Storm Barry will move over water where the Sea Surface Temperature is near 30.5°C.  It will extract a lot of energy from the Gulf of Mexico.  Tropical Storm Barry is forecast to strengthen into a hurricane during the next 24 hours.

Tropical Storm Barry is moving around the southwestern part of a ridge of high pressure over the southeastern U.S.  The ridge will steer Barry slowly toward the west-northwest during the next few hours.  Barry will turn more toward the northwest later on Friday.  On its anticipated track the center of Tropical Storm Barry will approach the coast of Louisiana late Friday night.  Barry is forecast to be a hurricane when it reaches the coast.  The broad circulation will cause mostly minor wind damage over a large area.  There could be widespread power outages.  Barry will also generate a storm surge of 6 to 9 feet (2 to 3 meters near where the center makes landfall.  Tropical Storm Barry will drop heavy rain when it moves slowly inland.  Flooding is a serious risk, since soils are nearly saturated and many creeks and rivers are already high.

Tropical Storm Barry Threatens Louisiana

Tropical Storm Barry threatened Louisiana on Thursday.  A low pressure system formerly designated at Potential Tropical Cyclone Two strengthened into Tropical Storm Barry on Thursday morning.  At 11:00 a.m. EDT on Thursday the center of Tropical Storm Barry was located at latitude 27.8°N and longitude 88.7°W which put it about 95 miles (150 km) south-southeast of the Mouth of the Mississippi River and about 200 miles (320 km) southeast of Morgan City, Louisiana.  Barry was moving toward the west at 5 m.p.h. (8 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.

A Hurricane Watch has been issued for the portion of the coast from the Mouth of the Mississippi River to Cameron, Louisiana.  A Tropical Storm Warning is in effect for the portion of the coast from the Mouth of the Pearl River to Morgan City, Louisiana.  A Tropical Storm Watch has been issued for the portion of the coast from the Mouth of the Pearl River to the Mississippi/Alabama border.  A Tropical Storm Watch has also been issued for Lake Pontchartrain, Lake Maurepas and New Orleans.

The circulation around Tropical Storm Barry exhibited more organization on Thursday morning, but there were not a lot of thunderstorms near the center of circulation.  Many of the thunderstorms were occurring in bands wrapping around the western and southern sides of the circulation.  Bands in the northern half of the circulation consisted primarily of showers and lower clouds.  Winds to tropical storm force were occurring in the southeastern part of Tropical Storm Barry.  Winds to tropical storm force extended out about 100 miles (160 km) from the center in that quadrant of Barry.  The winds were weaker in other quadrants of the circulation.

Tropical Storm Barry will move through an environment favorable for intensification during the next 36 hours.  Barry will move over water where the Sea Surface Temperature is near 30.5°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Tropical Storm Barry will intensify slowly until more thunderstorms form near the center of circulation.  If thunderstorms consolidate around an inner core, then rapid intensification would be possible.  Tropical Storm Barry is forecast to strengthen into a hurricane on Friday.

Tropical Storm Barry will move around the southwestern part of a ridge of high pressure over the southeastern U.S.  The ridge is likely to steer Barry slowly toward the west during the next 12 to 24 hours.  Tropical Storm Barry will move more toward the northwest when it moves around the southwestern part of the ridge.  There is still some uncertainty about the timing and location of the turn toward the northwest.  Based on its anticipated track Tropical Storm Barry could approach the coast of Louisiana on Friday night.

Tropical Storm Barry is forecast to strengthen into a hurricane before it makes landfall.  It will bring strong, gusty winds to coastal regions of Louisiana.  Those winds will also push a storm surge toward the coast.  The storm surge could be up to 6 to 8 feet (2 to 3 meters) near where the center makes landfall.  Tropical Storm Barry could drop heavy rain when it moves inland.  Many rivers and streams are already high and locally heavy rain could cause flooding in those locations.

NHC Initiates Advisories on Potential Tropical Cyclone Two

The National Hurricane Center (NHC) initiated advisories on Potential Tropical Cyclone Two on Wednesday morning.  NHC initiated the advisories in order to be able to issue watches for a portion of the coast of Louisiana.  At 11:00 a.m. EDT on Wednesday the center of Potential Tropical Cyclone Two was located at latitude 28.5°N and longitude 86.4°W which put it about 170 miles (270 km) east-southeast of the Mouth of the Mississippi River.  It was moving toward the west-southwest at 8 m.p.h. (13 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 1011 mb.  A Tropical Storm Watch was issued for the portion of the coast from the Mouth of the Mississippi River to Morgan City, Louisiana.

The circulation around Potential Tropical Cyclone Two was not well organized.  There was a large, but relatively weak circulation near the surface.  There was not a well defined center of circulation near the surface.  There was a stronger counterclockwise circulation between about 10,000 feet (3000 meters) and 25,000 feet (7600 meters) above the surface, which was located above the southwestern part of the surface circulation.  Many of the stronger thunderstorms were occurring in bands on the northern and western sides of the circulation above the surface.  There were fewer thunderstorms in the eastern side of the larger, surface circulation.

Potential Tropical Cyclone Two will move through an environment very favorable for development and intensification.  It will move over water where the Sea Surface Temperature is near 30°C.  The system will move through a region where the upper level winds are weak and there will be little vertical wind shear.  It is likely that a center of circulation will form at the surface underneath the counterclockwise circulation above the surface.  Potential Tropical Cyclone Two will strengthen slowly until the surface center is underneath the center higher in the atmosphere.  After the circulation becomes aligned vertically, the system could strengthen more rapidly.  Potential Tropical Cyclone Two is likely to become a hurricane within 48 to 60 hours.

Potential Tropical Cyclone Two will move south of a ridge over the southeastern U.S.  The ridge will steer Potential Tropical Cyclone Two toward the southwest.  It will move more toward the west on Thursday and then turn back more toward the northwest on Friday when it nears the western end of the ridge.  There will be significant uncertainty about the future track of the system until a well defined center of circulation forms at the surface.  On its anticipated track the center of Tropical Cyclone Two could approach the coast of Louisiana and northeast Texas on Friday.  Hurricane Watches and Warnings are likely to be issued for portions of the coast later this week.

Potential Tropical Cyclone Two presents a wide range of hazards.  It will bring hurricane force winds to portions of Louisiana and Texas and it will disrupt operations of offshore facilities in the northwestern Gulf of Mexico.  After the center of the system moves west of New Orleans, southerly winds will force water into the Mouth of the Mississippi River.  The level of the Mississippi River around New Orleans is already near flood stage and any additional rise in the water level could cause serious flooding around the city.  If Potential Tropical Cyclone Two strengthens into a hurricane, as expected, it will cause a significant storm near where the center makes landfall.  The system also has the potential to drop heavy rain and flooding could occur when it moves inland.

Potential Tropical Development Over Northern Gulf of Mexico

The potential exists for the development of a tropical cyclone over the northern Gulf of Mexico this week.  A low pressure system was over Georgia on Monday afternoon.  The low was drifting slowly southward, but it was forecast to move more toward the south-southwest during the next two days.  Several numerical models were predicting that the low pressure system would strengthen into a tropical depression or a tropical storm after it moves over the northern Gulf of Mexico later this week.  The National Hurricane Center was indicating that the low pressure system, currently designated as Invest 92L, had a 30% probability of developing into a tropical cyclone during the next two days and an 80% probability of developing into a tropical cyclone during the next five days.

The low pressure system exhibited a surface circulation on Monday afternoon, but the wind speed was near 15 m.p.h. (25 km/h).  Bands of showers and thunderstorms formed during the daytime heating over land, but they weakened at night.  There was also a counterclockwise rotation in the lower and middle troposphere which may have been the remnants of a mesoscale convective vortex (MCV), which developed over the Middle Mississippi River Valley a few days ago.  The low was not generating upper level divergence on Monday afternoon.

If the low pressure system does move over the northern Gulf of Mexico on Tuesday or Wednesday, it will move into an environment more favorable for the development of a tropical depression.  The Sea Surface Temperature of the water in the northeastern Gulf of Mexico is near 30°C.  The low pressure system will move southeast of an upper level ridge over the southern U.S.  The ridge will produce northeasterly winds, but the winds will be relatively weak and the vertical wind shear will not be too strong.  More thunderstorms are likely to develop when the low pressure system moves over the warm water.  If those thunderstorms generate upper level divergence that pumps mass away, then the surface pressure will decrease and a tropical depression will form.

The upper level ridge is forecast to steer the low pressure system toward the west after it moves over the Gulf of Mexico later this week.  On its anticipated track the low pressure system will move slowly toward the coast of Louisiana and Texas.  The future intensity of the system will be determined by how far the system moves into the Gulf of Mexico.  If the low pressure system takes a track along or near the north coast of the Gulf of Mexico, then it will likely become a tropical depression or a weak tropical storm.  Even if the low only strengthens into a tropical depression, it could drop heavy rain and the potential for flooding exists along the northern Gulf Coast.  If the low pressure system moves farther out into the Gulf of Mexico and remains over warm water for a longer period, then it might intensify into a hurricane.  Residents along the Gulf Coast should monitor this system carefully.

Tropical Storm Gordon Makes Landfall on the Gulf Coast.

Tropical Storm Gordon made landfall on the Gulf Coast near Pascagoula, Mississippi on Tuesday night.  At 11:30 p.m. EDT on Tuesday the center of Tropical Storm Gordon was located at latitude 30.4°N and longitude 88.4°W which put it about 30 miles (50 km) east of Biloxi, Mississippi.  Gordon was moving toward the northwest at 14 m.p.h. (22 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 997 mb.

A Hurricane Warning was in effect for the portion of the coast from the Mouth of the Pearl River to the Alabama-Florida border.  A Tropical Storm Warning was in effect for the portion of the coast from the Okaloosa-Walton County line to the Alabama-Florida border.

The circulation of Tropical Storm Gordon was asymmetrical.  The strongest bands of showers and thunderstorms were north and east of the center of circulation.  The strongest winds were occurring in those bands.  A C-MAN station on Dauphin Island, Alabama reported a sustained wind speed of 62 m.p.h. (100 km/h) and a wind gust of 72 m.p.h. (117 km/h).  The winds were much weaker south and west of the center of Tropical Storm Gordon and there was little rain in those parts of the tropical storm.

Tropical Storm Gordon will start to weaken as the center moves inland.  Gordon will continue to move around the western end of a high pressure system over the western Atlantic Ocean.  The high will steer Tropical Storm Gordon toward the northwest during the next day or two.  On its anticipated track Tropical Storm Gordon will move across southern Mississippi on Wednesday and over Arkansas on Thursday.  The wind will be strong enough to cause minor damage and it will cause some power outages.  Locally heavy rain and the potential for flash floods are the greater risks.  Flash Flood Warnings were in effect for parts of West Florida and Southwest Alabama.  Flash Flood Watches were in effect for Mississippi and Southeastern Arkansas.

Elsewhere over the tropical Atlantic Ocean, Hurricane Florence was continuing to intensify east of the northern Leeward Islands.  At 11:00 p.m. EDT on Tuesday the center of Hurricane Florence was located at latitude 20.7°N and longitude 43.9°W which put it about 1515 miles (2440 km) east-southeast of Bermuda.  Florence was moving toward the west-northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 100 m.p.h (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h).  The minimum surface pressure was 976 mb.

Tropical Storm Gordon Nears Gulf Coast

Tropical Storm Gordon moved closer to the Gulf Coast of the U.S. on Tuesday morning.  At 11:00 a.m. EDT on Tuesday the center of Tropical Storm Gordon was located at latitude 28.5°N and longitude 86.8°W which put it about 145 miles (235 km) east-southeast of the mouth of the Mississippi River.  Gordon 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 1001 mb.

A Hurricane Warning was in effect for the portion of the coast from the mouth of the Pearl River to the Alabama-Florida border.  Tropical Storm Warnings were in effect for the portions of the coast from Grand Isle, Louisiana to the mouth of the Pearl River including Lake Pontchartrain and from the Alabama-Florida border to the Okaloosa-Walton County line in Florida.

The circulation of Tropical Storm Gordon appeared to be getting more organized on Tuesday morning.  More thunderstorms developed near the center of circulation.  Storms near the center were generating upper level divergence which was pumping mass away to the east of the tropical storm.  Several bands of showers and thunderstorms north and east of the center were moving toward the Gulf Coast.  The bands southwest of the center consisted primarily of showers and lower clouds.  Winds to tropical storm force extended out about 80 miles (130 km) from the center of circulation, but the winds were weaker in the southwestern quadrant of Tropical Storm Gordon.

Tropical Storm Gordon could strengthen into a hurricane before it makes landfall.  Gordon will move over water where the Sea Surface Temperature is near 30°C.  An upper level trough over the southeastern U.S. was producing southwesterly winds which were blowing toward the top of the circulation.  Those winds were causing some vertical shear, but they will not be strong enough to prevent intensification.  The surface pressure decreased slightly on Tuesday morning.  Increased friction near the coast could cause the circulation to tighten around the center, when Tropical Storm Gordon gets closer to the Gulf Coast.

Tropical Storm Gordon will move around the southwestern end of a subtropical high pressure system over the western Atlantic Ocean.  The high will steer Gordon in a general northwesterly direction during the next several days.  On its anticipated track the center of Hurricane Gordon is likely to make landfall on the northern Gulf Coast on Tuesday night.  Gordon will produce winds to near hurricane force at the coast.  It could cause a storm surge of 5 to 8 feet (1.5 to 2.5 meters) east of the center where the wind blows water toward the coast.  The highest storm surge will occur in bays and the mouths of streams and rivers where the shape of the coast funnels water into those areas.  Tropical Storm Gordon will also drop heavy rain over portions of northwest Florida, southwest Alabama, Mississippi and eastern Louisiana.  Locally heavy rain could create the potential for flash floods.

Elsewhere over the Atlantic Ocean, former Tropical Storm Florence strengthened into the third Atlantic hurricane of 2018.  At 11:00 a.m. EDT on Tuesday the center of Hurricane Florence was located at latitude 19.7°N and longitude 42.5°W which put it about 1270 miles (2045 km) east-northeast of the Lesser Antilles.  Florence was moving toward the west-northwest at 12 m.p.h. (19 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.

Tropical Storm Gordon Forms, Causes Warnings for South Florida

Former Potential Tropical Cyclone Seven developed a distinct center of circulation on Sunday morning and the National Hurricane Center upgraded the system to Tropical Storm Gordon.  At 8:30 a.m. EDT on Sunday the center of Tropical Storm Gordon was located at latitude 25.1°N and longitude 80.6°W which put it about 10 miles (15 km) west of Key Largo, Florida.  Gordon was moving toward the west-northwest at 16 m.p.h. (26 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 1009 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Golden Beach to Bonita Beach, Florida.  A Tropical Storm Warning was in effect for the Florida Keys from Craig Key to Ocean Reef including Florida bay.  A Tropical Storm Warning was in effect for the portion of the coast from the Alabama-Florida border to Morgan City, Louisiana including Lake Pontchartrain.

The circulation of Tropical Storm Gordon became much better organized during the past 12 hours.  A distinct low level center of circulation formed and many more thunderstorms developed.  A C-MAN station on Fowey Rock, Florida reported sustained winds of 49 m.p.h. (80 km/h) supporting the designation as a tropical storm.  The circulation of Tropical Storm Gordon was still organizing.  More thunderstorms were developing in bands northeast of the center of circulation than in other parts of the tropical storm.  Those storms were beginning to generate upper level divergence which was pumping mass away from the core of Gordon.

Tropical Storm Gordon will be moving through an environment favorable for intensification during the next 36 hours.  Gordon will be moving over water where the Sea Surface Temperature is near 30°C.  It will be moving through a region where the upper level winds will be weak and there will be little vertical wind shear.  Tropical Storm Gordon will continue to intensify and it could intensify more rapidly once the inner core becomes better organized.  There is a chance that Gordon could strengthen into a hurricane before it reaches the north coast of the Gulf of Mexico.

Tropical Storm Gordon will move around the west end of a subtropical high pressure system over the western Atlantic Ocean.  The ridge will steer Gordon in  a general west-northwesterly direction.  On its anticipated track Tropical Storm Gordon will move away from South Florida later today.  Gordon could approach the north coast of the Gulf of Mexico late on Tuesday.  Locally heavy rain could cause floods in South Florida.  Tropical Storm Gordon could produce a storm surge of 6 to 9 feet (2 to 3 meters) along parts of the northern Gulf Coast.

Potential Tropical Cyclone Seven Causes Tropical Storm Watch for U.S. Gulf Coast

Potential Tropical Cyclone Seven caused the National Hurricane Center to issue a Tropical Storm Watch for a portion of the U.S. Gulf Coast on Sunday afternoon.  A Tropical Storm Watch was in effect for the portion of the coast from the Alabama-Florida border to Morgan City, Louisiana including Lake Pontchartrain.  At 5:00 p.m. EDT on Sunday the center of Potential Tropical Cyclone Seven was located at latitude 22.7°N and longitude 77.3°W which put it about 275 miles (445 km) east-southeast of Marathon, Florida.  It was moving toward the west-northwest at 15 m.p.h (24 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 1012 mb.

Bands of showers and thunderstorms began to form in a tropical wave over the Bahamas and the National Hurricane Center designated the system as Potential Tropical Cyclone Seven in order to be able to issue the Tropical Storm Watch for the north coast of the Gulf of Mexico.  The circulation of Potential Tropical Cyclone Seven was still organizing.  A distinct low level center of circulation had not formed.  Bands of showers and thunderstorms were developing and the bands were starting to revolve around the inner part of the weather system.  Thunderstorms were beginning to generate some upper level divergence.

Potential Tropical Cyclone Seven will be moving into an environment favorable for intensification.  It will move over water where the Sea Surface Temperature is near 30°C.  An upper level ridge is forecast to develop over Potential Tropical Cyclone Seven.  If that occurs, then the upper level winds would be weak and there would be little vertical wind shear.  Potential Tropical Cyclone Seven is forecast to intensify into Tropical Storm Gordon.  If the system moves slowly enough, there is a chance it could strengthen into a hurricane before it reaches the Gulf Coast.

Potential Tropical Cyclone Seven will move around the western end of a subtropical high pressure system over the western Atlantic Ocean.  The high will steer Potential Tropical Cyclone Seven in a general west-northwesterly direction.  On its anticipated track the system will move over the Florida Keys on Monday.  It will be over the eastern Gulf of Mexico on Tuesday and the system could reach the northern Gulf Coast late on Tuesday or early on Wednesday.

Elsewhere over the tropical Atlantic, Tropical Storm Florence was moving quickly away from the Cabo Verde Islands.  At 5:00 p.m. EDT on Sunday the center of Tropical Storm Florence was located at latitude 17.4°N and longitude 34.6°W which put it about 700 miles (1125 km) west of the Cabo Verde Islands.  Florence was moving toward the west-northwest at 15 m.p.h. (24 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 1000 mb.

Subtropical Storm Alberto Forms Over Northwest Caribbean Sea

Subtropical Storm Alberto formed over the northwestern Caribbean Sea on Friday morning.  The National Hurricane Center (NHC) designated an area of low pressure as Subtropical Storm Alberto on Friday morning based on data from buoys and ship reports.  At 5:00 p.m. EDT on Friday the center of Subtropical Storm Alberto was located at latitude 19.4°N and longitude 86.3°W which put it about 85 miles (135 km) south-southeast of Cozumel, Mexico.  Alberto was moving toward the east at 2 m.p.h. (3 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.

A Tropical Storm Watch has been issued for the portion of the U.S. coast from Indian Pass, Florida to Grand Isle, Louisiana including New Orleans.  The government of Mexico issued a Tropical Storm Watch for the portion of the coast from Tulum to Cabo Catoche.  The government of Cuba issued a Tropical Storm Watch for the province of Pinar del Rio.

The circulation around Subtropical Storm Alberto was asymmetrical.  The low level center of circulation was located just to east of the Yucatan Peninsula.  The strongest thunderstorms were occurring in a band located about 100 miles (160 km) east and north of the center.  Flow around an upper level trough over the Gulf of Mexico was producing westerly winds which were blowing toward the top of the circulation.  Those winds were causing strong vertical wind shear which was the reason why the thunderstorms were occurring well to the east of the center of circulation.

Subtropical Storm Alberto will move through an environment marginally favorable for intensification during the next 24 to 36 hours.  Alberto will move over water where  the Sea Surface Temperature is near 28°C.  So, there is sufficient energy in the upper ocean to support intensification.  However, the upper level trough will continue to cause moderate to strong vertical wind shear during the next day or so.  The wind shear will inhibit intensification.  Some gradual strengthening is possible.  The winds are weaker near the axis of the upper level trough.  If Alberto moves under the axis of the trough when it reaches the northern Gulf of Mexico, then the wind shear will decrease.  Alberto could strengthen more quickly if that happens.  There is a chance that Alberto could reach hurricane intensity.  If more thunderstorms form closer to the center of circulation, then NHC could change the designation of Alberto to a tropical storm.

Subtropical Storm Alberto is moving around the western end of a large high pressure system over the Atlantic Ocean.  The high is steering Alberto slowly toward the north-northeast.  A general motion toward the north is forecast during the next day or so.  When Alberto gets farther north, the upper level trough could steer it more toward the north-northwest.  There is a chance that the steering currents could weaken when Alberto nears the Gulf Coast.  Thus, there is much more uncertainty about the track forecast after that time.

The greatest risk with Subtropical Storm Alberto will be locally heavy rain and the potential for flooding.  Most of the heavy rain is likely to fall north and east of the center.  Much less rain is likely to fall from the western side of Alberto.  The coast of the Gulf of Mexico is very susceptible to storm surges.  The water level will rise along the eastern and northern coasts of the Gulf of Mexico where the winds blow the water toward the shoreline.

Hurricane Nate Brings Gusty Winds and Surge to Mississippi Coast

Hurricane Nate brought gusty winds, heavy rain and a storm surge to the coast of Mississippi on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Hurricane Nate was located at latitude 29.9°N and longitude 89.1°W which put it about 35 miles (60 km) south-southwest of Biloxi, Mississippi.  Nate was moving toward the north at 20 m.p.h. (32 km/h).  The maximum sustained wind speed was 85 m.p.h. (140 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 983 mb.

A Hurricane Warning was in effect for the portion of the coast from the mouth of the Pearl River to the Alabama/Florida border.  Tropical Storm Warnings were in effect for the portion of the coast from Grand Isle, Louisiana to the mouth of the Pearl River, for New Orleans and Lake Pontchartrain and for the coast from the Alabama/Florida border to Indian Pass, Florida.

Some drier air wrapped into the western side of Hurricane Nate on Saturday afternoon.  In addition an upper level trough approaching Nate from the west produced southwesterly winds which caused vertical wind shear.  The drier air and shear caused the circulation of Hurricane Nate to become asymmetrical.  The stronger winds are occurring in the eastern half of the circulation.  The winds are weaker in the western side of the hurricane.  The bands of showers and thunderstorms are also occurring in the eastern half of Hurricane Nate.  Very little rain was falling on the western side of the hurricane.

The partial eyewall north of the center of Hurricane Nate was moving over the coast of Mississippi from Pascagoula to Gulfport.  Strong gusty winds and heavy rain were falling on that section of the coast.  Winds blowing water toward the coast were pushing a storm surge onto the coast.  A water level gauge at a NOAA laboratory in Pascagoula, Mississippi was reporting a storm surge of 6.75 feet (2.06 meters).  The highest surges were occurring in Mississippi, but there were also storm surges on the coast of Alabama and Florida.  Bands of showers and thunderstorms were dropping heavy rain over southeastern Mississippi, southwestern and central Alabama and northwestern Florida.  Brief tornadoes spun up in some of the thunderstorms on Saturday.

Hurricane Nate will move inland over southeastern Mississippi during the overnight hours.  Nate will weaken after it moves inland, but it will continue to bring gusty winds as it spins down.  There is a strong flow of moist air from the south and heavy rain will continue to fall east of the track of Hurricane Nate.  Places west of the track will experience weaker winds and will receive little rain.  Locations west of a line from New Orleans to Hattiesburg to Meridian,  Mississippi could see little minimal impacts from Nate.  Nate will cross over west central Alabama on Sunday morning.  It will continue to move toward the north-northeast and the remnants of Nate could reach eastern Tennessee on Sunday night.  Areas of heavy rain will fall over northwestern Florida, Alabama, northern Georgia, eastern Tennessee and western North Carolina.  Fresh water flooding could occur in some of those areas.  Tornadoes could develop in the rainbands again on Sunday afternoon.