Tag Archives: Lousiana

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.

Tropical Depression 16 Organizes Near Nicaragua

Tropical Depression Sixteen organized near Nicaragua on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Tropical Depression Sixteen was located at latitude 12.8°N and longitude 82.7°W which put it about 95 miles (155 km) south-southeast of Puerto Cabezas, Nicaragua.  It was moving toward the northwest at 6 m.p.h. (10 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.

A Hurricane Watch was in effect for the portion of the coast from Punta Herrero to Cabo Catoche, Mexico.  A Tropical Storm Warning was in effect for the portion of the coast from Sandy Bay Sirpi, Nicaragua to Punta Castilla, Honduras.

The circulation of Tropical Depression Sixteen exhibited more organization on Wednesday.  An Air Force Reserve Hurricane Hunter reconnaissance aircraft found a distinct surface center of circulation on Wednesday afternoon.  More thunderstorms began to form near the center on Wednesday evening.  Bands of showers and thunderstorms developed on the northern and southern sides of the circulation.  There were sustained winds in some of the bands that were near tropical storm force.

Tropical Depression Sixteen will move through an environment that will be favorable for intensification during the next several days.  It will move over water where the Sea Surface Temperature is near 30°C.  The upper level winds will be weak and there will be little vertical wind shear.  Some of the western part of the circulation is passing over Nicaragua and the increased friction is the only factor inhibiting intensification.  If the center of circulation stays over water, then the depression will likely strengthen into a tropical storm on Thursday.  If the center of circulation moves over northeastern Nicaragua, then the depression will weaken.  The system is likely to strengthen when it moves over the northwestern Caribbean Sea on Friday.

A ridge of high pressure is steering the tropical depression slowly toward the northwest and that motion is expected to continue for another day or so.  An upper low near the west coast of Florida is going to move west across the Gulf of Mexico.  When the upper low gets northwest of Tropical Depression Sixteen, it will start to pull the depression more toward the north.  On its anticipated track the center of Tropical Depression Sixteen will move near or over northeastern Nicaragua on Thursday.  The depression could drop very heavy rain and cause floods in parts of Nicaragua and Honduras.  It is forecast to move over the northwestern Caribbean Sea on Friday and the depression could be near the northeastern Yucatan peninsula by Friday night.  The depression is expected to move into the Gulf of Mexico on Saturday.  There is more uncertainty about the future track of the system after that time.

Remnants of Tropical Storm Harvey About to Move Over Gulf of Mexico

The remnants of former Tropical Storm Harvey are about to move over the southern Gulf of Mexico.  At 2:00 p.m. EDT on Tuesday the center of the remnants of Tropical Storm Harvey was located at latitude 20.3°N and longitude 89.8°W which put it about 45 miles (75 km) south-southwest of Merida, Mexico.  It was moving toward the northwest at 15 m.p.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 1010 mb.

A broad area of low pressure that contained the remnants of former Tropical Storm Harvey moved across the Yucatan peninsula on Tuesday.  Thin bands of showers were rotating around the broad area of low pressure over land.  Several broken bands of thunderstorms were evident on the northern and northeastern periphery of the low pressure system.  There were several smaller centers rotating around inside the larger area of low pressure, but the circulation appeared to consolidating around a center near Merida.  A few thunderstorms were forming near that center as it neared the coast.

The National Hurricane Center indicated that there is a nearly 100% chance that the low pressure system will strengthen into a tropical cyclone again once it moves over the Gulf of Mexico.  The Sea Surface Temperature (SST) in the southern Gulf of Mexico is near 31°C.  An upper level low over the northwestern Gulf of Mexico was producing some vertical shear over the top of the surface low.  The upper low is forecast to move north and weaken.  An upper level ridge over the northwestern Caribbean Sea is forecast to move over the western Gulf of Mexico.  The upper ridge will produce southerly winds which will cause some vertical wind shear.  However, those winds are expected to be weak enough to allow for intensification.  The southerly winds could actually enhance upper level divergence to the north of the low pressure system in a day or two.

Given the large size of the low pressure system and the lack of a well defined center of circulation, the system will likely start to intensify slowly.  The rate of intensification will increase once a well defined center forms.  A period of very rapid intensification could occur later this week because of very warm SSTs and little vertical wind shear.  The area of low pressure could become a tropical depression within 12 hours.  It is likely to be a tropical storm on Wednesday.  The system has a good chance of becoming a hurricane over the western Gulf of Mexico.  If the system moves slowly and rapid intensification occurs, it could become a major hurricane.

A ridge in the middle troposphere near Florida is steering the low pressure system toward the northwest and a general northwesterly motion is forecast for the next several days.  There will be more uncertainty about the future track until a well developed center of circulation forms.  However, it seems likely that this system will move toward the coast of Texas.  The system could slow and/or turn more toward the north when it nears the coast.  It has the potential to become a significant hurricane by the time it reaches the coast.  It could bring strong gusty winds, which could cause a significant storm surge at the coast.  If the system moves slowly, it could also drop very heavy rain, which would create flash floods.

Tropical Storm Cindy Nears Northwest Gulf Coast

Tropical Storm Cindy neared the northwestern coast of the Gulf of Mexico on Wednesday evening.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Cindy was located at latitude 28.6°N and longitude 93.4°W which put it about 95 miles (150 km) south-southeast of Port Arthur, Texas.  Cindy was moving toward the north-northwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 992 mb.

A Tropical Storm Warning is in effect for the portion of the coast from San Luis Pass, Texas to Grand Isle, Louisiana.

Tropical Cyclone Cindy exhibits a hybrid structure in which a broad surface low pressure system is interacting with an upper low centered near the Upper Texas coast.  There is a distinct center of low pressure at the surface.  A band of showers and thunderstorms is northwest of the surface center.  Drier air in the middle and upper levels wraps around the southern and eastern sides of the center and there are no thunderstorms in those quadrants of the core of Tropical Storm Cindy.  A broad flow of moisture is producing bands of showers and thunderstorms in the outer portions of the eastern and northern sides of the circulation.

Tropical Storm Cindy is moving around the western end of a subtropical high pressure system centered over the Atlantic Ocean.  The subtropical high is steering Cindy toward the north-northwest.  On its anticipated track Tropical Storm Cindy will make landfall near the border between Texas and Louisiana on Thursday.  Cindy will turn toward the north and then the tropical storm will move northeastward on Friday.

Some locations will experience prolonged periods of rainfall and fresh water flooding will be possible in those area.  There could also be a storm surge of 3 to 6 feet (1 to 3 meters) near where the center makes landfall.  A few tornadoes could be spun up as rainbands move over the coast.