Tag Archives: Yucatan

Tropical Storm Earl Forms over the Western Caribbean

Based on data collected by an Air Force Reserve Hurricane Hunter reconnaissance plane, the National Hurricane Center designated a system previously known as Invest 97L as Tropical Storm Earl.  At 12:00 p.m. EDT on Tuesday the center of Tropical Storm Earl was located at latitude 16.3°N and longitude 80.2°W which put it about 535 miles (860 km) east of Belize City, Belize.  Earl was moving toward the west at 22 m.p.h. (35 km/h).  The maximum sustained wind speed was 45 m.p.h. (70 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1001 mb.

A Hurricane Watch and a Tropical Storm Warning has been issued for the portion of the coast from Punta Allen, Mexico to the Belize/Guatemala border.  A Tropical Storm Warning has been issued for the portion of the coast from Cabo Gracias a Dios to the Honduras/Guatemala border.

The recon plane found a small closed low level center of circulation on the western edge of a cluster of thunderstorms.  The circulation around Tropical Storm Earl is very small.  Winds to tropical storm force only extend out about 80 miles (130 km) from the center of circulation.  Most of the thunderstorms are occurring in the eastern half of the tropical storm.  Those thunderstorms are generating upper level divergence which has pumped out enough mass to allow the surface pressure to decrease a few millibars during the past 12 hours.

The environment around Tropical Storm Earl is somewhat favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 29°C.  An upper level low centered near the western tip of Cuba is producing southwesterly winds which are blowing over the western side of Tropical Storm Earl.  Those westerly winds are producing some vertical wind shear, which is why most of the thunderstorms are in the eastern half of Earl.  The wind shear is inhibiting intensification, but the upper low is forecast to move farther from Earl, which would reduce the shear.  If Earl move north of the coast of Honduras, it should intensify.  However, if the center of circulation moves over Honduras, then Earl could weaken fairly quickly because of its small size.

The subtropical high over the Atlantic Ocean is steering Tropical Storm Earl toward the west at a fairly rapid speed.  The high is expected to continue to steer Earl toward the west during the next several days, but the tropical storm is expected to move a little more slowly on Wednesday.  On its anticipated track the center of Tropical Storm Earl is expected to pass just north of the coast of Belize.  Earl could be very close to Belize in about 36 hours.

Earl is a small tropical storm and the greatest risks are locally heavy rainfall and flash flooding.

Disturbance Near Yucatan Could Develop Over Gulf of Mexico

A tropical disturbance over the northwestern Caribbean Sea near the Yucatan peninsula is moving northwest and it could develop into a tropical cyclone when it moves over the southern Gulf of Mexico.  The National Hurricane Center (NHC) has designated the disturbance as Invest 93L and NHC is putting the probability of development into a tropical cyclone during the next two days at 80%.  At 8:00 p.m. EDT the center of Invest 93L was located at latitude 18.5°N and longitude 87.5°W which put it about 170 miles (270 km) south of Cancun, Mexico.  Invest 93L was moving toward the northwest at 11 m.p.h. (17 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. (70 km/h).  The minimum surface pressure was 1005 mb.

Invest 93L consists of a broad area of low pressure at the surface.  Several bands of thunderstorms are occurring in the eastern and northern parts of the circulation.  There is no well defined center of circulation and there are fewer thunderstorms in the inner portion of the circulation.  The strongest winds are occurring in the bands of thunderstorms north and east of the center.  There is some upper level divergence to the east of Invest 93L.

The environment around Invest 93L is not totally favorable for development.  The Sea Surface Temperature in northwest Caribbean Sea is near 30°C, which means there is plenty of energy in the upper ocean.  However, an upper level low near Texas and an upper level ridge east of Invest 93L are combining to generate strong southwesterly winds that are blowing over the top of the disturbance.  Those winds are creating significant vertical wind shear which is inhibiting the development of Invest 93L.  The upper level ridge is enhancing the upper level divergence to the east of the disturbance which allowed the pressure to fall several millibars on Saturday.  The upper winds are lighter near the axis of the ridge which is why the stronger bands of thunderstorms are persisting in that area.

Invest 93L is forecast to move toward the Yucatan peninsula on Sunday.  If the broad area over low pressure moves over land that will prevent it from developing until it moves back over water.  Numerical models are guiding that the disturbance will develop into a tropical cyclone when the area of low pressure moves over the southern Gulf of Mexico.  The upper level ridge is forecast to extend over the southeastern Gulf and if that happens the wind shear could decrease enough to allow development to occur.  Invest 93L could become a tropical depression or a tropical storm over the Gulf of Mexico.

The southwesterly flow over the Gulf of Mexico is forecast to turn Invest 93L toward the northeast.  On its anticipated track the system could reach the west coast of Florida near Cedar Key late Monday or early Tuesday.  The primary risk is likely to be locally heavy rain.  However, the coast in that area is very susceptible to storm surge and there could be some rise in the water level.  The National Hurricane Center has tentatively tasked a reconnaissance plane to investigate Invest 93L on Sunday, if necessary.

Possible Tropical Development in Western Gulf of Mexico

An area of showers and thunderstorms near the Yucatan Peninsula has shown signs of a cyclonic circulation, although the rotation may be in the middle troposphere and not at the surface.  The formal designation of this system is Invest 91L.  At 2:00 p.m EDT on Saturday the center of Invest 91L was located at latitude 20.0°N and longitude 88.4°W which put it about 100 miles (165 km) southeast of Merida, Mexico and about 760 miles (1220 km) south-southeast of Galveston, Texas.  Invest 91L was moving toward the northwest at 5 m.p.h. (8 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. (70 km/h).  The minimum surface pressure was 1009 mb.  The National Hurricane Center is now giving Invest 91L a 50% chance of developing into a tropical depression or tropical storm in the next five days.  An additional reconnaissance plane has been scheduled to investigate it on Sunday afternoon.

The circulation of Invest 91L is not very well organized.  Almost all of the showers and thunderstorms are occurring in the eastern half of the circulation.  Visible satellite images indicate a possible center of cyclonic rotation over the Yucatan peninsula, but it is not clear if the rotation extends all of the way down to the surface.  Counterclockwise winds around an upper level low over the Gulf of Mexico are generating significant vertical wind shear over Invest 91L.  However, the upper level winds east of the upper low are diverging, which is enhancing rising motion and is supporting the development of the showers and thunderstorms in that area.  The upper level divergence is also causing the surface pressure to decrease slowly, which could lead to the formation of a surface center of low pressure.

When Invest 91L moves into the southern Gulf of Mexico, it will move over water where the Sea Surface Temperature is near 27°C to 28°C.  So, there is sufficient energy in the upper ocean to support the development of a tropical cyclone.  The key factor will be the interaction between the upper low and any surface center that forms.  If the surface center forms too close to the upper low, then vertical wind shear will likely inhibit development and the system will remain fairly weak.  If the surface low develops a little farther southeast of the upper low, then there will be less shear and more upper level divergence.  That could allow for more intensification.

Invest 91L is expected to move with the upper low as the upper low moves northward.  Most guidance from numerical models moves the system toward the north-northwest toward the Upper Texas Coast.  However, there will be above normal uncertainty in the track until a well defined center of circulation forms at the surface.

Interests in the western Gulf of Mexico should monitor the progress of Invest 91L.

Tropical Depression Nine Forms Over Bay of Campeche

More thunderstorms formed near the center of a small low pressure system over the Bay of Campeche and the National Hurricane Center classified the low as Tropical Depression Nine (TD9) at 11:00 p.m. EDT on Tuesday.  The center of TD9 was located at latitude 19.4°N and longitude 92.9°W which put it about 160 miles west of Campeche, Mexico and about 850 miles west-southwest of Key West, Florida.  TD9 was moving toward the east at 6 m.p.h.  The maximum sustained wind speed was 35 m.p.h. and the minimum surface pressure was 1000 mb.  The government of Mexico has issued a Tropical Storm Warning for the portion of the coast from Celestun to Frontera.

Westerly winds in the upper levels are still creating wind shear over the top of TD9 and most of the thunderstorms are located in the eastern half of the circulation.  However, the upper level wind speed is expected to diminish and TD9 is likely to intensify into Tropical Storm Hanna on Wednesday.  The westerly winds are also likely to continue to push TD9 toward the east or east-northeast during the next 24 hours.

 

Potential Tropical Cyclone Developing Over Bay of Campeche

A reconnaissance plane found a small center of low pressure within a broader area of low pressure over the Bay of Campeche on Tuesday afternoon.  The plane also found winds to near tropical storm force.  At the 3:00 p.m. EDT the low was centered at latitude 19.3°N and longitude 93.7°W which put it about 350 miles northwest of Campeche, Mexico and about 850 miles west-southwest of Key West, Florida.  The low was moving toward the east at 6 m.p.h.  The maximum sustained wind speed was 38 m.p.h. and the minimum surface pressure of 1001 mb.

Thunderstorms are forming mainly on the southern and eastern sides of the center.  The low could be pulling in some of the drier air over the northern Gulf of Mexico, which may be limiting convection on the northwest side of the low.  Westerly winds in the upper levels are also generating wind shear, which is inhibiting the development of the low.  On the other hand, the low is over Sea Surface Temperatures (SSTs) that are warmer than 29°C and there is plenty of energy in the ocean to support the development of a tropical cyclone.  The pressure has fallen about 5-6 mb in the past 12 hours and so the low appears to be getting stronger.  If more thunderstorms form around the center of the low, it could be classified as a tropical depression or a tropical storm.

The westerly winds in the upper and middle levels are pushing the low slowly toward the east.  Guidance from the forecast models seems to be divided into two main possibilities.  One group of models keeps the low relatively weak and forecasts it to move eastward across the Yucatan peninsula and into the northwestern Caribbean Sea before turning it northeastward and moving the low across the Bahamas.  A second group of models predicts that the low will be a bit stronger and that the upper level flow will turn it northeastward sooner and move the low across southern Florida.  If that second scenario occurs, the low could bring stronger winds and heavy rainfall to parts of south Florida.