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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.

Sandra Weakens to a Tropical Storm

Strong vertical wind shear weakened Hurricane Sandra to a tropical storm on Friday.  At 10:00 p.m. EST on Friday the center of Tropical Storm Sandra was located at latitude 21.2°N and longitude 108.8°W which put it about 155 miles (250 km) west of Las Islas Marias and about 205 miles (330 km) southwest of Mazatlan, Mexico.  Sandra was moving toward the north at 10 m.p.h. (16 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 990 mb.  Tropical Storm Warnings are in effect for the portion of the coast from Altata to San Blas, Mexico and for the Las Islas, Marias.

A large upper level trough centered over the southwestern U.S. generated strong southwesterly winds that blew the top half of Hurricane Sandra east of the low level circulation.  The strong wind vertical wind shear will continue, but it will take another day or two for the low level circulation to spin down.  Sandra could weaken to a tropical depression on Saturday and it could be classified as a remnant low by the end of the weekend.

Since the upper portion of the circulation is detached from the lower portion, the surface circulation is being steered by the winds in the lower atmosphere.  A ridge in the lower atmosphere is steering the surface circulation toward the north and that general motion is expected to continue for the next 24 to 48 hours.  On its anticipated track the surface center of Tropical Storm Sandra will pass near the southern tip of Baja California on Saturday.  The surface center could make landfall on the west coast of Mexico on Sunday.

Hurricane Sandra Turns Toward Mexico

Hurricane Sandra moved around the western end of a subtropical ridge and turned toward Mexico on Thursday.  At 10:00 p.m. EST on Thursday the center of Hurricane Sandra was located at latitude 18.0°N and longitude 109.7°W which put it about 340 miles (545 km) south of the southern tip of Baja California and about 490 miles (790 km) south-southwest of Culiacan, Mexico.  Sandra was moving toward the north at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 150 m.p.h. (240 km/h).  The minimum surface pressure was 956 mb.  The government of Mexico issued a Tropical Storm Watch for the coast of Baja California from Todos Santos to Los Barriles.

Hurricane Sandra appeared to develop concentric eyewalls on Thursday.  A primary rainband wrapped around the tiny pinhole eye at the center of the hurricane.  Satellite imagery suggests that the tiny inner eye still exists inside the larger outer eye.  Sandra reached Category 4 on the Saffir-Simpson Scale on Thursday morning, but the formation of concentric eyewalls weakened the hurricane back to Category 3 later in the day.  Sandra remains a well organized hurricane.  It has a well defined core surrounded by a ring of strong thunderstorms.  Spiral bands of storms are in the northeastern quadrant of the circulation.

Hurricane Sandra will move into a less favorable environment on Friday.  It will be over water where the Sea Surface Temperature is near 29°C.  However, a large upper level trough along the west coast of North America will generate strong southwesterly winds.  Those winds will cause strong vertical wind shear, which will tilt the circulation toward the northeast.  The upper level winds will also inhibit upper level divergence from the western part of Sandra.  The strong wind shear will weaken Hurricane Sandra on Friday.  Some models are predicting that the shear could be strong enough to blow the middle and upper parts of the circulation northeast of the low level circulation.  If that happens, then Hurricane Sandy could weaken very quickly,

The upper level trough will steer Hurricane Sandra toward the northeast on Friday.  Sandra will likely move faster toward the northeast by Friday night.  On its anticipated track Sandra could be near the southern tip of Baja California by Friday night and it could approach the west coast of Mexico on Saturday.  Sandra could still be a hurricane when it nears Baja California, but it is more likely to be a tropical storm.  It could be a tropical storm or depression by the time it reaches the west coast of Mexico.

TD 22E Intensifies to Tropical Storm Sandra

A core circulation organized quickly on Tuesday inside Tropical Depression 22E and it intensified into Tropical Storm Sandra.  At 4:00 p.m. EST on Tuesday the center of Tropical Storm Sandra was located at latitude 11.9°N and longitude 107.2°W which put it about 780 miles south-southeast of the southern tip of Baja California.  Sandra was moving toward the west-northwest at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 997 mb.

Eastern upper level winds which were blowing over the top of Tropical Depression 22E diminished on Tuesday and the depression intensified into Tropical Storm Sandra.  A primary rainband wrapped around the center of circulation  and an inner core developed near the interior end of the band.  As the band wrapped around the center of circulation a ring of thunderstorms began to take on the structure of an eyewall.  Those thunderstorms also started to generate some upper level divergence.  The circulation of Sandra is still organizing and other spiral bands are starting to form.

Tropical Storm Sandra is in an environment that is favorable for intensification.  It is over water where the Sea Surface Temperature is near 30°C.  Although there is still some vertical wind shear, it is much less than it was on Monday.  A combination of very warm water and little vertical wind shear could allow Sandra to intensify very quickly.  It is likely to become a hurricane with 12 to 18 hours and it could become a major hurricane within 24 to 36 hours.  In a couple of days Sandra will start to encounter strong upper level winds from the southwest.  The increased vertical wind shear at that time will cause it to weaken.

Tropical Storm Sandra is starting to move around the western end of a subtropical ridge that has been steering toward the north.  Sandra should gradually turn toward the north during the next 24 hours.  It is likely to move mainly toward the north until Thursday when southwesterly winds will turn it toward the northeast.  Sandra could be approaching the southern tip of Baja California by Friday night.

Tropical Depression 22E Forms Southwest of Mexico

A small center of circulation formed within a larger area of thunderstorms southwest of Mexico on Monday and the National Hurricane Center designated the system as Tropical Depression 22E.  At 4:00 p.m. EST on Monday the center of Tropical Depression 22E (TD22E) was located at latitude 10.8°N and longitude 102.9°W which put it about 465 miles (750 km) south-southwest of Acapulco, Mexico.  TD22E was moving toward the west at 18 m.p.h. (30 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were gusts to 45 m.p.h. (70 km/h).  The minimum surface pressure was 1005 mb.

TD22E is still in the early stages of an organizational process.  The small center of circulation is located near the western end of a long band of thunderstorms.  There are not many thunderstorms south and west of the center and there is not much evidence of spiral bands.  A subtropical ridge northeast of TD22E is pushing the depression quickly toward the west and its rapid movement is retarding the organizational process.

TD22E is currently in an environment that is marginal for intensification.  It is over water where the Sea Surface Temperature (SST) is near 30°C, which is very favorable for intensification.  However, the ridge northeast of TD22E is causing strong easterly winds to blow over the top of the depression.  The strong vertical wind shear and the rapid motion of the depression are negative factors for intensification.

As TD22E moves farther west, the vertical wind shear is expected to decrease and the depression is expected to move more slowly.  When that happens, TD22E will be able to more efficiently use the energy it is getting from the warm water and it will intensify.  A period of rapid intensification may occur once the core of the circulation is better organized.  TD22E could become a tropical storm on Tuesday and it could become a hurricane later this week.

The subtropical ridge is steering TD22E quickly toward the west.  In another 24 to 36 hours TD22E is likely to reach the western end of the ridge.  At that time it will slow down and turn toward the north.  TD22E will encounter southwesterly winds when it moves farther north.  Those winds will push TD22E toward the northeast later this week.  On its anticipated track TD22E could be near the southern tip of Baja California by the end of the week.

Disturbance Brings Squally Weather to the Northwest Caribbean Sea

A complicated disturbance over the northwestern Caribbean Sea is bringing squally weather to that area.  A tropical wave over the western Caribbean Sea is interacting with an upper level low over eastern Mexico.  The disturbance is causing thunderstorms over a region that extends from the northwestern Caribbean Sea to the southern Gulf of Mexico.  Upper level divergence east of the upper low has led to the formation of a surface low pressure system east of Belize.  At 7:00 p.m. EST on Thursday the center of the surface low was located at latitude 18°N and longitude 86°W which put it about 150 miles (240 km) east-southeast of Chetumal, Mexico.  The surface low was moving toward the west-northwest at 10 m.p.h. (16 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 1011 mb.

The disturbance is not very well organized, which is normally the case when a tropical wave interacts with an upper level low.  There is a broken area of thunderstorms that extends around the east and northern sides of the disturbance.  However, there are not many thunderstorms close to the center of the surface low.  The upper low is causing vertical wind shear over the western half of the surface low.  Some upper level divergence is occurring over the eastern half of the surface low.

A large high pressure system over the western Atlantic Ocean is steering the disturbance toward the west-northwest.  That general steering pattern is expected to continue for the next two days.  On its anticipated track the disturbance will move over the Yucatan peninsula and over the southern Gulf of Mexico during the next several days.

The disturbance is in an environment that is marginally favorable for tropical development.  The Sea Surface Temperature of the northwestern Caribbean is near 29°C.  There is vertical wind shear, but it may be just small enough to allow for slow development.  On the other hand, the disturbance will move over the Yucatan peninsula which will further inhibit development.  There may also be a chance for development after the disturbance moves over the southern Gulf of Mexico.  The National Hurricane Center is giving a 20% probability of tropical cyclone formation out of the disturbance.

Patricia Is Strongest East Pacific Hurricane on Record

Hurricane Patricia continued to intensify rapidly during the overnight hours and it is now the strongest hurricane on record for the Eastern North Pacific.  At 11:00 a.m. EDT on Friday the center of Hurricane Patricia was located at latitude 17.6°N and longitude 105.5°W which put it about 125 miles (200 km) southwest of Manzanillo, Mexico.  Patricia was moving toward the north at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 200 m.p.h. (320 km) and there were wind gusts to 245 m.p.h. (400 km/h).  The minimum surface pressure was 880 mb.

A Hurricane Warning is in effect for the portion of the coast between Sas Blas and Punta San Telmo, Mexico.  A Tropical Storm Warning and a Hurricane Watch is in effect for the portion of the coast from Punta San Telmo to Lazaro Cardenas, Mexico.

Hurricane Patricia has broken a number of records.  The maximum sustained wind speed increased from 85 m.p.h. to 200 m.p.h. between 5:00 a.m. EDT on Thursday and 5:00 a.m. EDT on Friday.  The rate of increase of 115 m.p.h. in 24 hours is the fastest rate of intensification observed in the Eastern Pacific. It exceeds the 100 m.p.h. in 24 hours that occurred in Hurricane Linda in 1997.  Interestingly, 1997 was also an El Nino year.  The minimum surface pressure of 880 mb is the lowest ever recorded in the National Hurricane Center’s Area of Responsibility which includes the Atlantic and Eastern North Pacific Oceans.  It is lower than the 882 recorded when Hurricane Wilma was over the Caribbean Sea in 2005.

Hurricane Patricia is an extremely dangerous hurricane.  It has a Hurricane Intensity Index (HII) of 50.0, a Hurricane Size Index (HSI) of 11.3 and a Hurricane Wind Intensity Size Index (HWISI) of 61.3.  Those indices mean that Patricia will be capable of causing catastrophic regional damage when it reaches the west coast of Mexico north of Manzanillo later on Friday.  Hurricane Patricia will be capable of causing catastrophic wind damage, generating a potentially destructive storm surge near the coast and producing heavy rain and flooding as it moves inland.

Category 5 Hurricane Patricia Threatens West Coast of Mexico

Hurricane Patricia continued to intensify very rapidly on Thursday night and it reached Category 5 on the Saffir-Simpson Scale.  At 11:00 p.m. EDT on Thursday the center of Hurricane Patricia was located at latitude 16.2°N and longitude 105.1°W which put it about 200 miles (320 km) south-southwest of Manzanillo, Mexico.  Patricia was moving toward the north-northwest at 10 m.p.h.  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 195 m.p.h. (315 km/h).  The minimum surface pressure was 924 mb.

The government of Mexico has issued a Hurricane Warning for the portion of the coast from San Blas to Punta San Telmo.  A Hurricane Watch and a Tropical Storm Warning is in effect for the portion of the coast from Punta San Telmo to Lazaro Cardenas.

Hurricane Patricia has a Hurricane Intensity Index (HII) of 35.0.  The Hurricane Size Index (HSI) is 12.4 and the Hurricane Wind Intensity Size Index (HWISI) is 47.4.  Those indices mean that Hurricane Patricia is capable of causing catastrophic regional damage.  Hurricane Patricia is currently about the same size that Hurricane Dennis was before Dennis hit the northern coast of the Gulf of Mexico in 2005.  However, Patricia is stronger than Dennis was at that time.

Hurricane Patricia remains in an environment with warm Sea Surface Temperatures and little vertical wind shear.  Only an eyewall replacement cycle could cause weakening in the short term.  When Hurricane Patricia moves farther north, it will start to encounter upper level winds blowing from the southwest, which will increase the wind shear.  The wind shear could start to weaken Patricia later on Friday.

Hurricane Patricia is moving around the western end of ridge and the hurricane has turned toward the north.  When Patricia encounters the southwesterly winds in the upper levels, it will turn toward the northeast.  On its anticipated track Hurricane Patricia could make landfall on the west coast of Mexico between San Blas and Boca de Apiza on Friday night.  Even though Hurricane Patricia could weaken somewhat before it makes landfall, it will still be a very dangerous hurricane.  Hurricane Patricia poses a major threat to cause significant regional wind damage and a storm surge at the coast.  Heavy rain could produce serious flooding, especially as Patricia moves inland over steeper terrain.

Hurricane Patricia Intensifies Rapidly to Category 4

Hurricane Patricia intensified rapidly on Thursday and it reached Category 4 on the Saffir-Simpson Scale.  The maximum sustained wind speed in Patricia increased from 60 m.p.h. to 130 m.p.h. in 24 hours, which qualified as very rapid intensification.  At 5:00 p.m. EDT on Thursday the center of Hurricane Patricia was located at latitude 15.4°N and longitude 104.6°W which put it about 250 miles (400 km) south of Manzanillo, Mexico.  Patricia was moving toward the west-northwest at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 953 mb.  The Hurricane Intensity Index (HII) for Patricia was 25.1, the Hurricane Size Index (HSI) was 10.4 and the Hurricane Wind Intensity Size Index was 35.5.  Those indices mean that Patricia is almost as strong and just a little larger than Hurricane Charley was when it hit southwest Florida in 2004.

The government of Mexico has issued a Hurricane Warning for the portion of the coast from San Blas to Punta San Telmo.  It has also issued a Hurricane Watch and a Tropical Storm Warning for the portion of the coast from Punta San Telmo to Lazaro Cardenas.

Patricia is a small hurricane, but it has a very well organized circulation.  A ring of strong thunderstorms surrounds a small, 12 mile (19km), eye (sometimes called a pinhole eye because of the way it looks on satellite images).  Multiple spiral bands are rotating around the core fo the circulation.  Thunderstorms in the core are generating strong upper level divergence in all directions.

Hurricane Patricia remains in a very favorable environment.  It is over water were the Sea Surface Temperature is near 30°C.  An upper level ridge over the top of Patricia is keeping the vertical wind shear to a minimum.  Patricia could intensify further, although if concentric eyewalls develop, then eyewall replacement cycles could produce fluctuations in wind speeds.

Hurricane Patricia is moving around the western end of a ridge that extends from the Gulf of Mexico over Mexico.  When Patricia reaches the end of ridge on Friday, it will turn toward the north.  As the hurricane moves farther north it will encounter westerly winds in the southern end of an upper level trough.  Those winds will turn Hurricane Patricia toward the northeast.

On its anticipated track Hurricane Patricia could approach the west coast of Mexico late on Friday.  It will pose a serious threat to the coast at that time.  Patricia will bring strong winds, heavy rain and a storm surge to the coast.  Very heavy rain could fall as Hurricane Patricia moves inland and serious flooding will be possible, especially in the more mountainous areas of Mexico.  The remnants of Hurricane Patricia could eventually move over parts of Texas and add moisture and rain to that region.

Tropical Depression Bill Crossing Red River Into Oklahoma

Tropical Depression Bill moved northward across north Texas on Wednesday and brought heavy rain to parts of Texas and Oklahoma.  At 11:00 p.m. EDT on Wednesday the center of Tropical Depression Bill was located at latitude 33.7°N and longitude 97.3°W which put it about 65 miles (105 km) north-northwest of Dallas, Texas.  Bill was moving toward the north at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h).  There were wind gusts to 50 m.p.h. (80 km/h) in some thunderstorms.  The minimum surface pressure was 999 mb.

Bill still has a well organized circulation at the surface and throughout the troposphere.  There is still a warm core in the middle troposphere and divergence in the upper levels.  The upper level divergence pumped out the same amount of mass as converged in the lower levels and the surface pressure remained constant on Wednesday.  Some drier air is wrapping around the southern part of the circulation and most of the rain is falling north and east of the center.  The slow movement of Bill has generated significant amounts of rain and flooding is occurring in some parts of Texas and Oklahoma.  A few thunderstorms have also produced damaging wind gusts.

Bill is expected to turn toward the northeast as is moves around the western end of a high pressure system centered off the southeast coast of the U.S.  It will move slowly across Oklahoma on Thursday and across Arkansas on Friday before moving up the Ohio River Valley during the weekend.