Tag Archives: Mexico

Strong Shear Weakens Adrian to a Tropical Depression

Strong vertical wind shear weakened Tropical Storm Adrian to a tropical depression on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Tropical Depression Adrian was located at latitude 10.5°N and longitude 93.1°W which put it about 420 miles (675 km) south-southeast of Salina Cruz, Mexico.  Adrian was moving toward the northwest at 5 m.p.h. (7 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 1007 mb.

An upper level ridge east of Adrian generated strong southeasterly winds which produced strong vertical wind shear and literally blew the top off of the tropical storm.  The upper half of the circulation was carried well to the northwest of low level circulation.  The low level circulation consists low clouds and weak showers.  No new thunderstorms have formed in the low level circulation since it decoupled from the upper half of the circulation.

Strong upper level winds are likely to continue to create strong vertical wind shear on Thursday.  Tropical Depression Adrian is likely to remain weak on Thursday.  If the low level circulation persists for several more days, then the upper level winds could weaken.  The Sea Surface Temperature is near 30°C.  So, if there is still a low level circulation, some strengthening could occur when the upper level winds diminish.

Tropical Storm Adrian Develops South of Guatemala

Tropical Storm Adrian developed south of Guatemala on Tuesday.  Adrian became the earliest tropical storm to form over the Eastern North Pacific Ocean during the satellite era.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Adrian was located at latitude 9.5°N and longitude 92.3°W which put it about 360 miles (575 km) southwest of San Salvador, El Salvador.  Adrian was moving toward the west-northwest at 7 m.p.h. (11 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 well defined low level center of circulation developed within a large area of thunderstorms over the Eastern North Pacific Ocean on Tuesday and the National Hurricane Center classified the system as Tropical Storm Adrian.  A primary rainband wrapped about half way around the western side of the center of circulation.  Additional bands of showers and thunderstorms formed farther away from the center.  There were more thunderstorms west of the center, but bands were forming in all quadrants of Tropical Storm Adrian.  The strongest winds were occurring close to the center of circulation, which is the typical structure of a tropical cyclone.  Thunderstorms near the core of Adrian were beginning to generate upper level divergence which was pumping away mass.

Tropical Storm Adrian will be moving through an environment that will be favorable for intensification.  Adrian will move over water where the Sea Surface Temperature will be about 30.5°C.  An upper level ridge east of Adrian is producing southeasterly winds which are blowing toward the top of the circulation.  Those winds are causing some vertical wind shear, but the shear should not be great enough to prevent intensification.  Tropical Storm Adrian is likely to intensify during the next several days and it could become a hurricane later this week.

Adrian is moving around the southwestern part of a subtropical ridge, which is steering the tropical storm toward the west-northwest.  A general west-northwesterly motion is expected to continue for several more days.  When Adrian reaches the western end of the ridge later this week, the tropical storm will turn toward the north and it will move closer toward the coast.

Possible Tropical Development South of El Salvador

A broad area of low pressure has formed over the Eastern North Pacific Ocean south of El Salvador.  The environment is favorable for the development of a tropical cyclone.  The National Hurricane Center (NHC) has designated the low pressure system as Invest 90E.  NHC is indicating that there is a 50% probability of the formation of a tropical depression during the next 48 hours and an 80% probability of formation during the next five days.

At 2:00 p.m. EDT on Monday the center of Invest 90E was located at latitude 7.9°N and longitude 89.5°W which put it about 370 miles (595 km) south of San Salvador, El Salvador.  Invest 90E was stationary.  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 1008 mb.

More thunderstorms formed on Monday around a broad area of low pressure south of El Salvador.  Visible satellite imagery suggested a broad counterclockwise rotation of the area of thunderstorms, but there were no indications of a well developed core of the circulation.  Several smaller centers of rotation were visible within the broad low pressure system, but these may be transient features.  The broad area of thunderstorms was producing upper level divergence.  The divergence is pumping out mass and if that continues, then the surface pressure will decrease.

The area of low pressure is in an environment favorable for tropical development.  It is moving over water where the Sea Surface Temperature is near 30°C.  The low is sitting underneath an upper level ridge and the winds in the upper level are weak.  There is little vertical wind shear and there is nothing to inhibit upper level divergence.  The circulation should continue to organize, which is why the probability of formation of a tropical cyclone is high.

The area of low pressure is in an area where the steering currents are weak and Invest 90E was nearly stationary on Monday.  A high pressure system northeast of the broad area of low pressure system is expected to strengthen.  When that happens, the high is likely to steer the area of low pressure toward the northwest.

Tropical Storm Otto Crosses Into the Eastern North Pacific Ocean

Tropical Storm Otto moved steadily along the border between Nicaragua and Costa Rica and crossed into the eastern North Pacific Ocean on Thursday night.  At 10:00 p.m. EST on Thursday the center of Tropical Storm Otto was located at latitude 10.9°N and longitude 85.6°W which put it about 20 miles (30 km) north of Liberia, Costa Rica.  Otto was moving toward the west at 13 m.p.h. (20 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. (140 km/h).  The minimum surface pressure was 990 mb.

The structure of Tropical Storm Otto remained intact as it crossed from the southwestern Caribbean Sea to the eastern North Pacific Ocean.  Radar images from Nicaragua and infrared satellite images both showed that the eye continued to exist.  A ring of strong thunderstorms still surrounds the eye and those storms are generating upper level divergence.

Tropical Storm Otto will be moving through an environment favorable for intensification.  It will move over water where the Sea Surface Temperature is near 28°C on Friday, and it will move over warmer water during the weekend.  The upper level winds are weak and there is little vertical wind shear.  Tropical Storm Otto is likely to strengthen back into a hurricane once the entire circulation moves over the eastern North Pacific Ocean and a period of rapid intensification is possible.

A ridge north of Otto is steering the tropical storm toward the west and that general motion is expected to continue for several more days.  On its anticipated track Tropical Storm Otto is expected to move steadily away from the west coast of Nicaragua and Costa Rica.

Tropical Storm Tina Forms West of Manzanillo

More thunderstorms formed near the center of a low pressure system west of Mexico on Sunday and the National Hurricane Center classified the system as Tropical Storm Tina.  At 10:00 p.m. EDT on Sunday the center of Tropical Storm Tina was located at latitude 18.5°N and longitude 107.1°W which put it about 185 miles (300 km) west of Manzanillo, Mexico.  Tina was moving toward the north at 3 m.p.h. (5 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.

The circulation of Tropical Storm Tina is not well organized.  Although there is a definite center of circulation in the lower levels, most of the thunderstorms are developing north and east of the center of circulation.  An upper level trough southwest of California is generating southwesterly winds which are blowing across the top of Tropical Storm Tina.  The strong vertical wind shear is tilting the circulation and it is causing the thunderstorms to be concentrated in the northeastern quadrant of the circulation.  The upper level winds are also inhibiting upper level divergence.

Although Tropical Storm Tina is moving over water where the Sea Surface Temperature is near 30°C, the atmospheric environment is unfavorable for intensification.  The strong vertical wind shear will prevent any significant intensification.  In fact, if the upper level winds get much stronger, the shear could blow the top half of the circulation northeast of the bottom half.  In that case the low level circulation will quickly spin down and dissipate.

If the vertical integrity of the circulation is maintained, then the upper level trough will steer Tropical Storm Tina toward the northeast and into Mexico.  However, if the circulation shears apart, a surface high pressure system could steer it slowly toward the west.  In either case the upper level winds could transport some moist air over Jalisco and Colima, where it could enhance rainfall.

Seymour Strengthens Into a Cat. 4 Hurricane

Hurricane Seymour strengthened into a small but very powerful Category 4 hurricane on the Saffir-Simpson Scale on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Hurricane Seymour was located at latitude 16.1°N and longitude 117.7°W which put it about 690 miles (1110 km) southwest of the southern tip of Baja California.   Seymour was moving toward the west-northwest at 15 m.p.h.  The maximum sustained wind speed was 150 m.p.h. (240 km/h) and there were wind gusts to 175 m.p.h. (280 km/h).  The minimum surface pressure was 943 mb.

The circulation of Hurricane Seymour is very small, but it is very well organized.  There is a circular eye with a diameter of 10 miles (12 km) which is surrounded by a ring of strong thunderstorms.  Winds to hurricane force only extend out about 18 miles (29 km) from the center of circulation.  Winds to tropical storm force extend out about 80 miles (130 km) from the center.  The Hurricane Intensity Index (HII) is 31.6, but the Hurricane Size Index (HSI) is only 7.1.  The Hurricane Wind Intensity Size Index is 38.7.  Hurricane Seymour is not as strong as Hurricane Patricia was in 2015 and Seymour is smaller than Patricia was.  When Hurricane Patricia had maximum sustained winds of 200 m.p.h. (320 km) its HSI ranged between 11.3 and 13.8.

Hurricane Seymour will remain in a very favorable environment for another 6 to 12 hours.  It will move over water where the Sea Surface Temperature (SST) is near 28°C.  The upper level winds will be light and there will be little vertical wind shear.  Later on Wednesday the upper level winds will increase and Hurricane Seymour will begin to move over cooler SSTs.  The increasingly unfavorable environment will cause Seymour to weaken.  Because of the small size of Seymour’s circulation, wind shear could cause the hurricane to weaken quickly.

Hurricane Seymour is moving around the western end of a ridge that is steering the hurricane toward the west-northwest.  When Seymour reaches the western end of the ridge, the hurricane will begin to move more toward the north.  On its anticipated track Hurricane Seymour will weaken well to the west of Baja California.  An upper level trough moving over the Northern Pacific Ocean could eventually transport some of the moisture from Hurricane Seymour over the western U.S.

Seymour Rapidly Intensifies into a Cat. 2 Hurricane

Tropical Storm Seymour rapidly intensified into a Category 2 hurricane on the Saffir-Simpson Scale on Monday as it moved farther away from Mexico.  At 11:00 p.m. EDT on Monday the center of Hurricane Seymour was located at latitude 15.5°N and longitude 112.6°W which put it about 540 miles (870 km) south-southwest of the southern tip of Baja California.  Seymour was moving toward the west at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 976 mb.

Hurricane Seymour intensified very rapidly on Monday.  The maximum sustained wind speed increased from 50 m.p.h. (80 km/h) to 105 m.p.h. (165 km/h) in a 24 hour period.  The circulation contracted and the primary rainband wrapped tightly around a small eye.  Seymour is a very small hurricane and hurricane force winds only extend out about 12 miles (19 km) from the center of circulation.  Winds to tropical storm force only extend out about 70 miles (130 km) from the center.  Although Seymour is a small hurricane, the circulation is well organized.  The small eye is surrounded by an almost continuous ring of thunderstorms.  Several other spiral bands are rotating around the core of Hurricane Seymour.  Thunderstorms in the core are generating upper level divergence which is pumping out mass in all directions.

Hurricane Seymour will remain in a favorable environment on Tuesday.  It is moving over water where the Sea Surface Temperature is near 30°C.  The upper level winds are light and there is little vertical wind shear.  Hurricane Seymour is likely to intensify on Tuesday and it could become a major hurricane.  When Seymour moves farther to the west, it will be nearer to an upper level trough which will produce southwesterly winds over the hurricane.  Increased vertical wind shear will begin to weaken Hurricane Seymour.

A ridge over Mexico is steering Hurricane Seymour toward the west and that general motion will occur for another 24 to 36 hours.  Hurricane Seymour will approach the western end of the ridge on Wednesday, and the hurricane will turn more toward the north when that happens.  On its anticipated track this turn will occur well to the west of Baja California.

Tropical Storm Seymour Develops Quickly West of Mexico

Tropical Storm Seymour developed quickly west of Mexico on Sunday and it brought to an end a stretch of three quiet weeks over the Eastern North Pacific Ocean.  At 11:00 p.m. EDT on Sunday the center of Tropical Storm Seymour was located at latitude 14.4°N and longitude 107.1°W which put it about 370 miles (590 km) south-southwest of Manzanillo, Mexico.  Seymour 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 1002 mb.

The circulation in a cluster of thunderstorms organized quickly on Sunday afternoon.  A primary rainband around the northern and western sides of the circulation wrapped almost entirely around the center and an eye appeared to be forming on microwave satellite images.  Additional bands of thunderstorms were developing.  Thunderstorms in the core of Seymour were beginning to generate upper level divergence.

Tropical Storm Seymour will be moving through a very favorable environment.  It is moving over water where the Sea Surface Temperature is near 31°C.  The upper level winds are relatively weak and there is little vertical wind shear.  Tropical Storm Seymour will continue to intensify and it could intensify rapidly.  Seymour will become a hurricane and it could become a major hurricane.

A ridge over Mexico is steering Tropical Storm Seymour toward the west-northwest and that general motion is expected to continue for several more days.  When Seymour reaches the western end of the ridge, it will turn toward the north.  On its anticipated track Tropical Storm Seymour will make the northward turn well to the southwest of Baja California.

Hurricane Paine Prompts Warnings for Part of Baja California

Tropical Storm Paine intensified into a hurricane on Monday and the government of Mexico issued a Tropical Storm Warning for a portion of the west coast of Baja California.  At 8:00 p.m. EDT on Monday the center of Hurricane Paine was located at latitude 23.4°N and longitude 116.5°W which put it about 315 miles (510 km) south-southwest of Punta Eugenia, Mexico.  Paine was moving toward the northwest at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 105 m.p.h. (170 km/h).  The minimum surface pressure was 979 mb.

There is a Tropical Storm Warning in effect for the portion of the coast from Punta Eugenia to Cabo San Quintin.

The circulation of Hurricane Paine is showing signs of weakening.  It had a well formed eye surrounded by a ring of strong thunderstorms a few hours ago.  The eye is no longer apparent on infrared satellite imagery.  There are still thunderstorms near the center of circulation.  The circulation appears to be pulling cooler, drier and more stable air around the southwestern quadrant of Hurricane Paine.  More thunderstorms are occurring in rainbands in the northwestern quadrant of the circulation.  There are few thunderstorms in the rainbands in the eastern half of Hurricane Paine.

Hurricane Paine will be moving into an environment that will be very unfavorable for a tropical cyclone.  The center is currently moving over water where the Sea Surface Temperature (SST) is near 24°C.  It will move over water where the SST will be less than 22°C on Tuesday.  Less energy in the upper ocean and cooler, more stable air will cause the circulation to weaken and it could weaken quickly.  An upper level low southwest of California will generate some vertical wind shear which could separate the upper part of Hurricane Paine from the lower level circulation as Paine weakens.

Hurricane Paine is moving around the western end of a subtropical ridge over Mexico which is steering Paine toward the north.  On its anticipated track the center of Paine will pass west of Punta Eugenia on Tuesday.  The center or the upper part of the circulation could be near Cabo San Quintin on Wednesday morning.  It is expected to weaken to a tropical depression or a remnant low before it reaches Cabo San Quintin.  However, Paine could bring tropical storm force winds to a portion of the coast, which is why the Tropical Storm Warning was issued.

Tropical Storm Paine Intensifying Quickly Southwest of Baja California

The Eastern North Pacific Ocean continues to spin out tropical cyclones.  Tropical Storm Paine intensified quickly on Sunday as it moved southwest of Baja California.  In 24 hours Paine intensified from a tropical depression to near hurricane strength.  At 11:00 p.m. EDT on Sunday the center of Tropical Storm Paine was located at latitude 19.5°N and longitude 113.8°W which put it about 345 miles (555 km/h) southwest of the southern tip of Baja California.  Paine was moving toward the northwest at 15 m.p.h. (24 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 992 mb.

Tropical Storm Paine moved through a very favorable environment on Sunday.  The Sea Surface Temperature (SST) was near 28°C.  The upper level winds were light and there was little vertical wind shear.  The favorable environmental conditions allowed a tight inner core to develop rapidly at the center of Tropical Storm Paine.  Infrared and microwave satellite imagery suggest that an eye could be forming at the center of Paine.  A nearly complete ring of strong thunderstorms surrounds the developing eye.  A primary rainband exists in the eastern part of the circulation.  Thunderstorms at the core of Tropical Storm Paine are generating upper level divergence which is pumping out mass in all directions.

Tropical Storm Paine will be in a favorable environment for another 12 to 18 hours.  It is likely to intensify into a hurricane on Monday.  After that time Paine will start to move over cooler SSTs and it should start to weaken.  The air over the cooler SSTs is also drier and more stable and Paine could weaken quickly on Tuesday.

Tropical Storm Paine is moving around the western end of a ridge over Mexico which is steering it toward the northwest.  When Paine reaches the western end of the ridge axis, it will move more toward the north.  On its anticipated track Tropical Storm Paine will pass to the west of the southern end of Baja California during the next several days.