Tag Archives: Tropical Storm Sandra

Tropical Storms Sandra and Terry Develop over East Pacific

Tropical Storms Sandra and Terry developed over the Eastern North Pacific Ocean on Sunday afternoon. At 4:00 p.m. EST on Sunday the center of Tropical Storm Sandra was located at latitude 14.0°N and longitude 115.2°W which put it about 705 miles (1135 km) south-southwest of the southern tip of Baja California. Sandra was moving toward the west-northwest at 10 m.p.h. (16 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 1006 mb.

At 4:00 p.m. EST on Sunday the center of Tropical Storm Terry was located at latitude 8.5°N and longitude 102.6°W which put it about 735 miles (1180 km) south of Manzanillo, Mexico. Terry was moving toward the west at 14 m.p.h. (22 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 1007 mb.

Based on data from a scatterometer on a satellite, the National Hurricane Center upgraded former Tropical Depression Nineteen-E to Tropical Storm Sandra on Sunday afternoon. It appeared from later satellite images that Tropical Storm Sandra might already be weakening. A large upper level trough approaching the west coast of the U.S. was producing strong southerly winds that were blowing across the top of Sandra’s circulation. Those winds were causing moderate vertical wind shear. The strong upper level winds blew the tops off thunderstorms near the center of Sandra. The strongest remaining thunderstorms were occurring in bands east of the center. Bands in other parts of Tropical Storm Sandra consisted primarily of showers and lower clouds. The strongest winds were in the eastern half of Sandra. Winds to tropical storm force extended out 90 miles in the eastern half of Sandra. The winds in the western half of the circulation were blowing at less than tropical storm force.

Tropical Storm Sandra will move through an environment mostly unfavorable for intensification during the next several days. Sandra will move over water where the Sea Surface Temperatures are near 27˚C. However, the large upper level trough will continue to produce strong vertical wind shear. The wind shear is likely to prevent Tropical Storm Sandra from strengthening. The strong shear could blow the top off of Sandra’s circulation and Tropical Storm Sandra is more likely to weaken during the next several days. Sandra will move south of a surface high pressure system over the Eastern North Pacific Ocean. The high pressure system will steer Sandra toward the west. On its anticipated track Tropical Storm Sandra will move farther away from Mexico.

More thunderstorms developed near the center of former Tropical Depression Eighteen-E on Sunday afternoon and the National Hurricane Center upgraded the system to Tropical Storm Terry. The circulation around Tropical Storm Terry exhibited more organization on satellite images. More thunderstorms also formed in bands revolving around the center of Terry. Storms near the center generated upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 60 miles (95 km) on the eastern side of Terry’s circulation. The winds in the western half of Terry were blowing at less than tropical storm force.

Tropical Storm Terry will move through an environment somewhat favorable for intensification during the next 24 hours. Terry will move over water where the Sea Surface Temperatures are near 28˚C. It will move through a region where the upper level wind are weak and there will be little vertical wind shear. Tropical Storm Terry could slowly intensify during the next 24 hours.

Tropical Storm Terry will move around the southern side of a surface high pressure system over the Eastern North Pacific Ocean. The high will steer Terry toward the west during the next few days. On its anticipated track Tropical Storm Terry will move farther away from Mexico.

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.

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.