Tropical Storm Narda formed south of Mexico late on Saturday. At 11:00 p.m. EDT on Saturday the center of Tropical Storm Narda was located at latitude 15.4°N and longitude 100.6°W which put it about 115 miles south-southwest of Acapulco, Mexico. Narda was moving toward the northwest at 9 m.p.h. (15 km/h). The maximum sustained wind speed was 40 m.p.h. (15 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1000 mb.
A Tropical Storm Warning was in effect for the portion of the coast from Acapulco to Cabo Corrientes, Mexico.
An area of low pressure exhibited more organization late on Saturday and the National Hurricane Center designated the system as Tropical Storm Narda. A low level center of circulation formed within the area of low pressure. Bands of showers and thunderstorms developed and began to revolve around the center of circulation. Many of the stronger thunderstorms were in bands in the western half of the circulation. Bands in the eastern half of the circulation contained more showers and lower clouds. An area of winds to tropical storm force was occurring about 120 miles (195 km) southeast of the center of circulation.
Tropical Storm Narda will move through an environment only marginally favorable for intensification on Sunday. Narda will move over water where the Sea Surface Temperature is near 29°C. However, an upper level ridge over Mexico will produce northeasterly winds which will blow toward the top of the circulation. Those winds will cause moderate vertical wind shear which will inhibit intensification. In addition, the circulation could draw drier air into the northern portion of the tropical storm. Tropical Storm Narda is not likely to strengthen much during the next 12 to 24 hours.
The ridge over Mexico will steer Tropical Storm Narda toward the northwest during the next several days. On its anticipated track Tropical Storm Narda will approach the coast of Mexico near Lazaro Cardenas in about 12 hours. Narda will move along the coast toward Cabo Corrientes. Tropical Storm Narda could drop locally heavy rain in parts of Guerrero, Michoacan, Colima and Jalisco. The rain could cause flash floods in some locations.
Potential impacts of Tropical Storm Xavier caused the government of Mexico to issue a Tropical Storm Warning for a portion of the coast. The Tropical Storm Warning was in effect from Punta San Telmo to Playa Perula, Mexico. At 1:00 p.m. EST the center of Tropical Storm Xavier was located at latitude 17.8°N and longitude 105.4°W which put it about 110 miles (175 km) southwest of Manzanillo, Mexico. Xavier was moving toward the north at 6 m.p.h. (10 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 1003 mb.
An upper level trough is producing strong southwesterly winds which are blowing toward the top of Tropical Storm Xavier. Those winds are causing significant vertical wind shear and they blew the upper portion of Xavier northeast of the lower level circulation earlier on Sunday morning. However, new thunderstorms formed around the center of circulation and in a rainband northeast of the center. There are several bands of showers and thunderstorms west of the center of circulation. The bands southeast of the center consist primarily of low clouds and showers. The strongest winds are occurring in the northeast portion of Tropical Storm Xavier. Winds to tropical storm force extend out about 80 miles (130 km) from the center of circulation. Winds are blowing to tropical storm force near the coast of Mexico which is why the Tropical Storm Warning was issued.
The future intensity of Tropical Storm Xavier will be determined by the strength of the upper level winds. Xavier will move over water where the Sea Surface Temperature is near 28°C. So, there is plenty of energy in the upper ocean to support a tropical storm. However, the upper level winds were almost strong enough to shear Xavier apart on Sunday morning. If the upper level winds do not get any stronger, then Xavier could persist as a tropical storm for another day or two. If the upper level winds do get stronger, which is the forecast of many numerical models, then Xavier will quickly weaken to a tropical depression. The official forecast from the National Hurricane Center follows the second scenario and it weakens Xavier to a tropical depression by Monday night.
The upper level trough will also determine future track of Tropical Storm Xavier. If the upper level winds allow Xavier to persist as a tropical storm, then the trough will steer Xavier north-northeast toward the coast of Mexico. If the upper level winds blow the top of the circulation away from the lower level circulation, then the winds closer to the surface would turn the lower part of Xavier back toward the west. The official forecast from the National Hurricane Center follows the second scenario.
Bands of showers and thunderstorms in the northeaster part of Tropical Storm Xavier are already dropping rain over the coastal regions of Colima and Jalisco. Prolonged heavy rain could cause flash floods in some locations. Winds could reach tropical storm force along the coast even if the center of Tropical Storm Xavier does not make landfall. There could also be a minor storm surge where the wind blows water toward the coast.
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.