Tropical Storm Polo is riding along the coast of western Mexico like horses in the game of his namesake. NASA's Aqua satellite saw Polo about 300 miles south-southeast of Baja California on its track north.
NASA's Aqua satellite flew over Polo on Sept. 18 at 4:35 p.m. EDT and the Moderate Resolution Imaging Spectroradiometer captured a visible image of the storm that showed that much of the clouds, thunderstorms and showers were west and south of the center of circulation, and away from the coast. That's an indication that easterly wind shear had increased and were pushing the clouds away from the center. The National Hurricane Center confirmed the wind shear in a discussion on Sept. 19: Polo is showing a sheared cloud pattern this morning, with the low-level center located near the northern or northeastern edge of the (clouds /thunderstorms) convection. This is consistent with analyses of 20 to 25 knots of easterly vertical wind shear impacting the cyclone.
On Sept. 19, a tropical storm watch is in effect for the southern Baja California Peninsula from Santa Fe to La Paz.
At 8 a.m. EDT, maximum sustained winds remained near 70 mph (110 kph) and slow weakening is expected during the next two days. Polo's center was located near latitude 19.3 north and longitude 107.6 west. Polo is moving toward the northwest near 8 mph (13 kph) and a turn toward the west-northwest is expected on Saturday, Sept. 20
NHC forecasters noted that on the forecast track Polo's center will pass south of the Baja California peninsula on Saturday. However, any deviation to the north of the track could bring stronger winds to southern Baja California.
NASA's Goddard Space Flight Center