Infrared satellite imagery from NASA's Aqua satellite showed only a swirl of low-level clouds some deep clouds around Polo's weakening center on Sept. 22 as the storm weakened to a depression.
The Atmospheric Infrared Sounder or AIRS instrument aboard Aqua gathered infrared data on Polo on Sept. 22 at 5:11 a.m. EDT, reading cloud top temperatures. There was a small area of high clouds, indicating that most thunderstorms in the depression had weakened or already dissipated except for that area.
At 5 a.m. EDT on Monday, Sept. 22, Tropical Depression Polo's maximum sustained winds have decreased to near 35 mph (55 kph) and additional weakening is forecast during two days. In fact, the National Hurricane Center expects Polo to become a remnant later in the day.
Polo was centered near latitude 22.5 north and longitude 113.8 west, about 250 miles (40 km) west of the southern tip of Baja California. It was moving toward the west near 8 mph (13 kph) and is expected to turn to the southwest by Sept. 23. Swells generated by polo affecting the southern Baja California peninsula are expected to subside late on Sept. 22.
The National Hurricane Center discussion noted during the morning of Sept. 22 at 5 a.m. EDT that Polo had been devoid of significant deep convection for 10 hours and that the satellite imagery showed the cyclone consisted of "a tight swirl of low-level clouds with a few deeper clouds located over 100 nautical miles west of the center near the mid-level remnants."
Polo will likely be declared a remnant low late on Sept. 22 and dissipate by Sept. 26.
Explore further: NASA sees Tropical Storm playing polo with western Mexico