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Polo (Eastern Pacific)
September 22, 2014

[image-112]NASA Sees Tropical Depression Polo Winding Down

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. 

Rob Gutro
NASA's Goddard Space Flight Center


[image-96]Sept. 19, 2014 - NASA Sees Tropical Storm Playing Polo with Western Mexico

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.

Rob Gutro
NASA's Goddard Space Flight Center


[image-80]NASA Marks Polo for a Hurricane

Hurricane Polo still appears rounded in imagery from NOAA's GOES-West satellite, but forecasters at the National Hurricane Center expect that to change.

NOAA's GOES-West satellite captured data on Hurricane Polo on Sept. 18 at 10:15 a.m. EDT. An image using that data was created by the NASA/NOAA GOES Project at NASA's Goddard Space Flight Center in Greenbelt, Maryland. The image showed thunderstorms wrapping tightly around the center of the storm while one broken band of thunderstorms extended to the northwest, while the other appeared on the eastern side of the center and paralleled the southern Mexican coastline.

Polo presents a threat to the coast of southwestern Mexico's coastline. A Tropical Storm Warning is in effect for Punta San Telmo to Playa Perula and a Tropical Storm Watch is in effect for west of Playa Perula to Cabo Corrientes.

Forecasters from the National Hurricane Center (NHC) examining satellite imagery today, Sept. 18 noted that "there is a small central dense overcast surrounded by a cyclonically curved convective band (a band of thunderstorms). Polo has the opportunity to strengthen before the northeasterly wind shear increases in 24 hours before it is expected to gradual weaken.

At 11 a.m. EDT on Sept. 18, the center of Hurricane Polo was located near latitude 17.3 north and longitude 105.7 west.  That's about 150 miles (240 km) southwest of Manzanillo, Mexico. Maximum sustained winds were near 75 mph (120 kph) and some slight strengthening is possible in the next day, according to the NHC. Polo is moving toward the northwest near 8 mph (13 kph) and is expected to continue in that direction for the next couple of days.

NHC noted that Polo will move parallel to the southwestern coast of Mexico, although any deviation from the forecast track could mean stronger winds to the coast. After Sept. 19, Polo is expected to weaken.

Rob Gutro
NASA's Goddard Space Flight Center


[image-64]Sept. 17, 2014 - NASA Sees Tropical Storm Polo Intensifying

Tropical storm warnings now issued for a portion of the Southwestern coast of Mexico as Polo continues to strengthen. Infrared imagery from NASA's Aqua satellite showed powerful thunderstorms around the center of the storm.

A Tropical Storm Warning is in force for the southwest coast of Mexico from Punta San Telmo to Playa Perula.  A Tropical Storm Watch is in force from Punta San Telmo to Zihuatanejo and from Playa Perula to Cabo Corrientes. Rainfall totals of 5 to 10, locally up to 15 inches, can be expected over coastal areas of Michoacan, Colima and Jalisco states in Mexico. Life-threatening flash-floods and mudslides could result.  Dangerous ocean swells from the tropical storm are expected to affect the coast of southern Mexico also causing rip-tides. 

NASA's Aqua satellite passed over Polo on Sept. 17 at 4:59 a.m. EDT and the Atmospheric Infrared Sounder instrument captured infrared data on the storm revealing bands of strong thunderstorms north and south of the center.

At 11 a.m. EDT on Sept. 17, Polo's maximum sustained winds increased to near 60 mph (95 kph) and the storm is expected to become a hurricane tonight or early Thursday. The center of Tropical Storm Polo was located near latitude 15.7 north.  and longitude 102.4 west. Polo is moving toward the northwest near 10 mph (17 kph) and this motion is expected to continue for the next two days. The National Hurricane Center noted that on the forecast track the core of Polo will remain offshore of and move parallel to the southwestern coast of Mexico. However, any deviation could bring stronger winds to the coast.  

Polo is forecast to become a hurricane in a day or two.

Rob Gutro
NASA's Goddard Space Flight Center


[image-49]Sept. 16, 2014 - Newborn Tropical Storm Polo Gives a NASA Satellite a "Cold Reception"

The AIRS instrument aboard NASA's Aqua satellite uses infrared light to read cloud top temperatures in tropical cyclones. When Aqua passed over newborn Tropical Storm Polo off of Mexico's southwestern coast it got a "cold reception" when infrared data saw some very cold cloud top temperatures and strong storms within that hint at intensification. 

Polo formed close enough to land to trigger a Tropical Storm Watch for the southwestern coast of Mexico. The watch was issued by the government of Mexico on September 16 and extends from Zihuatanejo to Cabo Corrientes, Mexico.  A tropical storm watch means that tropical storm conditions are possible within the watch area, in this case within 24 hours.

The Atmospheric Infrared Sounder or AIRS instrument aboard NASA's Aqua satellite captured infrared data just after Tropical Storm Polo was named by the National Hurricane Center on September 16. The AIRS data showed cold cloud tops of strong thunderstorms circled around the center of the storm's circulation. Those storms had cloud top temperatures near -63F/-53C indicating they were high into the troposphere and had the potential to generate heavy rain.

At 8:00 a.m. PDT (11 a.m. EDT) the center of Tropical Storm Polo was located near latitude 12.8 north and longitude 99.4 west. That's about 285 miles (460 km) south of Acapulco, Mexico. Maximum sustained winds are near 40 mph (65 kph) and the National Hurricane Center noted that strengthening is possible during the next 24 hours and Polo could become a hurricane by Thursday, September 18.

Polo is moving toward the northwest near 12 mph (19 kph) and is expected to continue over the next two days, paralleling the coast of southwestern Mexico.

Rob Gutro
NASA's Goddard Space Flight Center

AIRS image of Polo
This infrared image of newborn Tropical Strom Polo was taken by the AIRS instrument aboard NASA's Aqua satellite on Sept. 16 at 4:11 a.m. EDT and shows cold, strong thunderstorms around the center (purple).
Image Credit: 
NASA JPL/Ed Olsen
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AIRS image of Polo
NASA's Aqua satellite passed over Polo on Sept. 17 at 4:59 a.m. EDT and the Atmospheric Infrared Sounder instrument captured infrared data on the storm revealing bands of strong thunderstorms north and south of the center.
Image Credit: 
NASA JPL, Ed Olsen
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GOES image of Polo
On Sept. 18 at 10:15 a.m. EDT NOAA's GOES-West satellite saw thunderstorms wrapping tightly around Polo's center and broken bandd of thunderstorms extended to the northwest and east of center.
Image Credit: 
NASA/NOAA GOES Project
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MODIS image of Polo
NASA's Aqua satellite flew over Polo on Sept. 18 at 4:35 p.m. EDT that showed much of the clouds were west and south of the center of circulation, and away from the coast.
Image Credit: 
NASA Goddard MODIS Rapid Response Team
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AIRS Image of Polo
NASA's Aqua satellite 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 (blue), indicating that most thunderstorms had weakened or already dissipated except for that area.
Image Credit: 
NASA JPL, Ed Olsen
Image Token: 
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Page Last Updated: September 22nd, 2014
Page Editor: Lynn Jenner