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Lorena (Eastern Pacific)
September 6, 2013

NASA Sees Tropical Storm Lorena Bringing Heavy Rains to Mexico's West Coast  [image-78]

NASA's Tropical Rainfall Measuring Mission satellite known as TRMM passed over Tropical Storm Lorena from its orbit in space on Friday, Sept. 6 and measured the rate in which rain is falling from the storm. Lorena was soaking some areas of Mexico's west coast and is headed for landfall in Baja California, Mexico.

On Friday, Sept. 6, a tropical storm warning was in effect for Baja California Sur from Agua Blanca to Buenavista, and a tropical storm watch was in effect for Baja California Sur North of Agua Blanca to Santa Fe.

Tropical Depression 12E intensified into Tropical Storm Lorena at 5 p.m. EDT on Thursday, Sept. 5 when it was about 150 miles/245 km west of Manzanillo, Mexico.[image-94]

By early Sept. 6, although Lorena's center was south of the southern tip of Baja California, its eastern quadrant was dropping heavy rainfall along the coast when NASA's TRMM Satellite passed overhead at 08:24 UTC/4:24 a.m. EDT. TRMM saw heaviest rain falling at a rate of 2 inches/50 mm per hour near Culiacan along Mexico's west coast and over open waters just south of Cabo San Lucas on the Baja peninsula. TRMM data also showed that some of the thunderstorms around Lorena's center were over 9.3 miles/15 km high, indicating high, powerful thunderstorms.

Lorena's heavy rains are expected to total between 3 and 6 inches/76 to 152 mm over the southern portion of the Baja California Peninsula with isolated maximum amounts of 10 inches/254 mm possible. The National Hurricane Center or NHC warns that these rains could produce life-threatening flash floods and mud slides. NHC noted that tropical storm force winds are expected to begin in the warning area later this morning and could continue through Saturday, Sept. 7 and tropical storm force winds are possible in the watch area that day as well.

On Sept. 6 at 8 a.m. EDT/1200 UTC, Lorena's maximum sustained winds were near 40 mph/65 kph. The NHC noted that the center of Tropical Storm Lorena was located by radar from Cabo San Lucas near latitude 21.9 north and longitude 108.9 west, just 95 miles/155 km southeast of that city. Lorena is moving toward the northwest near 14 mph/22 kph and is expected to continue toward in that direction over the next couple of days.  

This weekend (Sept. 7 and 8), Lorena's center is expected to make a brief landfall near Cabo San Lucas at the southern tip of Baja California, Mexico, then briefly move over the Eastern Pacific. Lorena is expected to make a second landfall southeast of Cuidad Constitucion and move north over the Baja in the next two days while weakening.

Text credit:  Rob Gutro
NASA's Goddard Space Flight Center


Sept. 5, 2013 - NASA Sees "Hot Towers" in Newborn Tropical Depression 12E Hinting at Intensification  [image-51]

Tropical Depression 12E formed off the southwestern coast of Mexico at 5 a.m. EDT on Sept. 5. Just 40 minutes before, NASA's TRMM satellite passed overhead and saw some "hot towers" around the center, indicating that the low pressure area that was previously known as System 99E would strengthen.

A "hot tower" is a tall cumulonimbus cloud that reaches at least to the top of the troposphere, the lowest layer of the atmosphere. It extends approximately nine miles (14.5 km) high in the tropics. The hot towers in Tropical Depression 12E were reaching heights of 15 km/9.3 miles high around the depression's center.  These towers are called "hot" because they rise to such altitude due to the large amount of latent heat. Water vapor releases this latent heat as it condenses into liquid. NASA research shows that a tropical cyclone with a hot tower in its eye wall was twice as likely to intensify within six or more hours, than a cyclone that lacked a hot tower. Those hot towers also drop heavy rainfall.

On Thursday, Sept. 5 (today) at 4:20 a.m. EDT, NASA's TRMM satellite saw moderate rainfall in newborn Tropical Depression 12E off the southwestern coast of Mexico. Some of that rainfall extended over coastal areas. The National Hurricane Center expects locally heavy rainfall along the southwestern coast of Mexico today.

At 5 a.m. EDT/0900 UTC, Tropical Depression 12E had maximum sustained winds near 35 mph/55 kph. The National Hurricane Center expects the depression to strengthen further into a tropical storm later on Sept. 5. The center of 12E was located near latitude 17.6 north and longitude 106.1 west, about 155 miles/245 km southwest of Manzanillo, Mexico. The depression is moving toward the northwest near 6 mph/9 kph is expected to continue in that direction over the next couple of days.  

Text credit:  Rob Gutro
NASA's Goddard Space Flight Center

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TRMM image of 12E
On Thursday, Sept. 5 at 4:20 a.m. EDT, NASA's TRMM satellite saw moderate rainfall in newborn Tropical Depression 12E off the southwestern coast of Mexico. Some thunderstorms around the center top 15 km/9.3 miles high, indicating strengthening was likely.
Image Credit: 
SSAI/NASA, Hal Pierce
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[image-51]
TRMM image of Lorena
NASA's TRMM Satellite passed over Tropical Storm Lorena at 4:24 a.m. EDT and saw heaviest rain (red) falling at a rate of 2 inches/50 mm per hour near Culiacan along Mexico's west coast and over open waters just south of Cabo San Lucas on the Baja peninsula.
Image Credit: 
NASA/SSAI, Hal Pierce
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[image-78]
Youtube Override: 
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NASA's TRMM satellite flew over Tropical Storm Lorena on Sept. 6 at 4:24 p.m. EDT and noticed it did not contain large areas of precipitation. One thunderstorm complex on the northern side was dropping rain at a rate of over ~3.7 inches/hr where cloud tops reached heights above ~9.3 miles.
Image Credit: 
NASA/SSAI, Hal Pierce
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[image-94]
Page Last Updated: September 6th, 2013
Page Editor: Lynn Jenner