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Tropical Storm Keila brought strong winds and heavy rains to the Arabian Peninsula this week. Times of Oman described flooded roads, parked vehicles swept away by water, and emergency evacuations of hospitals.
Oman lies between latitudes 16° and 28° N., and longitudes 52° and 60° E. A vast gravel desert plain covers most of central Oman, with mountain rages along the north (Al Hajar Mountains) and southeast coast, where the country's main cities are located: Muscat, Sohar, and Sur. Normal annual rainfall in Muscat averages 3.9 inches (99 mm), most of which normally falls in January.
On November 3, OneOman reported 14 deaths and at least 200 injuries from the storm.
The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-color image on November 1. The center of the storm hovers just off the coastlines of Yemen and Oman, and storm clouds stretch hundreds of kilometers inland.
Observations by another NASA satellite, the Tropical Rainfall Measuring Mission (TRMM) indicated heavy rainfall resulting from Tropical Storm Keila. On November 3, the TRMM team reported that thunderstorms spawned by Keila produced about 5 centimeters (2 inches) of rain per hour off the coast of Oman.
Other news stories on the unusual storm - OneOman. (2011, November 3). Oman storm death toll rises to 14. Accessed November 4, 2011.
- Rejimon, K. (2011, November 3). It rains chaos. Times of Oman. Accessed November 4, 2011.
- Tropical Rainfall Measuring Mission. (2011, November 3). Top Story: TRMM sees weakening Tropical Storm Keila.Accessed November 4, 2011.
- Unisys Weather. (2011, November 2). Tropical Storm Keila. Accessed November 4, 2011.
SUB TROPICAL STORM SEAN
8,000 miles (12,800 km) away Subtropical Storm Sean formed east of Florida (below). The storm will bring squally weather to Bermuda later in the week but stay out to sea. Read more about Sub Tropical Storm Sean at the National Hurricane Center
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An unusual hybrid low pressure system has formed in the Mediterranean Sea, about 100 miles (161 km) south of the coast of France. The low began as an extratropical storm named "Rolf," but has stalled out over the relatively warm waters of the Mediterranean over the past two days, and has acquired tropical characteristics. Heavy thunderstorms have built over the northeast portion of the low, and the storm has a symmetric spiral shape with a cloud-free center, like a tropical storm. The Navy is calling this system Invest 99L.
The National Hurricane Center is not responsible for the Mediterranean Sea, so they are not issuing any products for 99L. NOAA's Satellite and Information Service (NESDIS) is giving 99L a tropical classification based on its satellite presentation, with winds in the 40 - 45 mph range.
French radar shows heavy rains from 99L are beginning to affect Southeast France and the island of Corsica. The Lion Buoy, located about 100 miles to the west of the center of 99L, recorded sustained winds of tropical storm force, 40 mph, at 00 UTC yesterday. Water temperatures at the buoy were 17°C (63°F), far below the 26°C threshold usually needed to sustain a tropical storm.
The coldest waters to spawn a tropical storm form were 22° C during Hurricane Epsilon of 2005. It is unlikely that NHC would name this system if they did have responsibility for the Mediterranean, due to the cold water temperatures.
Rolf is expected to move slowly northwards into the coast of South France by Wednesday night. Meteo France is predicting
heavy rains of 30 - 40 mm/hr (1.2 - 1.6"/hr) will affect the coast Tuesday night through Wednesday, with sustained winds of 50 mph, gusting to 75 mph.
Global Warming and Mediterranean Tropical Storms
Above: Hybrid subtropical storm of October 8, 1996, off the coast of Italy. According to Reale and Atlas (2001), the storm had characteristics similar to a hurricane, but formed over water of 21.5°C. "The maximum damage due to wind occurred over the Aeolian Islands, at 38.5°N, 15°E, to the northeast of Sicily: assistance for disaster relief was required." Unfortunately, no weather station data were available, but the media reported sheds, roofs and harbor devices destroyed, and houses and electric lines damaged, due to "extremely strong westerly wind."
"The perfect agreement between the observations at Ustica, the storm scale, the eye-like feature position and the damages over the Aeolian Island reasonably suggest that the hurricane-level intensity of 32 m/s (72 mph) was reached over the Aeolian Islands."
A similar hybrid low affected Algeria on 9 - 10 November 2001. This storm produced upwards of 270 mm (10.6") of rain, winds of 33 m/s (74 mph), and killed 737 people near Algeirs, mostly from flooding and mud slides.
According to research published by Gaertner et al. (2007), an increase in ocean temperatures of 3°C in the Mediterranean by the end of the century could lead to hurricanes forming there. Miguel Angel Gaertner of the University of Castilla-La Mancha in Toledo, Spain, ran 9 different climate models with resolutions of about 50 km and found that some (but not all) of the models simulated hurricanes in the Mediterranean in September by the end of the century, when ocean temperature could reach 30°C.
Mediterranean Tropical Storms Unlikely
Though the Mediterranean may start seeing hurricanes by the end of the century, these storms should be rare and relatively short-lived for three reasons:
1) The Mediterranean is quite far north and is subject to strong wind shear from jet stream activity.
2) The waters are shallow, and have relatively low heat content. There is no deep warm water current like the Gulf Stream.
3) The Mediterranean has a lot of large islands and peninsulas poking into it, increasing the chances that a tropical storm would weaken when it encountered land.
Read more about the rare French Tropical Storm Rolf
LaProvence.com (news Marseillle): Intempéries : la pluie retombe sur le Var, toujours en alerte orange. Marseille is the largest city in France likely to be affected by Rolf.
Meteo France has an interesting animation of the predicted winds and temperatures over the next few days.
Gaertner, M. A., D. Jacob, V. Gil, M. Dominguez, E. Padorno, E. Sanchez, and M. Castro (2007), Tropical cyclones over the Mediterranean Sea in climate change simulations, Geophys. Res. Lett., 34, L14711, doi:10.1029/2007GL029977.
Reale, O., and R. Atlas. 2001: Tropical Cyclone-Like Vortices in the Extratropics: Observational Evidence and Synoptic Analysis, Weather and Forecasting, 16, No. 1, pp. 7-34.
Meteo France has an interesting animation of the predicted winds and temperatures over the next few days.
Gaertner, M. A., D. Jacob, V. Gil, M. Dominguez, E. Padorno, E. Sanchez, and M. Castro (2007), Tropical cyclones over the Mediterranean Sea in climate change simulations, Geophys. Res. Lett., 34, L14711, doi:10.1029/2007GL029977.
Reale, O., and R. Atlas. 2001: Tropical Cyclone-Like Vortices in the Extratropics: Observational Evidence and Synoptic Analysis, Weather and Forecasting, 16, No. 1, pp. 7-34.
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