Odile Nearing the Arizona Border; Polo Nearly a Hurricane; Edouard Weakens to Cat 1

Tropical Storm Odile is being pulled apart by wind shear as it tracks northeast at 6 mph across the northern Gulf of California. At 11 am EDT Wednesday, Odile was still a minimal 40 mph tropical storm, and had advanced within 110 miles of the Arizona border. According to NOAA's Historical Hurricane Tracks website, only two other named storms since 1949 are recorded to have maintained tropical storm strength in the Gulf of California so close to Arizona--Nora of 1997, and Katrina of 1967. Both were still hurricanes when they made landfall at the northern end of the Gulf of California. Two other named storms, Raymond (1989) and Lester (1992), made landfall in the Gulf of California south of where Odile is, but managed to maintain tropical storm strength all the way into Southeastern Arizona (thanks to wunderground member Webberweather53 for pointing this out.) Satellite loops show that the low-level circulation of Odile is still over water, but nearly all of Odile's heavy thunderstorms and a circulation at mid-levels have moved ashore near the Arizona/Mexico border. Odile will likely become a remnant low Wednesday night. Copious moisture from Odile's circulation brought scattered heavy rains to Southeast Arizona and Southwest New Mexico on Tuesday, with 24-hour rainfall amounts of 0.5 - 1.5" common. Heavy rain will ramp up in intensity significantly on Wednesday evening, though, as the core of Odile's remnants cross the Arizona border. Southeast Arizona and Southwest New Mexico are at the at highest risk of flooding, with rainfall amounts of 3 - 6" likely, and up to 9" may fall in the mountains. A flash flood watch is posted for Phoenix and Tucson in Arizona, and for Las Cruces, New Mexico. Odile's heavy rains come just ten days after moisture from Hurricane Norbert drenched Southern Arizona, bringing Phoenix its heaviest single-day rainfall in recorded history. According the the NWS in Tucson, the arrival of moisture from Odile just ten days after Norbert marks the first time on record that moisture from two tropical storms have brought the state heavy rains in a 10-day span.


Figure 1. Predicted precipitation for the 3-day period 8 am EDT Wednesday - 8 am EDT Saturday, from NOAA's Weather Prediction Center. A large area of 3 - 7 " of rain (orange colors) is expected over Southeast Arizona and Southwest New Mexico.

Tropical Storm Polo brushing Southwest Mexico
The Pacific coast of Mexico has a new hurricane threat to be concerned with--Tropical Storm Polo, which had intensified to 60 mph sustained winds 260 miles SSE of Manzanillo, Mexico at 11 am EDT Wednesday. The models have come into increasing agreement that the core of Polo will stay offshore, but the storm is close enough to the coast that a Tropical Storm Warning has been issued for the coast of Southwest Mexico. The 11 am EDT Wednesday WInd Probability Forecast from NHC gave Cabo San Lucas on the southern tip of the Baja Peninsula a 22% chance of experiencing tropical storm-force winds from Polo, and a 1% chance of hurricane-force winds. Those odds were 43% and 1%, respectively, for Manzanillo. Satellite loops show that Polo has plenty of heavy thunderstorms that are steadily growing more organized.


Figure 2. Latest satellite image of Polo.

Edouard weakens to a Category 1 hurricane
After spending just 6 hours at Category 3 strength on Tuesday, Hurricane Edouard, the Atlantic's first major hurricane of the past two years, has steadily weakened to Category 1 status as of Wednesday morning. Edouard is headed northeast over the Central Atlantic, and is not a threat to any land areas. On Thursday, Edouard will encounter colder waters below 26°C (79°F) and wind shear will rise significantly to 30 knots, which should cause rapid weakening, with dissipation likely by Friday night. Satellite images show that Edouard remained well-organized on Wednesday morning with a prominent eye. Edouard was the first Atlantic major hurricane since Hurricane Sandy made landfall over Cuba as a Category 3 storm with 115 mph winds on October 25, 2012.


Figure 3. Hurricane Edouard as seen from the International Space Station at approximately 3 pm EDT Tuesday September 16, 2014. At the time, Edouard was a weakening Category 2 storm with top sustained winds of 100 mph. Image credit: Alexander Gerst.

New African tropical wave emerging from Africa
A tropical wave coming off the coast of Africa on Wednesday night is being given some lukewarm support for developing near the Cape Verde Islands by Saturday from our reliable tropical cyclone genesis models. In their 8 am EDT Wednesday Tropical Weather Outlook, NHC gave the wave 2-day and 5-day odds of development of 0% and 10%, respectively. This wave looks like it will have too much dry air to contend with to become a tropical storm.


Figure 4. MODIS true-color image of a tropical wave moving off the coast of Africa at approximately 8 am EDT September 17, 2014. Image credit: NASA.

Jeff Masters