96L Southwest of the Azores May Become Subtropical Storm Sean

November 13, 2017, 10:31 AM EST

Above:  MODIS satellite image of 96L taken on Monday morning, November 13, 2017. Image credit: NASA

A non-tropical low-pressure system with the potential to develop into a subtropical storm was located in the east-central Atlantic about 600 miles southwest of the Azores Islands on Monday morning. This system was designated Invest 96L by NHC over the weekend. The low is moving slowly northeastward towards the Azores, which is the only land area that needs to be concerned with this storm.

Conditions were marginally favorable for development on Monday, with moderate wind shear of 15 knots and ocean temperatures of 24°C (75°F). These temperatures are probably too cool to allow transition of 96L to a fully tropical storm, but may be warm enough to allow 96L to become a subtropical storm deserving of a name. Satellite loops on Monday morning showed that 96L was already beginning to take on some characteristics of a subtropical storm, with a large area of heavy thunderstorms located in a curved band more than 100 miles from the cloud-free center of circulation. In their 7 am EST  Tropical Weather Outlook, NHC gave 96L 2-day and 5-day odds of development of 30% and 50%, respectively. The next name on the Atlantic list of storms is Sean.

Watching the Caribbean for tropical cyclone formation next week

The waters of the south-central Caribbean off the coast of Nicaragua is an area we will need to watch for development beginning next week. Waters there are plenty warm enough to support a hurricane (30°C, or 86°F), and the long-range GFS model has been predicting low pressures and reduced wind shear supportive of tropical cyclones over this region for next week. Recall that last year, Category 3 Hurricane Otto formed in this region and hit Nicaragua on Thanksgiving Day—November 24.

People walk along a nearly empty boardwalk at Coney Island, 11/10/2017
Figure 1. People walk along a nearly empty boardwalk at Coney Island on a chilly afternoon in Brooklyn, New York, on Friday, Nov. 10, 2017. Image credit: Spencer Platt/Getty Images.

A 21st-century novelty: Record November cold in the Northeast

A fast-moving shot of unusually cold mid-autumn weather left dozens of daily record lows in its wake from the Upper Midwest to New England. Readings in the single digits (°F) were notched as far south as the regularly coldest parts of southwest Pennsylvania, as reported by weather.com. The region was moderating on Monday, but a more prolonged bout of cold may strike the northeast half of the nation next weekend into Thanksgiving week.

Among the daily record lows set on Saturday:

Boston, MA:  23°F (old record 24°F in 1901)
Morrisville, VT:  14°F (old record 16°F in 1999)
New York (Central Park), NY:  24°F (old record 28°F in 1933)
Bradford, PA:  5°F (old record 10°F in 1957)
Youngstown, OH:  14°F (old record 21°F in 1957)
Atlantic City, NJ:  21°F (old record 22°F in 1974)
Wilmington, DE:  20°F (old record 22°F in 1961)

These records become more noteworthy in the context of a climate being warmed by human-produced greenhouse gases. In the nation’s biggest cities, growing urban heat islands are also helping to keep nights warmer, making it tougher still to hit record lows. In Boston, the lows of 24°F on Friday and 23°F on Saturday are the only daily record lows the city has managed to set since 2000 during the entire three calendar months of October, November, and December. In those same three months, Boston has seen at least 11 daily record highs since 2000. Likewise, the 25°F on Friday and 24°F on Saturday in New York’s Central Park are the only record lows on the books since 2000 in Oct./Nov./Dec., whereas the park has seen 19 record highs since 2000 during those three calendar months.

For sheer misery, it would be hard to top the conditions that accompanied the cold blast at Mount Washington, New Hampshire, where winds topped out at 105 mph on Friday. Observer Tom Padham braved the fierceness in a video shot on Friday morning with a temperature of –2°F and a wind chill of around -40°F.

Frigid night in International Falls

The most impressive of the recent batch of U.S. record lows were the –13°F on Thursday and the –14°F on Friday at International Falls, Minnesota. These readings smashed daily records of 0°F for Thursday and –6°F on Friday. In data going back to 1897 at International Falls, Friday’s –14°F was the coldest ever recorded so early in the season. It's a fitting reminder of why the city has fought to keep its trademarked billing as “Icebox of the Nation” (although most people refer to refrigerators rather than iceboxes these days). As explained by The Christian Science Monitor, “the trademark for this slogan has been repeatedly challenged by the town of Fraser, Colo. In 1986, International Falls paid Fraser to relinquish its claim, and then registered it as a federal trademark. Ten years later, the town forgot to renew the trademark, and Fraser tried to snap it up. A 12-year legal battle ensued, with International Falls prevailing in the end. Needless to say, relations between the two towns remain chilly.”

Bob Henson wrote the non-tropical portion of this post.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.

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Dr. Jeff Masters

Dr. Jeff Masters co-founded Weather Underground in 1995, and flew with the NOAA Hurricane Hunters from 1986-1990.

jeff.masters@weather.com

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