July 2010

On July 6th, this strong ridge over the Mid-Atlantic and Northeast produced numerous heat records.
Anthony Watts pointed out that some of the highest temperature readings including Baltimore may have been due to poor station siting.

On July 8th, an unusual winter-like Aleutian low dropped to 969 mb:
High resolution visible and water vapor imagery from the next day:
On July 23rd, a supercell in central South Dakota dropped a hailstone 8 inches in diameter, 18.625 inches in circumference, and weighing 1.9375 pounds in the small town of Vivian, SD, breaking the record for diameter and weight. The Aurora, Nebraska hailstone of June 22nd, 2004 had the previous record for diameter - 7 inches - and still holds the record for circumference - 18.75 inches. The old record for weight was 1.67 pounds on September 3rd, 1970 in Coffeyville, Kansas. The Vivian, SD supercell had an estimated updraft velocity in the 160-180 mph range. Analysis charts and radar imagery available here.