Published: July 21,2017
A ring of fire weather pattern continues to grip the U.S., resulting in dangerous heat and bouts of thunderstorms that may contain damaging wind gusts, hail, isolated tornadoes and heavy rain.
Though "ring of fire" isn't a formal weather term, it's sometimes used by meteorologists to describe a particular summertime weather pattern that sets up occasionally.
Here's how it works: Sinking air associated with a strong upper-level high-pressure system east of the Rockies leads to very hot temperatures near its core. Forming a ring around the high's clockwise flow are disturbances aloft that tap into moisture, resulting in bouts of storms near its periphery.
You can see the general setup for this week's ring of fire weather pattern in the graphic below.
Ring of Fire Weather Pattern
Dangerous HeatThe worst of the heat into Saturday will grip areas from the central Plains into the mid-Mississippi Valley, parts of the South and mid-Atlantic states.
Excessive heat warnings and heat advisories have been issued by the National Weather Service in parts of the Midwest, South and East for a dangerous combination of hot temperatures and high humidity. This includes Kansas City and St. Louis, where heat index values are forecast to be 105 to 115 degrees again Saturday afternoon.
Highs in the middle to the upper 90s and a few 100s will be common from South Dakota to Missouri to parts of the mid-Atlantic states and the South through Saturday. Heat index values of 100 to 110-plus degrees are likely during the afternoon hours.
Forecast Highs This Weekend
Few daily record highs are forecast to be threatened since that bar is high now that we are in the climatological hottest time of year in most areas.
(MORE: July the Hottest Month in Most of the U.S.)
Cooler conditions will return to the Midwest and Plains by Sunday as the area of high pressure weakens. Temperatures will also retreat to near average in the mid-Atlantic by early next week.
Ring of Fire StormsThe periphery of the high will be the main focus for thunderstorms.
The northern Plains, upper Midwest, Great Lakes and mid-Atlantic will have the highest chance for bouts of severe storms, with damaging winds, hail and isolated tornadoes, as disturbances ride through the northern side of the high-pressure system. Flash flooding could also be problematic in those regions due to the several bouts of storms rolling through.
(FORECAST: Severe Weather Takes Aim on Midwest)
Saturday's Thunderstorm Forecast
Sunday's Thunderstorm Forecast
(MORE: Threats From the Southwest Monsoon)
The Northeast, Gulf Coast and Southeast coast will also see isolated to scattered showers and storms at times through Sunday.
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