A pair of upper level disturbances will be the catalysts for rounds for strong to severe storms from the Upper Midwest to the Northeast through Thursday afternoon.
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Focusing on the first upper level feature over the Northeast today, it is already responsible for intense storms from the northern Chesapeake Bay to New England.
The Weather Prediction Center (WPC) has a Slight Risk for Excessive Rainfall in place over the I-95 megalopolis that encompasses the DC/Baltimore metro areas to as far north and east the NYC metro area.
Meanwhile, the Storm Prediction Center (SPC) has a more expansive Slight Risk area that covers the DelMarVa Peninsula on north to Connecticut and southern New England.
Both national centers' Slight Risk areas highlight the threat for severe storms that could produce damaging winds, large hail, tornadoes, and flash flooding.
As of 2:30PM EDT, there was as many as 43 million people under a Severe Thunderstorm Watch from the DC/Baltimore area to southern New England.
Thunderstorms will likely contribute to travel delays in these affected areas this afternoon.
Storms will dissipate later tonight and result in drier conditions heading into early Wednesday morning.
Farther west, another upper level disturbance is set to produce more severe weather in parts of the Northern Plains and Upper Midwest.
SPC has a large Slight Risk area that includes the eastern Dakotas, northern Nebraska, southwest Minnesota, and northwest Iowa.
Damaging winds, large hail, and tornadoes are all possible in these areas.
By Thursday, the fast moving upper level disturbance and a frontal system at the surface will race east into the Great Lakes.
The confidence in severe weather is greater in parts of the central Great Lakes, prompting SPC to issue an Enhanced Risk (threat level 3/5) for southern Michigan, northern Indiana, and northwest Ohio.
The Slight Risk currently includes the Chicago and Cleveland metro areas.
Damaging winds and tornadoes are the most concerning modes of severe weather, although storms could also contain large hail.
WPC also has a Slight Risk for Excessive Rainfall for most of Michigan, including the Detroit metro area.
By Thursday, portions of the Northeast contending with severe storms today may see another round of severe storms Thursday afternoon.
Elsewhere, there are Marginal Risks for Excessive Rainfall in parts of the Southwest today and Thursday due to daily rounds of monsoonal thunderstorms.
In South Florida, there is a Marginal Risk on Thursday as heavy thunderstorms could result in flash flooding around the more populated areas of South Florida.
In other news, the expansive upper level ridge of high pressure over the Southwest and Southern Plains will work in tandem with a building Bermuda High to cause sizzling temperatures from southern California to the East Coast by Thursday.
Daytime highs will soar into the triple digits each day in the Desert Southwest, while a growing footprint of 100+ degree highs takes hold of the Nation's Heartland.
Sultry heat indices are forecast to stick around throughout the South and eventually make their way into the Mid-Atlantic by Thursday where heat indices are likely to exceed 100 degrees.
At this time, Excessive Heat Warnings are in place in the Desert Southwest and Lower Colorado River Valley, while Heat Advisories are more common in the Great Plains, Southern California, the Middle Mississippi Valley, and South Florida.
Lastly, Air Quality Alerts remain in place across portions of northern Minnesota and the Great Lakes due to smoke from Canadian Wildfires causing unhealthy air quality in these regions.
Farther west, the combination of gusty winds, parched fuels, and low RH values will be supportive of Elevated to Critical Fire Weather conditions over the northern Great Basin.
Isolated thunderstorms and their associated lightning strikes could also pose a threat to ignite additional fires in extreme northeast California, northwest Nevada, and southeast Oregon. ■