Weather across America

(NATIONAL) Flash flooding and severe weather possible for parts of the Upper Midwest, a heat wave for the Great Lakes into the Ohio Valley and Northeast, heavy rain and flash flooding possible for the central and northwest Gulf Coast, and late-season wet snow for the northern Rockies.

A very active pattern is in store for the Lower 48 this week which will feature a variety of weather hazards: Heavy rain and flash flooding. Two areas are noted for the potential for flash flooding/heavy rain along with severe weather. The first over the Upper Midwest as multiple rounds of heavy rain push through the Dakotas into Minnesota, where there is a Moderate Risk of excessive rainfall (central MN) and a Slight Risk of severe weather (per SPC) on Monday (Nebraska northward to MN). The second will be near the Gulf of Mexico. 

Tropical moisture will surge northward and westward from southern Louisiana westward into Texas through Tuesday (and into Wednesday), including in and around the Houston metro area. In addition, the National Hurricane Center is monitoring the southwestern Gulf of Mexico for possible future tropical development over the next few days. Rising temperatures over the northeastern 1/4 of the CONUS will approach and exceed record highs (including record warm overnight lows) over the Midwest/Great Lakes into the Northeast Mon/Tue (and beyond). High temperatures will climb well into the 90s for many areas, with upper 90s possible in the lower elevations in the East on Tuesday. 

Overnight lows may only drop into the upper 60s to mid 70s, offering little relief from the heat. The experimental Heat Risk outlooks shows major to extreme levels for many areas, owing to the duration of the upcoming heat wave. This is in stark contrast to the record cool temperatures Sunday morning over parts of the Northeast. Cool and snowy conditions will be impacting parts of the Northern Rockies over the next couple of days as a broader upper trough moves through the West. Temperatures will be well below normal for mid-June, and even near record cold for the date. 

The snow will be limited to higher elevations in Montana (especially above 7000ft), but accumulating snow is likely even down to 5000ft or so. This heavy and wet snow may cause some tree damage and power outages, and will likely make travel difficult across some of the passes. Hot/dry/breezy conditions over parts of the Southwest will result in a high fire danger, especially over northeastern Arizona, southeastern Utah, and into western New Mexico. Critical fire conditions are forecast for these regions per SPC, with a broader Elevated risk for much of the Four Corners and even into the Sacramento/San Joaquin Valley on Monday.