Weather

Showers and thunderstorms will extend from New England to the Mid-Atlantic Coast, Appalachians, Ohio and Tennessee valleys, southern Plains and southern Rockies on Wednesday. The downpours are forecast to occur along a boundary separating hot and humid air to the south and east from slightly cooler and less humid air to the north and west. This boundary will progress across the Midwest and Northeast but stall over the South-Central states. Some storms may get strong enough to bring damaging wind and flash flooding. Locations over the Southwest may also be hit with a storm containing very large hail. While the bulk of the storms are likely to occur in the afternoon and evening, some storms will develop in the morning and linger well into the night.

Most areas west of the Rockies will be at risk of wildfire ignition and spread. Most areas should expect another sunny and dry day with a hot afternoon. The most extreme heat, relative to normal, will be in the Northwest. Light winds will also allow smoke to linger and greatly reduce air quality. Only spotty storms are forecast to occur west of the New Mexico mountains and wander to parts of Arizona and Utah. A few storms may reach Southern California later this week, while cool air arrives across the Northwest this weekend.

The leading edge of cooler air is expected to spread into the Pacific Northwest, which will bring an end to the heat wave. Increasing winds may also lead to improved air quality. Hot air will retreat into the High Plains this weekend.