It's that time of summer when the Mid-Atlantic states are the graveyard of cold fronts, and that combined with tropical-like stickiness will continue to bring rounds of showers and thunderstorms across the region just about every day this week.
Sorry FloydFesters and anyone else with planned outdoor activities, right into the weekend. It won't rain every second of every day, and some locations might get skipped a day or two, but in general, there will be scattered to numerous showers and storms each this week in and near the Roanoke and New River valleys.
Some might find the rain welcome for their gardens, but it runs the risk of being a bit too generous at times. While there is greater risk of flooding rain west of our region, there is at least some potential rounds of heavy storms will line up over a spot repeatedly and bring 2 or 3 inches of rain in a short time, causing localized flooding.
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The "heat dome" high that sizzled the central U.S. and gave us a little taste of it over the weekend -- mid 90s for Roanoke, not upper 90s-100 as initially expected -- has retreated well west. A piece of that old high is parked over the South, and is a source of some really humid air, with near-70 dew points much of this week.
The southern "subtropical" high is also blocking cold fronts from clearing the region. They advance southeastward and just stall out, then wash out, near or over our region. These stalled fronts provide boundaries for showers and storms to form with even subtle daytime heating in the densely moist air. Also, storm clusters from the Midwest -- the St. Louis area has had flash flooding this morning -- follow the frontal boundary east-southeast toward our region. Even if the storm cluster don't reach our region intact, their remnant outflow boundaries are enough to trigger new clusters of showers and storms.
July weather patterns are typically very sluggish, and this one isn't changing much at least through the weekend. It's impossible to time the individual rounds of showers and storms days ahead of time, but you can generally know that afternoons and early evenings from about 1 to 9 p.m. are going to be the most active time for rumbles and downpours each day. We might catch a break a day or two in this stretch and have more sun, but that will just mean more heating and more potential to boil up afternoon storms. It's kind of a vicious cycle right now.
Long-term, looking deeper into August, the heat dome high shows signs of building east again more toward the Upper Midwest and Great Lakes. This makes me a bit concerned that we could finally see a full-on extreme heat wave in our region sometime around mid-August, as our worst ones historically build in from the northwest, not from the south or southwest as you might expect.
It's a long way out and a lot can happen, and having periods of rain like we're having to moisten the ground and keep the leaves healthy does a lot to retard the worst heat. It might help keep it being sticky-stormy off and on, rather than super-sizzling, for weeks to come in our region.