It looks like we can write off Tropical Storm Ernesto from having any significant effect on the United States, as it has dipped farther south and is making a westward run toward the Yucatan Peninsula, possibly never making hurricane status. It appears likely at this point that Tropical Storm Florence won’t be a factor for the states, either, as it will probably die off long before it gets close.
Monday will be yet another day of slow-moving showers and storms, dumping large amounts of rain on some localized areas while others get much less, or even nothing. The odds of getting at least something rather than absolutely nothing for any given location across Southwest Virginia have gone up because of a slowly meandering front — loosely defined as a “cold” front — that will sink southeastward into our region on this Monday and really have no clear long-term intentions of where it wants to go and what it wants to do. Ulitmately, this front will probably do what most July and early August cold fronts do, and simply wash out over the Carolinas. It will provide just enough lift and instability, combined with the abundantly thick moisture and at least some daytime heating (likely limited by cloudiness) to trigger more showers and storms on Monday. With the front washing out, it won’t clear this humidity out, and we’re likely stuck with warm but not all that hot temperatures (80s, mostly) and daily rounds of showers and storms through most of this week.
About a week out, the European model is fairly aggressive with bringing a shot of cooler, dry air south from Canada. The 12Z run depicts cooler than normal temperatures likely over a good chunk of the Midwest and East, including our region. Low-pressure troughing, or a southerly dip in the jet stream, is developing into the Great Lakes and likely to remain for several days. Whether this will be sufficient to push a significantly strong Canadian cold front all the way through the sticky, tropical-like air mass in place remains to be seen, but its presence should at least ensure that the extreme heat recently focused on the south-central states and shifting more westward this week.