While Southwest Virginia missed out on showers and storms with Monday’s cold frontal passage, a violent storm rumbled through Richmond and nearby areas, with more than 100,000 customers knocked out of power by high winds. The Richmond Times-Dispatch is following the aftermath of the storm. Thankfully, Richmond will get an unseasonably cool day and 2 nights for power to be restored — similar events have been extremely difficult in other areas when power outages are followed by heat and humidity.
We are going to experience an unusually wide temperature swing for summer this week. It is possible that some locations could experience a temperature Friday afternoon that is numerically twice what of Wednesday morning’s reading will be. Somewhere like Martinsville comes to mind, where valley effects often shave a few degrees off low temperatures in radiational cooling situations but high temperatures are a little warmer owing to its Southside location. A low of 50 on Wednesday morning and a high of 100 by Friday afternoon may be possible there. Or, an outlying rural valley area like Burkes Garden in Tazewell County could see 45 on Wednesday morning and clip 90 by Friday afternoon. As cool, dry air from Canada settles in, lows in the 50s will be widespread across the region both Tuesday and Wednesday morning (inset map shows lots of blue colors for Wednesday), with highs only in the 70s in most places (maybe a few low 80s — Roanoke, possibly) on Tuesday. We will begin a steady climb upward in temperatures on Wednesday afternoon, and return to the 90s in most locations from Roanoke south and east by Thursday.
Some national forecast maps are showing 100-plus readings both Friday and Saturday throughout much of Virginia, excluding only the higher mountain areas (roughly 2,000-feet plus). The overall weather pattern certainly favors a run of extreme heat — a large “heat dome” high pressure system building overhead from the west, possibly inducing some weak westerly surface winds that will compress the air and warm it by blowing downslope over the Appalachians. Whether the small-scale features line up (anything boosting convection to create clouds/showers would be the main limiting factor) for a rare 100-degree day or two in Roanoke (only six such days since 2000, and nine in the past 24 years) remains to be seen. Though it will be a relatively “dry heat” with lower humidity than we often see in summer, it will still be extremely hot by Southwest Virginia standards whether it makes 100 or not, with widespread 90s Friday and Saturday.
Tropical Storm Debby continues to spin off torrential rain and tornadoes over Florida, mainly. The front that passed here Monday — or more specifically, the jet stream trough associated with it — may nudge Debby eastward into the Atlantic over the next few days. After that, the high pressure system building over our heads will block it from moving north to affect our region. One bizarre scenario would see the high start pushing Debby back to the west a bit. That’s not projected, but Debby really hasn’t been about doing what anyone thinks it should.