UPDATED 12:10 AM, 7/7: Two more extremely hot days before hope of cooling relief (maybe even widespread rainfall) arrives
Weather Journal column: An interview with NWS-Blacksburg meteorologist-in-chief Dave Wert abput the forecasting/warning process surrounding the June 29 derecho. Also, a timeline of watches and warnings leading up to the event.
UPDATE 12:10 AM, 7/7: Just rolled over this blog entry, because it does appear there will be TWO more days of the heat wave — Saturday and Sunday — before the front arrives and begins to bring cooler air. That collision of air masses will likely result in some strong to severe storms late Sunday — the Storm Prediction Center has had our region in a slight risk of severe weather for that timeframe — and quite possibly some significant rain early to mid next week. But first, a high near 100 in Roanoke and places south and east on Saturday, with widespread 90s over most of our region below 3,000 feet. Sunday may be similar or just a few degrees cooler, depending on when the front and any associated storminess arrive. END UPDATE
For those ready for a break from the heat, I’m going to tempt you with the Hydrometeorological Prediction Center’s projected temperature map for next Thursday — low to mid 80s for highs regionwide. It appears we have two more days of extreme heat — potentially near 100 each day in the Roanoke Valley and points south and east, upper 80s to mid 90s to the west – before the changes start taking shape. Sunday may be a pretty hot, sticky day before a cold front begins pushing in, triggering showers and thunderstorms. Once the front goes by, a much cooler air mass will move in, and that will likely take our highs below 90 — and maybe below 80 for areas above about 2,000 feet in elevation, mainly west of Roanoke — for several days next week. It does not appear at this time as if it will be a long cool snap — the Climate Prediction Center’s 6-10-day map and 8-14-day map show warmer than normal temperatures building back across the Upper Midwest and Great Lakes toward us by late next week or the following weekend. But it looks to be a respite from the extreme heat wave.
As for storms, the odd south-southwest movement of Thursday’s storm cluster that stayed well west of Roanoke and just west of most of the New River Valley — eventually reaching Alabama and Georgia — is a sign of how the upper-air steering currents are weakening. Pop-up storms, more on the order of what the eastern side of the Roanoke Valley and the Smith Mountain Lake area have seen the past two days, will be possible each hot afternoon, more so on Friday before warm air aloft may cap convection more firmly for Saturday. For those looking for more meaningful widespread rain, forecast models are suggesting the front may be sluggish moving south Sunday and Monday, serving as a focus for some heavier rain. Until and unless that happens (still iffy), your local rain prospects will be hit or miss, with far more missing than hitting.