UPDATE 12:30 AM, 9/12: Another night of clear skies, calm wind and dry air will allow lows to again drop into the 40s to low 50s on Wednesday morning– perhaps a couple degrees warmer than Tuesday’s lows (which were 43 at Blacksburg and 48 at Roanoke). The rest of the week will present similar warm days (mid 70s-low 80s) and cool nights (50s-low 60s) as the same dry weather pattern dominated by high pressure continues. END UPDATE
One thing I vividly remember from 11 years ago on that infamous Tuesday morning, Sept. 11, 2001: The perfect clear blue sky belying such a tragic day. This being another Tuesday, Sept. 11, likely to dawn very clear will undoubtedly surface some of those memories for me and many others.
Tuesday, Sept. 11, 2001 had a high of 83 and low of 55 in Roanoke, while Blacksburg was 78/48. This Sept. 11 is likely to be cooler than that one by 4-7 degrees or so. A high pressure system is settling right on top of us for Tuesday morning, which means skies will likely be clear, winds calm and dew points very low. That combination will maximize radiational cooling (heat escaping to space, cooler air sinking to the surface without being mixed) and allow for a temperature drop that may be a little larger than even the last two mornings, which were 47/49 at Blacksburg and 53/54 at Roanoke. Widespread 40s are likely the result, and perhaps even a few upper 30s in some of the rural valley and exposed ridgetop locations that often record the coldest temperatures. Blacksburg has not been as cold as the National Weather Service-projected low of 44 since June 3,while Roanoke has not been as cold as the projected 47 since May 12. Whether or not those projected lows verify exactly, Tuesday will very likely be a third straight morning of low temperatures 4 or more degrees below normal at both sites and throughout the region.
Tuesday’s highs are again expected to stay in the 70s almost everywhere, but a slow warmup will commence afterward, with highs returning to the upper 70s-mid 80s over most of the region and lows warming back up closer to 60 toward the latter part of the week. It will be hard for the atmosphere to rebuild much moisture before a weekend cold front, though some showers or storms may be possible then. Repeated cold frontal passages with slight warmups in between will remain the dominant weather pattern for our region likely for the next couple of weeks, at least.