UPDATE 9:50 PM, 7/15: 94 in Hartford, Conn., on Monday. 97 in Newark, N.J. 74 in Dallas, Texas. Topsy-turvy summer of 2013 continues. We’ll still be underneath the high bringing excessive heat to the Northeast, with enough low-level moisture trapped that a few afternoon pop-up showers and storms will be possible on Tuesday. Expect highs near 90/low 90s in Roanoke on Tuesday, cooler to west, maybe a touch warmer in Southside. END UPDATE
We all know this has been an exceedingly wet summer. But it’s not really been a “cool” summer, which may be a surprise to some. Blacksburg averaged 0.8 degrees above normal in June and is running 0.9 degrees above normal in July. Roanoke averaged 0.7 degrees ABOVE normal for June and is only 0.2 below normal halfway through July, likely to rise above normal this week. The reason for it not being cool relative to normal: Muggy nights. Humidity is holding low temperatures above normal even as daytime highs have generally been below normal because of frequent clouds and rain.
Morning clouds and fog in Southwest Virginia (on Monday morning) show we still have lots of surface humidity around. But the atmosphere has dried out significantly aloft underneath high pressure that has build west and southwest, and the sun will eventually burn through it and send highs into the 80s to near 90 today. We may in fact see some low to mid 90s in the Roanoke Valley, Piedmont and Southside this week (projected Wednesday highs at left) as a more typical mid-July pattern sets in. With this much moisture, there will be a chance of scattered afternoon showers and storms most days this week, primarily from afternoon heating combined with terrain effects rather than organized systems. But of course that is what we expect in a “normal” July. One thing to keep an eye out for will be whether any storm complexes in the Ohio Valley and Northeast can slide a little farther south, or send an outflow boundary farther south to trigger storms near us, on Tuesday and Wednesday. By late week we will likely see new cold fronts from the northwest begin to erode the high, and a cooler, wetter pattern may be restored by next week.