As is typical when a high pressure system pushes in cooler weather, the return flow around its backside as it has slipped eastward out to sea has returned some Gulf of Mexico moisture into our region , as evidenced by a few light evening and overnight showers. A weak cold front pushing through later today and tonight — the second of several installments of cooler air in the new weather pattern — will be lifting and condensing some of this moisture into showers and thunderstorms. There is no huge heavy rain and severe storm threat today, but a few spots may get downpours, gusty winds or small hail — most locations will not get strong or severe storms, and some won’t get any rain at all. The Hydrometeorological Prediction Center is projecting rather tame average rainfall amounts of .10 to .25 west of Roanoke and perhaps .25 to .50 to the east – and those are averaged-out amounts between the haves and have-nots. The atmosphere is just not as juicy top to bottom as it was before the weekend cold front, and the upper-atmospheric flow is not strong enough to support a larger threat of severe storms. This front also does not have a radically cooler air mass behind it, but it will reinforce the slgihtly cooler than normal air mass we’ve been seeing. Temperatures Wednesday will likely run about 3-5 degrees below normal, with upper 70s/low 80s highs and upper 50s/low 60s lows by Thursday morning.
A much stronger cold front is still poised to move through Friday or early Saturday. Highs may not reach 80, even for Roanoke, on Saturday or Sunday with widespread lows in the 50s, and perhaps some 40s in rural valleys and higher elevations.