UPDATE 5:20 PM: Much of the rain from earlier today went north of much of Southwest Virginia, while storms developed to the south and east. A few scattered showers remain, but it looks like they will be very spotty. Many high school football games will get in tonight with little or no rain. Rain gear is still wise just in case you’re in one of the spots that do get rain. END UPDATE
UPDATE 8:30 AM: Rain chances for later today into this evening have gone up, as the cold front has not made as much progress southeastward as earlier projected, and clusters of showers and storms now in Kentucky will affect part or all of Southwest Virginia as the day progresses. Keep track on Radar Future / Cast linked here. END UPDATE
The National Weather Service Doppler radar located in Floyd County, utilized by the weather service office in Blacksburg, will be down much of next week as it undergoes a major technology upgrade to “dual polarization.” In a nutshell, that means the radar will be emitting horizontal and vertical pulses, rather than just horizontal ones. This will enable meteorologists to more accurately view the types and amounts of precipitation that are falling, among other features. Every weather service radar nationally will eventually be upgraded — many already have, with the last ones scheduled in 2013. Link to the .pdf file here for much more on dual polarization.
The radar may well be missing some significant rainfall. There are growing indications that a wet low will work along the Gulf Coast and throw abundant oisture northward toward us — perhaps even an “overrunning” set up of warm, moist air on top of a wedge of cooler air near the surface — by early next week. Early Hydrometeorological Prediction Center forecast charts are showing 1-inch amounts to be likely in Southwest Virginia by Monday and Tuesday. In the short term, there may be some showers on Friday as a cold front pushes through, but it looks like the timing may be off (morning passage) for a lot of rain or storms, plus the main low-pressure system will be well north of us. Better chances of showers and storms (some strong) will occur the farther south and east you are, relative to the Roanoke Valley, where the front may catch afternoon heating at its peak. The front will hang up close enough to our south over the weekend that there will be at least some chance of showers, as ripples of low-pressure moving along the front may stir some up, but overall, it doesn’t look like it will be anything close to a soaker. After one more sticky day with highs in the mid 70s to low 80s on Friday, temperatures behind the front will settle back more into the upper 60s/low 70s highs and upper 40s/low 50s highs that are near norms for this time of year. If the wedge fully sets up next week, we could have a rainy, rather chilly day or two with highs much lower than currently forecast.