Making my cool, perhaps frosty, return to the blog … with a few pictures of some valley fog (don’t expect KP-like rhymes like that all the time)
Once again, my thanks to Kathryn Prociv for her marvelous job of filling in on the Weather Journal blog during my 5-day break. And thanks to everyone for helping her feel right at home here. I, too, hope she’ll be back with some comments from time to time.
Several days ago on a clear, chilly morning, frequent Weather Journal commenter Doug Griggs made a field trip to Burkes Garden in Tazewell County, the crater-like geological formation that is frequently the coldest spot in Southwest Virginia when radiational cooling conditions (clear skies, calm winds, surface warmth radiating into space) are optimum. If the clouds and winds die down enough — which they most likely will sooner to the west than in the Roanoke and New River valleys, as the calming high pressure system is moving in from the west — Burkes Garden could dip well into the 20s on Thursday morning, with 30s to low 40s possible in most other spots in Southwest Virginia, again IF the clouds break and the winds die down in time. (Even 2-3 hours near sunrise could lead to a precipitous drop in temperatures.) In honor of a potentially chilly morning of radiational cooling, I’m posting some photos Doug sent me from his field trip to Burkes Garden. The foggy valley photo linked here even has his shadow, if you look closely. Linked here and here are a couple of other foggy valley photos from Burkes Garden. There will likely be less fog, but more frost, there come Thursday morning. I’m thinking the Roanoke Valley likely escapes frost, with patchy frost in the New River Valley. Again, the farther west you are (bore out by the National Weather Service’s frost and freeze advisories), and the more in a sheltered valley you are, the more likely you are to see some frost. Frost can sometimes be thick in one location and non-existent over the hill at another spot less sheltered from any remnant breezes behind the cold front passing through tonight. Friday morning may be almost as cold, and more likely to have calm winds.
The weather pattern ahead has lots more cold fronts in it for us — but not the same kind of cold fronts that brought us a record cold early fall day Monday (with snow in West Virginia’s mountains) and potential frost on Thursday morning. Some rearranging is occurring that will lead to a bit more of a west-to-east flow across the country rather than northwest-to-southeast (or even north-northwest to south-southeast, as we’ve seen at times), so the fronts that will pass through Friday, Sunday and beyond will not have intense cold air from near the Arctic, but rather typically autumn cool air from the Pacific and southern Canada. These fronts will also be mostly dry, not dipping down to dig moisture out of the Gulf of Mexico, but rather zipping through from across the dry states west of us (some of which will get a little wetter over the next few days). We are likely entering a prolonged period of mostly dry, sunny days with temperatures close to normal – mild to warm days with highs commonly in the 60s and lower 70s, and cool nights with lows in the 40s to lower 50s, the kind of October weather that often gets the colors turning in Southwest Virginia. The Climate Prediction Center suggests a lean to warmer than normal weather in the next 1-2 weeks as a broad area of low pressure develops over the Rockies, angling some wind flow toward us from the Southwest. Forecast models are not settled in the long range yet, and the negative phases of the North Atlantic and Arctic oscillations suggest the potential for another surge of cold air at some point later this month.
Meanwhile, some of these weather pattern changes may ignite the fall severe weather season — usually, but not always, a shorter, somewhat weaker shadow of its spring cousin — in the central U.S.