UPDATE 5:40 PM, 1/12: Roanoke’s official high of 73 and Blacksburg’s high of 71 have set records for Jan. 12, topping those listed below. It also appears Blacksburg’s temperature was the second warmest ever recorded in January, only exceeded by 73 on Jan. 30, 1975. Roanoke’s high is the warmest in January since 74 on Jan. 3, 2004. There’s a good chance of more records on Sunday, before rain arrives to hold temperatures down Monday-Tuesday — but still well above normal. END UPDATE
Milder air is moving in from the southwest, and will be advancing northeast at the higher elevations first and then working down into lower elevations. That’s why places like Bluefield and Hillsville are in the mid 50s on this Friday afternoon while Roanoke is clinging to the low 40s in the drizzly wedge of cold air. A result of this temperature inversion will be dense fog, and that’s why the National Weather Service in Blacksburg has posted a dense fog advisory for most of Southwest Virginia east of the I-77 corridor. Beware if traveling.
The warm air regime should be in full control by mid-morning Saturday, and that will lead to a weekend of potentially record-setting high temperatures. Below are the standing records for the next two days at Blacksburg and Roanoke, each one in jeopardy.
January 12 January 13 BLACKSBURG 67 (2005) 64 (2005) ROANOKE 71 (2005) 73 (1932)
The general idea on what the weather is going to do over the next 7-10 days is simple, but the specifics are complicated. It will get really warm this weekend, and then get cold next weekend — possibly the beginning of a very cold period. In between there will be a vigorous storm system that may bring a genuine soaking rain to our region. That’s now looking more like a Monday-Tuesday matter.
The cold air is coming. At first it will be sort of a slow drift downward toward near-normal temperatures (40s highs/20s lows, generally, this time of year for Southwest Virginia) as modified polar air behind the initial front oozes in Wednesday and Thursday. But there are lots of signals of much sharper pushes of Arctic air later, though timing, extent, duration and intensity have all been highly variable on the forecast models — not unusual when huge changes in weather patterns are afoot. Today’s European model (12Z) shows extremely cold air making a brief foray into Virginia — minus-18C at 850 millibars would translate to near zero Fahrenheit on some of our higher ridges around, and probably some single digits/teens at lower elevations — on Friday before moderating some next weekend — and then more cold shots arriving later. This particular run is probably overdone on the initial push of cold for Friday, but the larger picture the various recent versions of the Euro are setting up suggests a strong chance of a much colder pattern than we’ve seen developing for the central and eastern U.S. The Global Forecast System model has been more frequently showing a push of extreme cold after January 20. While specifics of the cold pattern ahead are not clear, confidence is growing that a below-normal temperature period is ahead, beginning late next week. Much less certain are the prospects for wintry precipitation. A disturbance working across northern Mexico and Texas late next week has some chance to help fire a storm system somewhere in the South that could throw some moisture up over the invading cold air near or over us late next week. It is possible though that the system will be crushed by a convergent upper-air pattern (wind vectors blowing into each other, rather than spreading out) as Arctic air pushes southward. So, for now, I’m not likely to go bonkers with the flakes on the snow meter for this coming week.
Meteorological winter — Dec. 1 to Feb. 28 — reaches its halfway point early in the coming week. Is it possible that this will be a winter of sharply different halves?