First, a few climatic notes, as we’ve put January in the books with a very dramatic week of weather.
* It was the wettest January on record at Blacksburg with 7.74 inches of rain, topping the 7.41-inch mark of the extreme El Nino-soaked January in 1998. Blacksburg’s records date to 1952.
* It was the fifth wettest January on record at Roanoke with 7.21 inches. January 2013 joins the Januarys of 1998, 1936, 1937 and 1995 as the only ones to top 7 inches of rain. Roanoke’s records date to 1912.
* It was also Blacksburg’s eighth warmest January, averaging 35.9 degrees, dating to 1952. January 2013 was 0.3 degree warmer, on average, than that of last winter.
* January was not in the top 10 warmest for Roanoke, dating to 1912, though it was 5.1 degrees above normal at 41.7 degrees. December and January, together, have averaged 43.2 degrees, which is exactly where last winter ended up, finishing as second warmest on record. If February is a few degrees warmer than normal, this winter will incredibly have a shot to edge out the last one for second warmest. 1931-32′s 46.5-degree average for winter appears to be safe as the warmest winter.
VERY COLD SATURDAY MORNING
Tonight will not help February toward a warm average. In fact, Saturday may be the coldest morning we’ve seen this winter, or even a couple of winters, as clear skies, diminishing winds and low dew points may allow radiational cooling to set in, especially anywhere that retained snow cover from this morning’s quick-hitting Alberta clipper. Lows in the single digits may occur west of Roanoke, and the 10-15 range looks reasonable for Roanoke and east. Roanoke’s lowest temperature of the season so far has been 17, so it won’t take much to beat that (and yes, that means I did miss on my prediction a few weeks ago that Roanoke would hit both 70 and 10 in January, as we hit 70 three times but never even close to as low as 10. Would feel a little redeemed if we got close to 10 on Feb. 2.) I say MAY because the hard-to-predict factor is how much cloud cover moves in before dawn ahead of the next Alberta clipper storm system. If the clouds move in early, radiational cooling will be hindered or halted altogether, and temperatures could even nudge upward a few degrees (many commenters have noted this has happened on several nights recently, for one reason or another.)
ALBERTA CLIPPER NO. 2 SPREADS SNOW SATURDAY EVENING
Alberta clipper No. 2 dives southeast in our general direction late Saturday afternoon into the evening. Many indications are that this one will be a little bit stronger and more moist than the one that brushed us Friday morning with a dusting to 2 inches, but it too will be hitting the same dry air/downslope wall as it crests the spine of the Appalachians. Snowfall amounts will drop off rapidly from west to east across our region, with 2-4 inches possible in the counties close to the West Virginia border and west of I-77, 1-2 inches in much of the New River Valley, and an inch or less for the Roanoke Valley and points eastward, eventually dying out into just flurries in the Piedmont and Southside. It is always possible with a clipper that a narrow band of heavier snow will develop eastward that could boost totals locally — snow can be impressively heavy for a while if you happen to be in one of these bands. Upslope northwesterly flow behind the clipper will keep the snow going well into Sunday in West Virginia’s mountains, bleeding into western Virginia at times. It appears we will be on track for the third in the trilogy of clippers by late Monday or early Tuesday.