UPDATE 4:40 PM, 2/18: Despite springlike Saturday, confidence grows in significant snowfall for SW Virginia late Sunday
UPDATE 4:40 PM: Winter storm warning issued Bedford, Roanoke, Floyd, Carroll counties and westward; winter weather advisory Franklin, Henry and Patrick counties eastward. New blog post next hour.
UPDATE 1 PM: Numerous signals continue to point to more/heavier snow potential Sunday afternoon and evening for SW Virginia. I will post a full new blog update around 5 p.m. Short answer to those asking about travel on Sunday: Earlier in the day will be better. Enjoy the spring afternoon! END UPDATE
UPDATE 7:20 AM: A few quick points to add:
* The winter storm watch has been expanded southwestward and to include the Roanoke area and the New River Valley, all the way to the North Carolina border at Carroll and Grayson counties. Bedford and Franklin counties are barely outside the watch, but their western areas and higher elevations near the Blue Ridge may have similar accumulation with some totals possibly exceeding 4 inches.
* The Hydrometeorological Prediction Center has boosted much of Southwest Virginia into a HIGH RISK of 4-plus inches for the period from Sunday morning to Monday morning, with a slight to moderate risk of 8-plus inches in much of the region as well. The slight southward shift shown on many forecast models is reflected in the new bullseye area.
* With expected sunshine and southwesterly downslope winds today, the National Weather Service has boosted Roanoke’s forecasted highs into the lower 60s! So we may really stretch this spring-to-winter-and-back concept. It may be after dark Sunday before a lot starts sticking in lowest areas of the Roanoke Valley, but more of the snow is expected to happen at night with the later arrival.
So get out and bask in your winter storm watch today!
What I often like to do when we’ve been following a storm closely for several days, mainly on the forecast models, is bring it back to reality by showing what it looks like on radar or satellite. While the upper-level low has been moving across the Southwest the last few days, the low-pressure system that has been the focus of our speculation for days and will be the focus of our attention the next 48 hours is getting organized in south Texas. Radar composite from late Friday night (at left), just before midnight, shows heavy showers and thunderstorms — very welcome ones in a drought-parched state — rumbling in much of central Texas. This is pretty much just what the models have been showing, so this system is, so far, on track and on time. It really exists now, not just in a silicon chip.
A few quick notes on where we stand on Sunday’s morning in the wee hours of this Saturday morning:
* Confidence continues to grow that there will be snow, and likely significant snowfall, in Southwest Virginia on Sunday. It’s a classic winter storm setup for this time of year, and there is absolutely no forecast model that does not show snow developing in our region. Amounts, intensity and timing vary somewhat, but not the existence of snow. The models could change, or be wrong, but they all show snow for several hours.
* Forecast guidance from Friday night has tended to slow down the system and nudge it a little south. This seems to be largely the result of more cold air being forced southward. All of those factors lead to the idea that Southwest Virginia will be even more in centered in the snow band than thought previously, This could result in somewhat greater snowfall amounts.
* Because of the storm system being slower, it is possible precipitation may not begin until well after the sun has risen Sunday. Colder air already in place may lead to a mix with sleet or even starting directly as snow rather than a long period of rain. It also appears precipitation will continue well into Sunday night, possibly even the pre-dawn hours of Monday.
* Highs today are still likely to reach the 50s, unless there is sufficient cloud cover to shave some degrees off of that. Today will be a day that doesn’t seem anywhere close to a possible snowfall, and it will cause many to doubt that it can happen. There are numerous historical examples of multiple-inch snowfalls occurring a day after similar temperatures or even much warmer than what we have today, but of course, we won’t know til Sunday whether this one will join the list.
As for amounts, I’m thinking — as of now, subject to change up or down with later data — that 2-6 inches will be the range for most of our region, with less in Southside from Stuart east to Danville and a little more in the Alleghany Highlands, west of I-81 and north of I-64. There will be issues with warm ground and some early melting, and like I said Friday, accumulations will be a little lumpy with snow sticking more quickly on grass and trees while not sticking as well on bare ground and asphalt. Snow may fall heavily enough at times to overcome those warm surfaces, so be aware of the possibility of finding slushy or even snow-covered roads if traveling on Sunday.
You can check in with the National Weather Service in Blacksburg and the Hydrometeorological Prediction Center winter weather forecasts page for some updates on Saturday morning.