2009.01.26
Advisory for Roanoke/Blacksburg, warning to the north
Not unexpectedly, the National Weather Service has issued a winter weather advisory for several counties in and near the Roanoke and New River valleys, and a winter storm warning for counties to the north, including Botetourt, Rockbridge, Alleghany, Amherst and Bath. The weather service is in the process of updating its current events page as of 3:50 p.m., but it can be found by clicking here.
Forecast models have continued to show a stronger low pressure system moving west of us, therefore bringing warmer, moist air into the middle layers of the atmosphere much more strongly. The result will be more rain and freezing rain rather than snow/sleet, though that depends largely on how much precipitation gets here early in the storm. A lot of moisture arriving before 6 a.m. could provide a big "front-end thump" of snow and sleet, raising the totals, which are projected as up to 2 inches along the Roanoke-Blacksburg corridor and as much as 5 inches to the north.
My concern for icing has increased some because of the failure of temperatures to achieve forecast highs in the 40s, and by the lack of sunshine to warm the ground during the day. Even without snow cover, the ground is very cold from 2 weeks (minus 1 day) of below-normal temperatures. That cold ground will help keep surface temperatures a little lower than they would otherwise be, and might undercut some forecast models a couple of degrees. In the morning, the first waves of precipitation will fall into cold, dry air, and evaporational cooling will take temperatures down a few degrees. It will just be a matter of how much that cold air can hang in as the air warms high overhead
Someone in Western Virginia will get a very severe ice storm out of this. We'll just have to monitor details hour to hour to see if that's a few in isolated areas or many in populated areas, too. Conditions will vary quite a bit, so even if it's not icy where you're at, don't presume that it won't be somewhere you're traveling tomorrow, especially if you're headed north, even just a few miles.
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Timing for tomorrow couldn't be any worse.
I go in at 6 A.M. and I'm supposed to leave at 2 P.M.
things could be fine when i go in but get worse as the day goes on.. and it's going to hard to monitor roadways all over from my location..
does vdot have a website that would show icy road conditions by street or highway? i live in northwest roanoke but work out next to the bonsack wal-mart..
Comment by Snowless in Roanoke — January 26, 2009 @ 4:08 pm
http://www.511va.com has lots of information
Comment by kevinmyatt — January 26, 2009 @ 4:17 pm
The 511 site is only good for interstates and Virginia primary highways like 460, 11, 220, and the like. Neighborhood or minor road conditions are not reported to 511, so figuring out what their conditions might be like isn't nearly as easy. It also depends on localities, VDOT crews, and law enforcement to report the conditons to the 511 folks, so sometimes the conditions are not completely up to date...although they have been fairly accurate of late (they weren't so good when the system first launched).
Comment by Other John — January 26, 2009 @ 4:30 pm
Thank you Kevin for mentioning the temperature forecast bust today...when we are on the borderline...a few degrees makes a huge difference. I watched the temps all day and they didn't meet projections all over the state... Since they were basing their temp forecasts on a little bit of sun (which we didn't get), do you think that they think there will not be as big a swing downward as they originally thought this morning or are they still just a little off?
Comment by Betsy — January 26, 2009 @ 5:03 pm
Kevin, u da man!!
Seriously, of all the forecasts and forecasters, I trust you the most. You always explain thing so that a layman, like myself, can understand what is happening. The models you cite are like code to me, and you always seem to have the key. Whenever there is doubt on if we will get snow, we don't get it. I am confident this is the case for Tuesday. Thanks for all you do, Peter
Comment by Peter Nylander — January 26, 2009 @ 5:14 pm
Temperatures will probably only slowly drop overnight because of the clouds ... the question is where will they be after the evaporational cooling once the precipitation begins, and how long will they hold at those levels before the low begins dragging more warm air northward ... I'm guessing we bottom out about 30 in Roanoke and probably 28-29 in Blacksburg ... we could hold at 32 for hours tomorrow.
Comment by kevinmyatt — January 26, 2009 @ 5:22 pm
The 511 site does list secondaries. Click road conditions, pick your locality then click the blue link for a list of secondaries. It is text and is updated several times a day during events or as conditions warrant. The morning update is at 4 a.m., I can't remember the other times. You can also set up your 511 control room and receive text alerts.
Comment by Johnny — January 26, 2009 @ 5:32 pm
Thanks for that update Johnny. The first several times I used the system it didn't list that detail for road conditions, so it's nice to see that they do now. That's far more helpful for those of us who live on secondary roads more than a mile or so from a major roadway.
Comment by Other John — January 26, 2009 @ 5:49 pm
IT SEEMS LIKE EVERYTIME WE ARE IN A SITUATION LIKE THIS THE COLD AIR HANGS AROUND LONGER THAN FORECASTED.IN THIS CASE MY GUESS IS FOR ALOT OF FREZZING RAIN AND NOT MUCH OF ANYTHING ELSE.
Comment by JAMIE — January 26, 2009 @ 6:19 pm
The wording in the forecast on the NWS is a bit troubling.
They seem to be implying we could have several (10+ hours?) of freezing rain.
Comment by Snowless in Roanoke — January 26, 2009 @ 6:22 pm
I have notice that the weather channel has changed their forecast at least 3 times since I been home at 4:30 pm. from any where from all rain to snow/sleet. I believe this weather event is still developing and it looks like they do not know for certain. The weather service is using data hour by hour to try to fine tune our forecast. I believe that we will have it all in one form or another during this whole event by Wednesday night.
Comment by DAVID S — January 26, 2009 @ 8:06 pm
Guys and gals, here are 4 things to keep in mind with icy roads. 1. If there are widespread icy conditions where you live or you know they will be prevalent on your commute, consider staying at home or taking a bus if at all possible or even a taxi if you do not have to travel too many miles or carpooling. 2. What types of road surfaces are the quickest to freeze?? BRIDGES!! The wider the bridge and the more (cold) air underneath it, the more likely it is to freeze. 3. If you can tell that a road is icy, allow triple the normal spacing between you and the vehicle in front of you (6 to 9 seconds instead of 2 or 3) and when approaching a slowdown area or stop area, use the transmission by DOWNSHIFTING instead of the brake. 4. If you still go into a skid, AND THIS WILL SOUND BIZARRE IF YOU HAVE NEVER DONE IT, take your foot off the brake and steer TOWARD the direction of the skid. And remember that the more traffic a road gets, the warmer the raod surface is likely to be, and vice versa. Several times during previous ice events the major roads are just wet or maybe a little slushy, but the side roads, and especially low spots in heavily shaded areas, can be very bad news.
Comment by Doug Griggs — January 26, 2009 @ 8:44 pm
FEI (For Everybody's Information): The Weather Channel Weekly Planner map for SW Virginia for tomorrow stretching from what appears to be the Carroll County area and all the way up I-81 both east and west all the way up to at least Lexington shows dark green ... = moderate rain. I also looked up the hourly forecast for the zip code (24017 in NW Roanoke city) where I deliver, and it shows the lowest reading at 32 degrees between 2AM and 8AM. Light rain/freezing rain at 2, 3, 4, and 5 AM, then rain/frz. rain (in other words, a bit heavier level of precip) at 6, 7, and 8 AM. Then 34 degrees or higher the rest of the day.
Comment by Doug Griggs — January 26, 2009 @ 8:57 pm
NRV Fans of "the Kevin." I just called up the hourly forecast on weather.com and it shows EXACTLY the same pattern for Blacksburg (24060 zip) as for 24017 zip!! Light rain/freezing rain from 3AM - 5AM, then rain/frzing rain from 6AM until 8 AM, then a jump in the temp for the rest of the day to temps well above 32 degrees. Weird ..... Of course it doesn't mean that any of it will come true. As KM typed beautifully, weather happens in the atmosphere, not inside computers. But methinks that all of you snowfans are going to be very disappointed again if you live anywhere in the Roanoke Valley or NRV, unless you have 3000 feet of elevation (and perhaps even there will be no good) or more ....
Comment by Doug Griggs — January 26, 2009 @ 9:07 pm
Actually, elevation won't help there be more snow when there is a warm layer aloft ... it's not unheard of in a warm air advection situation for somewhere like Mount Rogers (5,700-plus feet) to shoot into the 50s while Roanoke is hanging near freezing ... one system in 2007 brought freezing rain to Bent Mountain but mostly sleet to the Roanoke Valley, as the precipitation had more time to freeze solid falling to a lower surface ... the atmospheric profile for an elevation snow event is very different than for a freezing rain event.
I would take the TWC numbers with a grain of salt, as they are computer-driven and not adjusted for local geographic quirks.
Comment by kevinmyatt — January 26, 2009 @ 9:15 pm
I was out for about 2 hours and the precipitation area has really exploded in that time back in Missouri and Arkansas (where my parents will be getting a big ice storm tonight), even spreading about a third of the way east into Kentucky. These kind of overrunning setups often develop rapidly, where there can be nothing anywhere close on radar and then 3 hours later the local radar is covered solid. Looks like we're headed for a sunrise arrival, give or take a couple of hours.
Full national radar in high-def here: http://radar.weather.gov/Conus/full.php
Comment by kevinmyatt — January 26, 2009 @ 9:22 pm
I just checked the evening balloon sounding out of Blacksburg, and as of 2 hours ago the temperature was below freezing from just above the surface to the stratosphere which would be a snow profile ...it's just barely below freezing, though, in the lower mile or so ... it stresses the need to get some moisture in here quickly if you want to see some morning snowfall before the muck and rain set in ...
Comment by kevinmyatt — January 26, 2009 @ 9:45 pm
So, with that information, what are your current thoughts on this?
I'm thinking a bit of snow and then freezing rain all day.
Comment by Snowless in Roanoke — January 26, 2009 @ 9:48 pm
Kevin,
Where would I look for classes pertaining to weather in the NRV area?
Comment by Angela — January 26, 2009 @ 9:52 pm
I am more concerned about the ice storm threat than I was earlier. I think snow will last less than half an hour and turn to a couple of hours of sleet/snow/freezing rain mish-mash before going all freezing rain/rain. We'll see more snow if a solid area of precipitation arrives on our doorstep in the 4 a.m.-6 a.m. timeframe, but I'm thinking it doesn't start in earnest until about 7 a.m. or 8 a.m. If I'm right about that, it won't make the school superintendents happy trying to make decisions.
Comment by kevinmyatt — January 26, 2009 @ 9:57 pm
If I were in charge of Roanoke COUNTY schools, I would definitely impose a day off. Better to put up with a few ticked off parents having to scramble to arrange child care than to risk a bus accident on one of the twisty steep roads, such as those in our neighborhood. Roanoke city is different. They have had zero days off so far, so they can definitely afford to take one, but the number of ticked-off parents would be much, much higher. Probably go with a 2-hour late arrival decision.
Comment by Doug Griggs — January 26, 2009 @ 10:30 pm
Kevin, I realize that you have access to far more weather models and info than me, but I am going to go against you for tomorrow. I bet that after 8:30 AM I see nothing but very cold rain on my postal route, except for some occasional sleet pellets.
Comment by Doug Griggs — January 26, 2009 @ 10:36 pm
May depend on what part of your route you're on ...
There isn't any kind of model out there that can tell exactly what the atmosphere will look like from surface to stratosphere 8:30 a.m. tomorrow ... so you could be right ... but don't only go by what it is outside your door right now, because what's going on in the thousands of feet above us is more important
Comment by kevinmyatt — January 26, 2009 @ 10:44 pm
at this point, I'm just going to try and sleep.
I hope we can get a good idea of what's going to happen before 5 A.M. I'm not going in to work if there is ice on the roads. Period. I'll just have to use a sick day.
Comment by Snowless in Roanoke — January 26, 2009 @ 10:50 pm