Overnight pre-snow thread — speculation turns to expectation
Speculation ends today! We’ll see in a few hours how much snow manages to fall (and accumulate) in Southwest Virginia after days of rampant weather talk on this blog. (Thanks to all who have been a part of it, or merely tuned in to read some of it.)
At this late hour (just clicked midnight) the national radar (linked here) has blown up quite impressively as the upper level low, located roughly over Mississippi, is really starting to dig into some Gulf of Mexico juice. It’s quite apparent we are not going to miss that developing precipitation shield. The question is just when it turns to snow and how much of that snow accumulates. Forecast guidance points to snow spreading from west to east and from higher elevations to lower elevations through the mid and late morning with everywhere in the region snowing by 1 p.m. at the latest.
Looking at this ramped up moisture on radar, I’ve decided to stick with my accumulation guesstimates of 5-9 inches west of I-81 and above 2,000 feet east of I-81, 3-7 inches east of I-81 (below 2,000 feet) to Lynchburg and Stuart on the east side, and 1-3 inches east of there through Martinsville and Henry County. I think most of the amounts will be more toward the lower end of those scales, and especially in the immediate Roanoke area where elevations range from 850 feet near the Roanoke River to nearly 4,000 feet on Poor Mountains, amounts will vary quite a bit with elevation. It will start snowing early, and will stick better, the higher up you go. A few hundred feet can make a lot of difference.
There could be some extremely heavy snow bands that dump an inch or two in an hour. You can’t even rule out a clap of thunder or two somewhere with such cold air aloft and strong lift in an upper-level low. Whether your location has a particularly heavy snow accumulation or not, there’s a good chance you’ll see some heavy snow falling at least for a few minutes.
Whose forecast will be right and whose will be wrong? Some will fare better than others, but the correct answer is that every single forecast will be wrong on amounts, either up or down, for at least some locations. There’s just too many variables at play and inevitably some will not be correctly predicted by the weather service, TV meteorologists, private meteorologists, and even by a certain weather blogger, for particular locations.
Remember that if you comment about your current conditions, please let us know where you are.
January 26, 2011 - 12:20 AM
RSS feed 
33 degrees here in Floyd already. Light rain. Probably be slick in the morning. Thanks for the update.
I want to clarify my previous post. I was not attacking the mets on a personal level nor doubting their forecastin abilities.
Just merely stating some consistency between NWS and TV stations would be nice when it comes to amounts. However, it was pointed out to me that the NWS doesn’t even seem to have a good grip on their forecasts.
So let’s just move along.
Temp is down to 39 at Roanoke Regional.
Singleton says thundersnow can’t be ruled out tomorrow as well.
I’m getting excited again. Time to crank up that hype machine!
Light, steady rain on drive home around midnight in SW Blacksburg. No icing.
If Quagmire finds us in this new post — to answer his question — upper low appears to be in central/northern MS entering Alabama and moving pretty much due east. Rotation more obvious now with stuff in west TN moving south and convective bands in eastern AL/western GA moving north/northeast.
We’re not going to miss it. And it looks pretty stout.
0Z GFS and 0Z RGEM say party is still on for us but it throws heavier precip a little more north now. And here I was about to throw in the towel.
4-8″ still in play for ROA. Waiting for Euro to verify this first.
Kevin, thanks for all the work you put into this. This is my second snow season following your blog. Ive recommended your blog to many people. I’m in cburg and my thermometer is saying 33. It’s very close to the house but I think its pretty accurate at night. I’m hoping the weather stations are playing the sage card and we see the warning go up tomorrow. Hoping to see white in the morning!
One look at the national radar about an hour ago and I knew there would be no towel-throwing from me.
The winds aloft in lower AL, MS and LA are now W-WNW putting the ULL center about Tupelo to Muscle Shoals moving at 080 degrees at 25-30 knots.
Those west winds below the ULL are cutting off Gulf Moisture but if the ULL can speed up a little more, maybe it can draw off the new SC low….
back in a sec…checking on current obs.
080 degrees would be just a hair north of due east.
I’ve never experienced thunderstorm. Out of curiosity what causes this and does it have any impact on the weather? Thanks in advance.
Nashville and Crossville at 37 and 39 light rain.
KBNA showed all rain so far with N winds 14 gusting 20 precip moving NE.
I’m up for the long haul…rough day with death in the family and snow really cheers me up! Go snow!
ULL near Huntsville at 11:00 PM
MSL and all MS stations now have NW winds gusts to 21.
looking for the coastal low…brb
Sean, you’ve never experienced a thunderstorm or thundersnow? Thundersnow is a much rarer subset of thunderstorms. Short answer is that thunderstorms are created by rising air that carries water particles very high, until they freeze into ice droplets that collect static electrical charges as they mix and mingle. These charges then lead to bolts of electricity with opposite charges elsewhere in the cloud or on the ground. The lightning heats the air near it, which expands rapidly then contracts, causing thunder. Thundersnow is rare because you don’t have the hot updrafts you do with summer storms, but can occur when there is strong lift and very cold air aloft, like with this approaching upper level low.
Sorry. Thundersnow. My driod autocorrected for me Haha. Thanks for the information.
new coastal low due east of CHS by 50 miles starting to form.
CHS winds N
SAV NW
Bouy 80 miles E CHS ESE 38-49 KTS
Frying Pan Shoals SSE 40 KTS
What was left of the Gulf Low is being sucked NNE towards ULL.
Sorry for your loss, Scott. I lost my father in late 09.
I think you’ll see your snow.
I am going to sleep at some point, though, for a few hours.
Sean…
try flying in one…I do it for a living
Boone and Ashe Co NC at 33 with sleet. Jackson only TN only observation with snow at 1:00 AM.
It wasn’t the trauma of losing a parent, I still have my father…my mom passed away several years ago fairly young. It was my uncle(dad’s brother) and he was a really good person. Thanks for the condolence. It took me by surprise. I was worried my comment saying come on snow, may have sounded insensitive, but the psychology behind my love for snow has always been that of a comforter and source of extreme joy since childhood. Anyway, thanks for all the wonderful and very well educated posts you do, esp. keeping everyone in line during a the winter season!
Temperature down to 37 here in Old Southwest Roanoke. Wonder what the temps aloft are like.
Your support of the weather blog is much appreciated, Scott.
I’m going to step off for a few hours and let this storm figure out what it wants to do. So I won’t be approving comments for a few hours — but post anything interesting and I’ll get it on whenever it is I wake up again (baby alarm clock can go off at anytime).
Shutting down the Command Post til 07:00
!!!!!
http://forums.accuweather.com/index.php?act=attach&type=post&id=118636
36 degrees in Old Southwest Roanoke with moderate rain.
Euro QPF shows is 0.65. WRF (posted above) is over an inch.
FWIW, the WRF is fairly decent in short range forecasting.
Drove to Galax for a high school basketball game from Liberty, and back tonight. Shew – I’m worn out.
But there is hope
Galax was at 33 when I left, with sleet. They will be all snow.
Lynchburg is around 40, with some additional precip to come through, it will be 34-35 by morning so not worried here.
I heard talk about this thing moving north of us – - just talk, or does that look to be the case?
VERY wet glops of snow mixing with rain here in Old Southwest Roanoke.
Temp is still 36 degrees.
KM: My little one decided to wake me up bright and early. Kind of glad he did. DC is split down the middle right now and I don’t mean politically. Here in Northwest it’s snowing moderately and 35 degrees while it’s raining in Southeast. The rain snow line is literally sitting on Capitol Street which runs north-south thru the city. Interesting stuff!
National radar is beautiful this morning. I can feel colder air starting to filter in down to the surface.
Radar will fill in even more as the day progresses.
Slight risk of 12″+ snows is not that far from Roanoke.
I meant to post this with my previous comment.
http://www.hpc.ncep.noaa.gov/wwd/day1_psnow_gt_12.gif
Judging by HPC QPF and some of the trends I’ve seen… nah. I won’t go there yet. :}
Things are developing rapidly.
National Weather Service mentioned thunder and very heavy snowfall rates in their discussion.
UVV’s continue to be very impressive on the models. And I’m told this is significant but maybe you can better explain what it means.
http://w1.spc.woc.noaa.gov/exper/mesoanalysis/new/viewsector.php?sector=19&parm=pmsl#
Per new snow estimates from LWX discussion and snow graphic map just out, Fluvanna and Louisa (first piedmont counties straddling I-64) to the north moved from a watch to advisory. Map also indicates a very elevation-dependent setup here, just as you indicate in ROA. Next door Albermarle could see 8 on the ridges.
Sleet & Snow coming down hard here in Marsahll,Fauquier County.Temp at 30 now,ground is already white.Gonna be an interesting day. Everyone be safe on the roads.Mike in Marshall
Radar and model trends appear solid for significant snow across the region later today. I am not noticing any stations in eastern Kentucky that have changed over yet, but Jackson Ky office noting Louisville has changed over, and these siutations with an upper low and cold air advection into a surface storm often spread quickly rather than gradually.
Blacksburg office has acatually slightly re-upped snow totals south/southwest of Ronaoke on its new accumulation map back to 3-5 levels — with a little spot of less in Roanoke city lower elevations where the urban heating may limit accumulation.
http://www.erh.noaa.gov/rnk/emer/emer.php
For snow lovers, this may be a tough wait today for the cold air to drain to the surface and the rain to change to snow.
Had to go to work for a few minues. 37 degrees and light rain/drizzle here in Glenvar. Odd it felt almost warm out in spite of the rain. It’s going to be a long day kids! Remember a watched pot never boils.
Hey…I am new to this blog. Bring on the SNOW! I am 50+ yrs old and I love all the banter about weather, snow, amounts, lows, etc. I still love weather extremes like I did when I was a kid. Thanks for all the scientific thoughts and reasoning! Misting here in Bonsack, too warm yet.
FWIW: In Salem, light rain and no ice on the roads. Perfect for swim practice!
I started following Kevin last year and of all the forecasts, his forecasts are about the most accurate that I have ever read. I am up in Waynesboro and usually the weather that hits Roanoke will be upon Waynesboro in a few hours. Right now in Waynesboro it is 37 degrees and drizzling rain.
Just got called into work and looked outside here in western Roanoke county (1/4 mile west of I81) to see a solid dusting on the yard.
Dr. K,
I’m interested to know if the dusting you received was in a higher elevation.
Thanks.
Dr. K: Do you know your elevation there? Also, where are you in relation to other localities?
Kevin, not sure on the elevation here, and now that I am fully awake I looked again and will change my observation to a very light dusting with no visible precip falling. Road is wet..street sign looks a little icy. I am two miles west of main street in Rke Co.
SW Roanoke County near Back Creek Elementary, about 1400 feet, no accumulation as of yet. We are getting a very light precip which is starting to freeze on hard surfaces.
Looks like the cold air is being pulled into storm. In the last hour radar has shown quick transition from rain to snow in comma head of stom. Somebody is going to get some impressive snow totals. Roanoke Co. schools dismissing at noon today. May be letting them go just as the worst moves in.
Good Morning All…35 degrees in Hardy….09″ rain overnight…
Looks like Bedford and Franklin school systems have decided that they are going to try and get their school day in…hope they are making the right decision…may everyone be safe today…
Took a walk in the neighborhood (near Patrick Henry HS in Roanoke) about 20 minutes ago. Foggy with light rain. No sign of snow, sleet or ice. Off to Blacksburg in a little bit.
We’re still well above freezing in New River, 38.2, barely dipped after midnight. Nothing but rain here with the storm, though we haven’t had anything for a while it would appear. Elevation here is right about 1900 feet.
Jumping to a new thread for the morning.
Temperature and dew point continue to creep downward just about everywhere. It’s pretty much on track with forecasts so far.
oh man, Roanoke County is going with a three hour early dismissal today… can you even imagine how my day’s gonna go? A bunch of excited students, very short classes, and no lunch at the secondary schools… Okay, TWLS, we can do this. Snow will come. It WILL snow.
Kevin, when is your next update and also how many inches would we be getting let’s say before 9PM. have to go to work. grand opening and can’t miss work unless it is totally immposible to get out. I go from salem over on 220 by Franklin Road.
At exactly 9:20am, after it was sleeting for a while, it starting sleeting hard like hail and snow started mixing in and within a few minutes changed over to HEAVY wet snow. Still some hail mixing in occasionally and temps rose slightly to 35 degrees (low so far, including overnight, has been 33.2 degrees). Ground is now all white on top of a slushy mix. Not going to be driving in this! I am close to 2800 ft in elevation.