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My instincts have been not to let go of the Monday-Tuesday snow possibility entirely just yet, and some new computer model runs late tonight have confirmed that. They are showing the possibility that precipitation -- first rain, then snow -- may develop over the area Monday afternoon and evening as upper-level disturbances move through the region on the way to spinning up a potent low-pressure system off the coast to our east that could become a bigger snow maker in the big cities to our northeast. If these models are on to something, it is worth following the next 24-36 hours to see if it might even develop farther south and west. The major obstacle to snow in our region would be the milder air that will build in Sunday and Monday, with highs possibly topping 50. A stronger low pulling in cold air more rapidly could offset that on Monday evening, but with a weaker system, the moisture might move out before the cold air moves in.

It remains something to watch, not something to hype.

Looking at a few discussions and model runs tonight, I have to say I'm no less confused, and quite a bit more flummoxed, about next week's system than I was. I'm kinda disappointed this wasn't settled in my two days of infrequent computer access. (I say that tongue in cheek. I knew it would be quite a bit more complex when I got back to it).

I'm pretty convinced this will NOT be anything resembling a blizzard, as there simply isn't enough cold air already in place ahead of the storm, and the strength of the storm certainly doesn't look as impressive as it did a few days ago. Really, I'm not surprised by that ... there is a reason true monster snowstorms are rare, and I didn't really expect this one to be even a quasi-1993 Superstorm. I'm not quite ready to bail out on the idea of snow for Southwest Virginia just yet because so much is unsettled. A more eastern track, as the Hydrometeorological Predication Center favors, would allow more cold air to filter southward behind the storm.

I say give it another 24 hours to see if there is anything resembling model consensus. Though the weather service in Blacksburg has bailed on its "snow likely" forecasts for our area, I wouldn't be surprised to see some snow in the area late Monday or early Tuesday. But a major snowstorm, as looked at least possible a couple of days ago, is doubtful.

Let's take a deep breath now that the Great Muck Storm of 2009 (a lot more muck for many others than us) is moving out, hammering New England on its way, and a few days of seasonable cold settle in. There could be a couple of waves of mountain snow showers with weak disturbances each of the next two nights, but nothing big.

The next big-ticket item on the table is the potential for a strong low pressure to develop in the Gulf of Mexico or near the Southeast U.S. coast early next week, deepen quickly and ride northward somewhere near the East Coast. Some variation of the scenario is shown by multiple forecast models, and considering the pattern, with waves of energy diving into a deep jet stream trough over the eastern U.S., it is certainly plausible. But it's all about the details, as this system showed, and we're a few days out from getting much of a handle on those. Whether the storm will in fact develop is the biggest detail, of course, and if it does, its exact track would be huge in determining its impact.

This would be a very different animal than the ugly beast that just wallowed across the country. At its greatest potential, this would be a beautifully but powerfully wound-up cyclone that could be almost like a winter hurricane, known as much for its wind as the quantity of rain and snow it puts out. The reality will probably be something less, but could still be potent for somebody. Whether this system finally gives Roanoke our first 1-inch snowfall of 2008-09, even muddled by rain, or (gasp!) has a shot to crack our 13-year hiatus of foot-deep snows ... well, let's just take a deep breath and continue to be as skeptical as the recent winters' weather patterns have deserved, until there is reason to prove otherwise.

I've been watching this storm system on the computer forecast models since early last week. I knew from the outset that it wouldn't be a nice, fluffy snow for our region, but would be a mess. I thought there might be some snow, but that didn't happen. Instead, we endured a day of 34-degree rain in Roanoke, and now we're getting freezing drizzle late at night. Some places around have it much worse, with ice having collected all day. Others have yet to see any ice. But everywhere, it's a cold mess.

It could have been much, much worse. My parents in northeast Arkansas are suffering that region's worst ice storm in a generation. I don't even have contact with them right now, as the power and phone service have blinked in and out. Last I heard, large limbs were crashing down all around, and the Weather Channel has even reported live from my hometown of Jonesboro tonight, showing trees coated with thick ice hanging at the point of breaking. Click here to read more about the severe ice storm in the central U.S.

Please don't be too cocky in the morning when you first head out, just in case there is lingering ice. Just because it wasn't icy today doesn't mean it won't be in the morning. I just found icy spots on the asphalt pavement of a parking lot here in south Roanoke County.  Light freezing drizzle and possibly some harder freezing rain will continue overnight.

The good news is that a sweep of warm air on gusty southwest winds will finally arrive during the day Wednesday as the low pressure system moves northeastward to our west, and we might even hit 50. It will quickly melt any ice that has accumulated, and will signal that this very unpleasant winter storm system is moving on out.

This system was a disappointment to anyone wanting snow, but the chances of more than an inch or two of snow for our region were never that good, anyway. More importantly, though some of you have enough ice to break some small branches, we dodged a major ice storm. I dislike 34-degree rain and don't care for freezing drizzle, but the moisture helps with our drought, and it hasn't left the region dark and cold with trees crashing.

UPDATE 6:10 PM: The winter storm warning has expanded southward to include Bedford County and the Lynchburg area, where ice has accumulated much of the day. Temperatures are dropping in the Roanoke Valley and patchy ice has developed on trees and exposed objects in some areas. Spotty ice may become more widespread as slightly colder temperatures work in for a time overnight. END UPDATE

You don't have to go too far off the floor of the Roanoke Valley to find some light ice accumulation. I drove up to Happy Hollow Gardens, a park not far from Valhalla Vineyards on Mount Pleasant Road in southern Roanoke County, and found a winter wonderland of ice-tinged trees and fence railings. (Click here to see two more photos on the SwoCo blog) Temperatures have been hovering 33-34 along the floor of the valley but have dropped to 31-32 in some of the higher elevation areas just outside the valley. I noticed the ice line was about 1,600 feet, though that's variable, and it's spotty up to about 2,000 feet.  The ice isn't thick enough to cause problems with tree damage or power lines, at least not yet, and I found no ice at all on any roads.

The National Weather Service in Blacksburg isn't giving up on the ice just yet ... in fact, the same advisories and warnings remain in effect with just a few western counties like Pulaski sliced out. If you've followed the temperatures today, you may have noticed that places like Dublin and Bluefield, W.Va., have shot into the 40s while it remains near or slightly above freezing at Roanoke and Lynchburg. Two different forces are at work this afternoon and evening. One is warm air advection being pulled primarily to our west by the developing low pressure system much farther west. The second is a slight tendency for high pressure to wedge in cold air to our east. We're caught between those forces today. The weather service is actually hinting that temperatures may drop a few degrees from Roanoke eastward and northeastward because of the wedge. If that is the case, we might still have some ice to deal with overnight in many spots before the warmer air eventually wins the battle.

Precipitation is moving in rapidly into Southwest Virginia this morning, and so far, it is mostly wet, with a little sleet thrown in. That said, it is close enough that someone, somewhere in the region is probably getting ice, so be vigilant driving this morning, especially on bridges and overpasses, especially traveling north. Temperatures are hovering a few degrees above freezing at Roanoke and Blacksburg, and the question now is whether the evaporation cooling from precipitation will be enough to pull temperatures back to freezing. Blacksburg's dew point is already around 30, so there's not a lot of room for cooling there, while Roanoke's is still near 20, giving much more room for temperatures to drop to meet the dew point. It will be a touch and go situation for a few hours to see if the mercury settles back to near freezing or hovers just above it. If layers of air cool aloft, it's not unheard of in these situations for a brief but heavy fall of sleet or snow to temporarily interrupt the rain, but there is no doubt the upper layers will be considerably warmer than the surface much of the day and the primary precipitation type will be liquid. Whether that liquid freezes on objects near the surface depends on a razor-thin margin of how much it cools in the bottom few feet of the atmosphere, called the boundary layer. That answer will vary with elevation and location across the region.

National Weather Service-Blacksburg radar

Latest warnings and advisories from NWS-Blacksburg

Well,  here it comes, pretty much right on schedule. The regional radar composite at the right shows abundant precipitation spreading across Kentucky as of shortly before 1 a.m., heading our way rapidly. For a more recent image whenever you are looking at this overnight or early in the morning, click here for a series of regional and national radar images, or you can click here for local radar from the National Weather Service in Blacksburg (the radar dome is located on Poor Mountain in Roanoke County).

The big question is what kind of precipitation it will be when it arrives, and then throughout the day. Temperatures in the low to mid 30s with dew points in the low to mid 20s would tend to indicate that as the precipitation falls this morning, evaporational cooling will take us down to the freezing mark. Very early in the event, it may be cold enough at all layers for snow, but that shouldn't be more than an hour or two. If heavy precipitation falls very fast early in the morning, we could pick up a few inches of snow. More likely, the snow will go quickly to sleet with less than an inch in the Roanoke area (more to the north), then to freezing rain or rain, depending on exactly where the mercury lands at your location. Whatever the temperature is when the evaporational cooling levels off, it may not change for several hours, and if it's 32 or below, ice accumulation could be a problem in your local area.  It could vary across the region, even within a few miles in some areas, but the National Weather Service in Blacksburg is continuing to fly winter storm warnings for the counties north of Roanoke and winter weather advisories along and just south of the Roanoke-Blacksburg-Lynchburg corridor (U.S. 460).  Click here for the latest warnings and advisories.

While roads may get very treacherous in some areas, the biggest concern with freezing rain when it's in the low 30s is collection on trees and power lines. If several hours of freezing rain occur, there could be power outages in some locations. Eventually, temperatures will likely rise above freezing, but whether that occurs later today, tonight or Wednesday will vary across the region, and will determine much about how severe the ice is in your local area.

As precipitation begins and conditions develop, please leave a comment below about what it is doing where you are at (I will have to approve those for publishing when I get back to this in the morning). Remember that just because it may not be icy on your doorstep doesn't mean that everyone in Southwest Virginia is missing the winter storm.

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.

Don't be surprised to see a few snowflakes drifting down this morning from the New River and Roanoke valleys northward ... I saw a few when my dog insisted on a 6 a.m. walk. A weak disturbance is squeezing out some light snow as it zips through the region this morning. The radar echoes will probably be a little overblown (more is falling than actually reaching the ground) but a dusting to locally up to an inch is not impossible this morning, especially in mountain areas west of Roanoke. This round of snowflakes should be over by noon.

The bigger issue, of course, is the Tuesday situation that still has a winter storm watch flying for Blacksburg, Roanoke and points northward (plus Franklin and Floyd counties to the south). Forecast models are continuing to trend a little warmer as overrunning precipitation is swept northward by a fairly weak low pressure system early Tuesday. If that trend proves to be real, rather than a figment of silicon imagination in a computer, then the likely result would be less snow and sleet and more rain or freezing rain on Tuesday.  Seeing as almost everyone doesn't like ice, a narrow escape from the ice storm is a growing possibility for many areas (probably not the usual cold spots that get ice in borderline situations) if the warm trends continue. But there is considerable doubt about it, as models often overestimate surface temperature in a cold air damming situation, though this one is definitely not a strong setup. And how much evaporational and/or dynamic cooling will there be with the onset of precipitation into what at first will be cold, dry air? The Hydrometeorological Prediction Center continues to show a slight risk of signfiicant (.25-inch) ice for most of Southwest Virginia, with a moderate risk north of Roanoke and Blacksburg. So let's keep the vigilance for Tuesday morning, but be aware that it might end up being mainly a cold rain for many.

The newest wrinkle is the possibility of some snow on the backside of the storm by Wednesday as cold air moves in behind the departing low. The Hydrometeorological Prediction Center's snowfall forecast map for Day 3 (Wednesday morning to Thursday morning) reflects that possibility, with a slight risk of 4-plus inches extending to just east of Roanoke and a moderate to high risk in the more mountainous areas to the west and southwest. Some of this is upslope-enhanced, but there may be enough moisture behind the storm with a new push of cold air for snowfall in some parts of the area come Wednesday. Beyond the regular upslope stuff, the National Weather Service in Blacksburg isn't really biting on this yet, and I would say I'm skeptical, seeing as we don't get many significant snowfalls out of rain-changing-to-snow situations. But it's definitely something to stick in the back of our minds as we keep our focus on the Tuesday ice potential.

 The National Weather Service in Blacksburg is taking no chances with the upcoming winter storm potential, issuing a winter storm watch from midnight Tuesday through Wednesday afternoon for most of the New River Valley and all of the Roanoke Valley. South of Interstate 64, it is mostly an ice-driven winter storm watch ... 1-3 inches of snow is expected, followed by a heavy glazing that could top 1/4 inch. Along and north of I-64, it is mostly a snow-driven watch -- 3-7 inches are expected, with a thinner ice coating on top. These amounts are highly changeable depending on how deep the cold air is, how fast the moisture arrives, and how heavy it falls. There's no use going into all the possible scenarios right now beyond saying that a wintry mix of snow, sleet and freezing rain appears very likely starting overnight Monday and continuing through much of Tuesday and possibly into Wednesday in some areas, with precipitation type leaning more toward snow early on and more toward sleet and freezing rain as time goes along. Eventually, enough warm air should move northward to change it to above-freezing rain almost everywhere by Wednesday afternoon (as early as Tuesday night in some places)... but keep in mind that cold air masses are often stubborn to leave in a situation where an early ice/snow pack is laid down.

I'll keep a close eye on this and get back with some more possible scenarios as time gets closer. My thanks to everyone who has left a comment since I last posted last night and I will get to your questions.

The latest from the National Weather Service in Blacksburg