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Now that it looks more and more as if the weekend system will brush us to the west and north like so many have ... and quite possibly rain on us a bit as milder air is pulled north ahead of the system on Saturday ... let's look at what's down the road beyond the weekend. If the Climate Prediction Center is right, it will be warmer than normal in both the 6-to-10 day and 8-to-14 day timeframes, which will take us through most of the first week of March, the start of spring on the meteorological calendar. A zonal pattern with strong west to east flow from the Pacific is expected to take hold after this mini-shot of Arctic air lets go early next week. That kind of pattern brings in mild storm systems and races them across the country. (I didn't post them here, but the precipitation maps are green, suggesting the potential for needed wetness ... but still even that pattern favors the Ohio Valley and Northeast more than our region).

Does this mean winter's over, at least in terms of ANY chance of snow? It's quite possible that we have seen the last significant intrusion of Arctic air of the season, and possibly, that this weekend's likely non-event might be the caboose on the end of winter storm "threats" (using the term very loosely) for 2008-09, none too soon for many are growing tired of these chilly winds that scatter few if any snowflakes. More likely, though, there will be at least some recovery of cold air from Canada after the upcoming mild period.  March occasionally dumps a surprise on it ... and in this winter, it would be a surprise, indeed.

I say we get at least one more snow threat in March. We've still got to play the ninth inning.

While the familiar upslope snow machine has triggered some winter storm warnings and advisories over in West Virginia ... and a few flakes will probably blow over this way too ... the next meteorological mess to sort out is this weekend. There are two versions that forecast models have been kicking out: (1) Clipper system dives through the Ohio Valley to the Northeast; maybe we get some snow, maybe we get some rain changing to snow showers, or maybe it jumps us entirely; (2) the clipper breaks into two, with one piece pretty harmlessly passing north of us, while the other digs all the way to the Gulf of Mexico, fires up a strong low pressure system that climbs the coast and gives much of the eastern U.S. south of Philadelphia its first real winter storm of the season.

Now, if you've followed the weather even halfway this winter, you know automatically that option 1 is far more likely than option 2. That's what's been happening all winter! But option 2 has showed up on enough models enough times that it can't be written off entirely.

This is the winter of 2008-09 ... I'm sticking with Door Number 1, and probably more of a rain showers turning to snow showers scenario.

I wrote this morning about bright-banding on radar, when heavy wet snow or sleet reflects back so much radar signal that appears to be heavy thunderstorms. Well, heavy echoes are on the National Weather Service-Blacksburg radar again now, but this time, they are very real thunderstorms. Some hail is even possible, primarily west of I-81, as warmer, moist air that has worked in bubbles up into cold air aloft. The situation is so serious in states not far to our west, with greater instability, deeper moisture and more wind shear, that a series of tornado watches have gone up. And new winter storm watches and winter weather advisories are out in West Virginia for the upslope snow machine that will kick in by Thursday. It's a dynamic storm system with a little of everything.

UPDATED 9:30 AM: If I saw this radar shot and didn't know anything else about it, I would presume there were strong to severe thunderstorms lined up from Roanoke  into North Carolina, possibly with hail and flooding rains. It even has a "bow echo" type appearance common with thunderstorm lines that produce violent winds. But in fact, these heavy echoes are the result of "bright banding," a  phenomenon that occurs when radar beams reflect off sleet or especially heavy wet snowflakes (snow clumps would be more accurate, as they are composed of many flakes partially melted into each other) aloft. Some of this sleet and wet snow has reached the surface for a time in parts of Southwest Virginia as temperatures hover near to a few degrees above the freezing mark. Temperatures have been pulled downward a few degrees this morning not only by evaporational cooling, or the cooling produced by precipitation evaporating in drier air, but by dynamic cooling, cold air aloft pulled downward by falling precipitation. Later today, the milder, moist air being pulled northward by the low in the Ohio Valley will win out, and temperatures will rise enough so that everything is rain. But until that time, some locations could get a quick slushy/white ground with a quick burst of heavy sleet or snow underneath a "bright band." END UPDATE

Don't be suprised to see/hear sleet pellets pecking on your windshield heading to work this morning, and possibly even some wet snowflakes, but the majority of the precipitation today will be rain. If it gets heavy enough early today, there could be some slushy accumulation with temperatures near or slightly above the critical threshhold of 32. Some bridges/overpasses/higher elevation areas could have slick spots. The low-pressure system causing this precipitation is tracking to our north, so it will draw up warmer air throughout the day, and everything should be rain by about noon, if not earlier, as temperatures climb toward the 40s. Colder air will sweep in behind the low as a cold front pushes through overnight into Thursday, and there will probably be some mountain snow showers, a few of which may spill into the New River and Roanoke valleys. But once again, it appears we will dodge anything remotely resembling a winter storm.

Please drop me a comment if you note anything of significance this morning in regard to wintry precipitation.

Occasionally, we get a winter weather situation where warm air and moisture are rushing in ahead of a storm system, but at first, they hit a wall of cold, dry air. That is what will be happening overnight into Wednesday. That it will warm up and rain after a cold night is almost inevitable. But will the moisture arrive fast enough for some wintry forms first? Sleet and snow are a possibility late tonight and early Wednesday as the first waves of moisture arrive in cold, dry air, which will likely trigger evaporational cooling that could keep the atmosphere chilled enough from cloud to ground for a little while to even produce snow, especially from the Blacksburg-Roanoke-Lynchburg corridor northward. Sleet will be the more likely widespread form of precipitation, though, until it all goes over to rain. The tricky thing is that IF this wintry scenario develops (a very big IF this particular winter), it could occur to create slick spots for morning traffic. By early Wednesday afternoon, anything wintry that falls should nothing but another weird little memory in a very strange winter.

Precipitation is beginning to show up in the states to our west, but it will probably be many hours before it arrives here. And most of what would affect us hasn't even developed yet. Click here for latest national/regional radar.

The tiresome winter of 2008-09 is trying to produce another tiresome winter weather flirtation for Wednesday. The next storm will be centered in the Ohio Valley, so there is really no threat of a winter storm from it ... but there may be just enough cold air banked against them mountains upon the arrival of the first waves of moisture it flings out that a mix of snow, sleet and freezing rain is possible early Wednesday on the front edge of the precipitation. But then, it will warm up, turn to rain (except for maybe a few stubborn elevated valleys that hang on to freezing rain a while longer) and then, at the end, the cold front goes through, chilly northwest winds kick up, and the mountain snow shower machine kicks up for much of Thursday and Friday.
 
Same song, I've lost count of how many verses now.
 
There still is an Alberta clipper type system to keep an eye on for Saturday. On many model runs, it looks pretty potent and dives pretty far to the south, but we've seen what these tend to do this year. That will probably be the last shot at snow this month, with a mild period lasting at least a week to follow. 
 
I wrote in Monday's Weather Journal column that winter was down to its last at-bats. For the record, I think we have 1 out in the 8th inning, with 2 batters up this week. There will probably be a ninth inning in early March, but by then, spring has its ace closer on the mound, and it's hard for winter to get a hit. Sometimes there's a home run ... more often, strikeouts for snow fans.
 
I keep expecting a weird ending, whatever that may be.

Three things to watch this week, weatherwise, in Southwest Virginia:

(1) Disturbance moving just to our south Sunday night and Monday may trigger light rain or snow as it whizzes by, on its way to spinning up a rather substantial low pressure system off the coast to our east. Don't expect much out of this, as temperatures will be marginal and moisture limited. The best chances for measurable snow will be just to our south in the mountains of North Carolina.

(2) A stronger low will be crossing the country the next few days, moving through the Ohio Valley and toward New England by Wednesday and Thursday. The track will likely be too far north for wintry precipitation in our area, unless it's brief freezing rain at the very front end of the storm in a few deeper valleys. In fact, it might pass so far north that we get a brief shot of milder air in the 50s. But once it passes, the storm will spin in lots of cold air, getting the northwest flow/upslope snow machine going again in West Virginia and bringing temperatures down in Southwest Virginia to below-normal levels for next weekend into at least some of the following week.

(3) There is some indication of a storm system moving near or even south of our region by the weekend. The track and the depth of cold air would determine what, if anything, that system can produce. It's too far out, too iffy, and too dependent on everything else that occurs this week to get into many details.

A visit to the Roanoke Times roof garden earlier this evening resulted in an unexpected treat. The late-day sun, out of view to my left, was refracting through high ice-crystal clouds known as cirrus, creating a phenomenon known as a sun dog. A sun dog almost looks like a second sun, with a slight rainbow effect as light rays are scattered by ice crystals.  So the photo at left may look like the sun itself somewhat obscured by clouds near the horizon, but fact, it is the sun's light some distance north of the setting sun. (full-size version of photo linked here)

Colder than normal. Wetter than normal. That's what Thursday's maps from the Hydrometeorological Prediction Center show for our region in both the 6-to-10 day and 8-to-14-day periods. (Click for: 6-10-day temperature, 6-10-day precipitation, 8-14-day temperature, 8-14-day precipitation). It's really the first time all season that the cold and the wet have lined up on extended forecasts for so long a period.

Does that mean it will definitely snow across Southwest Virginia? Don't be silly, this is the winter of 2009, the great tease. This could just mean we're in for several cold rains. But these maps do signify a weather pattern that yields more of a chance than any we've seen this entire winter for a significant amount of the s-word sometime in the next couple of weeks. Two of the three major elements will be present that produce a higher threat of wintry precipitation in our region: a strong southern branch of the jet stream, ushering in wet systems from the Pacific, and high pressure blocking in the north Atlantic near Greenland that will force the jet stream southward over the East, allowing cold air in as the storm track is pushed south. Missing, at least at first, will be strong high pressure near the West Coast to firmly drive Arctic air southward. We will be dealing with cold-but-not-frigid Canadian air rather than the much more blistering Arctic air like we had in January.  So cold air depth is the major question with any system as we enter this new pattern ... but how often  over the years has it been that we've scored a bigger snow with a wet storm and temperatures near freezing rather than a dinky disturbance and temperatures well below freezing?

A series of systems will be shooting at us from the Pacific over the next several days, starting on Saturday. This will be associated with a cold front that will get us back to seasonal temperatures (highs in the 40s to low 50s, lows in the 20s and 30s). The next system on Sunday night and early Monday is depicted on some model runs as a potential snow maker, though most forecasts are leaning toward rain as there are doubts about surface-level temperatures.  A bigger storm may develop about midweek, and it will all be about its track and the depth of cold air at the time of its arrival. The lean right now is a storm going north of us that could be ice or sleet if there's sufficient cold-air damming, more rain if there's not. Details like that are highly speculative at this point, as we've all seen this winter.

The midweek system, whatever its direct effects on us, will probably rearrange the pattern to drive even more cold air southward into the East, and that cold air may hang on for the rest of the month, maybe even into early March. And there will probably be some more Pacific storms behind these.

So, snow fans, the season is on the line for you in the next 2 weeks or so. If we don't get snow out of this pattern, I think the march toward a historic low-snow winter for Roanoke will be locked.

In Friday's Weather Journal column, looking at Thursday's winds but primarily reviewing the Feb. 10, 2008, windstorm, I only got to use a very small portion of my Q&A with Stephen Keighton and Phillip Manuel of the National Weather Service in Blacksburg. If you are interested, I have posted the entire e-mail conversation we had regarding the Feb. 10, 2008, windstorm in the extended entry below (click on "Read More" if you are in full blog mode). Read more »