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Saturday's 80-degree weather in Roanoke is giving way to a short snap of colder weather that could even produce a few snow showers in the highest elevations on Tuesday night and early Wednesday. But after a couple of chilly mornings in the 30s to low 40s, very warm weather is likely for the weekend as upper-level high pressure builds just west of our region. That dome of high pressure will bring June-like temperatures, with highs possibly reaching the mid 80s by the weekend. This appears to be the start of a weather pattern change that will switch us from a mostly cool, moist pattern to a very warm pattern that will, at first, be drier as well. The Climate Prediction Center is suggesting the likelihood of warmer than normal weather in the Appalachians/Mid-Atlantic/Southeast/Tennessee Valley region for the next two weeks. In time, some rainy systems may start eroding the high pressure dome. But for the next several days, after this brief shot of fairly cold weather, expect toasty warmth and drier weather.

As is common, the threat of severe storms today will stay east of Southwest Virginia, where instability will be greater combined with strong atmospheric shear (winds moving different direction with height) as a cold front pushes into the area. There may still be a few showers in Southwest Virginia as an upper-level low moves east, but the bulk of this rain is likely over. It was another good spring rain for the region, as the list of amounts below (click "Read More" in full blog mode) indicate. It appears that we may break out of the pattern of regular rains for at least a few days, with no rain expected after this system clears on Tuesday, through the weekend.

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Saturday is going to be an ideal spring day to be outside, with highs in the 70s and lots of sunshine.

Rain moves back in late Sunday into Monday, as a very textbook spring weather pattern continues. The next storm system in a progressive series of them is currently moving through the central U.S. , triggering both heavy snow in the Rockies and severe weather in the Southern Plains. This storm, powered by a large but slow upper-level low, will gradually make progress across the South over the weekend, with severe weather spreading east into the Tennessee Valley and Southeast. Again, at this point, it looks like our atmosphere will be a little too dry and stable at the outset on this side of the Appalachians for much severe weather (though locations closer to the coast may be more unstable), but another decent helping of showery rain appears to be in the offing.

A clear, calm night will allow temperatures to fall into the 30s over most of Southwest Virginia, maybe even colder in a few sheltered valleys. The result will be scattered to locally widespread frost. With the immediate Roanoke metro area and the counties east of the Blue Ridge now considered to have entered their growing season, a frost advisory has been issued from 2 a.m. to 8 a.m. Friday. Frost will also develop in counties farther west, but those areas are not considered to be in their growing season yet, so no frost or freeze advisories are in effect.

Frost can form on surface vegetation with temperatures a little above freezing because cold air sinks, so the temperature at ground level or on exposed vegetation or objects may be near freezing when the official air temperature at 6 feet above ground is a little higher. Tenperatures will rebound nicely on Friday, likely punching 70 degrees in Roanoke, before another chilly morning on Saturday.

After yet another day that could be showery on Wednesday (April showers definitely living up to their billing this year), cooler and drier weather will move in, with lows possibly in the 30s both Thursday and Friday mornings, threatening frost/freeze issues in some areas. Though the weekend will likely include a warm and sunny Saturday topping 70, the longer-term continues to look rather cool. The Climate Prediction Center colors most of the central and eastern U.S. blue in the 6-to-10-day range, indicating a heightened chance of below-normal temperatures. This likely won't be really dangerous freezing type weather so much as persistent coolness like we've seen lately.

A large high-pressure system building into the West will bring warmer, drier weather across the western half of the nation over the next 1-2 weeks. In time, does that high get broken down by the jet stream coming off the Pacific, does it tighten its hold and turn into a summerlike heat dome, or does it shift east over us toward month's end? The answer to that question could determine a lot about how April ends and May begins.

The pattern of regulary occurring light to moderate rains is poised to continue this week. The Hydrometeorological Prediction Center is forecasting amounts of about an inch in Southwest Virginia over the next 5 days, most of which will likely fall from Monday night to early Wednesday with the next low pressure system and cold front. While another round of severe weather will be possible across several Southern states, a cool-air wedge building in from the northeast against the Appalachians will be even thicker this time, so barring major changes, there will be almost no threat of severe weather in our neck of the woods, and probably not even any thunder. The low moving just to our south will sweep up Gulf of Mexico moisture over the dome of cool air, resulting in what will likely be a raw and dank Tuesday, with temperatures holding in the 40s and 50s.  (Yes, snow fans, this would have been a very tempting scenario a couple of months ago.)

True to the current progressive timing, there is likely to be another chance of rain about Saturday.

It's not really the mountains themselves that do this. 3,000-foot ridges don't shred 45,000-foot thunderstorms. But how the mountains affect the lower layers of the atmosphere can change the entire situation. Cooler, drier air trapped east of the mountains simply didn't have the lift instability (or an overcoming source of lift) to maintain the thunderstorms' intensity as they crossed from west, where the air was plenty juicy and unstable, to east, where it was not. So the mighty storms that spun out deadly tornadoes and large hail in Tennessee, Kentucky and states to the south are little more than a mass of rain now as it moves through our area. There is some heavy rain, likely some thunder, to the south near the North Carolina border, but up toward the Roanoke Valley, mostly light to moderate rain can be expected.

Click here for latest National Weather Service-Blacksburg radar.

Storms can cross the mountains if there are similarly unstable conditions on both sides. In early spring, that's hard to come by, although it does happen sometimes. Later in the spring and the summer, there's more of a chance of that happening. Though the Plains and the South can reasonably expect to be shredded by repeated rounds of severe thunderstorms and tornadoes the next three months, it really isn't the core of our severe weather season yet, as I wrote about in today's Weather Journal column.

It has been a very active night of weather in the south-central United States. There have been numerous reports of tornadoes, large hail and high winds, which of course is not unexpected this time of year. But the bigger story of the night may be the wildfires that have burned down numerous homes in Oklahoma and Texas.  The tornadoes and the wildfires are part of the same storm system. A strong low pressure system winding up has pulled a punch of extremely dry air eastward. East of the "dry line," storms fired in the moist air, spun by the strong winds aloft into supercells with localized areas of extreme spin spawning tornadoes. West of the dry line, fast blowtorch like winds have whipped flames into a fury. Very dry conditions in Oklahoma and Texas have been fuel for the fire, quite literally, as this U.S. Drought Monitor map shows. (Also note the continued lessening of drought conditions in the Southeast, Appalachians and Mid-Atlantic regions)

The same storm system affecting the south-central states will affect our region by Friday evening. As of Thursday evening, Southwest Virginia was on the edge of the slight risk zone for severe weather. The biggest threat is to our west and southwest, but there is some chance a few storms with strong winds will have enough momentum to push into our region during the evening.

If the Hydrometeorological Prediction Center is right in its 6-to-10 day and 8-to-14 day precipitation maps, it definitely looks like all of the South up into our region has turned a corner in regard to rainfall. Many dry areas in the Southwest and Southeast stand to pick up more as a series of storm systems move west to east across the southern half of the nation. There are chances of rain in Southwest Virginia later tonight and again on Friday and Saturday, but the HPC's 5-day rainfall totals map shows pretty light amounts here through early Monday, with heavier stuff to the west that could advance our way early next week.

The cold spell that spat out a few snow showers today will be short-lived, but there isn't any blazing warm weather in sight either. Looks like highs in the 50s and 60s now through the Easter weekend, with occasional chances of rain ... Wednesday night, Friday, and then early next week. At least right now, Easter itself looks dry and seasonable in temperature (around 60 for a high).