www.roanoke.com

Winter is getting an early start in the Rockies and High Plains, where "the biggest snowmaker to hit Colorado's Front Range in October since 1997" is under way. Click here to read the Associated Press article. This same powerhouse low could become a severe weather producer the next couple of days  and also spread more heavy rain through the central U.S. It will pull a Pacific cool front through our region by the weekend, triggering a few showers around Halloween.

The storm that formed over Vinton and eastern Roanoke County on Wednesday was fairly impressive. It appeared to develop a rounded base and some lowerings for a short time, as this photo I took looking north from Buck Mountain Road in south Roanoke County shows (lowered cloud bases are hanging over the ridgeline). There may have been some weak rotation in the storm for a time, and I have got at least one report of wind gusts that would have been near severe level (58 mph and higher). The storm spread westward and southwestward dumping heavy rain on much of the Roanoke Valley, with a flash flood warning posted for Roanoke city for a time. While the Roanoke Regional Airport only received .33 inch of rain, a couple of automatic gauges in eastern parts of the Roanoke Valley quickly gathered rainfall near or over an inch. I was out in some of that, with water ponding on the roads along Franklin Road and into downtown. Other parts of Southwest Virginia, from the New River Valley west and south, also saw some locally heavy downpours on Wednesday.

With east and northeast winds pushing low level moisture against the mountains today -- a "wedge" effect -- we're likely to stay too cloudy and cool (low 70s for highs, at best in Roanoke) for much in the way of big storms today. Scattered light showers and some patches of drizzle will be more the mode today. If skies clear tonight, it could be rather chilly with an air mass pushed in from the northeast, as lows in the upper 40s to mid 50s would be widespread.

An upper-level low slipping southeast from the Ohio Valley will likely trigger widespread showers and thunderstorms today, especially from the Roanoke Valley westward. The atmosphere is pretty thick with moisture, so locally heavy rain will be possible, as will gusty winds and some hail in the stronger storms, especially with a pool of cold air aloft that these storms may be able to bubble up into.  The best chance of hail or high winds is over far Southwest Virginia no farther east than Wytheville, and not enough to rate a slight risk of severe weather (only a "See Text") by the Storm Prediction Center. 

The coastal low is still there, though more offshore and weaker. Nonetheless, it is likely to affect our weather Thursday and Friday, as it meanders a bit back to the west, by pulling cooler air from the northeast into our area. Though the forecast for Thursday now is for highs in the 70s, it might not get out of the 60s if a thick bank of moisture, fog and clouds develops.

Speaking of the coastal low, David Sobotta, who goes back and forth between homes on a mountain overlooking the Roanoke Valley and the Crystal Coast of North Carolina (he has a local blog, View from the Mountain), measured 8.3 inches of rain on Labor Day from the coastal low. Here is a blog post he made about that.

The good news is that the National Hurricane Center no longer considers this low even a slight tropical development risk ... and distant Hurricane Fred is not going to get close to any significant land mass before sputtering out in the high-shear upper winds that are killing Atlantic tropical systems left and right this season.

Southwest Virginia is straddling the southern edge of a large slight risk zone for severe weather stretching all the way to New England, according to the Storm Prediction Center. A rather strong  cold front will push into extremely humid tropical air mass that has produced daily (but streaky) "monsoonish" type rains in our area. The questions for our immediate area upon which our risk of severe weather hinges are (1) how much sun will break through morning clouds and fog to create instability? and (2) how far east will the front be when maximum instability occurs? The more sun, the warmer it will be, and therefore the more unstable it will be and the greater the potential will be for severe thunderstorms, with damaging winds as the primary threat. But if the front pushes a little farther east than expected, the main focus for severe weather will shift east with it into central and eastern Virginia. The greatest threat for widespread and violent severe weather will be farther north, from northern Virginia to New York, where shearing winds will be greater and more likely to produce storm rotation.

In any event, at least another showery day with locally heavy rainfall is likely again today. Saturday, too, could be a little showery, as the front may be unable to push all the way off the coast as Hurricane Bill well off shore resists it. But then, from Sunday into the middle of next week, the cool, dry pattern I write about in today's Weather Journal column sets in. The overall pattern will last much longer than that, but there may be a hot day or two late next week before a reinforcing cold front arrives.

Latest National Weather Service-Blacksburg radar

On Tuesday I posted a non-tornado photo from just east of Roanoke near Explore Park -- scud clouds being pushed along a ridgetop by outflow winds. Danny Vinson e-mailed me a photo of something similar today at Blacksburg, taken by his-co-worker Ross Spoon. This, too, has a tornado-ish appearance, but is really steamy scud clouds lifting upward toward a somewhat lowered cloud base. No rotation, just sort of a "funnel."

While no tornadoes have been reported in today's storms, there has been some wind damage and street flooding in Franklin County, which experienced a strong thunderstorm this afternoon.  With tropical moisture firmly in place, daytime heating and some upper-level disturbances preceding a rather strong cold front on Friday, additional thunderstorms will be likely intermittently over the next 48 hours. Locally flooding rain will be the biggest threat, but some high winds can't be ruled out.

From an overlook just off the Blue Ridge Parkway near Explore Park east of Vinton, I watched a storm go across the Roanoke Valley this afternoon, and shot several frames (click here and here for examples) that show a funnel-like extension reaching a ridgetop. It has wider base near the surface similar to a debris cloud that could be spun up by a funnel. So was it a tornado?

NO!  it was not in any way, shape or form a tornado, but rather scud clouds being pushed along by the outflow boundary of a thunderstorm. There was no rotation, and what's more, the wider piece along the ridgetop actually formed independently before the clouds above connected to it. It was one of those foggy kind of low clouds that form in the mountains from evaporation of rain, and eventually the lowering at the front of the outflow connected with it as they both blew along in front of the storm.

It was a picturesque storm that produced some photogenic scenes as it brought heavy rain and briefly gusty winds to the valley this afternoon. But it wasn't a severe storm, and it certainly didn't spawn any tornadoes.

We got a little taste of thunderstorms on Tuesday when an outflow boundary from more intense and widespread storm action to our west blew into the area, interacting with daytime heating and increasing humidity to trigger a narrow line of storms that moved through the New River and Roanoke valleys and points east. Some severe thunderstorm warnings were issued, and there were scattered reports of wind damage in Franklin and Bedford counties. An approaching cold front on Wednesday will provide a bigger trigger for, perhaps, more widespread shower and storm activity. The Hydrometeorological Prediction Center in D.C. thinks widespread rain amounts of over half an inch could occur in our area.  I would not be terribly surprised to see a severe weather risk area raised over us or at least not far away to our west and south on Wednesday ... check the Storm Prediction Center for the latest on that.

Latest National Weather Service-Blacksburg radar

A strong disturbance spinning through the southern states triggered an unusual out-of-season outbreak of tornadoes and damaging winds near Memphis today (tornadoes are more common in January in that region than in late July).  That disturbance will be swinging northeastward overnight and into Friday, with a cold front also dragging through during the day. Showers and thunderstorms are likely to develop Friday morning, and there may be enough wind support this time for some supercells and possibly isolated tornadoes in parts of Virginia ... primarily east of the Blue Ridge, where instability will be stronger and daytime heating will have a better chance to take hold. It's just close enough that it bears some watching in our neck of the woods for a few severe storms, particularly in the late morning to mid afternoon period. A warm, sticky pattern with occasional bouts of storminess in our area is projected to continue through next week.

Instead of a gradual transition from the weekend's mild, dry air mass to more of a showery situation, it happened quite suddenly with heavy thunderstorms moving northward along the Blue Ridge this morning. A flash flood warning is in effect until 1:30 p.m.  for the Roanoke Valley and points southward along the Blue Ridge (western and central Franklin County, eastern Floyd County southwest Botetourt County in addition to Roanoke, Roanoke County and Salem). Reports of water over roads were received earlier by the National Weather Service in Blacksburg from Mudlick Road in Southwest Roanoke and from Virginia Route 116 near the Franklin-Roanoke County line southeast of the city. There was also a report of up to quarter-sized hail at Hollins earlier this morning. Rainfall amounts of 1-3 inches have been reported in Roanoke and central and eastern Roanoke County.

A flash flood watch has recently been issued for most of Southwest Virginia. There will be a threat of continued showers and storms today as moisture continues to converge along the Blue Ridge, thanks to a slow-moving upper-level disturbance to the west and east winds being drawn off the Atlantic up the slope of the Piedmont and Appalachians.

Latest National Weather Service radar

Rainfall totals at remote sensors in the Roanoke area

Rainfall totals at remote sensors throughout western Virginia

The advance of a reinforcing shot of unseasonably cool, dry air into the hot, humid air that moved in on Thursday triggered a round of thunderstorms this morning, some of which were severe. It appears there has been widespread wind damage in the southern half of Campbell County near Brookneal, and the storms continue to march eastward where they may gain strength with daytime heating. Closer to home, here are reports of severe weather (mainly wind damage, with 1 big hail report) turned into the National Weather Service in Blacksburg this morning.

* Burnt Chimney, Franklin County: 71 mph wind gust, roof of trailer ripped off, numerous trees uprooted.
* 2 miles north of Pittsville, Bedford County: Two trees blown down
* 6 miles south of Moneta, Franklin County: Trees blown down at Brooks Mill Road and Scruggs Road
* 2 miles south of Boones Mill, Franklin County: Large tree blown down at Leaning Oak Road and Green Level Road
* 7 miles south of Moneta, Franklin County: Trees blown down at Route 122 between Harmony School Road and Hardy Road.
* Burnt Chimney, Franklin County: Several large trees down.
* 2 miles south of Callaway, Franklin County: Large trees blown down on Old Forge Road.
* 3 miles south-southeast of Boones Mill, Franklin County: Hail 1 inch in diameter.
* 3 miles east-northeast of Callaway, Franklin County: Limb 4 inches in diameter ripped off walnut tree.
* 4 miles north-northwest of Fries, Carroll County: Large trees blown down, Route 94 and Ivanhoe Road.

UPDATE SATURDAY 7PM: It should be added to this report that an EF-1 tornado was confirmed just north of Pittsville in Pittsylvania County, with damage mainly to trees; one tree was blown onto a home.