UPDATED 9:15 AM, 7/7: Low 90s are possible on this Tuesday in the Roanoke Valley and points to the south and east. As is discussed below, high pressure is re-asserting control over the Southeast, which will lead to a resurgence of heat in the states south of us. We'll be on the edge of that, which means it will be getting a little hotter than it has been overall, but fronts from the northwest will play more of a role, bringing chance of showers and storms and edging off the heat a bit at times. The next front begins affecting us Wednesday. Any showers or storms that develop on this Tuesday will be of the isolated, pop-up variety, driven by heat and terrain effects -- normal summer stuff. END UPDATE
The evening of July 4 was a great time to catch a break between rounds of showers and storms, but it wasn't the end of rain with this stubborn pattern. An upper-level low over Tennessee will slowly drift northeastward over the next couple of days, and that will spin thick moisture back into Southwest Virginia. Interacting with a slow-moving front wagging back and forth, plus some daytime heating and typical terrain effects, this will bring rounds of showers and storms to the region during the day and night on this Sunday. The chances of getting longer lasting and heavier rain will be better to the west of Roanoke, where a flash flood watch has been issued along and west of the I-77 corridor.
UPDATE 6:20 PM, 7/4/2015: Looks pretty good for the Roanoke and New River valleys this evening, as some drier air is working in from the west after a round of scattered showers. A few more showers will linger to the south, but even those should diminish with the setting sun. Enjoy your Fourth of July fireworks shows! END UPDATE
A warm (but not quite hot), sticky and occasionally (not constantly) showery/stormy run to and through the Fourth of July weekend is ahead. The Inclement Conditions Index for the next 5 days is below.
UPDATE 4:50 PM, 7/2: The murky skies you see today over Southwest Virginia are caused by two sources of particles intersecting over us: Canadian wildfire smoke and dust from the Sahara Desert of Africa. High pressure aloft over the Atlantic has helped guide rounds of Saharan dust westward over the past several days, while the northwest flow that has developed in recent days has brought in the Canadian smoke. END UPDATE
UPDATE 11:15 PM, 6/29: Warmth, humidity and scattered daily storm chances will increase as we move toward midweek ... but again, nothing all that close to what we were experiencing this time 3 years ago is expected. There is a slight risk of severe storms in much of Virginia today. Keep an eye on the National Weather Service at Blacksburg website for any watches or warnings through the day. END UPDATE
The first sign that something is unusual in our weather is the wind advisory that has been posted generally along and west of the Blue Ridge for much of Sunday. We get a lot of these in Southwest Virginia in fall, winter and spring, mostly when strong cold fronts roll over the mountains with much colder weather. That's generally what is happening this time, too, but breezy cold fronts like this are pretty atypical for late June. Some wind gusts may top 40 mph, especially in higher elevations, and with so many leaves on the trees and wet ground in many areas, there may be a few trees blown down. The hot, muggy, showery/stormy weather that has been with us for many days now is being pushed out in favor of a refreshingly dry and significantly cooler air mass. Highs in the 70s to low 80s will be on tap Sunday, with lows falling back into the 50s with maybe even some upper 40s in a few spots west of Roanoke come Monday morning. Perhaps even more importantly, dew points that reached as high as the mid 70s today will fall back about 25 degrees into the low 50s on Sunday. Even if sunshine does help it nudge above 80 in Roanoke on Sunday -- actually higher than the 79 it reached on Sunday with clouds and showers -- air that dry will feel much, much cooler than the muggy stuff we've had for a while.
UPDATE 9:35 AM, 6/27: The flash flood watch has been extended through 6 p.m. with a couple of counties added, including Bedford, for the potential of locally heavy rain with additional storms later today as a low-pressure system and cold front push into thick moisture. This is a FLASH flood watch, which emphasizes relatively short bursts of heavy rain that can flood streams and roads quickly, as opposed to a general flood watch, which emphasizes a long period of widespread rain that can cause large rivers to flood -- so that means amounts of rain will likely vary quite a bit across the area with some spots getting much more than others. There is also a slight risk of severe storms later today, pending whatever daytime heating can occur. Lift and shear are quite strong for late June with the surface low that will track to our northwest. This may significantly raise the risk of supercell thunderstorms with a few tornadoes closer to the D.C. area, but line segments or storm clusters are more likely near us, with locally damaging winds possible, especially if there is any appreciable daytime heating. END UPDATE
One batch of rain and storms has passed through Southwest Virginia this morning. How much the atmosphere can recover from the morning "overturning" -- cooler air aloft brought down to stabilize the atmosphere -- will determine how much of a severe storm risk we have later today, either from new storms developing or pre-existing storms moving in from the west. Sunshine is likely to return at some level by midday, and if so, temperatures will easily climb into the 80s with thick humidity, augmented by evaporation of morning rain. A series of disturbances moving along a nearly stalled front draped near our region should be sufficient, combined with the heat and humidity, to trigger additional storms this afternoon and evening, capable of locally heavy rain, some damaging winds and perhaps some large hail (1 inch in diameter or greater). Atmospheric shear (winds changing direction and/or speed with height) was sufficient on Thursday for some atypically impressive supercell thunderstorms in Southside and Central Virginia. Shear will be near the borderline for supercells (rotating thunderstorms) today as well, but multicell clusters are likely to be the more prevalent mode of thunderstorms.
UPDATE 7:20 AM, 6/26: Waking up to the first of what could be several waves of storms and rain in Southwest Virginia. Morning arrival, at coolest part of day, dampens severe threat with first round. Will post new later this morning looking ahead to afternoon-evening threat of storms and heavy rain.END UPDATE
A fairly weak cold front is pushing through our region this morning. That will usher in some drier air aloft which may quell thunderstorm activity today. Temperatures will only very slightly be affected -- a mostly sunny day will still send highs in the upper 80s and low 90s at most locations -- but the dry air aloft may put a lid on convection. You can't entirely rule out a few isolated showers or storms, however, when it is that hot with surface dew points in the 60s.
UPDATE 9:20 PM: The severe thunderstorm watch has been lifted for the Roanoke/New River localities and northward that were affected. For the most part, storms moving southeast from West Virginia have dwindled crossing into Virginia, likely dried up by downslope westerly surface winds. A few small cells have popped up in late day heat and humidity farther east, including a couple that passed over parts of the Roanoke Valley. The bulk of severe weather this evening has occurred in stronger instability and shear from the D.C. area northward. ... So in short, a hot day, but not as hot as it could have been, with a few evening showers and storms, but not as severe as it could have been. Heat, humidity and chances of storms linger through the rest of the week, until cooler weather arrives for the weekend, likely staying several days. END UPDATE
Pretty much, more of what we've seen. Perhaps a bit hotter and a little less stormy Monday and Tuesday with growing high pressure ... then a little more stormy and less hot on Wednesday and Thursday with a stalling front ... but subtle day-to-day changes can shake this up, as we've already seen at times. Just be prepared for heat, humidity and occasional storms through Thursday. Maybe some pull-back from the heat, at least, beyond this period of the Inclement Conditions Index.
UPDATE 6:25 PM, 6/21: I took a few hours off from weather and the Internet for Father's Day, but a quick glance at radar around 5 p.m. revealed severe storms moving through the Roanoke and New River valleys, so I found an elevated viewing point in southern Roanoke County to get the photo above. There were several reports of hail -- mostly small, but some near 1 inch in diameter -- and gusty winds as these storms blew through. With heat and humidity plus variable atmospheric triggers day to day, storms can quickly develop any afternoon this coming week, with locally strong to severe storms possible. END UPDATE
UPDATE 9 PM: The flash flood watch has now also been lifted for the counties along and west of I-81 in Southwest Virginia. Most of the remaining rain with Bill's remnants is going north of our region, while the severe storms have occurred to our east. The closest wind damage I'm aware of is in Pittsylvania County. Bill has been long-lasting storm that has been a problem for many people from Texas to Maryland, but it's a bit of a bust here. END UPDATE
UPDATE 6:10 PM, 6/19: Wind gust of 67 mph recorded at Roanoke airport with downburst from thunderstorm after 5 p.m., near the time I shot this photo looking in the general direction of the airport from The Roanoke Times roof. That is a severe level wind gust (58 mph is lower limit) even though the storm did not carry a severe warning at the time. The cycle of daytime heating, thick humidity and localized strong to severe afternoon storms will continue through the weekend. END UPDATE
UPDATE 9:45 PM, 6/17: Severe storms blew through the Roanoke area late this afternoon and early evening with some wind damage and power outages, especially in the Vinton area. I was out much of the day in eastern West Virgnia, but actually saw some interesting storm structure on the early stages of the cells that would ultimately affect the Roanoke area. We may have more rounds of storms in the days to come as heat and humidity linger and interact with disturbances moving through. (Indeed there are some storms pushing through the New River Valley as I type this). More on that in the next blog post on Thursday morning. END UPDATE
UPDATE 5:20 PM: High of 93 for Roanoke and 88 for Blacksburg today -- a degree higher than Monday, not records at either site. A few storms are moving through the New River Valley toward the Roanoke Valley and Blue Ridge, but any severe weather threat looks to be slight and localized. Generally for the rest of the week, expect more showers and storms each afternoon than we've seen to start the week. END UPDATE
UPDATE 7:40 PM, 6/15: Roanoke's high hit 92 and Blacksburg's hit 87 on Monday, a little short of daily record highs but 7-8 degrees above normal for mid-June. Expect similar highs on Tuesday, perhaps a degree or two warmer, on Tuesday. Roanoke's June 16 record of 96 from 1957 is probably a little out of range, but Blacksburg's 88 from 1994 may be in jeopardy. END UPDATE
The 2015 Hokie Storm Chasers' second trip arrived in Blacksburg on Monday evening ... just in time for an amazing shelf cloud (at left) to overtake us ahead of a bowing squall line segment. It was an appropriate ending for our trip, as we spent the last four nights of the trip running from bowing squall lines (we prefer to stay out of these while driving vehicles).
Starting Monday (6/1), I'll be out helping lead this year's second group of Hokie Storm Chasers in seeking supercell thunderstorms -- and whatever tornadoes they produce -- in the central U.S. That means I'll be taking about two weeks away from the Weather Journal blog -- mostly.
UPDATE 8:15 AM, 5/29: Only one small change to below, the potential for somewhat cooler weather (70s highs, maybe some 60s) with a wedge of cooler air working in from northeast Sunday and/or Monday. In the meantime, highs have a decent chance of reaching 90 for the first time in 2015 on Saturday in the Roanoke area, with perhaps a little less in the way of afternoon storms (though not zero). ... Check out Trevor White's blog for a couple of very good pics from Hokie Storm Chasers' Wednesday tornado intercept in the Texas Panhandle. The first group arrives back in Blacksburg today with a new group headed west Monday. END UPDATE
It was just about as flawless a Memorial Day weekend weatherwise as it could be in Southwest Virginia.
UPDATE 8:30 PM: Memorial Day (thanks to all who have served!) still looks warm in the upper 70s to mid 80s across Southwest Virginia, with a little bit more humidity than the weekend. Hotter, stickier weather is on the way for later in the week. I'll take a look at that in my next Inclement Conditions Index, which I will post on Tuesday morning, a day later than normal due to the holiday. In the meantime, check out the blogs of Virginia Tech student storm chasers Jordan Pegram (first-timer) and Trevor White (3rd-time returnee as grad student). They've had some pretty good success after a major automotive breakdown in one of the vans. END UPDATE
Thursday will begin with some light rain across the region as an upper-level storm system quickly moves across from the northwest. As the National Weather Service in Blacksburg notes, this is more like a winter-type rain system, not the muggy summerlike sporadic storms we've seen in recent days, so it will mostly be light (a quarter-inch or less), with no thunder, and cool temperatures hanging on for a while. It may not get above 60 in some locations until after midday, when the rain will move out and the sun may start breaking through.
You probably felt something different in the air on Tuesday, and that will be even more obvious on Wednesday, as much drier air behind a cold front has pushed out the mugginess of the weekend. Dew points, which have been in the 60s to low 70s, may be as low as the 30s for some by Wednesday afternoon, certainly in the 40s. Temperatures will also be cooler on Wednesday, 70s highs for most, maybe barely scraping 80 in the Roanoke Valley and Southside. Even that is considerably cooler from back-to-back highs of 82 in Blacksburg Monday and Tuesday and 87-86 those two days at Roanoke.
Sometimes it's amazing how repetitive the weather can be on the same days in consecutive weeks. Roanoke's temperature has hit 88 with muggy conditions on consecutive Mondays. And now Tuesday looks to be very similar to last Tuesday, as a cold front passes through that at first won't be a "cold" front. Instead it will serve two purposes today: (1) bringing in drier air to quell the humidity of recent days and (2) producing westerly winds that will actually heat up as they blow down the Appalachian slopes this afternoon. So we may see a bit of heat surge today, but less humid, with highs similar to Mondays -- and I wouldn't even rule out a degree or two higher in some spots, possibly near 90. Showers and thunderstorms will not be as numerous as recent days, but a few may pop up along the front in the afternoon heating especially east and southeast of Roanoke.
May has already been an active severe period in the Plains states, the latest coming Friday/Saturday with 47 tornado reports. The first of two groups of Virginia Tech storm chasers -- primarily meteorology students -- begin heading to the Plains on Monday for 10-12 days or so in the field forecasting and observing severe storms. A second group heads out June 1 -- I'll be with that one, but until then, I'll post some interesting things the first group catches on its journeys. (It's usually easier for me to post from the trip I'm not on rather than the one I am on, as most of my day is consumed driving and forecasting on the trips I am a part of.) You can also check out the Hokie Storm Chasers blog, Hokie Storm Chasers Facebook page and @hokiestorm on Twitter, all linked here, for updates during the trip. (Pictured above, an up-close-and-personal look at a supercell in southeastern New Mexico last May.)
UPDATE 12:25 AM, 5/16: There isn't much to add or change about the weekend weather. It will be warm and increasingly sticky with a chance of afternoon showers and storms -- similar to those that occurred on Friday afternoon. Overall, not a washout this weekend, but do have an umbrella or a place to go inside in mind if you're out and about. Another "cold" front moves through early in the coming week with a temporarily raised chance of showers and storms, then a slight cool-off. END UPDATE
After some summerlike weather early in the week, we've had a little taste of fall in May the last couple of days, with cool breezes and low humidity. But the pattern continues to look more summerlike for us, and the warmth and accompanying humidity will gradually build back over the next few days, along with some showers and storms.
INCLEMENT CONDITIONS INDEX
FOR THE ROANOKE AND NEW RIVER VALLEYS
Thursday, 5/14/2015 to TMonday, 5/18/2015
(Scale of 0 to 10 based on both likelihood and intensity of weather events. 0 indicates no chance of even a minor event. 10 indicates a high-impact event is nearly certain.)
Extreme temperatures: 4
UPDATE 9:45 AM, 5/13: Expect some genuinely cool temperatures -- 40s lows -- for Thursday morning and a couple of days with highs in the 60s and 70s, near or even a tad below mid-May normals. But it won't last long. END UPDATE
INCLEMENT CONDITIONS INDEX
UPDATE 8:15 AM, 5/10: Tropical Storm Ana has come ashore near Myrtle Beach, South Carolina, still spinning bands of squally rain, but weakening. On Saturday, there ended up being 50 reports of tornadoes in the central U.S., most in open terrain, but at least one fatality in Texas. More severe storms are expected today, a bit farther east. And blizzard conditions are blasting western South Dakota this morning. So the three-ring circus has happened, and continues in many locations. For Southwest Virginia, daytime warmth combined with perhaps a little extra moisture edging westward from Ana may trigger a few scattered afternoon showers and storms, but for the most part it will be another sunny, warm day for Mother's Day, once the morning low clouds with the inland marine air burn off. END UPDATE
What we've talked about as a possibility this week has happened: Subtropical Storm Ana has formed off the southeast U.S. coast, according to the National Hurricane Center. This would signify a storm with at least 39 mph sustained winds that has a closed circulation and a mixture of tropical and non-tropical characteristics, and the Atlantic hurricane season's first named storm 24 days before the season technically begins. Tropical storm watches are from Edisto Beach, South Carolina, to Cape Lookout, N.C. -- including Charleston, Myrtle Beach and Wilmington -- for potential wind gusts of up to 50 mph and, possibly, a ton of rain. Ana was pulling in quite a bit of dry air on Thursday, but new squalls may develop around the circulation center as it spins over the warm waters of the Gulf Stream.
Thunderstorms made some impact on Southwest Virginia on Wednesday evening, including a storm that rolled through the Roanoke Valley with about 3,000 power outages related to lightning and wind, as well as reports of pea-sized hail and quick but intense downpours. I took the photo above as it was getting organized north and northwest of Roanoke, before it intensified and enlarged and moved over the Roanoke Valley a bit later.
UPDATE 9:35 AM, 5/6: The National Hurricane Center gives the system off the Southeast U.S. coast -- currently disorganized -- a 60 percent chance of developing into tropical or subtropical cyclone as it drifts north. Further discussion about the potential subtropical/tropical storm threat for the coast of the Carolinas is in today's Weather Journal column, linked here. For Southwest Virginia, a weak "backdoor" cold front will push through from the north over the next 24 hours, possibly enhancing the chance of afternoon/evening thunderstorms. There is not much cooler air behind the front, and it will barely affect the above-normal daytime highs on Thursday, before the front washes out entirely. END UPDATE
When I left for vacation a week ago, the coming week's pattern looked a little more like winter than spring. Now, upon my return, this new week looks more like summer, with stagnant high pressure, above-normal temperatures for early May, the possibility of scattered afternoon and evening thunderstorms, and maybe even an Atlantic storm system with some tropical characteristics to watch.
Got to go on vacation sometime. I usually don't take vacation time in winter when interest is high for snow potential, so they get scheduled in other seasons. I'll be off the blog through Monday, May 4, with no new blog posts or updates. I will return on that date with a new Inclement Conditions Index.
Our frequent visitor the cool-air wedge is making another return this weekend, with plenty of Gulf of Mexico being lifted up and over it by a strong low-pressure system in the central U.S. After a sunny, mild but still a bit breezy Friday, this will result in a cool, damp weekend, with periods of rain especially the latter half of Saturday into Sunday. Temperatures probably will not reach 60 in Southwest Virginia east of Interstate 77 and may not reach 50 in some spots throughout the weekend -- mid 60s to low 70s are the normal highs this time of year in our region. One impact of the cool-air wedge -- that is, cooler air trapped by easterly winds against the Appalachians -- is illustrated in the map above from the National Weather Service. The trapped cool, stable though very moist air will just about entirely eliminate any severe storm risk we might otherwise have. Over the mountains, in the Tennessee Valley and much of the South, there will be a much higher risk of severe storms, where it is warm and unstable. Most of the rain will be light to moderate, but could be quite persistent Saturday afternoon and evening, with some periods of showers continuing into Sunday as the system only slowly pulls away.
It doesn't look like we'll pull out even a single sunny, dry day out of this coming weekend, as a cooler-than-normal pattern continues to set up that is likely to last at least a week, maybe 10 days to two weeks. And there may be some temperatures cold enough to threaten some outdoor vegetation on Friday morning. (UPDATE 8:45 AM: A freeze warning has been issued Friday morning along and west of the Blue Ridge for pockets of sub-freezing temperatures. END UPDATE)
Warmth is ridging in western North America over the next several days, and that means that cooler air will be digging into the eastern U.S. We've seen this pattern repeatedly over the last couple of years, and it's happening again. The cold front passing through later on this Wednesday will continue our trek toward a significantly cooler pattern, triggering some showers and perhaps a few thunderstorms as it pushes into somewhat warm but not terribly moist air today. It will be cold and a bit windy aloft, though, and that might allow for a few storms capable of localized strong wind gusts. (It may also be a little gusty even without storms at times -- a wind advisory has been issued for possible 40+ mph gusts.) This most likely will not be any kind of widespread severe weather outbreak, and there isn't nearly enough moisture to pull off anything close to the widespread heavy rain of Sunday or the localized intense downpours of Monday.
Storms produced streaks of heavy rain, gusty winds and hail in Southwest Virginia on Monday afternoon and evening, dumping some downpours on some areas that were already inundated by Sunday night's rain. I took advantage of the severe setup to do some regional storm chasing, focusing on a supercell near Yanceyville, North Carolina, (south of Danville) that split into two pieces. The right-splitting cell, as is often the case, developed stronger rotation for a time, and briefly a tornado warning, though no tornado appears to have occurred. I saw broad rotation within a lowered cloud mass called a wall cloud. For me, it's good practice preparing for the annual Virginia Tech storm chase I help lead, this time in June.
INCLEMENT CONDITIONS INDEX
UPDATE 5PM: Above is the map for the flood watch that continues into the night for much of western Virginia. Periods of rain, some heavy, will continue much of the evening, lessening toward morning. Storms may develop in the area on Monday. END UPDATE
The two-day cool, damp wedge is finally letting go on this Friday morning, and a partly cloudy, warm day with many highs in the 70s is expected. As a barely perceptible upper-level trough crosses the region, there will be some chance of showers and thunderstorms developing with the effects of daytime heating. You can never entirely rule out an isolated storm becoming strong to locally severe in this situation, but it is not likely to be a widespread severe weather situation, or even a widespread rainy situation, this afternoon and early evening.
Lots of rain in the days ahead for Southwest Virginia ... but substantial hope for Blue Ridge Marathon runners Saturday that you won't get soaked.
We have a winner in the 2014-15 Weather Journal snowfall prediction contest: Erinn Hokanson of Roanoke. The difficult part of predicting this snow season was that Blacksburg and Roanoke had first 1-inch snowfall dates nearly 3 months apart -- Nov. 26 and Feb. 16, respectively. Most entrants didn't split their dates nearly that far apart. Hokanson split hers just far enough (Nov. 30 and Jan. 25, respectively) and got close on her snow totals (guessing 20 inches for Roanoke and 24 for Blacksburg when 22 and 28 fell) for a total of 32 points (days and inches missed) in the lowest-score-wins contest. That was 13 points better than second place. You can read about how the contest went down for several top entrants in today's Weather Journal column linked here.
I was just talking yesterday about how the weather can change during the course of the four days of each Inclement Conditions Index period, and that has indeed happened for the heavy rain aspect -- which is now more like a 5 or 6 for the Roanoke/New River valleys rather than a 4. It now appears that heavier rain will make it farther north, centered over Kentucky, West Virginia and Southwest Virginia generally west of Roanoke. For that reason, a flood watch has been issued for Giles, Pulaski and Carroll counties and westward. This still doesn't look like a widespread flooding situation, but 1-2-inch rains now look to be for much of our region Tuesday into early Wednesday, perhaps more in spots, especially where easterly to northeasterly winds can lift and condense more moisture on eastern mountain slopes. Tuesday night into Wednesday morning, Gulf of Mexico moisture will be overrunning a developing "wedge" of cooler air banked against the mountains, and this will mean frequent to continuous rain with some locally heavy rain. By late Wednesday into Thursday there may be a break in the rain, at least reducing to showers, as a slow-moving cold front moves more to the south, focusing the rain farther south.
Before launching into the newest Inclement Conditions Index, a few words on the intent of the index, which I have been posting twice weekly since November.
Any threat of storms is past for Southwest Virginia, as a cold front is pushing through that will bring a dry, mostly sunny weekend with mild afternoons (60s to low 70s) and cool mornings (40s on Saturday morning, 30s to low 40s on Sunday morning).
Dorothy (Dottie) Boothe Atkinson, 88, of Salem and formerly of Pulaski County, passed away on Saturday, July 4, 2015.
David Lucas, 58, of Rocky Mount, passed away Saturday, June 27, 2015. Funeral Mass will be 11 a.m. Wednesday, July 8, 2015, at St. Andrews Catholic Church in Roanoke. Arrangements by Conner Bowman Funeral Home, Rt. 220, Rocky Mount, Va., 540-334-5151.
Joe Bill (Bill Edwards) Edwards, 94, of Galax, passed away Saturday, July 4, 2015. Funeral Services will be 1 p.m. Thursday, July 9, 2015, at Longview United Methodist Church. Arrangements by Vaughan-Guynn Funeral Home, Galax, Va., 276-236-2442.
Mary M. Clark, 58, of Marion, passed away Monday, July 6, 2015. The family will hold a private memorial service. Arrangements by Seaver Brown Funeral Services, 276-783-7107.