www.roanoke.com

It may be hard to believe, but it appears there is a growing chance the second named tropical system will form in the western Atlantic off the Southeast U.S. coast BEFORE hurricane season officially begins on June 1 (next Friday). As of late Thursday evening, the National Hurricane Center was giving a disturbance centered near the Bahamas a 60 percent chance of becoming at least a tropical depression. Should it gain 40 mph surface winds and be determined to have a closed circulation either partially or entirely powered by evaporative energy from warm ocean waters, it would be named Beryl. The system’s movement is rather unclear, but the general idea is that it will dawdle a bit offshore and then get slowly nudged west into the Southeast over the weekend or early next week, where it could be a big help for extreme drought in Georgia and South Carolina. For our weather, Beryl has the potential to add some more moisture and clouds to dampen the expected heat some, raise humidity levels and possibly trigger more showers and storms than we were expecting by late weekend or early next week.

I haven’t done exhaustive research on the topic, but the last time there were two named Atlantic storms before the start of hurricane season was in 2007, when Ana (a subtropical storm, with mixed tropical and non-tropical characteristics) formed on May 6 and Barry followed on May 31. To have two preseason named storms in a very similar region is extremely unusual, if not unprecedented.

The tropical-like weather of the past few days, with scattered afternoon showers and storms, will slowly dwindle over the next couple of days, but that may still be enough for a few more localized downpours, especially Thursday. Over the Memorial Day weekend, the weather will become influenced by a dome of hot, dry air building in the Upper Midwest and Great Lakes region. This will likely push temperatures well into the 80s and some 90s in our region for the holiday weekend. Because we are not underneath the core of this high pressure system — its location depicted well by the location of the hottest temperature anomalies on Sunday morning on this European model map (remember, these numbers are Celsius, so the peak heating area depicted in and near Michigan of  13 degrees is more than 20 degrees Fahrenheit above normal) — there may still be a few scattered showers and storms as daytime heating and terrain effects create lift that may not be entirely checked by warm air aloft. But coverage and overall intensity are likely to be much less than the last three days and that of Thursday.  There are many signals this pattern entirely reverses by late next week, so that cooler air is centered over the East and hotter weather settles into the West.

UPDATE 6:30 AM, 5/23: Not much reason to renew this post entirely, as Wednesday and Thursday are likely to be very similar to Monday and Tuesday, with scattered showers and storms developing as the day heats up. This will be the case until an upper-level low over the Carolinas finally moves northeast away from us late in the week. The good news for anyone with Memorial Day weekend plans is that it looks to be much drier overall — maybe a  slight chance of some scattered afternoon showers and storms — and definitely hotter, with some low 90s quite possible. END UPDATE

It’s following me home! After reaching Blacksburg and working for a while to strip the equipment off three vehicles we used in the first round of the Virginia Tech storm chase, storms began to develop over the Blacksburg/Christiansburg area and followed me toward Roanoke through Shawsville and Elliston (I too the U.S. 11 route so I could pull off a few times, observe and photograph more easily). The photo at left was from between those two towns — here’s a bigger version. Storms with heavy rain, frequent lightning, some gusty winds and small hail occurred across parts of Southwest Virginia this afternoon and evening, and will slowly dwindle overnight. The thick moisture, however, will linger, and the approach of a cold front (the same front that fired storms we chased in Nebraska on Saturday — I’ll have more details on that at some point as we prepare for the second trip next week) and daytime heating will again squeeze out numerous showers and storms by Tuesday afternoon. Locally heavy rain from slow-moving storms will be the main concern, but some strong winds and hail are also possible. Wednesday and possibly Thursday look showery/stormy too, before a high-pressure ridge starts pushing us more toward warm, drier weather by the weekend.

I will start taking entries for the annual SUMMER FORECAST CONTEST now through May 31. Email weather@roanoke.com with your name, your location of residence (city, town or part of county), and 2 guesses: Roanoke’s highest temperature, and the date on which it will occur between June 1 and August 31.  As a matter of reference, every year on record since the late 1940s had had a highest temperature between 91 and 105. I will put out some more reminders on this.

UPDATE 9:30 AM, 5/20: Tropical Storm Alberto is expected to remain mostly offshore, gradually weakening as it possibly brushes eastern North Carolina. A cold front approaching from the west (actually, the same cold front that helped trigger severe storms the Virginia Tech storm chasers caught in Nebraska on Saturday) will begin increasing thunderstorm chances early in the coming week. I will be on the road westward toward home today after a fairly good series of storm intercepts on Saturday, with wall clouds and gustnadoes (larger whirls of ground dust spun by strong outflow winds) being among the highlights. Will have some more details later. END UPDATE

UPDATE 2 AM, 5/20: Tropical Storm Alberto was named earlier this afternoon. For more, visit the National Hurricane Center website linked here. END UPDATE

Keep an eye on this little whirl off the coast of the Carolinas. The National Hurricane Center is. The low pressure system has a chance to take on tropical characteristics — i.e. a warm core arising from evaporation of warm ocean waters — if it hasn’t already. If the National Hurricane Center judges that it has developed sufficient tropical characteristics, it could become the first named storm of the Atlantic season (or pre-season, since the hurricane season technically begins June 1). As a tropical storm or subtropical storm (mixed tropical and non-tropical characteristics) with winds topping 40 mph, it would become Alberto. Keep this in mind if you are traveling toward the coast of the Carolinas. A full-blown hurricane is unlikely, but some windy, rainy weather is possible along the coast. Whether it’s Alberto or not, it may drift inland late in the weekend, and possibly farther west early next week, bringing a chance of showers and storms to Southwest Virginia.

I will be out today on the most active day of the current Virginia Tech storm chase, and a long return trip the next couple of days, so monitor the National Hurricane Center (click on Atlantic) and the National Weather Service-Blacksburg for further updates.

HAYS, Kan. — We didn’t have storms to chase on Friday, so we visited an unusual geological formation instead — the Monument Rocks in western Kansas. The erosional remnant rocks rise 60-80 feet  from an ancient river bed in the Plains, quite a stunning site amid the cattle ranges and gas wells that dominate that part of Kansas. It was a beautiful day for sightseeing — but of course, that is the problem when you’re out here to see storms. Those are  expected to pick up on Saturday, when a cold front and associated jet stream trough dig into the Kansas-Nebraska area. Moisture is a bit shallow, the wind fields are not all that strong, and warm air aloft may be too strong for convection to overcome, especially the farther south we may go. It will be up to the student chasers to figure out the specifics of the pattern on Saturday morning to determine where we need to go for the best chance of seeing a supercell or possibly even a tornado. This is the last, best chance for the first round of the Hokie Storm Chase … with no more severe weather events expected in the window of time set aside for the first trip, we plan to start heading back on Sunday. A second group will be preparing to head to the Plains next week.

Southwest Virginia’s weekend looks beautifully sunny, but a westward-moving low off the Atlantic may spread some showers by early the coming week — about the time we arrive home from the first trip.

WaKEENEY, Kan. — Supercells and tornadoes are the first priority of any storm chase in the Great Plains. They occur with much more regularity and usually more intensity here than in the Appalachians, and of course, are more visible due to the lack of tall ridges and trees.  That’s why we come out here. But when they’re not happening, other kinds of storms are capable of providing a memorable experience for students who have never experienced a Plains storm.  Thursday afternoon provided just such an opportunity, as we were successful in planting ourselves right where one of many high-based, pulse-type storms collapsed into a outflow that spread Kansas dust all around us. We clocked winds as high as 55 mph, just short of severe level of 58 mph, and may have had a few higher gusts. The winds kept going for about 20 minutes, only splattering a little rain, as dry air between the high storm bases and the surface evaporated much of the precipitation.

We ended up in WaKeeney, Kansas, for the evening, a familiar setting for Virginia Tech storm chasers over the years, with numerous tornado intercepts very near here in 2007 and especially 2008. We expect a few storms to develop near the Kansas-Colorado border today, perhaps in similar fashion as Thursday. Saturday appears to be the one and only big shot at supercells for this first trip, over central Kansas, most likely. After that, we’ll start working home, and prepare for a second trip that may start a few days earlier than planned to try and catch a potentially more conducive severe weather pattern developing late next week.

A few strong to severe pulse storms also affected Southwest Virginia on Thursday. Some of the students were getting the warnings on their smartphones as we drove toward the northwest Kansas storms. A few more storms may occur today, perhaps a bit farther to the southwest, but the overall pattern is leaning for generally nice weather the next few days in Southwest Virginia.

YORK, Nebraska — Contrary to what you may have seen on TV, tornadoes don’t drop out of the sky left and right in a timely manner when storm chasers are around. Finding supercells and locating to observe and track them effectively can be challenging even in the most ballistic severe weather pattern, let alone one that is far less so. The next few days present such a pattern for the first of two Virginia Tech storm chase teams. Pieces of puzzle are coming together, particularly over the weekend, for severe weather potential in the northern Plains states (think Nebraska and the Dakotas). But none of those pieces is shaped perfectly to fit with the others. Gulf moisture is returning northward, recovering after the big upper-low that drenched much of Virginia helped sweep it away from the central U.S., but it is returning in a much weaker manner than is common in mid May.  Upper-level winds are starting to pick up as a trough, or dip in the jet stream, begins to dig southward and eastward, but those winds are gradually weakening as the trough moves eastward. And while there is plenty of warmth at the surface to bubble moisture upward, it will be capped by similarly warm air aloft in many places, preventing the warm air from rising into cold air high in the sky for tall cumulonimbus clouds to build into storms. But these imperfect pieces are starting to align, and are likely to yield some level of severe weather, particularly Friday and Saturday. Exactly where and when is something our student chasers must unravel. And while the overall pattern is unlikely to yield a widespread severe weather outbreak, at least as we see it now, there will be probably be localized areas of enhanced spin that could produce a few, maybe just 1 or 2, rotating storms known as supercells, and perhaps a few tornadoes. Finding those is what we’re out here to do .

We’re in York, Nebraska, after a 2-day drive from Blacksburg. Some storms are possible on Thursday, in Nebraska or one of its bordering states, but any activity will likely be scattered and probably not severe or only marginally so.

Looks like some nice weather has settled into Southwest Virginia for a few days after Monday’s floods.

Roanoke Times report on Franklin County flooding

For most of the next 4 weeks, my attention will  largely be turned elsewhere other than Southwest Virginia weather. I’ll be keeping an eye on the weather back home (which today does include a good chance of more heavy rain showers and some thunderstorms developing – after several reports of flooding with excessive rains in Franklin County on Monday night), and may post about it from time to time, especially if there is something especially noteworthy, but most of my days will be spent driving a van full of Virginia Tech student storm chasers. So I may not be timely or detailed on local weather. I’m sure the community of commenters can and will fill in some of that gap — and of course there are links to the National Weather Service forecast and to the Radar / Future Cast on this blog site.

This is the eighth consecutive year I will be on board what has become known as the “Hokie Storm Chase.” I started in 2005 as a journalist and photographer “embedded” in the chase trip  for an award-winning series we called “Chasing the Wind.”  I was invited back  as a volunteer co-leader from 2006-11. This year, I am serving in an adjunct instructor capacity on back-to-back trips, the first starting Tuesday morning and continuing until Thursday, May 24, or so. The second will begin a few days later, depending on the pattern, and continue until no later than June 10.

This is a for-credit college field course for VT meteorology and geography students, and we will be gathering data via mobile mesonets, or weather instruments attached to the top of 3 vehicles (2 for the second trip). Many aspects of the journey can be a “fun” road trip, as we roll through Plains towns and countryside whose people are almost unfailingly extremely welcoming to us, but it is a serious endeavor focused on severe weather. Though certainly every student wants to see one, and we will put ourselves in the best position possible to safely view one, a tornado is not necessary for the trip to be worthwhile or successful. Some of our best storm intercepts over the years have not included tornadoes. We are looking for supercells, thunderstorms with strong rotating updrafts. Sometimes they produce tornadoes; sometimes not. The forecasting and observational experience the students get in this real-life laboratory as big as the heart of America is the most valuable aspect of the trip.

Each year I struggle with how to cover this on the blog. Since I’ve been doing it so long now, it seems a bit old and overexposed, so I did much less with it last year. But each year, I find folks interested in what we’re doing and where we’re going. I will try to post a short item, perhaps a photo, on most days I am out, but the timing will be rather erratic and I may have to skip a day or two now and then just out of simple exhaustion.

My Twitter account — @kevinmyattwx — will have a bit more frequent updates — you can follow that in the right margin of this blog even if you are not on Twitter yourself.  The official Hokie Storm Chase online sites include hokiestormchase.wordpress.org (blog and website), @hokiestorm on Twitter, and the Hokie Storm Chasers page on Facebook. Two Twitter handles that will have much more frequent updates than mine — because they won’t be driving — are from returning chasers Dan Goff (@WxDan) and Kathryn Prociv (@KathrynProciv).

CLICK HERE FOR LATEST FLOOD WATCHES AND WARNINGS

UPDATE 9:30 PM: The yellow/orange/red spot on this National Weather Service map southeast of Roanoke represents radar-estimated rainfall totals of 3-plus inches — the red in the middle 5-plus inches. Much of that has occurred in cloudburst downpours since 4 p.m. from the Rocky Mount area east and northeast through Wirtz, Burnt Chimney, toward the west end of Smith Mountain Lake. Rain is resurging in the area again this evening as another upper-level impulse is triggering heavier showers and storms, and upslope southeasterly flow ahead of a low-pressure system continues to bank moisture against the higher terrain of the eastern slopes of the Blue Ridge and the western Piedmont. The Future Cast image I posted last night below appears to have been on the right scent for location of the heaviest rainfall. You can follow the latest location of rainfall on the Radar / Future Cast in the right margin of this blog. END UPDATE

As you can see on the radar display in the right margin, rain is spreading across Southwest Virginia this evening, likely to overtake all of the Roanoke and New River valleys in the next 3 hours. Over the next 36 to 48 hours, there will be several periods of rain, as a slow-moving upper-level low to our west continues to pull it out of the Gulf of Mexico and the Atlantic ocean, hurl it against our higher terrain, and squeeze out  heavier periods of it (some possibly accompanied by thunder) as upper-level disturbances traverse the region. I ran the “rain accumulation” feature in the Future Cast at right about 5:30 p.m., and it showed amounts of 1.5 inches widespread over the region through 3 p.m Tuesday with a zone of 2-plus inches generally along the eastern side of the Blue Ridge just east of Roanoke. The National Weather Service in Blacksburg and the Hydrometeorological Prediction Center have similar ideas on rainfall in the region. A soaking period is obviously ahead for Southwest Virginia.

UPDATE 9AM, 5/13: As expected, a flash flood watch has been issued for part of our region, generally from Roanoke southwestward along Interstate 81 and southward along the Blue Ridge into northwestern North Carolina. It is effective from 9 p.m. tonight to 9 p.m. Tuesday night. So far we’ve started Mother’s Day with a little bit of sunshine in the Roanoke Valley and nearby areas. Moisture will gradually build today with showers encroaching from the south and west later in the day into this evening. END UPDATE

UPDATE 1 AM, 5/13: Saturday night’s rainfall projection fls through Tuesday evening from the Hydrometeorological Prediction Center show rainfall may top 3 inches in some locations from the slow-moving upper-level low that will begin spreading showers into Southwest Virginia during the day Sunday, with heavy rain possible overnight Sunday into Monday. Don’t be surprised to see the National Weather Service in Blacksburg issue flood watches during the day Sunday for some or all of our region. You can follow the advance of rainfall and its potential for the region on the Radar /Future Cast link at right. (Just ran the Future Cast for rain accumulation, and it concurs with HPC, with about 3 inches of rain for Roanoke by 1 a.m. Tuesday). END UPDATE

It would have been hard to create a prettier day for Virginia Tech’s commencement Friday than the one that occurred (well, OK, I know some folks would have liked it warmer, especially after a morning low of 36 in Blacksburg and kind of a nip in the breeze even as it pushed into the 60s). Saturday will be similar, though a bit warmer, over most of Southwest Virginia (far southwest areas west of I-77 may get a few showers). But Mother’s Day — and especially the day after — are likely to be a different story. A slow-moving upper-low bringing rain and storms to Texas is going to dawdle east and northeast over the next few days. That will supply a lot of Gulf of Mexico moisture, squeezed out by upper-level impulses and our region’s higher terrain. The result will a period of significant to downright heavy rain, possibly exceeding 2 inches in many places by Tuesday. Mother’s Day is a bit of a question mark — the best chance of showers will be west of Interstate 81, as moisture slowly builds ahead of the storm system. By sometime in the afternoon or evening, rain will become widespread, and periods of rain are expected to continue into Monday and at least some of Tuesday.

Having a slow-moving Southeast U.S. upper-level low deliver a period of significant rain has become a tradition connected to the departure of the Virginia Tech storm chase team for the Plains states. We’ve seen this happen with amazing regularity the day we leave or a few days thereafter, and the circulation patterns leading to rain here often dry out the central U.S. for a few days. We’re planning to leave Tuesday, likely headed for the Northern Plains as moisture and jet energy slowly recharge in that region by next weekend.