#vawx A July 5th bonanza

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A backdoor front sagging south through Virginia plus an upper level wrinkle approaching from the west were the two factors in Wednesday’s (7/5) decision to chase. SPC had the southern third of the state under a Marginal Risk with mostly a threat for damaging wind from wet downbursts:5 July Day 1 outlook

After perusing short term model solutions I decided to pick up my chase partner at 1 pm and head to the U.S. Route 29 corridor. The models had storms firing by mid-afternoon along the backdoor/wedge front just east of Rte 29 with another convective round due from the upper level support after 6 pm further southwest. As we rolled east the low clouds cleared and sunshine began to heat the very soggy airmass over the Piedmont. Shear wasn’t much but promised to increase as the front crawled south and west.

We sauntered to Gretna, sat for a while, and then moseyed south to the Blairs truck stop while watching radar. Storms did fire along the front but looked like a globby unchaseable wedge front mess on radar (been there done that too many times in 2017). Moreover they were a bit further east than I’d anticipated and I was concerned that if we went after them we’d be woefully out of position to catch the next round.

So…we sat…and waited…and sat some more. Giving up on the eastern activity we finally motored south to Danville where we turned west on U.S. Route 58. At Martinsville we continued west on 58 and waited a while longer at the Blue Ridge airport with this view to the west:Blue Ridge airport view

Finally tiring of this magnificent view (we wanted storms!) we backtracked to Rte 58 and drove west through the municipalities of Patrick Springs and Stuart VA just to say we did. After a U-turn literally at the base of the Blue Ridge Mountains we rolled back east to a convenience store that we knew from a previous chase had some decent eats for dinner.

Grabbing our purchases we headed outdoors to a shaded picnic table to feast. Just as we sat down we heard a peal of thunder and this showed up on radar:IMG_7649

The second wave had arrived! Since this cell was moving rather slowly we finished our dinner and then pushed back west to an open field where storm #1 was in full view:Storm #1 with wall cloud

It was visually rotating – note the striations – and the lowering on the leading edge was likely a wall cloud that didn’t last long. We watched from here for a bit before diving back east for this awesome view:Storm #1 crossing the mountainsThis was a full-fledged no kidding Virginia supercell complete with mesocylone and tilted updraft. It spun for quite a while as we watched it slowly float eastward occasionally dropping lowerings, none of which lasted long.

Meanwhile a line of discrete storms had formed across the mountains and began marching eastward. Reluctant to leave the open vista of storm #1 we gave in and pushed back west to check out the new activity. Storm #2 was approaching from the southwest with a wall cloud under its western edge:Storm #2 first view

Meanwhile storm #3 – our heads were on a swivel at this point – was moving in from the north and west with more interesting features:Storm #3 first look

To catch a better glimpse of this we again moved back east to our previous vantage point to watch this third storm cross the mountains with a large shelf cloud pushing out ahead of it:Storm #3 second look

Even while we observed this I had the itch to head back west to recheck storm #2 since we couldn’t see it from here. It was booming out loud peals of thunder and my recollection of the small wall cloud we’d seen kept eating at me. So we moved back west – again! – and were rewarded with a clear view of a much bigger (and obviously rotating) wall cloud as this storm literally headed directly toward us:Storm #2 wall cloud

As we watched storm #2 with its wall cloud approach our location storm #3’s shelf cloud – backlit by the evening sun – neared from the west:shelf cloud approaching from west

It was about this time that I realized we were sitting under the spot where these two storms were going to collide:IMG_7700

As these two complexes neared each other the outflow from storm #3 interacted with storm #2 and the wall cloud morphed into a shelf cloud as we watched. Some interesting greenage was evident right in front of us:Greenage under storm #2

After my chase partner reminded me (I was very busy looking at other things) I checked the VIL on storm #2 and became a bit apprehensive about being blasted by hail from it. Fortunately the heaviest core passed by just to our east and weakened as it neared. Otherwise I was prepared to quickly scoot westward on Rte 58 to avoid it.

As the two systems collided overhead we were treated to a tremendous display of very close CG strikes as we huddled inside the chasemobile with windows rolled up and not touching anything metal. (Hopefully my dashcam video caught some of them but I haven’t reviewed it yet.) This was the radar velocity frame (left) and reflectivity frame (right) just as the two updrafts began to merge:

Surprisingly enough the rain wasn’t that heavy at our location and we completely avoided any hail that may have resulted from this merger. We let things move off to the east a bit and then called it a day, rolling back toward home with an ultimately very successful chase under our belts.

#vawx Targeting weak convection just for a taste of chasing

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Yes, today was a questionable day to chase. Decent moisture and instability was offset by warm upper level temperatures (capped atmosphere) and very little shear, adding up to low-topped updrafts with little hope of organization. However it had been almost 2 weeks since my last real chase and I wasn’t going to chase the more volatile conditions coming along tomorrow (Saturday 7/1).

Picking up my chase partner just before 3 pm we rolled south on U.S. Route 220 to Rocky Mount and turned east on VA Route 40. An initial round of convection had already fired and moved north of that highway but we were targeting cells over Danville that were slowly traversing toward the north-northeast. We pushed through Gretna to get east of the updrafts but other cells went up ahead of us. After maneuvering southward through and around them without seeing anything exciting (not even lightning) we made our way via VA Route 57 back west toward Chatham.

We briefly stopped at a vantage point just south of Tightsqueeze to observe a cell ostensibly moving north from the Rte 58 corridor. However the updraft kept back building along what must have been an outflow boundary, remaining almost stationary to our southwest:IMG_7625

So we relocated west and south to VA Route 41 and made our way to a rural vantage point northwest of Danville to catch a glimpse of the base of this updraft. This was our best view:Storm W of Danville

The low level scud clouds very nearly exhibited Kelvin-Helmholtz wave action as they scooted along left to right in front of us.

Driving further west and south we targeted another cell near Martinsville, winding up with this southwestern view from a newly discovered vantage point in eastern Henry county:Storm near Martinsville

By this time the convection was weakening and we still hadn’t seen lightning or heard thunder from the low-topped cells. We motored north along more rural routes, paralleling one last cell that didn’t do anything other than chase us with rain. We called it a day when we reached the Rte 40 corridor and adjourned for dinner in Rocky Mount.

#vawx Lots of convection but mostly shelf cloud action today

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SPC had most of Virginia under either an Enhanced or a Slight Risk today:VA_swody1

An approaching trough provided shear plus cooler temperatures aloft while a surface cold front fired several line segments along and ahead of it. The first line popped up before noon so I rolled down the driveway at 11:45 am to get ahead of it in the vicinity of Bedford.

What followed was such a mish-mash of convective activity that I’m not even going to try to detail everything that happened. Instead here are a number of photos that are – hopefully – in chronological order with brief descriptions of what was going on.

Storm #1 Bedford county

This was storm #1 in western Bedford county just off US Rte 460. I let this one go on its merry way northward into undesirable chase territory and of course it went severe-warned.

After a gasoline and comfort stop I dropped south to a vantage point along Joppa Mill Road and spied this lowering under the next cell on this first convective line. I’m pretty sure this was at least briefly a wall cloud as surface winds were at my back, i.e. they were flowing into the storm.

funky scud under southern end of line

After the first line went by with several cool renditions of shelf clouds I cooled my heels a while at a local park. When a second convective line crossed the Blue Ridge I motored back to the Joppa Mill Road location to watch. The above photo shows a SLC (scary looking cloud) under the shelf cloud on the southern end of the line.

Meanwhile the northern end produced a very mean-looking shelf cloud that I left behind when it approached too close. I leap-frogged ahead of this second line into eastern Bedford county and watched for quite a while.

Third storm near Blairs

When the rain approached again I dove south along VA Rte 43 to Altavista and then continued south on US Rte 29 past Chatham to check out a third line segment. This was the view I had of a very interesting feature from the Blair truck stop on the eastern slope of White Oak Mountain just before the rain closed in. Was it a mesocyclone signature? Perhaps, but I only had a few seconds to observe it.

Shelf cloud under fourth storm near Blairs

Yet another line segment (#4) moved toward Danville from the southwest. This was the southern edge of it with another shelf cloud. I motored a bit south and east to stay ahead of it but wound up conducting a static core punch a couple miles east of Rte 29.

Calling off the chase I grabbed dinner and then headed home up Rte 29. I turned off on Old Mine Road to cut the corner to VA Rte 43 and as I rolled along that rural route I caught a glimpse of Kelvin-Helmholz waves. KH waves from Old Mine Road

Not a bad way to bookend a busy day!

 

#vawx An easy local storm view

Not every view of a storm requires a chase to get into position. This one on Saturday June 17th bubbled up very near the house. I only needed to move a half-mile south of it to check out this nice shelf cloud:shelf cloud view_2

And as it got a bit closer:shelf cloud view_1

With plenty of CAPE (instability) and almost no shear I wasn’t inclined to actually chase Saturday so this was the next best thing!

#vawx A ho-hum Friday chase with a surprise ending

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I succumbed to the urge to chase Friday June 16th for no other reason than I wanted to. SPC had most of Virginia under a Marginal Risk with a stationary front retreating northward as a warm front. CAPE (instability) and PWAT (available moisture) values were both high but shear was almost non-existent. Thus slow moving heavy rainers were almost a certainty.

I “armchair chased” at home for a while until convection showed up over northern North Carolina. Departing around 3 pm I drove south on U.S. Route 220 toward Martinsville, stopping at Bassett Forks to fill the chasemobile’s gas tank and to regain situational awareness. Several cells showed on radar just above the I-40 corridor in NC and were drifting slowly northward toward the Patrick Springs vicinity.

Departing Bassett Forks I turned the chasemobile west on U.S. Route 58 and stopped first at the Blue Ridge Airport where I switched on the live feed. I could see the updrafts to the south but they were crawling along frustratingly slowly. After sitting still through the 5:00 pm weather segment on the local TV station (in case they wanted to use the live stream) I made the command decision to meet the storms halfway.

Maneuvering down rural roads through the metropolis of Moorefield Store – my first visit there –  I finally found a decent south-looking vantage point near the VA/NC state line. Unfortunately despite the promising warm and sticky conditions at the surface these storms had weakened and weren’t looking very healthy on radar:IMG_7400

However I could still see a lowering under the base of the westernmost cell with a moisture band still feeding into it from the left (east):wall cloud under NC storm

So in my not-so-humble opinion this was another wall cloud I’d bagged under a fading storm. (I didn’t see the point in sending in a spotter report on it.)

When this convection continued to weaken I packed it in, shut off the live stream, and motored back toward Martinsville for dinner. While at the fast food restaurant I noticed a cell going up north of the city along the Rte 220 corridor but I wasn’t enamored enough with its potential to cram down the rest of my meal and scoot out the door. Perhaps I should have…

When I neared the Oak Level vicinity it became very obvious this storm had intensified and was back-building with a vengeance (along an outflow boundary, perhaps?). I struggled to find an open vantage point from which to watch and finally had to retreat west of Rte 220 along a winding rural route to stay out of the rapidly expanding precipitation shaft.IMG_7426

I finally found an open spot amid the ever present tree lines on the edge of what appeared to be a family cemetery and watched as the shelf cloud and associated “whale’s mouth” approached. With the late evening sun at my back it was an impressive sight.Whales' mouth N of Oak Level

When the cell inevitably weakened I made my way back to Rte 220 north of the storm via more rural routes, stopping to observe the remnant shelf cloud as it slowly drifted toward me. To the west the setting sun provided another impressive sight:sunset iPhone style

And that was the end of it. No severe warnings, no strong winds, and no hail, although I may have witnessed some brief mesocyclonic rotation as I desperately sought to get out from under the expanding base of the storm near Oak Level. Perhaps I’ll see more details when I go through the videos.

#vawx Detective work plus video review convinced me this was indeed a wall cloud

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After sitting down to view videos from yesterday’s chase of non-severe storms I’ve concluded that, yes indeed, I did witness a wall cloud formation. Here’s a still photo of said feature:
nascent wall cloud

At the time I was hesitant to label this a wall cloud given a decided lack of deep layer shear in the overall setup. However after examining the evidence I’ve concluded that local factors (i.e. an outflow boundary from another storm) provided the necessary low level shear. A significant part of that evidence came from tree damage in the Chamblissburg VA vicinity that temporarily blocked VA Route 24.

First, a geographic reference. Here’s a screen shot showing my location vs where the tree damage and road blockage occurred:June 14 2017 storm chase location data

The photograph was taken looking slightly west of due north (call it 350 degrees). Now, here’s a radar reflectivity grab 5–10 minutes before the wall cloud formed:IMG_7284

I had watched the convective line east of my location in this radar frame from a couple of other locations before stopping here. During a brief stop at Staunton River High School I noticed low level clouds pushing west from this activity. Thus I suspect that an outflow boundary from that storm interacted with the cell developing to my north in the radar scene.

Here are two radar VIL grabs showing intense precipitation – and probable hail – just to my northwest over the Chamblissburg area during or shortly after the wall cloud formation:

This certainly looked strong enough to have caused the tree damage in that area. In addition I noticed the next VIL radar sweep (which I didn’t save) showed a much diminished signature, indicating that the core of the storm had collapsed over Chamblissburg. That would go hand in hand with the wall cloud morphing into a linear shape, becoming an outflow-dominant shelf cloud as I watched it.

For the final piece of evidence the video of the wall cloud (sped up 8x) can be found here.  The rotation is obvious and the development of a tail cloud back toward the precipitation shaft also lends credence to this being a wall cloud.

Yeah, I’m a weather geek as well as a storm chaser…

#vawx A Flag Day non-severe chase

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With an SPC Marginal Risk in place across Virginia and a backdoor front dropping south across the state it was time for another June chase today after a quiet start to the month. Given the heat and humidity levels I waited comfortably at home watching radar until finally deciding to leave after 2:30 pm. A Mesoscale Discussion had been issued for strong storms but with almost no prospect for a watch issuance. CAPE was plentiful but shear – again – was very meager.

A cluster of storms was slowly edging south from the Lexington area across the Blue Ridge mountains toward Bedford. Thus I made my way east on U.S. Route 220 to that municipality, pausing at the visitor center just off VA Route 122 exit to observe the cells as they crossed the ridge line. When the rain approached I dropped south a bit to watch some more and eventually had this view of a developing shelf cloud that looked at first like a wall cloud (and was in the correct position for one on the southwestern edge of the cell):shelf cloud near Bedford

I sat at this location for quite a while as the slow moving storm drifted south toward me. I had thoughts of keeping ahead of this complex by rolling south to VA Route 24 and turning east but another cell fired ahead of this activity as shown in here its beginning stages:IMG_7276

With an intensifying rain/hail shaft blocking my way I turned back to a spot just west of Rte 122 (off Joppa Mill Rd) where I snapped this photo of the oncoming storm: storm approaching Joppa Mill RdAs it rumbled in my direction it spit out lots of CGs (cloud-to-ground lightning strokes) so I wound up staying rather close to the chasemobile.

I tried yet again to find another route east but the precipitation shaft on the southern cell had intensified greatly so I finally gave up on that idea. When the storm complex I’d been chasing kept developing on its southwestern edge I decided to push west on VA Route 24. I stopped briefly at Staunton River High School to watch before continuing west.

I dove south of Rte 24 on rural routes and wound up at a farm entrance watching the western edge develop and head toward me.IMG_7284

As it neared my location scud began to gather and this feature showed up as what may have been a nascent wall cloud:

nascent wall cloud

The feature continued to develop into what looked like a wall cloud with an inflow tail from the precipitation shaft:wall or shelf cloud

Given the outflowish structure of this cell I’m uneasy claiming this as a wall cloud but it certainly had the appearance of one.

When the precipitation approached I decided to stay put for a static core punch, This hail core made me a bit nervous but it weakened and passed just west of me so I didn’t see or hear any ice falling:IMG_7311

After waiting in the rain for what seemed like an interminable amount of time I rolled back north on Joppa Mill Road into dry conditions. Instead of calling it a chase I maneuvered into western Bedford county on rural roads. I wanted to find a vantage point from which I could watch (and live stream) the back edge of the convection. I never found an acceptable spot so I eventually gave up and headed back home.

Along the way I passed through the Chamblissburg vicinity and noticed some tree damage on the sides of the road. Apparently both hail and high winds had passed through there, literally a couple miles west of where I’d been sitting at the farm entrance.  None of these cells had been severe-warned but I was surely glad I didn’t feel the brunt of that storm directly!

#vawx June convection finally gets off the schneid

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Today began a pattern change in which storms are finally back in the forecast almost every day this week. Unfortunately the jet stream has parked itself well north of the region so shear is at a premium all week. With high CAPE values and low shear we typically get “whack-a-mole” hailers and that’s what I chased today.

With a weak short wave traversing the mountains storms were already firing by mid-morning over West Virginia. The SPC actually issued a Mesoscale Discussion near 1 pm just after I’d left home:mcd1009Driving south on US Route 220  my intention was to intercept some strong storms that were moving southeast across the New River Valley. While I was rolling down the road one of those cells went severe-warned and aimed itself more or less at Rocky Mount:

IMG_7251

Therefore I stopped in Rocky Mount to refuel the chasemobile and, deciding to close with the storm, I edged back west to head south toward the metropolis of Callaway. Roughly 4 miles north of the town I pulled off, switched on the live feed, and snapped this photo of a fading wall cloud crossing the Blue Ridge:Fading wallcloud near Callaway

As this storm complex crested the mountains it weakened but a portion of the same line further south still looked strong. I decided to intercept the latter activity and maneuvered back to Rte 220 via rural roads. However as I rolled along yet another storm over the Roanoke valley received a severe warning so I redirected to catch up with it, turning north on 220 instead of south.

I was able to catch up with this cell only because it was moving very slowly toward the north-northeast. Making my way through Rocky Mount I pushed up VA Route 122 through the Smith Mountain Lake area, finally stopping at a known vantage point which provides a nice view of the Peaks of Otter. I remained at this spot for a while both to observe this second storm and stretch my legs.
Storm over Peaks of Otter

By this time the severe warning had been lifted and the complex was beginning to merge with other storms moving southeast from the Buchanan area. I zoomed up to U.S. Route 460 at Bedford and turned east to regain position on this system. But between the storm merger and the overall movement the activity was drifting into undesirable chase territory north and west of Lynchburg.

There wasn’t much else to chase within decent range of my location at this point. But given the still available instability it was likely that more strong convection was going to fire (and it did). However with storms likely each day this week I chose to call it a chase instead of pushing further from home.

#vawx Whence goeth the June storms?

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The storm action has come to a screeching halt here in early June during a typically very active part of the chase season. An upper level trough early this week did fire a bit of convection but I was otherwise occupied and couldn’t chase. The now building East Coast ridge and accompanying Bermuda High are combining to squash any decent convective chances for the next several days.

There are hints of some increased activity next week but the GFS provides little hope of shear so these would likely be air mass thunderstorms more typical of July and August than early to mid-June. Still, these type storms can provide some fun chasing with a variety of shelf clouds and perhaps a brief wall cloud or two accompanied by hail and strong winds.

Meanwhile this photo is still one of my favorites from northern Virginia chasing. I was fleeing eastward in southeastern Fauquier county just ahead of a wall of rain pouring out of this April 3 2006 squall line.OLYMPUS DIGITAL CAMERA

I stopped long enough to snap a couple of photos with the rain shaft literally pounding down a couple hundred yards behind me.

Need more storms!!

#vawx A nice and calm chase on a very nice day

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Today was an enjoyable relaxed chase in which I saw three non-severe storms. SPC had most of Virginia in a Marginal Risk but even though deep layer shear was plentiful the CAPE was a bit limited all day.

I rolled south on US Route 220 toward Martinsville to intercept cells that short range models forecast would fire in that vicinity by 3 pm. They did, and I wound up moving east of Martinsville via US Route 58 to get ahead of the storm. As I did the original cell split on radar with the left split having a lowering underneath it:

To both check out and get ahead of the right hand split I dropped south of Rte 58 at Axton, stopping after several miles to switch on the live stream. Repositioning after a few minutes I found another rural location and sat for a while to watch:Storm #1

A shelf cloud began to form as I watched and kept growing while I retreated eastward. This storm was moving and developing such that the business end was quickly moving south of the state line into undesirable chase territory. Thus when I noticed another convective line moving across the Blue Ridge mountains I decided to pull off this storm and roll north to meet the next one.

After splashing through some rain I reached a spot alongside US Route 29 between Chatham and Gretna where i pointed the chasemobile westward to continue the live stream. The southern edge of this convection exhibited a nice shelf cloud:Storm #2

As the complex edged closer to my location the shelf cloud developed a nice layer-cake look:Shelf cloud layers storm #2

Since this system was weakening visually and on radar I let it wash over me with ~25 mph outflow winds. I skirted the southern edge of the precipitation to head north and then west on VA Route 40 toward Rocky Mount. As I did so another storm west of Martinsville began to look appealing out my window. Thus I stopped at Glade Hill to evaluate.

Given that it was a nice afternoon I was in no hurry and decided to move south to check out convection that was bubbling along the rear flank of storm #3. It actually showed a bit of a lowering under a rain-free base:Storm #3 at a distance

Utilizing rural roads to get closer I stopped at the edge of a farm field to watch this flanking cell as it dissipated.Storm #3 rear flank updraft

Storm #3 developed on its southern edge – again – and went severe-warned just across the state line in North Carolina. Having no desire to go back down to that latitude I called it a chase and drove to Rocky Mount for dinner, satisfied that I’d seen what there was to be seen on this nice but non-ballistic day.