#vawx Is WeatherBrains ready for us?!!

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Turns out that Monday July 23rd will be a watershed moment for Mid-Atlantic ChaserCon. At 9:30 pm EDT Bill Hark and I will be the guests on WeatherBrains Live! Bill (a member of the ChaserCon planning committee) and yours truly will be talking at length about our event scheduled on October 27th at the Science Museum of Virginia in Richmond. Of course we’ll also talk about storm chasing!! Bill is a very accomplished chaser and photographer here in Virginia and is very well known in the chaser community out on the Great Plains. I’m anxious to hear what he has to share.

I actually made a minor appearance as a guest panelist on WeatherBrains episode 447 which aired in August 2014 but this will be a bigger deal. I’ll have to up my game!!19 May 2011 Wakita OK

 

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#vawx Marginal Risks can lead to acceptable results (like today)

Today was about what I expected. Those expectations plus some luck netted an intercept of a severe-warned storm rolling through Bedford and Franklin counties. But first, the SPC Day 1 outlook:VA_swody1

A surface front sagging south through Virginia didn’t quite have enough ooomph to fire storms today so it was left up to a weak upper level wrinkle (a very small shortwave trough) to provide the vertical lift. Short range models varied a bit in timing but agreed pretty well that the convection would be scattered in nature.

I headed south on U.S. Route 220 and then east on VA Route 40 at Rocky Mount with the thought of posting up in Gretna to await the action. However I’d noticed on radar a persistent storm moving southeast across Botetourt county which looked like it would hold together and continue into Bedford county. Thus I rerouted to Burnt Chimney just off VA Route 122 to catch the southern end of the convection but by the time I arrived the main cell had fallen apart.

Shrugging my shoulders I continued east to Gretna following a line of building updrafts. Stopping at the western edge of town I watched radar and the sky for a bit. I was sorely tempted to jump onto Rte 29 north and pursue an impressive looking severe warned system cruising southeast toward Dillwyn and Farmville but I hesitated. The remnants of the earlier storm seemed to be regenerating over central Bedford county both on radar and visually so I motored just north of Gretna to check it out:

Sure enough by the next radar scan NWS Blacksburg had issued a severe warning on this cell and I switched on the livestream. From my perch just north of town I could clearly see a lowering underneath the rain-free southern edge approximately 15 miles away. (The bright western sky proved too much for my weak contrast-y photos.)wall cloud under Franklin co storm

The storm had turned right and was steaming toward the south-southeast. By the time I’d decided to relocate further south to keep up with the system the wall cloud had grown a bit:wall cloud_3

Reluctantly leaving my vantage point I rolled down Rte 29 to a spot between Gretna and Chatham which was just outside the warning polygon.

Unfortunately while I was diving south the storm had become a lot less impressive visually.view from rte 29

Within the next 20 minutes or so this storm had run its course and weakened below severe status so I switched off the livestream and pulled up stakes. Heading south to Chatham I turned back west to check out new convection rolling off the Blue Ridge into Franklin county, Alas that activity quickly fell apart and my chase day was done.

But chalk up one more severe storm plus wall cloud on a Marginal Risk day!

#vawx SPC vindication: tomorrow’s chase potential isn’t a fantasy after all

Guess I wasn’t simply wishcasting in yesterday’s blogpost. (Gotta love that northwest flow with moisture in place and upper level short wave support.)VA_swody2

Tomorrow morning it’ll be a matter of determining timing and location, altho’ at the moment it looks like the U.S. Route 460 corridor by mid-afternoon would be a safe bet. Just need to figure out how far east to go for the initial target.

#vawx I may have spoken hastily last night

I may have to eat my own words regarding this week’s weather. When I was asked yesterday whether there was potential for any storm chasing this week I answered in the negative. Then I took a look at this morning’s 12Z model runs for Wednesday afternoon when a cold front is forecast to sag south across Virginia.

First, the 500 mb winds at 21Z Wednesday which look a bit more vigorous than I’d thought:GFSMA_500_spd_057

Then the 0-3 km EHI and forecast precipitation at the same time Wednesday:

As can be noted these are all from the 12Z GFS run. The 3 km NAM 12Z output looks much the same with regard to precipitation timing and adds a bit of updraft helicity to boot:

So, there you go. I am now officially on watch for a Wednesday afternoon chase. This time I’ve – hopefully – ironed out the bugs in the newer livestreaming software so it will recognize my camera instead of forcing me to go back to the old application to get things to work.

And since it’ll be 7/11 maybe I’ll stop by a store for a Slurpee deal!!

#vawx A chase with slightly better results than anticipated

Got in a nice chase today that actually began before noon and ended just after 5 pm. With a cold front pressing south into a soupy air mass storms were inevitable especially with a non-existent cap. Unfortunately also non-existent was deep layer shear so the only hope for rotation was low level localized interactions. Not surprisingly the SPC only had Virginia under a general thunderstorm risk. My expectations were thus to see a shelf cloud or two and perhaps a hail shaft.

I picked up my chase partner right at noon and we motored south on U.S. Route 220, stopping only briefly in Wirtz to check out a cell building over the mountains near Floyd. We continued on to the Martinsville area while keeping an eye on the numerous storms growing to the west. We turned onto U.S. Route 58 in hopes of getting to a known vantage point at the Blue Ridge airport but convection had progressed to where it was no longer practical to push west to that spot.IMG_0081

We pulled off Rte 58 at a point where we could watch the base of the convective line develop lowerings that gradually morphed into a shelf cloud.lowering S of Martinsville

When the rain approached our position we headed back east on 58 and rolled toward the Axton area east of Martinsville. After pausing a few minutes alongside a rural route north of Rte 58 we noticed an interesting cell south of that highway so we dropped back in that direction in hopes of finding a – very – rare open vantage point.

Fortunately we came across such a spot that allowed us to stay put and observe the action just to our south while avoiding the copious rainfall under the now severe-warned system. Not long after this a flash flood warning was also issued for this slow moving complex.IMG_0092

The system had broad rotation but was basically outflow dominant and developed this feature complete with greenage. I was convinced at the time we were seeing a shelf cloud that progressed right-to-left in front of us.shelf cloud with greenage

However as the situation developed this feature became what was likely a mesocyclone with this view of the updraft base shown here ahead of the chasemobile…updraft base and chasemobile

while this was the radar velocity data at the time:IMG_0097

Compelling evidence of this being a mesocyclone was the incredible CG show we witnessed as we stayed inside – or very close to – the chasemobile. Eventually this did change over to an outflow-driven shelf cloud but the awesome lightning show continued. These are a few screen grabs from my dashcam video that recorded many such CG strikes.

Finally, however, the rain shield pushed toward us so we waved goodbye to this system as it continued south of the state line into undesirable chasing territory. We headed back north toward home for a very early conclusion to the chase day.

More storms fired later that afternoon and evening but I doubt we’d have seen anything to top what we did witness.

#vawx A First Friday chase for July

Given the recent tropical humidity reinforcing the heat dome across the East the cold front scheduled to come through tomorrow – Friday July 6 – will provide a welcome relief. Both dew points and temperatures look to moderate over the coming weekend.

The cooler and drier air mass plowing into the existing sogginess will fire up thunderstorms which, of course, triggers my internal chasing antenna. Unfortunately there won’t be much shear to speak of since the jet stream has vacated the premises for its annual summer vacation in Canada. Storm motions will be in the neighborhood of 10 knots which is a prescription for local flash flooding if the downpours are vigorous enough.

This is the simulated reflectivity at 17Z (1 pm) Friday from the 06Z 3 km NAM:NAMNSTMA_prec_radar_035

Every model I’ve checked this morning shows the cold front pushing east of the mountains early tomorrow afternoon so I’ll need to head out by lunch time to stay ahead of the action. With the predicted parameters I’d expect to see shelf clouds and perhaps a hail shaft.

Hey, it’s a chase opportunity!

#vawx Mid-Season chase gear updates

The next chase opportunity won’t arise until at least next weekend when a “cold” front will get pushed through the Old Dominion by a trough.  Given this quiet interlude I’ve finally had the the time to review and update my chasing gear after two ventures to the Plains this year.  I fully enjoyed both trips but they delayed my full adaptation to this year’s most efficient chase gear setup.

Thus I am still refining the interior setup of the new chasemobile. Overall I have more room for gear especially since I’ve adapted the Hokie Stormchase methodology of using bungee cords with which I’ve mounted my power inverter to the rear of the center console. That represents an incremental increase in technology level above the painter’s tape – which I still use – to mount my livestream webcameras.

Speaking of the livestream camera I finally moved the forward looking unit to the left center of the dashboard. Given this year’s shift of the Virginia state inspection sticker to the left side of the windshield I was left with a sticky smeared mess in the center. When I finally realized how much this had degraded the livestream’s clarity it was obvious that camera needed to be moved.

Moreover my livestreaming service – Severe Studios – announced they would no longer be supporting the Adobe software package I had been using to livestream. So I finally downloaded OBS (Open Broadcaster Software) and spent a few minutes this past week online with the Severe Studios help desk to set it up. Assuming next weekend provides chaseable storms I’ll be able to field test this software package.

I’m resisting buying a laptop stand given the $200+ pricetag for a decent model so I’ll still use bungee cords to hold my chasing laptop in place. I did spring for a refurbished iPad mini (and a corresponding CD mount) to provide a larger screen for radar displays than the iTouch I’d been using. By doing so I also made it worthwhile to upgrade my RadarScope account to Tier 1 which provides split screen views and lightning data.

Now, bring on the storms!!

#vawx Video review = possible funnels from June 27th Bedford county storm

Took the time to go through dashcam videos from yesterday’s intercept in Bedford county (still need to review the livestream recordings). A couple of interesting things popped out that seem to confirm what we were seeing real time.

The first one is a possible funnel (tornado?) that we witnessed behind the shelf cloud that we saw from this vantage point in Bedford county (courtesy Google Maps):Bedford county VA location 27 June 18 #1

The shelf cloud was a couple of miles to our north and west while the wall cloud was a couple miles due west of us. The dashcam video – sped up 4x – verifies what we were seeing behind the shelf. At about the 10 second mark in the video a lowering appears that resembles a cone funnel which is shown in these edited video frame grabs roughly 30 seconds (real time) apart:

 

The radar reflectivity and velocity scans at about the same time looked like this:

 

Note the velocity couplet southeast of Bedford that kinda corresponds to the direction in which we were seeing this feature. Funnel? Possibly, and we noted this feature in the audio portion of the video even though behind a shelf cloud isn’t the usual position to see one. Tornado? (Shrugs.)

About 30 minutes later we were located at our final vantage point for this intercept (again, courtesy Google Maps):Bedford county VA location #2 27 June 2018

At this point the mesocyclone was nearly overhead but the precipitation shaft and possible hail stayed just to our north even as CG’s pummeled our vicinity. Keeping the dashcam active we watched as the wall cloud rotated a mile or so north of our position. At roughly the 30 second mark in this video  a funnel-like feature begins to coalesce and rotate, ending up looking like this (edited frame grab):possible funnel_edited

Could this have been another funnel? The position within the storm is about right and this feature does appear to be (a) laminar and (b) rotating. And per the radar views there was definitely rotation happening on the western edge of this cell:

 

Although it’s interesting to speculate on what we saw I’m not big on counting possible funnels/tornadoes. Although I’ll likely send this info on to NWS Blacksburg just watching this storm was fascinating enough for me!

#vawx Sometimes the models and the SPC convective outlooks need to be ignored

OK, so even SPC had a hard time dealing with today’s setup. Short and longer range models disagreed on timing of today’s convection but all of them indicated potential trouble as 700 mb temperatures hovered in the 8-9 degree C level. That’s a pretty stiff cap for the Mid-Atlantic, suggesting a strong forcing mechanism was needed to sustain updrafts…and there wasn’t such a mechanism evident. Moreover destabilization was dependent on a cold air damming wedge eroding which is always a crap shoot in the Mid-Atlantic.

Thus this succession of malleable SPC Day 1 convective outlooks. First, the morning graphic showing much of Virginia in a Marginal Risk:VA_swody1

Then the mid-day and mid-afternoon outlooks came out looking very different:

Notice any differences????????? That’s quite a range, indicating lots of uncertainty about today’s setup.

Regardless of any lingering doubts I rendezvoused with Nick Gilmore, a former Hokie Stormchaser and WDBJ7 intern who now works for public radio. He is putting together a story about storm chasing and wanted to chase with me in an opportunity to gather more material. We met at 2 pm and headed for the VA Route 40 corridor east of Rocky Mount.

After stumbling across road construction – the bane of storm chasers everywhere – on Rte 40 we found a relatively quiet spot near Union Hall to await the action. Two areas of convection developed, one south of us along the U.S. Route 58 corridor and another along and north of the Roanoke valley. Given that more sunshine and thus higher CAPE (instability) values was evident to the south we drove in that direction.

Winding up in a favored observation point in eastern Henry county we watched and waited for the southern activity to approach. As it did so the rain shield weakened and shrank, dashing our hopes of a southern storm intercept. All was not lost, however, as the northern convection had held together and looked to be strengthening.

Of course this meant we were woefully out of position so we rolled east on Rte 58 at highway speeds and curved north on U.S. Route 29 to continue the journey. Fortunately the northern complex was chugging eastward at a sedate pace so we were able to match latitudes by the time we reached the VA Route 24 intersection. Diving west there we wound up on VA Route 43 where we finally were rewarded with this view of the storm base:First look at storm base

By this time the cell was severe warned, the only such warning in the state of Virginia:

As it ponderously slid eastward we found another vantage point from which we had this view of the obviously rotating southern wall cloud:Bedford county wall cloud

Retreating south once more as the rain/hail shaft approached this was our next view of the nearing wall cloud from the intersection of Rtes 24 and 43:Second view of wall cloud

Wanting to avoid a potential hail shaft we then retreated a couple miles further east on Rte 43 and conveniently found a spot where we parked as the mesocyclone base passed just to our north. CG’s accompanied by booming thunder rained down all around as the cell cycled up one more time. It came very close to pushing out another wall cloud right in front of us:last view of wall cloud

We were literally at the western edge of the complex at this point:

Shortly after this the storm ramped down, the wall cloud faded, and the severe warning was removed. So we pulled up stakes and headed for home satisfied with the knowledge we’d intercepted the storm of the day in Virginia.

#vawx Wednesday could be a decent chase day ahead of the coming heat

Just before the heat dome builds over the Eastern states this upcoming weekend a low pressure center will cross the Great Lakes and drag a cold front along with it. Wednesday thus looks to bring a chance of severe storms through the Old Dominion even though the SPC Day 3 outlook isn’t jiving with that thought. If the models continue to trend the way they look now I expect the SPC will modify this graphic significantly by the time Wednesday’s Day One outlook is published.VA_swody3

What’s most intriguing is the 500 mb wind field on the southeastern edge of the upper level low Wednesday afternoon. Those winds are relatively strong for late June, rendering some decent 0-6 km shear values.NAMMA_500_spd_051

Moisture won’t be a problem given 70+ degree (i.e. yucky) dew points. The lifting mechanism will need to be the lee trough east of the Blue Ridge since the surface front will lag back over the Ohio valley Wednesday afternoon.

The resulting 0-3 km EHI (Energy Helicity Index) looks favorable for severe storms as does the supercell composite:

To look at this setup in more detail I’ll host a Google Hangout Tuesday evening at 8:30. Join us for the discussion and then tune in for a potential livestream Wednesday afternoon if there is something worth pushing out live video for.