#vawx A Hangout regarding the 2018 Mid-Atlantic storm chase season

This past Monday, January 14th, I hosted an online Hangout discussion of the 2018 Mid-Atlantic storm chase season which can be viewed here. Although the invitation to speak went out in early December via the Mid-Atlantic ChaserCon FB page we wound up with four Virginia-based chasers. Peter Forister covered a tornado he witnessed in Charlottesville and both Andrew Smith and Bill Hark detailed the chasing they did separately during the September 17th tornado outbreak in Richmond. I talked about the Bedford county tornado-warned storm I chased in June (no tornado) which is where this photo is from:June 22 Bedford Co wallcloud copy

Collectively we agreed that the 2018 season was somewhere in the middle of the scale when compared to the hyperactive 2016 chase season and the rather sedate 2017 season. Of course the record rainfall in 2018 made for more rain-wrapped storm features than usual so that was a tradeoff.

Hey, it was something to do to take our minds off the upcoming bitterly cold forecast for the Mid-Atlantic! On to spring and the 2019 storm chase season…

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#vawx Top ten stormchase photos of 2018

It’s that time of year so here are my top ten favorite storm chase photos of 2018. I haven’t ranked them in any particular order so they are listed in chronological order. (Dates and location precede each photo.)

May 6th, cemetery just east of Brookneal VA:

6 May Brookneal cemetery copy

May 18th, Quinter KS vicinity:

18 May KS storm copy

May 23rd, Lake McConaughy NE:

May 23rd sunset copy 2

June 7th, Crawford NE:

June 7th Crawford NE copy.jpg

June 10th, northwestern South Dakota:

June 10th tornado warned storm SD copy

June 22nd, Bedford county VA:

June 22 Bedford Co wallcloud copy

July 6th, Henry county VA:

6 July meso Sandy Level copy

September 22nd, north of Altavista VA:

22 Sep shelf cloud NW of Altavista copy

September 26th, Pittsylvania county VA:

Sept 26 storm over tobacco field copy

December 21st, Bedford county VA:

21 December rainbow under storm base

 

And that’s a wrap for 2018. Let the 2019 season begin!

What’s the rationale for the SSW social media buzz?

Apropos of nothing severe-related I decided to post here regarding the latest craze in weather social media: “Sudden stratospheric warming“, or SSW. The research and analysis conducted by folks like Dr, Judah Cohen is certainly valid and has implications for broadening our understanding of what affects global weather beyond a narrow focus on factors like El Nino / La Nina (i.e. ENSO).

Observed changes in the upper atmosphere from SSW have a delayed effect on our weather here at the surface of the Earth. Most accounts I’ve read state that several weeks are necessary for SSW to cause – for instance – a shift in the polar vortex (a former weather social media “darling”) that could bring frigid conditions into the U.S. during winter. I understand why forecasting such long term weather changes are important to businesses (utility companies, retail establishments, etc). The processes used by such entities have enough inertia that they require sufficient lead time to adjust their operations to prepare for significant changes in weather conditions.

What I am having difficulty in comprehending is why many weather folks on social media who communicate weather information to the general public are so enthralled with reporting on every little SSW tweak or hiccup that comes along. What is the average non-weather geek person supposed to do with information that suggests temperatures several weeks from now “might” be colder or warmer than it currently is? Or that snow storms “might” be more or less prevalent a month or two from now? To me that’s akin to seasonal hurricane forecasts: what do they mean to the average person regarding the weather over the next 5-7 days? How do these long lead time outlooks benefit Joe or Jane Q. Public?

I suppose SSW is just the latest fad to keep the weather social media buzz (dare I say “hype”?) alive.

#vawx Yes, Virginia, today was a chase on the winter solstice

So it happened…my first chase on the winter solstice. I wasn’t totally sold on the idea even though a deep trough was pushing through the region. The severe parameters (instability, shear, moisture, and lift) just didn’t quite line up per the models which is why SPC only had a general thunderstorm risk across Virginia. Nevertheless I talked myself into heading east of the Blue Ridge into Bedford county this morning to intercept some convection zooming northward.

I found myself under a linear discrete cell before 11 a.m. just south of U.S. Route 460 between Bedford and Lynchburg.

This was the view to the south as I switched on the livestream:Oncoming storm base Bedford county

As the action quickly traveled northward I pulled back out on Rte 460 and motored west a couple of miles to this view of the rear of the storm looking north:rainbow under storm base northern Bedford county

This was the overall view of what turned out to be the discrete storm of the day a few minutes later as it disappeared across the Blue Ridge mountains:overall view of northern storm

Up to this point this storm had exhibited no lightning but as it continued northward some strikes showed up on radar. It remained discrete on radar for quite a while.

With that action out of reach I retreated back west toward Bedford to await more development. While I pondered the situation in a local park I witnessed another brilliant rainbow:rainbow #2

I finally chose to dive south on VA Route 122 to a known vantage point which allowed a clear view to the south and southwest. As I came to a stop I quickly snapped photos of backlit showers to the south near Smith Mountain Lake:backlit showers over SML

Here I sat for quite a while waiting on a developing squall line that showed various signs of strong winds and possible rotation on radar.

I did see the cloud base under the line as it approached but  not much else. When the rain overtook me I rolled north again to Bedford before running east ahead of the deluge. This was my last view of the oncoming line from a location south of Rte 460 on a rural road:last view

There were more showers building to the south but on radar they didn’t look much different from what I’d already seen so I called it a chase.

#vawx Further pondering about tornado formation

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In a previous post I referenced an article (abstract here) whose basic premise is that the use of mobile Doppler radars has shown that tornadic circulation begins at ground level and then works its way upward. (It should be noted that the dataset to date consists of only 5 storms.) I sent the reference to Dave Carroll – meteorology instructor and leader of the Hokie Stormchasers at Virginia Tech – and he referred me to the “dynamic pipe” effect as a potential analog.

Now I don’t doubt the data collected or the research team’s analysis (after all, Howie Bluestein is one of the authors!!) but as I mentioned in my previous post this doesn’t account for funnels that never become tornadoes. In my years of chasing here in Virginia I have observed roughly three dozen funnels that never produced a discernible ground circulation. After pondering this seeming contradiction between my observations vs. the article’s data I have begun to wonder if there are multiple mechanisms that create tornadoes.

Another piece of anecdotal information is that over the past 15+ years I have read a number of statements by storm chasers in the Great Plains that almost every time they see a funnel there is a resulting ground circulation, i.e. a tornado. That is in direct contrast to my experience here in the Mid-Atlantic in which a quick review of my chase accounts shows a 7:1 ratio of funnels:tornadoes. This difference could be due to a couple of factors. Perhaps the terrain and abundant tree lines here have prevented me from seeing a ground circulation under the funnels I’ve observed. If that is true then tornadoes occur a LOT more often here in the Mid-Atlantic than typically thought.

27Oct10_edited copy

10/27/10 near Fredericksburg VA

7May13 White funnel near Hurt copy

5/7/13 near Hurt VA

Or does the study’s conclusion apply to only stronger tornadoes, like the 2013 El Reno Oklahoma beast that the researchers observed? Or perhaps there is indeed a different funnel/tornado producing mechanism at work here in the Mid-Atlantic vs. the Great Plains. If that is the case then it provides even more justification for research efforts in this part of the country similar to VORTEX SouthEast.

Still pondering…

#vawx On the winter solstice?? You have to joking, right?

You’re kidding, right GFS? A measurable supercell composite parameter on the Friday before Christmas? The first day of astronomical winter??GFSMA_con_scp_111

A peek at the Euro shows plenty of deep and low layer shear across southern / central Virginia Friday. CAPE is a bit weak on both models (a couple hundred j/kg) but still…

I guess I’ll have to pay attention as this setup evolves. I haven’t had any productive December chases to date that I can recall.

#vawx Top-down or bottom-up? More data required

Via social media I came across an interesting study referenced in a Capital Weather Gang column. The study was to be presented today (Dec 14th) at the American Geophysical Union Fall Meeting in Washington DC. The essence of the study is that an examination of detailed data from five tornadic storms indicates that the circulation began on the ground before it showed up in the parent supercell thunderstorm. The use of mobile radars located very close to the tornadoes was crucial to gathering the data and the El Reno tornado of May 31 2013 was one of the cases mentioned. The tentative conclusion was that the typical “top down” tornadogenesis” theory may not be correct.

I’m expecting a torrent of reaction from the meteorological research community regarding this conclusion. I don’t have the degrees or research experience to jump into that debate but I do have questions based on my own experience. If tornadogenesis indeed occurs from the ground up what about funnels that never touch down, i.e. never become an official tornado? I’ve witnessed plenty of those while chasing here in Virginia with several examples shown here:

22Jun10 Greene county funnel copy

June 22 2010 Greene Co Virginia

28May09 Stafford funnel_edited copy

May 28 2009 King George Co Virginia

Funnel W of Museville 9:29:16_edited copy

September 29 2016 Franklin Co Virginia

To my recollection each of these funnels swirled downward from a parent wall cloud (and I could show other examples as well) with no evidence of ground circulation.

Now perhaps the “ground up” hypothesis applies to particularly violent tornadoes – like the El Reno event – and not the lesser cousins on the EF scale. That could well be the case, but IMHO more than five data sets are necessary before completely rewriting current tornadogenesis theories.

#vawx A look back at the June 22nd 2018 chase

The onslaught of winter weather threats continues with an Alberta Clipper swinging across Virginia tomorrow and then the potential for a major winter storm this coming weekend. Meanwhile my thoughts are turning back to warmer days and storm chases of 2018.

One of my favorites occurred on June 22nd when I latched onto a storm in Bedford county that eventually became tornado-warned. I actually witnessed two wall clouds under this storm, with the northernmost one (on the right in this photo) rotating anti-cyclonically.

IMG_9956 copy

My dashcam video – sped up several times – can be viewed on YouTube at this location.

The southwestern wall cloud became dominant and was the portion of the storm that caused the tornado warning to be issued.wall cloud and chasemobile

I followed this cell through rural Bedford county and wound up in driving rain on U.S. Route 460 heading into Lynchburg. I never saw a funnel underneath this storm but it was a fruitful and enjoyable chase.

#vawx A 10 year anniversary of a mid-November chase

I missed this date yesterday while dealing with the snow/ice/rain/flooding yuck that was happening. Ten years ago yesterday (11/15/08) my son and I intercepted this wall cloud in King George county VA (east of Fredericksburg):Nov152008 wallcloud_2 copy

We had chased storms all the way from central Culpeper county eastward through Fredericksburg and into King George county, witnessing shelf clouds and multiple lowerings under the cloud bases.

The area was under a Slight Risk issued by the SPC. The storms that day were decent for November with enough updraft helicity to create visible rotation (note the flag indicating surface winds blowing toward the wall cloud, i.e. inflow). A non-chaser friend who lives further west in King George county mentioned that even he’d noticed rotation in the base of a storm that crossed over his neighborhood.

#vawx Nope. Not today.

Just a quick note that underscores yesterday’s doubts about a possible chase today. Nothing has really changed in this morning’s model solutions which are still showing LOTS of shear oriented parallel to a weakening squall line crossing the Appalachians. In addition there is very little instability (CAPE) to create sustained updrafts that could tap into the strong upper level wind field until the squall line is well east of the mountains. Thus the SPC has pared back its convective outlook for today to this:VA_swody1

The Slight Risk area has been pushed further east while the tornado probabilities have been dropped from yesterday’s 5% to today’s 2%. Both the Marginal Risk and the general thunderstorm areas have been edged completely east of the Blue Ridge crest.

A peek at the forecast for updraft helicities (i.e. potential for rotating storms) shows little evidence of such until this afternoon east of the I-95 corridor, about where any rotating storms looked to appear per yesterday’s model runs. So no chasing for me today!