#vawx Nix on a Saturday chase

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I’m now officially doubting today – Saturday – will be a chase day. Oh, yes, there will be storms, some of them likely to be rip-snorting supercells. But timing and location seem to be conspiring against me chasing today.

Besides the fact that the better shear is along and north of I-64 the 700 mb temperatures look too warm south of that corridor. Short term models (HRRR and various WRF models) have showers firing and rapidly dissipating across much of southern and south-central Virginia. That screams CAPPING to me.

Moreover the cold front that will add lift to the storm equation appears to exert its influence south of I-64 after sunset when convection will begin to wane. Some decent cells look like they’ll fire by 7 o’clock in the Charlottesville vicinity but I’m not going anywhere near that area today!

Meanwhile there will be some awesome storms today, just not when and where I’m willing to chase. The HRRR did an excellent job of forecasting the path of the tornado-warned supercell that plowed across northern VA Friday afternoon/evening. Here’s today’s 15Z HRRR depiction of reflectivity and updraft helicity at 8 pm:HRRR reflectivity at 0Z

If I still lived in the Fredericksburg area I’d be out chasing near sunset while simultaneously advising my wife to take shelter. But not living near that area any longer I’ll pass on this opportunity.

So, unless things drastically change in the next couple of hours I’ll be sitting here at home watching baseball and radar…probably in that order.

#vawx Not Friday but Saturday

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I seriously considered chasing today even before the SPC issued a Marginal Risk across much of Virginia:

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However I wound up punting today for a few reasons and it looks like I didn’t miss much since I wasn’t willing to stray into far NW Virginia. The cool stuff is happening north of the I-66 corridor while the majority of the activity south of U.S. Route 60 is a rainy blob. Oh, and did I mention the KFCS (Blacksburg) radar is still down? Relying on the edges of neighboring radar sites’ coverage is okay given discrete storms and good visibility but that’s not the case today.

Tomorrow looks a bit better for chasing as a cold front approaches from the west. A prefrontal trough looks to fire convection east of the Blue Ridge by late afternoon. Decent deep layer shear and instability values led the SPC to issue a Day 2 Marginal risk across most of the Old Dominion:VA_swody2

The best parameters per both the NAM and GFS will be in the southeastern corner of the state. But there is enough potential just east of the mountains to convince me to head to the Piedmont. Time and target is still TBD but for now Saturday’s the day.

#vawx An unusual August setup and chase

Plenty of shear, moisture, CAPE, and lift…sure doesn’t sound like August in Virginia but Monday August 7th proved to be an anomaly. An East Coast trough coupled with some potent shortwaves and a vigorous surface front led to a compelling desire to chase. The best parameters were well east of my normal territory as exhibited in the SPC Day 1 outlook but they weren’t ballistic enough to tempt me to head out that far:VA_swody1 (1)

The most worrisome factor was a persistent overcast left over from morning rainfall which limited the available sunshine and thus instability. However old Sol peeked through the clouds enough to boost CAPE values over 1000 j/kg east of the Blue Ridge so I headed down the driveway just before 2:30 pm. Given a wide variation in short term model solutions (both between models and run-to-run) I chose to head toward Gretna on the US Route 29 corridor to split the difference between a northern and a southern target.

Another factor that didn’t help was that the NWS Blacksburg radar – KFCX – was down (and will be down most of the month). I used a plethora of other sites to keep checking for over-the-horizon convection but obviously details were fuzzy at the edges of the coverage areas. I paused along VA Route 40 a couple of times as I motored eastward and noted the relatively vigorous southwest surface winds. Low level shear was very obvious…again, rather unusual for August.

Finally reaching Gretna around 4 pm I ambled around the area a bit while awaiting the action. I did note an impressive updraft to the north associated with a cell over Buckingham county that appeared to be near or along the surface cold front. After twiddling my thumbs for a while I decided the southern stuff wasn’t going to happen early enough so about 5 pm I pointed the chasemobile north toward the cold front.

Rolling north on Rte 29 I diverted east on VA Route 24 through Rustburg to the US Route 460 corridor east of Lynchburg. I kept heading north across 460 via rural roads and found an open vantage point near the hamlet of Stonewall where I could see the base of a cell near Amherst:

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I switched on the live stream and began snapping photos as I watched scud gather and coalesce under the base:

When the rain approached (never heard thunder from this storm) I pushed east along a rural route to another spot where I paused for the six o’clock TV news to use the stream. This feature got rather close:a REALLY close lookI was almost convinced this was just another typical late summer shelf cloud except that I never felt outflow. As I faced this feature surface winds were quartering from behind me toward the right (eastern) edge of this cell. At the same time this was the best radar velocity view I could obtain: IMG_8016

The radar view of the storm structure didn’t look like a shelf cloud producer and my suspicion that this was actually a wall cloud grew as I continued east and then south to avoid the precipitation. Traveling south back to Rte 460 I used the highway speed to scoot east a bit and found a vantage point from where I had this view of the feature:

To my chaser-trained eyes this was a wall cloud at this point, although I hedged my bets when I sent out a photo on social media stating that it “looks like a massive wall cloud”.

As this storm steamed almost due east I decided to get ahead of it via Rte 460. I wound up going all the way to US Route 15 near Farmville where I turned north. Jumping on a rural route as I neared the leading edge I wound up with this view of an obvious shelf cloud at this point:definite shelf cloud N of Farmville

I bade farewell to this storm just after this and rolled into Farmville for a late dinner break. By the time I pointed the chasemobile westward on Rte 460 several line segments had developed with areas of heavy rain along my path homeward. During one such downpour just west of Concord (intersection of VA Rte 24 and US Rte 460) I had slowed to ~45 mph due to poor visibility plus water ponding on the road. About 100 feet ahead of me I suddenly noticed headlights wildly gyrating before coming to a quick stop.

An older model SUV laden with all manner of tools and equipment had spun out, making a couple of 360 degrees spins before rolling on its side at least once while spewing construction material all over the roadway. To make a long story short the driver was immediately treated by an ambulance crew that fortuitously arrived on the scene just after I did. I got completely drenched during the ongoing downpour and grew a bit concerned about the lightning that began to flash around the scene as local emergency crews arrived and took charge. Once law enforcement arrived and spoke with a couple of us witnesses I finally continued homeward in my wringing wet clothes.

It was a rather eventful day!

 

#vawx Uncertainty among all concerned

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The blogpost title says it all. I was unsure about today’s setup given differing model solutions and I discovered that I wasn’t alone. The local NWS office hedged their bets in the forecast discussion text and the Storm Prediction Center continually downgraded the severe threat from a Slight Risk in yesterday’s Day 2 outlook to a Marginal Risk in this morning’s Day 1 to just general thunderstorms in the afternoon Day 1 update.

Outflow from a short wave crossing the Appalachians did kick up a line of storms across West VA which continued into Virginia. After deciding to leave home around 1 pm after I saw the “whites of their eyes” (radar returns) I headed for Burnt Chimney in Franklin County. Strong cells were coming across the Blue Ridge both toward the U.S. Rte 460 corridor and toward the VA Rte 40 corridor so I figured an initial target of Burnt Chimney would hedge my bets.

My main concern when I stopped to review conditions was that the SPC mesoanalysis page showed a persistent 10 degrees C isotherm over the area at 700 mb. That represents a pretty stout cap for these parts and it didn’t seem to be either cooling or advecting away. Nevertheless I chose to target the southern portion of the area when a discrete cell went up ahead of the line near the Wirtz/Boones Mill area. (Did I mention that visibility was rather poor due to the haze from the high dew point values?)1st storm near Wirtz

When the rain approached I drove south on U.S. Route 220 and then turned east on Rte 40, stopping near Glade Hill to watch for a while. I could hear thunder grumbling to my north as this cell merged with the line. When the rain again approached I moved south from Glade Hill and then east again, leapfrogging from one vantage point to another to keep dry.

At the intersection of Sago and Museville Roads in western Pittsylvania county I had this view to the west of the approaching shelf cloud:shelf cloud at Sago Museville Rd intersection This feature stretched almost 180 degrees along the horizon and after a brief stop here I relocated once again to a spot just west of Callands where I snapped a photo of this section of the line with some incipient greenage showing:shelf cloud W of Callands

Reaching VA Route 57 at Callands I dropped southwest to a vantage point where I finally decided to conduct a “static core punch” instead of continuing to leapfrog ahead of the line. The cap’s influence was being felt as none of the cells looked to be intensifying either visually or on radar. Radar VIL values didn’t indicate any hail and the velocity data didn’t show any particularly strong winds so I pointed the chasemobile’s nose at the oncoming shelf cloud and waited.

Having made that decision I continued photographing the line’s approach:The rain cometh S of Callands

Just before the rain began in earnest I had a good view of the “whale’s mouth” under the shelf cloud itself:In the Whales mouth S of Callands

I let the rain do its thing for a few minutes before pulling up stakes and motoring back north to Callands. I wound up taking the Museville Road back and then rolling along via another county route to Snowville Road which led northward to Penhook. Along the way I came across this vista of a foggy post-rainfall Smith Mountain:Smith Mtn after the rain

All in all it was a pretty benign chase, one in which I really didn’t have high expectations due to the uncertainties. Now the question is what will happen tomorrow as a strong short wave / vorticity lobe drops into the Mid-Atlantic? Will we really see enough severe threat to warrant the current Day 2 Slight Risk?

I’m not going to lose any sleep dithering about it.

#vawx Late July ponderings

At this point in the summer there is still hope for chaseable storms albeit a dwindling one. Instability is rarely a problem this time of year but shear is hard to come by and the combined heat and humidity make sitting in the chasemobile for long periods a less than desirable activity. Last year (2016) held some pretty good action in August and September even without tropical influence:

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Wall cloud near Clarksville VA 9/28/16

However, the 2017 chase season is proving to be a different – and less active – animal.

Hence the pondering…what should I consider for next year’s chase season? What follows are a few random thoughts that may guide my chasing decisions in 2018:

(1) I haven’t been chasing on the Plains since 2015. THAT will change next year someway somehow, preferably to involve traversing the central and northern Plains states in search of storms.

(2) Live streaming while chasing adds a layer of complexity and cost to the overall operation. (And while it has garnered some money the amount doesn’t begin to cover the costs associated with streaming.) Frankly it’s a pain in the neck and tends to detract from my enjoyment of the storms themselves.

(3) The Ohio Valley is close enough to reach via an early morning start. I will definitely make at least one of those setups next year.

(4) One goal I haven’t made much progress on to date is taking existing forecasters out chasing who have never been in the field. I feel it’s very important for them to see first-hand the results of forecasts typically made in an office or studio.

Enough pondering on a late July afternoon. Bring on the storms!

#vawx Sometimes the models are right

Even though short range models predicted that MCS-driven storms would weaken quickly once east of the Blue Ridge this afternoon I had already decided I would give chase today. When the mid-day SPC convective outlook with a small Marginal Risk over Virginia came out I felt a bit justified:VA_swody1 1231EDT update

I waited until convection closed in from the west before heading out since it was too hot and miserable to sit very long while awaiting action. Unfortunately the NWS Blacksburg radar was hiccuping  this afternoon so I left home using the MK 1 eyeball to maintain situational awareness.

Models had indicated better parameters along and north of U.S. 460 so I rolled to Bedford where I paused for a while at a local park. When towers began building over the Blue Ridge mountains I motored to the Visitor’s Center where I had this view of a wall cloud under the convection:Wall cloud W of Bedford

This feature quickly dissipated as the cells moved away from the mountains.

I dithered a bit on which way to go when the rain approached and wound up heading east on Rte 460 and then diving south on rural roads. (I discovered yet another gravel road in Bedford county (!) that appeared on the map to be paved.) I eventually made my way down to VA Route 43 which I followed south and east to the Mentow vicinity.

By this time the convective line had weakened both on radar (it was working again) and visually so the models had been correct. I experienced cool outflow winds of 15-20 knots at this final stop on today’s chase. Although this sunshaft was a cool sight it was another indication that the action was over for the day as the convection began breaking up.Sunshaft near Mentow

However tomorrow is another (chase) day!

#vawx Late July chasing in the Old Dominion

Should I admit that I’m considering chasing the next two very sultry July afternoons?

A couple of upper level “wrinkles” plus a weak front sagging southward are all keeping my attention focused despite the summertime doldrums. Things to watch: overnight MCS’s, remnant outflow boundaries, and upper level temperatures (e.g. cap strength). Oh, and not leaving to chase too early is high on the list as well. It’s too miserably hot and sticky to sit by the side of a highway somewhere waiting for storms to fire.

Saturday might involve a hike northward to the I-64 corridor; I’ll have to decide on a target that morning. Monday may also be on the table for a chase but that will have to wait a couple more days before I commit. This year has been somewhat less productive than the 2016 chase season so I could be grasping at straws here.

#vawx A midsummer “Whack-A-Mole” chase

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Today’s plentiful instability with dew points in the 70s accompanied by an uncapped atmosphere meant that showers and storms fired early, forming over the mountain ridges before noon. However with no shear the main threat looked to be heavy rain and high winds from collapsing cores along with some chances of hail. Thus the SPC had our area in a Marginal Risk (level 1 of 5) for severe weather:VA_swody1

I had already decided to arbitrarily limit my chasing radius as slow moving storms would pop up just about anywhere…and they did. I headed out just before 2:30 to check out the situation and was greeted with this view across southern parts of the Roanoke valley:Storm over Cave Spring

That particular cell dropped “grape-sized” hail in the Cave Spring area (size estimation provided by a friend in that area). Turning a bit more toward the east I noticed this dissipating shower:Dying storm E of Roanoke

But instead of sticking around to observe this action I was drawn toward a storm crawling southwest along the I-81 corridor toward Daleville. I thus motored in that direction to a hilltop sports complex that affords great vistas and was rewarded with this sight of a developing cell just west of the area.

This developed into a linear complex that drifted further southwest so I dove south one exit on I-81 and took position at another favored vantage point near Hollins. There I watched a rain-free base slowly undulate, occasionally sucking scud into the base but without any visible rotation.

As the northern end of the line segment neared I moved a bit south to watch as it intensified and began spitting out noisy CGs. I thought I’d captured at least one bolt on video but a quick review revealed that I’d missed it. When an extension of this complex developed overhead I rolled home to get out of the rain.

So it wasn’t a chase to crow about…but it was something on a hot and sticky July afternoon.

#vawx Back in the saddle again but Monday doesn’t promise a lot

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Having been out of the chasing mode for a week it’s time to keep an eye on the sky again. Tomorrow (Monday 7/17) the SPC has the mountains of Virginia in a Marginal Risk area:VA_swody2

I’ve peeked at the NAM NEST and several WRF models and all I see so far is a chance for a few scattered cells firing tomorrow afternoon. Shear is minimal but a weak boundary looks to push southward along the Blue Ridge, dividing westerly winds from an easterly push of moisture off the Atlantic. Upper level temperatures seem to be cool enough to prevent a cap forming so we’ll see what happens. One never knows what outflow boundaries could do.

I’ll likely chase at some point Monday but it may be a case of watching radar and satellite and heading out once something convective rears its head. Storm motions will be slow enough to allow a standing start (I hope). Mid-July is too hot to park somewhere and wait for storms to fire.

Need a Plains trip next year!!!!!

#vawx Other sights from July 5th

After having a chance to go through my dashcam videos from July 5th (still haven’t looked at the livestream video caches) I found these two so-so frame captures of the same CG stroke:

There were many such CGs that alighted around us as storms #2 and #3 merged overhead. It’s possible the livestream cache contains better captures but there’s a LOT of video to go thru and I just haven’t done it yet.

Of the video I have reviewed this link to a YouTube post provides three different views of storm #1, the long-lived spinning supercell / mesocyclone combination. Each section is sped up 8 times to show the rotation more clearly.

And what I didn’t mention in the original writeup is that there was some interesting action going on in storms to the north of this first cell. This closeup shows a shelf cloud beginning to push out ahead of one of these northern storms while we were keeping an eye on our southern trio:Northern storm forming a shelf cloud

All in all it was a very busy couple of hours of chasing after an afternoon of nothingness. That’s the essence of storm chasing.