Not a Moderate Risk bust!

Today started out in the Outer Banks as we wrapped up our family vacation this morning and headed back home, arriving a little after noon. Given the SPC prognostication of a Moderate Risk for our area I was a bit wary of a bust, given our previous track record. However, I couldn't pass up the chance to check out a supercell composite value of 12 (a one provides a decent probability of supercells...12 is obscene!!) in our general area so I scampered west to Culpeper where I used a known wifi location to check radar. An outflow boundary from this morning's Mesoscale Convective System (MCS) was pushing up storms in northern Virginia, but I had no desire to fight that sort of traffic so I moved south to intercept a small storm that was pushing east from Orange into some pretty juicy air. It turned out to be a good decision as I found a wallcloud exhibiting rotation and a likely funnel south of the main rainshaft while enjoying a very nice CG show. As the storm rolled eastward I paralleled it as best I could on the county roads just north of Lake Anna in southwestern Spotsylvania county, glimpsing another possible funnel through the trees (although it was probably just interesting-looking scud). I found a decent vantage point and saw some greenage along with a decaying wallcloud that could have been mistaken as a funnel. At this point convection had begun to fire all around me so I wound my way eastward to Rte 208 just north of Lake Anna, where I sat for a while to let the line push by me and allow me to (a) watch the rear flank and (b) not have to drive in the heavy rain. While I watched I saw a significant hailshaft manifested on a storm just to my southeast. I finally wandered my way home around 4:30 having put sufficient mileage on my bones for the day.

Saturday May 31

Hmmmmm... things are still looking up for chasing tomorrow, especially if the SPC is calling for a 30% chance of severe weather. With pretty impressive instability forecast (CAPEs>3000 j/kg) for the Mid-Atlantic plus some wind speed shear with height we will likely see some strong storms with high winds and large hail. It looks like the only way we'll see any rotation is if a line forms and bows outward; the rotation would happen near the bow echo portion. But even without rotation it appears that Nature is going to put on quite a show tomorrow.

Saturday's severe potential

Guess the SPC has made it official for Saturday, altho' the buzz for several days on various weather forums has been that the Mid-Atlantic is in for some severe weather on the last day of May. The Sterling WFO forecast discussion this morning backed off from previous discussions in the area of rotating storms, but the instability and windshear could very well provide a probability of tornadoes in our region Saturday afternoon. I'll be watching conditions and radar and will be out somewhere awaiting convection initiation...just not sure exactly where yet.

Vacation musings

Given a relatively slow internet connection here on the Outer Banks I haven't bothered to check the forecast models, but I have been following the SPC convective prognostications and the Sterling forecast discussions. It seems that we may have a chance at severe weather in the Mid-Atlantic on Saturday, which is fine since we'll be back in town by then and I should be able to chase given the opportunity. Having said that I have found it curious how the loosely-defined storm chasing community views situations in which severe weather damages property and/or causes injuries. Some chasers seem to just focus on the opportunity to bag tornado video and associated chasing notoriety, and others are genuinely concerned about helping victims of storms as in the case of several chasers who are actively helping and following up with the victims of the devastating Greenburg KS tornado of 2007. Personally I have always been fascinated with severe weather and welcome the chance to experience it, but I certainly don't want anyone to suffer because of it. That's why I feel a strong sense of responsibility to phone in severe weather to the NWS forecast offices as a Skywarn spotter. We have witnessed many instances of severity (wall clouds, funnels, and tornadoes) that we have called in to a forecast office after which the forecasters have issued severe weather warnings based on their radar depiction and our onsite observations. Many times things happen below the radar horizon of a local forecast office, and forecasters have no way of knowing for sure that bad things may be starting to happen. Anyway, I'll keep chasing to satisfy my severe weather fascination. I realize that I have nothing to do with causing the weather, but I at least can help provide warnings to folks in the path of the storms I am watching.

Reflections on the 2008 Plains chase season

From our lofty perspective here on vacation this year's Plains chase season seems to reflect the 2004 season, especially when our chasing luck (or lack thereof) is factored in. The number and timing of tornadoes this month seem to mimic the outbreaks in May 2004, especially when you consider that we missed all of the action both then and now. The chase group from Virginia Tech that just got back home yesterday wound up bagging 8 tornadoes in one day last week. I have to admit I'm insanely jealous of their success while at the same time happy for them. However, the chase season in the Mid-Atlantic is still incomplete so maybe we can see more action here in our own back yard. Meanwhile, back to the family vacation...

Dry Weather??!!

According to Doug Hill's blog post today thus far May has been the second wettest May at BWI airport, the third wettest May at Dulles Airport, and the fourth wettest May at Reagan National Airport. The good news is that the forecast for the next five days is for dry weather, including the Memorial Day weekend. The bad news is that this means the chasing potential for the area is just about nil until next week. That's okay...vacation time is coming!

Enhanced details

The picture shows a few details behind the leading edge of the convective line as it approached Wares Crossroads this afternoon. In addition to the rather chilly outflow and the onrushing rain, these details caught my eye but didn't amount to anything other than an interesting sight. I overdrove the darkness, contrast, and backlighting on the original photo to force this to show. It's amazing what the human eye can see that a standard camera can't.

18 May rural Virginia convection

SPC Day 1 convective outlook had the Northern Virginia region in a Slight Risk for severe weather with a small but significant tornado probability this afternoon due mainly to wind shear profiles and upper level cooling. Surface instability was very weak due to overcast left over from the morning's rainfall, so the approaching cold front was the only forcing mechanism available to push updrafts. We left at 1300 for Culpeper where we sat and watched conditions and radar returns until almost 14oo when we turned first northward on Rte 29 to follow a developing line...that is until my son caught a glimpse of a stronger section to our south, so we cut cross country to catch Rte 522 southward. We jumped ahead of the eastward-moving line and took the above picture (matched to the corresponding radar return with an "X" for our location), winding up at Wares Crossroads - again - where we turned north on Rte 208 and proceeded to get caught in heavy rain thanks to the obliging but unhelpful Virginia rural road network. We may have seen a shelf cloud or two, but we never saw any other specific features nor any lightning. Not exactly a bust, but not the most productive chase we've ever had either.

16 May Tidal Potomac storms

The SPC and the local Sterling forecast office didn't hold out much hope for storms this afternoon, but after I reviewed the models around lunchtime and saw enough instability and an approaching cold front to trigger storms I headed out at 1300. Sure enough a line of convection fired along the front and I was able to get a ringside seat at Fairview Beach to watch as a shelf cloud appeared to have a lowering behind it that may have been a wall cloud. A break in the line appeared in front of this lowering and I saw what looked like some organized inflow so I watched carefully to see if any rotation would appear, but none was evident. As the line approached I hopped eastward to Dahlgren at the roadside park next to the Harry Nice bridge across the Potomac and experienced the approach of the front itself, complete with the "fingers of death" leading edge scud that teased with some pseudo-rotation.
I followed the line southeastward after a brief stop to grab a radar picture via wifi and wound up just across the Essex county line on Rte 17 as the southern end of the line approached with heavy rain. Nothing severe, but an enjoyable chase even so.

Friday's severe potential in eastern Virginia

The SPC convective outlook for tomorrow shows a probability of thunderstorms just east of I-95 in Virginia, and a slight risk of severe weather closer to the Chesapeake Bay. I'll be keeping my eyes (and my options) open in case the chasing potential looks good and I can get to the area without fighting my way through flooded roads. It won't take much rain for us to see that again given the deluge of last Sunday/Monday. If the predicted low pressure center forms near the Bay and we can get some sunshine to bake the humid air tomorrow afternoon, it may be worth heading toward Tappahannock and points south and east from there.

And now for more regarding Palmyra VA tornado

Not to beat a dead horse (I'm already looking forward to the next chase) but here are a couple of maps of our location and viewpoints for the 8 May events courtesy of Mapquest.com. The top map shows our southern Palmyra location (white dot and yellow arrow) where we saw the wall cloud and substantial funnel shown in the top two vidcaps from my previous post, and the bottom map is of the northern Palmyra location where we witnessed the darker vidcaps of the touchdown/tornado.

A few vidcaps from Palmyra

Here are a few vidcaps from yesterday's chase. The later (darker) two are from video taken north of town where we witnessed at least one tornado. They seem to indicate touchdowns on the left and right of the main funnel...possibly a very broad circulation.

May 8 Palmyra tornado

We left home around 5:45 pm to creep through rush hour traffic and head for Thornburg to get our bearings as conditions for storms were looking better to our SW. Once we checked out current conditions and forecasts we proceeded from there down Rte 208, stopping to check out an updraft (here) that wasn't very impressive except that it was exhibiting signs of rotation, piquing our interest greatly. We continued to Ware's Crossroad, then through Mineral to Louisa where we stopped around 7:00 to pick up a WiFi connection to check our bearings. About that time my son's cellphone connection showed a storm exploding in Buckingham county so we nixed the internet check and charged down to I-64, jogged west to the Rte 15 exit, and continued southward. As we approached Palmyra a rain-free base was evident and my internal antenna began twitching. Sure enough as we popped over a hill a wall cloud came into view and we stopped just south of town at 8:00 to watch it grow and drop a substantial funnel (video) that may have touched down as a tornado below one of the ubiquitous Virginia treelines that obscured our view. When the funnel and wall cloud disappeared behind heavy rain we pulled up stakes and headed north a couple of miles where my son took a couple of good still photos (link) as we watched at least one touchdown. Somewhat confused on which NWS forecast office to call (we were in the mutual corner of Wakefield, Sterling, and Blacksburg coverage areas) I finally reported our sightings to the Wakefield office which promptly issued a tornado warning for the Palmyra area. As we watched the wall cloud retrograded to the southwest and faded while the storm behind us grew in intensity as evidenced by fierce and increasingly frequent lightning. That's usually a very clear signal that the wall cloud and possible tornado was reforming to our south, and it was now getting very dark. We scooted north and east a few miles to see if we could use the lightning to help us spot more rotation, but heavy rain obscured our view so we skedaddled up Rte 15 and wound up at home around 10:30 pm. Little did we know that this very supercell was following us all the way (radar path) and dropped tornadoes just to the west of I-95 in Stafford county, damaging homes and rendering several dozen people temporarily homeless. Great chase, but our enthusiasm was tempered by the damage that happened near us.

Palmyra VA tornado

Yep, we bagged another Virginia tornado this evening. We headed south into some riper conditions and wound up in Fluvanna county in the vicinity of Palmyra filming a wall cloud that dropped at least one tornado northwest of town as we watched. I will be getting some video together tomorrow and will also post a still picture or two if they come out...it was after 8 pm local and the light was failing, so I'm pinning my hopes on the video. The radar view above was taken about the time we spotted the tornado. I called it in to the Wakefield WFO and they posted a tornado warning on the storm shortly thereafter. Of course when I got home I saw a Tornado Vorticity Signature (TVS) on a cell just west of here, but I wasn't going back out at 10:30 in heavy rain and full dark! Success strikes again!

Frontal timing

What's the deal with the timing of the cold frontal passages through the Mid-Atlantic in 2008? So far the vast majority of cold FROPAs have been at night, far from the time of peak heating that helps fire convection and produces thunderstorms and some much needed rainfall. The synoptic level systems seem to be off kilter this year, which seems to be borne out by a general lack of forecast model convergence. This is still early May and our storm season has a ways yet to go, but these night-time cold front events are getting old. Let's keep the severity in rural areas away from people and property, but we need some storms to rumble through and dump rain on us.

Video from the Suffolk VA tornado

Here's a link to a video from the 28 April tornado outbreak in the Suffolk VA area. I love to chase storms, but I'd much rather see them in rural areas with no property damage or injuries.