Chasing opportunities this weekend

The better weekend chasing choice is Sunday ahead of an approaching cold front, but once again I have other priorities that afternoon/evening. Thus I am pinning my hopes on late Saturday afternoon, which - per at least one model - should have decent CAPE and a bit of wind shear in northwestern Virginia. I'll obviously refine my target area based on later model runs, but right now I'd be aiming for somewhere in the Front Royal to Winchester corridor between I-81 and the Blue Ridge mountains. I've also got my eye on the Warrenton vicinity but that is less favorable territory due to traffic volume, hilly territory, and lots of trees. Given work and personal schedules I'll have to be very judicious in my chase selections the next few weeks, but I've had to do that during previous years so it's no big deal. I just can't make all the chases I'd like to ...(sigh!).

Edited video from 26 April chase

The three clips in this video are from yesterday's chase. Clip #1 is normal speed from my first observation point east of Culpeper, watching the development of the southern end of the line from which the severe storm eventually formed and plowed through the Fredericksburg region. Clip #2 - sped up 4 times - is of the cell just to the north of the first one near the Culpeper airport, showing a clear slot and perhaps the beginnings of rotation. Finally, clip #3 (also sped up 4 times) is from just west of the I-95 / Route 17 interchange looking east at a lowered cloud base that is sucking up scud and apparently rotating. This is the storm that pounded the Fredericksburg region with hail and spawned at least one waterspout over the Potomac River.

Storms? check! Chasing? check! Traffic? Yuck!!!!

The SPC didn't think Northern VA had enough atmospheric "ooomph" (that's a technical term) for severe weather today, but when I noticed that a dissipating warm front was hanging around east of I-95 my severe weather antenna perked up as I knew the resulting shear could pump up a supercell or two. I had hopes for convection today anyway so I went to Thornburg around 1:15 pm to check out some showers moving northeastward from the Richmond area, but they wound up escaping into eastern VA territory that I hesitate to chase in given the abundant treelines and randomly inconvenient roads. Casting about for where to go next I picked up a WiFi signal and found that a line was beginning to build near the Blue Ridge mountains so I cruised up I-95 and picked my way through the typically awful traffic on westbound Route 3, arriving at a Culpeper county viewing spot to watch the southern end of the line build.
As this cell approached and threw rain at me I moved north a few miles to the Culpeper airport to witness another cell begin to get its act together and exhibit minor rotation near a flanking line.
Determined to keep up with the line as it neared the weak warm front east of I-95 I motored north to Remington and then southeastward on rural Fauquier county roads, keeping just behind the rain/hail shaft and watching nearby updrafts and bases for more rotation signs. When I finally popped out on Route 17 southbound I wasn't able to avoid the rain so I pulled off and phoned my son for a nowcast. He indicated that the section of the line I was tracking was coalescing around a radar-indicated mesocyclone and I got pumped about doing a core punch! Unfortunately reality set in as I got within a couple miles of the I-95 interchange as traffic came to a dead stop. I ducked off on a side road, pulled into a shopping center, and saw what appeared to be a wall cloud.
As this part of the storm moved eastward I struggled to plow my way through the burgeoning traffic to no avail, losing a good 20-30 minutes in my trek to catch up with the line. I finished up in King George county watching another cell to my south as it transited my windshield, knowing I had lost too much time. When I arrived home I found that the section of the line I had originally been following had produced a waterspout over the Potomac River just across from King George county. Foiled again by traffic!

Northern Virginia severe weather today?

The Day 1 convective outlook from the SPC has us under a Slight risk, with a 5% chance of tornadoes here in our area (a significant value for the Mid-Atlantic). The shear (both directional and speed) and CAPE values combine to provide a great-looking storm chase day for our area, especially with a warm front lurking just to our north. This latter factor provides two key ingredients for severe weather: it puts us in the warm sector of the approaching low pressure system and it keeps a shear boundary - which can cause an average thunderstorm to go severe - nearby. That, plus an upper level impulse and some sunshine makes me very optimistic for a severe weather event in Northern Virginia...even tho' I probably won't be able to chase today.

First High Risk of the chase season

Wow! The Mississippi valley is under the gun today! That's great for storm chasers - altho' that's not terrific chasing territory - but the residents there need to keep an eye on the sky today. Meanwhile we are under a slight risk for severe weather tomorrow, but I doubt I'll have an opportunity to chase due to other priorities.

Storm chase Sunday/Monday?

A warm front looks like it will hang up and stall just south of us Saturday, keeping our region in the cool stable air with plenty of plain ole' rain. Sunday looks more promising for convection as the warm front clears out and possibly some afternoon boomers which I won't be able to chase due to other commitments. The big HOWEVER is that Monday afternoon may also present an opportunity to track down some storms just south of the Fredericksburg area. Depending upon workload Monday afternoon and on how far south I'd have to travel I may be back in the hunt next week. Still gotta keep an eye on the models as a slight shift in timing or geography could improve the potential!

AccuWeather.com - WeatherMatrix | Severe Thunderstorms, Tornadoes, Lightning All Down in 2010

AccuWeather.com - WeatherMatrix | Severe Thunderstorms, Tornadoes, Lightning All Down in 2010

At least I'm not alone in my mostly futile quest for chaseable storms this season!

Casting aspersions on next weekend's convection

The long range GFS model is showing a definite cold air damming signature next weekend for the Mid-Atlantic. Even though a potent surface low is forecast to approach from the west the above graphic for 8 pm Saturday evening shows a stubborn cold pocket holding on over Virginia, which would quash any convection that would be associated with a warm front that could otherwise lift northward. Given that the European model tends to agree with this setup the low looks like it will slide by south of us, keeping all the warm juicy convective conditions further down the coast. Model forecasts this far out can certainly change, but right now my hopes for a Saturday chase are dimmed significantly.

Awaiting more convection

Given that it's April I don't hold out a lot of hopes for chasing every week here in Virginia... but it sure would be nice. The next chance looks like Friday afternoon but I'm not sure I'll be free to chase then. The next viable chance appears to be the following Friday, but that's so far out that I don't trust the models very much. Thus, I'm learning patience (again!!!!).

So far no good...

I did chase today, starting out in Culpeper at 4:30 to - hopefully - intercept a lone cell out ahead of the approaching cold front. The models and forecasts indicated that a cap (an upper level "lid" on convection) existed but would start breaking down after 5:00 pm east of the mountains, and sure enough it did. The cell shown above went up west of Culpeper and screamed northeastward at 40+ mph, so my "chasing" involved trying to catch up to it before it reached the horrendous Northern Virginia traffic. I did see a lowering south of the rain shaft about 5:25 or so but was unable to photograph it as I was on a major highway amidst mondo traffic.
After losing the race with this cell I returned to Culpeper to (a) grab some dinner and (b) grab some WiFi for some situational awareness, finding out that a large amorphous rain mass was headed my way. That explained the gray/black mushiness to my southwest, so I hightailed it eastward toward Fredericksburg in an attempt to get east of the area and see if there was anything interesting on the backside. Alas, this rain mass was also moving along at a pretty good clip and it caught me before I reached Wilderness. I saw nothing of interest so I headed home to watch the radar and see if anything chaseable would occur nearby. So far that hasn't been the case, so it looks like this chase is done for the day.

Thursday chasing could be good!

Glad to see the SPC agrees with my analysis of tomorrow - Thursday - as a potential chase day! CAPE looks to be nearing 1000, and upper level winds approaching 50 knots should be enough to create reasonable convective havoc. The SPC text mentions the need to look for mesoscale (e.g. localized) features tomorrow that could influence the development of supercells out ahead of the cold front. That plays right into all the factors here east of the mountains and west of the Bay, so guess what I'll be trolling for tomorrow? Off the top of my head I'd say the probability of a severe TS watch covering our area tomorrow is pretty good, with the odds of a tornado watch being issued somewhat lower. Either way I think we'll see some rough weather tomorrow as the approaching cold front shoves aside the abnormally warm air mass and sends us back to more April-like conditions for the weekend. Keep an eye on the sky!!

A chase washes away the Monday blahs...

Although the day started with the NWS not too excited about storms in our area, and even though the SPC didn't have us under a slight risk for severe weather, Mother Nature improvised in the form of a lee trough that focused the existing instability and fired off what proved to be a severe thunderstorm that plowed right through the Fredericksburg region.
My first chase attempt was aimed at a couple of mediocre cells that went up near Culpeper and aimed themselves at the Stafford airport, so I obligingly set up shop at the latter location and watched this approach at about 5:30 pm:
Although it looks menacing - and headed straight for me - it fell apart as I watched so I motored home to eat dinner. As I did so, however, I discovered a trailing cell that began to look very interesting so I gulped down dinner and headed back out.
I wound up in eastern King George county as the now severe thunderstorm crawled through the region (black "X" marks my location):
I videoed the storm and recorded a small bit of hail as the aft end of the hail shaft (purple areas in the above radar view) scooted just to my south, but the best was yet to come as I waited for the whole thing to pass by and get some structure shots:

All in all it was cool local chase, possibly a warm up for Thursday!

Cold frontal passage now Thursday pm?

Things have changed a bit since last night's model runs. The GFS and the European models are now forecasting a decently strong cold front to push through here late Thursday afternoon, with at least a modicum of CAPE present to fire storms. Wind shear - if any - will be speed only, with directional shear almost non-existent at this point. I'm not exactly getting pumped up yet, but I'll be watching the progression of the model solutions closely for chasing potential.
Given the strength of this cold front the temperatures next weekend should be much more seasonable, in the 60's vice this weekend's 80's. (That's degrees F, of course!)

Still keeping fingers crossed for Wednesday

Both the GFS and the European models are showing a cold front approaching the Mid-Atlantic on Wednesday afternoon, with a bit of convective instability (CAPE) out ahead of it. This morning's forecast discussion from NWS Sterling casts doubt on the timing, preferring to go with showers on Thursday, so my certainty of a potential Wednesday chase is a bit lower than it was. This strong East Coast ridge that is bringing us unseasonably warm April temperatures is going to be hard to dislodge without a hard-charging Canadian air mass, and I don't see one of those on the horizon yet. However, we do have enough local factors - mountains, sea/bay/river breezes, etc - that could combine with even weak instability to fire a few storms, so I'm not giving up the ship yet!