high risk

Yes, those early morning wind speeds Monday will be incredible, and that's probably our best shot at SVR. The warm air will be racing north, and there may be a window in the early hours during which the amazing wind fields are overhead and we get a little bit of sfc-based instability. Ultimately, we probably won't have sfc-based convection, but if we do, watch out! But even with the front slowing down a lot, I'm not too excited about SVR potential during the afternoon (as of now). The strongest wind fields and best moisture will quickly shift to our northeast Monday morning, and we're going to end up in the dry slot with strongly veered low-level flow. The downscoping will likely send us into the low 80s, but we're going to dry out a lot in the low levels. Maybe we get a strongly-forced low top line with some wind later in the day, but I don't see more than that as of now, although there is still time for changes.

Looks like a box will be coming soon for DC and points east and northeast. Two lines intensifying to our west now, with SPC mesoanalysis showing 500+ sfc-based cape in the area where the watch is being considered. That's probably enough instability, given the strong wind fields and fast storm motion, to get some impressive gusts.

Not a bad call by LWX. Good reflectivity persists in several CAMS as the storms make it western VA, and soundings do show some modest potential for momentum transport to the ground. Still think that that most of us (except for the western and southwestern areas) have a shot at strong midday gusts in a line along the front followed by strong post-frontal gusts too.

I have to say that I'm surprised to see the microburst in Bethesda. It seemed like a setup in which the instability was elevated which would have led to minimal wind threat but a decent hail threat with the good lapse rates (which materialized). Progs showed much more most unstable cape than sfc cape, but I guess that the line was able to find just enough sfc-based instability in that area.

Yeah, that's our best shot, although the warm front is going to have a tough time getting here no matter what. I'm still not giving up on tomorrow, although solutions showing instability ahead of the front are not the majority. Seems like an early morning dying line hurts our chances.

00z NAM nest also does the split with the late night MCS around the metro areas, but on the plus side, it looks WAY better for Thursday. The midday line has 2000 j/kg of sfc-based cape to work with and healthy deep layer shear. This is the first cycle to show that good instability, so will need to see it maintain that signal.

It's still on the table for sure. I was super optimistic about this threat in my morning posts, but my enthusiasm has been tempered by multiple CAMs showing the section of the MCS in the DC-Baltimore corridor falling apart just before it arrives, while the sections further east and west persist. Still, some of the solutions have at least some of the system surviving into the metro areas, and the lapse rates aloft are still progged to be terrific, so I'm not ruling out storms with hail very late tonight.

Well, THAT is depressing. If this evening and late tonight fail, I still think we have a good shot at a line of storms Thursday, even if limited instability keeps them sub-severe.

I generally agree, but it depends on whether the GFS is right with the secondary low forming near the Carolinas. That would keep us well in the cool air for sure. The Euro would at least give us a (small) chance of getting into the warm sector.

I'm still intrigued by the very late night stuff, although the morning CAMs definitely trended towards washing it out. I'm also now looking closely at midday Thursday. Nice line progged on the NAM nest with impressive wind fields. Instability looks meager, which is for now tempering the severe threat.

morning CAMs also seem to be locking in a cell or small complex developing this afternoon over north-central VA and rolling southeast on the west side of DC during the mid-late afternoon hours. This is a bit further north and east than previously shown. This activity has the best opportunity to be sfc-based, with some wind potential.

yeah, I feel good about convection in the area during the evening. The soundings just don't look great, though, in terms of any severe potential. but the soundings ahead of the late night line show lapse rates and most unstable cape values that are not common around here. That's why I think that this is our best chance on the Maryland side for severe (hail).

The late afternoon storm threat looks to be on the west side of DC, but I like the chances for a lot of us to hear thunder in the early evening. The time period to watch, though, may be the 3-6 am period, when multiple cams show a line racing southeast across the area. It will be elevated, but impressive lapse rates will be overspreading the area, leading to some severe hail potential.

Looking at the CAMs, it looks like round 1 develops as a weakening Ohio Valley MCS undergoes intensification in central VA early Tuesday afternoon and rolls southeast. For the rest of us, our best chance appears to be in the evening hours, when storms that initiate in the late afternoon over eastern OH move southeast towards us. (A few solutions have another batch of storms rolling through from the northwest in the early morning hours Wednesday). Lapse rates look good, so I like our thunder chances - the potential for SVR will depend on how warm we get Tuesday afternoon and stay into the evening hours. While I like our thunder chances with that event, I'm less excited about SVR potential, as I think they'll be elevated, although I suppose I can't rule out some hail.

definitely. and SPC today mentions the mid-Atlantic for both Wednesday and Thursday. A quick check of the morning guidance suggests that the timing is off here for good potential on both days, but there is certainly time to adjust the setup.

Some decent forecasted reflectivity structures in some of the CAMs for later this afternoon, especially in the HRRR and especially over northern VA. Instability is meager, but freezing levels are low, and low-level lapse rates are good. Would not be surprised to see a little small hail and perhaps even a lightning strike or two in the strongest cores.

Realizing that this isn't really the right local forum for this question, but since the correct forum isn't very busy and there has been plenty of discussion about this case in this thread, does anyone have a good feel for why the Jonesboro violent tornado occurred? SPC's outlook didn't have hatched probs in AR, and the MD they issued a little while before the event mentioned the possibility of only a few QLCS tornadoes. The mid-afternoon LZK sounding had decent a decent wind profile, but low-level shear was very modest. The environment in northeast AR didn't seem particularly special. Was there a rapid improvement in parameters late Saturday afternoon that wasn't captured? Or did the storm find a boundary to latch on to?

These soundings aren't too bad - wind profiles in the lowest 1 km are a bit weak but still fairly good. Kmlwx has a good analysis - the problem is that not much guidance shows robust convective development in this area. The one way we could sneak into a better event is if the NAM nest is correct about the slow progression of the warm front. If a cell interacted with that boundary, it could get interesting.

wow! low-level directional shear is lacking a bit, but the low LCLs and impressive low-level cape would make that a volatile environment. Even if we chop off a few degrees from the T and Td, it's still scary.

for us on Sunday, right now the forecast soundings look terrible with limited instability and weak low level flow. It's also unclear whether the cool air will erode over the northeastern half of this subforum. Gonna need a huge improvement in the setup to give us anything of interest.

1500 is probably enough cape to handle that kind of instability, especially given that it's not "tall, skinny" cape, and there is enough low-level instability for good parcel accelerations. The forecasted soundings keep getting better, and SPC now has a day 2 MDT which looks justified. Still questions about evolution of elevated convection earlier in the day and resulting impact on how far north the warm front can get, but areas just south of wherever the warm front ends up look primed.

The problem seems to be that the sfc high to our northeast is moving out faster than was being shown, leading to the sfc winds shifting from north in the morning to southeast by the end of the day. In the NAM and GFS, that allows the sfc dew points, which start the day in the low teens, to recover to the low 30's by evening. That certainly won't get the job done. If we can somehow hold in northeast sfc winds for more of the day, we'll be able to keep the drier air in place and potentially reap some wet bulb benefits when the precip arrives.

NAM nest still shows that the front will sink back to the southwest later today and cool things down for those northeast of DC. HRRR seems to be coming on board.

While it's an obvious long shot, and I won't try to pretend otherwise, this is a chilly and very dry air mass that will settling in over us on Sunday. (The GFS shows dew points dropping perhaps into the single digits early Sunday). So IF the low can track south of us and we can get precip in here overnight Sunday, that could work for some of us.

There has been discussion about this line over in the severe thread. It's been going for a couple of hours now.