high risk

There are some small hints of it in the previous HRRR runs, but it's overall really tough for a model to get this, as it has to get the initial forcing and cold pool dynamics. Forecast soundings show a strengthening unidirectional wind profile and some downdraft cape......

This line is producing. I've seen a few events like this over the years, with a fast-moving line of low-topped showers requiring warnings. Will be interesting to see how far southeast they survive.

not at all saying that this will end up as a severe event, but the radar is supposed to look empty right now, regardless of whether we get severe. The guidance shows storms breaking out over central WV in the next 2 hours and then racing east-northeast.

lots of signal around 7 or 8pm, but a general 6-9pm range should cover it. overall severe threat seems fairly low but not non-zero, consistent with the SPC outlook. But lightning would be a nice early March bonus.

you have a very legit chance of seeing convection, for sure.

pretty stong agreement among the CAMs this morning that the threat later today is all north of the DC Beltway, and depending on your model of choice, it could well north.

right. because the HRRR is 5-8 degrees warmer.....

18z HRRR has a sfc-based bow echo moving across the areas north of the DC Beltway early Tuesday evening. It's an outlier solution in terms of having much warmer sfc temps than other guidance, but IF it were correct, it would be a SLGT risk day.

This post is spot-on. I can see why they didn't have any thunder marked around here on the prelim day 1, but the 12z guidance has clearly shifted towards more favorable parameters AND explicit convective signatures in the simulated reflectivity. It warrants a general thunder outlook in the new day 2 for sure, and it's honestly not that far off from a MRGL.

well, crap. Those got added in pretty late, so I guess that LWX had to look pretty hard to find them but in seriousness, the Culpepper reports don't totally surprise me, but the Fairfax reports do. I didn't see anyone in this forum report strong winds inside of the Beltway.....

O storm reports. Lack of sfc-based instability, ftw!

Perhaps the smallest amount of sfc-based instability for that cell to work with down by Culpeper, where sfc temps are 5-6 degrees warmer than around the DC Beltway and points north and east.

Agreed. We'll have no problems mixing behind the front.

Several of the morning CAMs show the same thing now. Seems like some showers break out ahead of the line in those runs and ruin the convergence.

This is a very good point! But that event had some actual sfc-based instability.

I still don't understand why SPC is now even considering an upgrade to SLGT, but there is no argument that if sfc-based parcels can find a way to be buoyant, the wind fields are amazing. A faster evolution of the event might allow the line to take advantage of daytime warming for the western part of the outlook, so I understand the outlook expanding west. I'm setting my goal for getting a torrential downpour and maybe hearing thunder. Seeing several consecutive HRRR cycles wanting to break up the line as it moves east is giving me some pause, though......

For sure. The reflectivity looks so impressive! But it's not surfaced-based. That said, there is some elevated cape, so while there wouldn't be any severe threat with that (assuming that the NAM nest is correct with the stable sfc layer), there would definitely be some chance of lightning. I would call that a win!

LWX is pretty bullish in their afternoon AFD, and as Yoda mentioned, the MRGL risk now comes into the DC metro area. I still, however, haven't seen guidance showing surface-based instability here. I do see good mid-level lapse rates, so there will likely be some elevated cape, and I certainly believe that some lightning is possible. Until, however, I see some sfc-based instability being progged, I can't buy in to SVR potential until you get well south of the DC Beltway.

I'm always interested in high shear low CAPE setups, but it could be a high shear NO CAPE setup. I tend to trust the NAM nest when it keeps us cool at the sfc in these events, but if the HRRR is right, it would be a SLGT risk day for sure.

So we're in to the range of the NAM nest now, and it has been emphatic for several consecutive cycles now that a strongly forced convective line will move through the area early Wednesday evening. But it's also been emphatic that the line will not be surface-based, and most of the guidance I've seen agrees with that, so the chances of taking advantage of the excellent shear profiles seems low. That said, the GFS is trying harder to find a tiny bit of sac-based instability, so I won't totally close the door, even though I'm really hesitant to consider the GFS it wants to scour out the low-level cold air.

Great looking 500 map for sure. Right now, most of the guidance I've seen keeps the warm front south of the DC metro area, but it's obviously still 5 days out.....

While the main synoptic precip shield is obviously going to be way south of here, there are hints in several of the hi-res runs for a band of snow showers moving southeast across the DC metro area this evening.

classic event in which SPC takes the approach of "we didn't call for it, so we're not going to box it and hope it goes away quickly"

Thank you. I should quit posting for the year now, as I likely won't make a better call......

Some folks are thinking about snow showers in northern MD tomorrow, and that is on the table, but I'm more interested in the "warm sector" along the I-95 corridor tomorrow morning ahead of the occluded front. A lot of guidance briefly puts this area into the low-mid 50's, and there should be a band of convection along the front. Some of the CAMs develop a little bit of instability, and it's really cold aloft with decent lapse rates, so while I'm not ready to call for thunder, I'm wondering if some places might get a burst of graupel or small hail.