high risk

Good point, and the HRRR is still struggling to initialize them. The only guidance that explicitly showed this was the ARW2. Some of the other guidance has shown cells developing later this afternoon south of DC and moving north, so I think that these solutions correctly captured the northward-moving forcing mechanism but struggled to initiate storms much earlier and much further south.

Dew points have been lowering at all 3 airports over the past few hours (likely due to mixing), which seems to match what the HRRR has been forecasting.

HRRR seems to have a good handle on the environment. It's going for roughly 80/58 by mid-afternoon which seems reasonable. NAM Nest is too cool - it really raises the dew points later this afternoon, and I'm not sure that's going to be right.

Yeah, the signal for this started showing up yesterday, and even the Hi-Res Windows are buying in, although they disagree a bit on location and timing. (The HiResW FV3 initiates the lead cells notably further north.) Seems like several cells will race from south to north out ahead of the more organized line rolling east. Still unclear how much instability will be available: the HRRR is much warmer (but drier), while the NAM Nest is more moist (but cooler). Perhaps there is a temperature/moisture "sweet spot" in there that could increase the potential for some hail and wind.

seems to be some growing potential for the Tuesday deep offshore low to loop back to the south/southwest, which opens the door to rain rotating back into our area during the afternoon, likely accompanied by some stiff winds. This is after the likelihood of heavy convective rains Monday evening. And with the potential for a big soaker Friday/Saturday, this will be a much-needed wet week.

This post didn't age well, as the timing now appears to be much faster. If we toss the anemic, outlier NAM Nest solution, a large area of convection should be approaching from the southwest in the early evening with perhaps a few lead cells out ahead racing south to north. Deep layer shear is good but is mainly due to very fast winds at the higher levels; the combination of weaker shear in lower levels and limited instability will likely mitigate the threat in the DC/Baltimore area, although an earlier arrival would open the door to a slightly higher threat.

SLGT for the southwest part of the area and MRGL for the rest. The question will be how warm it can stay after dark. Clouds and southerly winds should keep temps up through the evening and overnight hours, but it will still be cooling, and instability will be limited. The better threat is definitely well west and southwest of our area, but a line of storms (or heavy showers) well after dark with some wind potential is probably worth the threats SPC has assigned.

Nothing has really changed. Instability is going to limit the severe threat, but a forced line of convection will sweep across the area during the early to mid afternoon hours on Saturday. Lightning threat is limited, but I would still not be surprised if some healthy gusts accompany the line.

Certainly possible. Looks likely that there will be a line of forced convection along the cold front in the late afternoon. Deep layer shear will be robust, but as you note, the instability is the question mark.

Fabulous lightning show to my north-northwest. It's not frequent, but it's super bright and looks amazing in the drier air with stars out.

Yeah, I'm not sure what to make of this. The HRRR continues to be very emphatic about an active evening, but it doesn't have any of these early stuff. The current evolution seems to match more of some of the other CAMs which had an earlier, more scattered event.

My lawn could use a drink too... hope that we all cash in. SPC has put our region in a MRGL risk for SVR, which is consistent with the idea of more organized convection occurring.

There isn't much agreement in the timing, but the morning suite of CAMs suggests a really good chance of moderate or even fairly widespread convection over central and northern Maryland either during the dinner or early evening hours.

We've gone from multiple inches of rain for the week ahead to 0.5-0.75" on the WPC maps. To its credit, the GFS was never really on board with the Euro's big event.

Coverage will be limited, but there should in theory still be a few storms on the front over the next 4-5 hours. And any of those storms that are able to sustain strong updrafts could produce some severe winds or hail. I'm not super excited about this event, but I'm also not ready to say that it's over.

Those "good" runs earlier this morning had these showers on the north side of DC during the late morning, so I'm not terribly worried. That said, don't look at the 12z NAM Nest.

I'd generally agree, but a complicating factor is that no guidance has a very good handle right now on the strengthening convection over northeast WV and far western MD. Curious to see whether that has any influence on the evolution today.

Agreed with all of this. While I think that there are several mitigating factors (most notably the potential for subsidence behind the morning wave), I will note that 1) the 6z NAM nest for whatever reason tends to go weak on convection 2) I usually take it as a very positive sign when a morning, elevated MCS somewhere in the Mid-Atlantic is producing lightning. That's a great sign that we have steeper than usual lapse rates.

Might end up with a small SLGT risk area at some point tomorrow, but right now, there are too many questions on magnitude of instability and location and coverage of storms to justify the upgrade, IMHO.

The lapse rates and resulting instability tomorrow certainly have my attention. Deep layer shear looks to be good - will become stronger a bit too late. I can't help but notice a general consensus for the best threat to from DC to the east and southeast, so it doesn't look for now like those of us north or west of the city have the best chances, but there is certainly still some time to change that.

Confirming the previous two posts, there is some sneaky TOR potential for early Thursday morning, as low-level shear will be very strong. Instability will be limited, and these super wet early morning environments don't often work out for us, but it's a non-zero threat for sure.

NAM nest (and other guidance) has trended much faster now for tomorrow's activity. Still perhaps a small threat for an embedded circulation somewhere during the morning, but instability will be limited.

Yeah, I won't assess the end of the season yet, but Thursday (maybe later tomorrow night for western areas) has some sneaky potential, particularly if the slowest solutions are correct. I still think it's more of a flooding threat, but shear will be strengthening. If we can get some heating ahead of the main frontal band on Thursday, at least some modest SVR potential is possible.

The I-95 corridor of Howard County was total Loserville today.

For those of us north of DC, there seems to be a fairly decent signal in the 12z CAMs for showers/storms to develop over the upper Eastern Shore and Bay during the mid afternoon hours and rotate to the west into the Baltimore area and northern AA, Howard, and Montgomery Counties.