high risk

Several of the CAMs this morning do break out some showers on the east side of town in the 1-2pm hour, although it appears that they are actually just behind the front. This lessens a threat of big wind, although it may still be sufficiently mixed to bring some decent gusts to the surface. The question is still whether something can form just ahead of the front around noon. Only the HiResW ARW2 suggests this scenario.

I mostly agree with this. April tends to struggle to generate much SVR here (even the best setups often leave the Mid-Atlantic in a cold air damming scenario), but there are notable exceptions. And it certainly seems to be our best month for hail. It feels to me (and I'm too lazy to go check) that our best TOR threat here runs something like May 15-June 15 (maybe June 15 is a bit late, but I think you need to include at least the first 10 days of June), and after that, we get more of the linear or MCS severe threat. But I may be speaking out of my @ss on this.

The Euro is clearly in the "faster front camp". Seems like the GFS/ECMWF/HRRR camp gets things going either just east or a good distance east of our area. The NAM and several HiResWindows (some of which are initialized from the NAM...) have a slightly slower front which gives most of us east of the Potomac a good event. A 1 or 2 hour change in the timing of the front is going to make a huge deal.

I agree fully. Could be like that Sunday event in March when we had no lightning but had a bunch of wind reports. I still think, though, that the timing is the biggest factor that is *potentially* working against us. The HRRR is still faster with the front, and the better activity gets going just east of the area. The latest NAM nest is still good verbatim, but it has notably sped up the front, relative to earlier runs. A 1pm frontal passage vs an 11am passage could make all of the difference here.

One clear fail scenario being depicted is the front going through too early in the day, as shown in the 00z HRRR and 12/18z GFS. If I had to wager, I'd say that the GFS is too fast, and the HRRR gets some indirect synoptic influence from the GFS, so that *might* explain why it looks similar. But I'm not confident at all in saying that. Ultimately, the later the front arrives, the better the chances of severe.

check out the severe thread. The front is probably going through in the early afternoon, and there is some severe potential (mitigated somewhat by limited instability), but some guidance has the frontal passage in the late morning which would really limit the threat. Regardless, as you note, regardless of the timing of the front, the winds are going to howl behind it.

SPC did give us the day 3 MRGL, and the 06z NAM nest shows the idea of the scenario described above with a strong line of convection moving through the area (not an event for the western folks) early Wednesday afternoon.

It's not a pipe dream; I'll say that. It looks like there will be a line of forced convection just ahead of the front early Wednesday afternoon in an environment with fairly decent speed shear. It should warm up to the mid to upper 60s ahead of the front, but dew points will struggle to reach the low 50s. Forecast soundings have only a small amount of CAPE, but they show a strong inverted-V structure, suggesting some possibility of stronger wind gusts. It's possible that SPC puts us in a day 3 MRGL, although I don't think it's anything close to a given.

It's not awful, but it's overall not going to be a particularly nice stretch of weather ahead, with lots of clouds and below average temps. Not to bash LWX too much, but their forecasts haven't really conveyed this very well in their products.....

FWIW, the GFS is showing that we don't get above 60 throughout the DC metro area on 5 of the next 6 days, but it could very well be overdoing clouds, and it will be way too cold with its temps if we end up with more sunshine.

Yeah, that was some impressive mixing, but the dews rebounded a bit right ahead of the storms. I was thrilled to get a a nice storm here.

Unfortunately, the trends for the week ahead are not good. There is growing agreement that a coastal low will form, and while it probably won't be a washout for the Mid-Atlantic, it certainly (barring a flip back to not emphasizing that feature) seems like we are headed for several days in the 50s in the mid to later week period.

I think they spelled out the competing factors quite nicely. We want heating today, but too much heating is going to mix out the low-level moisture. There is probably a combination of balance somewhere in there, and most guidance is showing at least a few widely scattered stronger cells later today. I'm going to be watching the dew points closely. I don't buy the low 50s shown by the HiResW ARW (which shows basically no storms), so if we stay stay in the mid 50s, I think we can crank out a few cells. Anything above that probably increases the coverage (like the NAM Nest shows).

Good point, although the lack of storms in the ARW is due to it dropping our dew points tomorrow afternoon into the 40s which has seemed really implausible to me. Regardless of the magnitude, it certainly seems now like dew points will drop during peak heating tomorrow.

My call (as well as LWX's high PoPs) is in big danger now of busting. Pretty much all of the 00z CAMs now really mix out the moisture Sunday afternoon, and as a result, it's pretty tough to find more than very isolated showers/storms in any of the simulated reflectivity forecasts.

I think it makes sense. Still come questions about how much heating will occur and whether some of the low-level moisture will get mixed out, but the solutions with the warmer and more moist PBLs certainly suggest scattered strong storms during the afternoon.

It's possible, but the threat would be after dark this evening, and most sfc-based instability should be gone by then.

That was a nice start to the convective season this afternoon. As for Sunday, my guess is that we wake up in the morning to a Day 2 MRGL. Seems quite likely that there will be some storms around later in the day (especially north of DC), and parameters aren't great, there is probably just enough low-level and deep-layer shear to get some decent wind gusts and hail. This will become a more robust threat if the higher NAM dew points (low 60s) are attained.

c'mon over to the April obs thread.

moderate graupel shower here in southern Howard County

I actually wouldn't totally rule out snowflakes in some of the heaviest cores.

The freezing levels are really low, so I'm pretty sure that any heavier cores like that would put down some hail or graupel here in the metro areas.

One potential bit of sneakiness for tomorrow: while most guidance seems to have backed off on the chances of the early morning precip ending as a period of wet snow (although it still seems like a few mangled flakes are possible north and northwest of DC), they are more bullish on the idea of some showers in the afternoon as the upper trough axis swings through, especially on the west side of DC. If you squint at the P-type maps, you can see a little blue in the heavier cores, and the forecast soundings have very low freezing levels and a little bit of instability. I would not be surprised to see some heavier graupel (or even briefly wet snow) showers around.

maybe 50s Saturday and near 70 Sunday? 850 temps still look pretty low on Saturday......

500 j/kg of CAPE will do that....