csnavywx

That was mainly via SO2 forcing via the stratosphere.

Yeah, that's almost a complete shutout of ECS <= 2C by their calculations. While the mean looks to be around 3.2, that PDF is .... not great. Anything under 2.5 is pretty unlikely and pretty decent probs of something closer to 4. From what I'm gathering, that's also just from the observational record. Paleo suggests ECS itself might be variable depending on the state (higher during warmer climates for instance). https://advances.sciencemag.org/content/5/9/eaax1874 Having said all of that -- I'm also wondering if the laser-like focus on ECS is a bit troublesome in itself. It's possible, for instance, that we're focusing a bit too hard on global temps and not enough on downstream effects -- like asymmetric hemispheric response. All evidence points towards the NH losing ice much faster than the SH and indeed paleoclimate tends to suggest that the NH and SH can exist in a "decoupled" state where most of Antarctica can still be relatively cold and glaciated and the NH is essentially much closer to something resembling a greenhouse climate. The GIS will still be around for quite a long time but the amount of resistance it can put up pales in comparison to the combination that the circumpolar current and EAIS can put up. It's worth noting that Antarctica glaciated pretty early on (30-40mya at around 650 ppm I think?). I'm sure the isolating power of the circumpolar current helped, but if folks like Tierney are right, that doesn't have as much of an effect as one might initially think.

Yep, HRRR has some pretty nasty (4-6SM vis) smoke descending to the surface tomorrow and especially late Wed. I would expect a lot more smoke haze aloft over the next couple of days, but the weak cold advection behind Wednesday's little front will probably help drag more of it to the surface. Not going to be great for folks with respiratory issues. Can't imagine what later this summer and fall are going to look like with the way it's going out West this year.

I generally use the difference between the mixed boundary layer and a representative sample of the theta-e minimum aloft (generally 700-600mb), though there are a few effective methods to choose from depending on the situation.

Latest skew-T fcst soundings spitting out widespread 45-55kt wind gusts (and theta-e differences between the mid-levels and boundary layer of about 25-27K, which matches) so probably a good call there by the SPC on emphasizing the wind potential. Though I think it'll mostly be outflow dominated by the time it approaches the bay, wouldn't be surprised to see some weak rotation in any discrete activity and a bit better organization in general as the windfield is already backed and dews are higher there. We're at the time of the year where the Bay is very warm (80+F) and tends to help convective activity by pumping dews and providing instability after sunset.

Convective initiation west of IAD and down closer to CHO. The cell west of IAD started putting off quite a few strikes before there was much of a BR signature. Some high grade instability to work with today and a strong sign that today's storms will likely be electrically active.

90/77 here. Absolutely soupy and miserable.

Such a huge difference from here. At 6.70" on the month already at NHK. Almost certainly going to add to that total tomorrow. Outside shot of reaching 10" this month.

Yep, fat CAPE profiles tomorrow with some solid 2500-3000 values showing up on fcst soundings this morning. There's *just enough* shear for high CAPE to mostly compensate, so wouldn't be surprised to see a similar setup to Wednesday, if a bit less organized. Edit: Theta-e profiles indicate about 25K/C in between the boundary layer and mid-levels and combined with PWATs around 2", that argues for some wet microburst activity tomorrow as well. There's very little to no capping, so I would expect a bit earlier of a start time for initiation than usual. Any storms that fire early will have a good chance of being able to pulse to severe limits before weakening.

Combined with winter temps, that'll end up being the kill-shot in the long run (few decades). Easy to forget that diabatic processes only go so far during the summer. If you keep mixing in much-above normal airmasses into an otherwise favorable ice-retention pattern, the lower limit is raised and the window shifts towards melting, even in good patterns. We may yet stay in this "transitional plateau" for a while longer but the creeping risk of a rapid collapse will eventually catch up as winter freezing degree days drop below a critical threshold and summer T-min increases during low pressure regimes, narrowing the stable space upon which the current pack is balanced. My eye is on the mid-2030s for something like that.

Might be faster if we don't figure out why CH4 seems to be taking off again over the last 10-15 yrs (and subsequently stop it). It rose 15 ppb last year and we might beat that this year. That's going to significantly bolster warming at those rates. I don't think any of AR5's scenarios -- aside from RCP 8.5 -- had it rising like this. (RCP 8.5 had 1923ppb for 2020 actual, and we were at 1880ish; no other scenario is as high as current until after 2040).

I'm gonna add on just a bit to what Don said for this particular event. In this case, the incredibly strong Rex block that is baking BC and WA/OR had its origin in an unusually juiced episode of convection along the Meiyu/Baui front in E. Asia. Moisture transport for that event likely originated over the SW Pac and E Indian Ocean, both of which are running above normal over a very wide area (and abnormally high ocean heat content to boot), which very likely contributed to amp'ing the intensity of the event. The latent heat release from that event helped boost the N.Pac jet significantly, causing a big downstream rossby wave break and the big ridge/block. So in a way, there's even an entangling between enhanced and extreme rainfall events and this heatwave. It's just not the kind of thing that's inherently obvious until you start digging.

After the miserable bust of Saturday, it looks like we've got a somewhat better chance today. Issues include a cap and some deep mixing potential. We're also going to probably be a bit dependent on LEWPs or bows surging well out ahead of the front to get the job done, since forcing locally will be pretty weak.

Some high-based shallow convection (just showers for now) SW of DC on the lee side. It's possible this activity could become surface based as it gets further east.

CI appears likely soon W and SW of DC.

So far, so good. That mass of convection will probably produce a coherent MCV for the region later on today. SPC keeping an eye out as well:

New MCS is up and going over OH and IN. Initiation likely in the next few hours over IA. HRRR really pressing this (in the form of an MCV or remnants) as a viable trigger for tomorrow. It looks like the current MCS may track far enough south to prevent it interfering with insolation too much tomorrow morning.

There tends to be a delay of several months between when an ENSO phase begins and ends and the atmosphere responds. It lags by 2-4 months or so. So, we're still probably feeling some of the effects of the faded Nina. The current drought episode in the West is probably being exacerbated by it (by helping shift the jet north and imparting extra subsidence). Sometimes those effects "spill over" downstream into the Plains.

Nina years tend to have a higher chance for summer drought but this isn't always a given. As far as climate change goes, the trend has been for (so far) has been for relatively rapid increases in rainfall and absolute humidity (dewpoint) in the STL area but relatively modest increases in temperature. There's some evidence to strongly suggest this is due to the rapid increase in corn planting area and density, which transpires rapidly and has served to keep temperature increases somewhat muted at the expense of increasing humidity. Since corn and crop land area has reached near its maximum nowadays, I would expect temperature increases to start taking over. If that's the case, the future may include a bit more rainfall on average, but with ever bigger swings between wet and dry. Increasing whiplash or flickering, if you will. Drought sets in and ends quicker, rainfall tends to come in bigger bursts and less towards gentle, soaking rains.

It appears to be a continuation of an overnight MCS that gets going over IA/IL tonight. HRDPS has it too (and the 12km NAM to a lesser extent). It's a possible scenario. HIgh bust potential tonight, though, especially with effectively 3 convective complexes (including the decaying one over OH right now) "in the way" before we get there.

I have a problem with a lot of economic studies and projections concerning climate change because they do not incorporate risk of ruin. The amount of risk and potential damage goes up exponentially with each degree of warming. I think it would be nigh impossible to calculate warmings of 4-6C just because of the non-linearities involved. Even 2-3C could really be stretching it.

It looks like a remnant EML plume gets wrapped in ahead of that front. As long as we can get some forcing strong enough to trigger convective initiation on Sat. afternoon, there will likely be some severe and good parameter space for some evening supercells.

This 1000 times over. Science is a developmental process, which means you aren't going to always get it right on the first go, or it might need to be adjusted or tossed down the line. In this case, he's refuting his earlier research based on new evidence. That's called updating your priors. The only real failure would be to *not* do this.

Don't sleep on the Monday shortwave. A compact, digging shortwave embedded in NW flow aloft possibly intercepting a plume of moisture and instability fed in ahead of the wave. One of the major questions is timing. A bit earlier and this could easily cause some significant trouble, given the progged shear and instability values progged on the NAM (and trending on the GFS).

3-day total up to 3.21" so far with rain continuing.