vortex95

"If it's not in Weymouth, it doesn't matter!" What kind of attitude is that?

04z HRRR suggesting "cells ahead of line." So 1-2 punch for some areas. Also, nice sliver of high 0-3km CAPE SNE and a second area for NNE.

Hmmm, CoastalWx and WxWiz be like "???????." 5% tor risk? How can this be? No EML!

Ineedsnow will be "X-static" if we get 5% tor, but WxWiz will not b/c he can't chase!

We have a lot of climo for TC tracks globally, so AI has a lot to draw from, so it should do well here. Intensity, not so much. There are still so many things we can't model well for the stronger TCs. The inner cores of the intense ones are basically mesoscale features. RI occurs often in such a short time frame and it is hard for physics-based models to handle. For decades, we have seen a steady improvement in TC tracks, but very little for intensity until the 2010s, when significant improvement occurred. So again, AI should do well for TC tracks. And TC tracks often are latitude/longitude dependent, so this variable is a solid base indicator for AI to use.

This happens *every* time new technology becomes available. It is sold as the best thing since sliced bread w/ lofty claims. I recall in the 80s it was said "in 10-15 year advancement in computer modelling will make human forecasting obsolete!' Right, how did that work out? In fairness, computer modelling advancement has removed a lot of manual work a human used to do, but this is a *good* thing actually. Why?, b/c the shear volume of wx data now is enormous and keeps increasing. We need faster computers and AI to help sort and manage it all (do the grunt heavy lifting) so the human forecast can provide the insight/wisdom/understanding -- which AI does not have -- to give concise and clear messages to all. That's one reason why IDSS is so big in the NWS. Forecasts have become very good, but the real challenge is *communicating* it all effectively in this information overload and social media world. So I would not worry about AI "taking over," so to speak, anytime soon.

You are missing the point. Teleconnections deal w/ broad scale patterns. That only works/is useful to a point. When it comes to actual sensible wx in a specific area, that's an entirely different ballgame. How many times do we have a -NAO, and no big East Coast snowstorm occurs, as one example? I pointed out the mesoscale details being everything for all to read here, and learn something from it. You look on social media, and far too often you see people hyping certain patterns, and stating this or that will happen in X or Y region w/o stating any caveats or how it's not so simple/linear as a 1-1 correlation. People on this forum, some are still learning and other are eager to learn more, and furthering the discussion is of value net-net. And in New England, many just think about the outbreak sequence June 8-9, 1953. That is a high-end, outlier exception, and that can skew the perception of things from a local bias POV.

Charleston IL spinner PT.

Spinner paradise!

So here are the last 3 runs of the HRRR 12/18/00z all valid 6pm Thu. Which one will be right? It's impossible to tell. Small details on the mesoscale can make a big difference as to storm mode. Either way, the timing for this is ideal. 0-3 km CAPE from central NH to CT is high as 150 at 6pm. And that is big for spinner potential and 150 is more than enough. Perhaps this is what we will get Thu. Li'l spin-ups w/ nice crisp titled CB vistas! Punxsutawney PA spinner 6/14/26. https://www.facebook.com/reel/1355336163205600

Working overnights so hence my delayed response. I say to CoastalWx and WxWiz, SPC added a 2% tor risk in New England in the DY2 1730z update!!!! (adding the exclamation points to be like Indeedsnow - LOL). "As I had been saying for tor risk..." 18z HRRR VT 22z Thu. 3 discrete supercells. PWM, PSM, and one just N of Woburn MA (where I am from). Scott needs a plan to chase!

Yes, but when it comes to sig tor events no matter where you are, the very small details are everything. One parameter off, or not sufficient, can make a big difference. For instance, dew points are few degrees lower in in BL than fcst. That raises the LFC, decreases 0-3 km CAPE, and makes supercells more outflow dominant, which curtails the high-end tornado potential or any tornadoes at all. There is very little difference between a sig tor event and a weak tor event if you look at the large picture. It can look perfect synoptically, but it comes down to the mesoscale in the end.

But that's how you get an EML!

But the CAPE is too low! "Only" 1291! Lapse rates not high by Midwest standards. So it works there but not here?

Good, we need the R+.

06z HRRR fcst sounding valid 20z Thu for central MA attached. Rhetorical question: Is that not a great hodograph for the NEUS? Nice long curve? CAPE is almost 1000. Yes it could be higher, but you can't just shake a stick at this sounding. Look at the shear values. Also, look at the 0-3km CAPE valid 22z. As high as 205. Anything above 75 is considered good for low-level vortex stretching and tors. Yes, SPC does not even has a 2% tor risk anywhere for E Coast, but that does not mean any can't occur. Also, HRRR fcst 22z, MU CAPE as high as 2100 over "WxWiz land." Hmmm. 1500-2000 CAPE w/ very high shear can and has "got it done" historically in the past for CONUS sig spinner days. Timing is ideal. Not trying to hedge or hype here, just calling it as I see it. The svr wx parameters look quite good to me. Coverage of svr I bet will be limited, but any individual storm could be nasty! "But we need an EML!!!!" Ugh, not every sig tor in New England has had a solid EML present!

EML for sig tor outbreak, yes, but it depends what we expect. SPC isn't going big, and I agree w/ how they are approaching it. However, I think the uncertainty is higher than usual due to the setup. When you have high-end anomalies, such as the wind fields here, that can lead to more surprises. I said earlier, I don't have a good analog for this particular setup, so that makes me nervous as to the surprise factor.

Took a look at it (attached). Not quite the same. Sfc low passed right over SNE rather than over srn Quebec. Also, sfc low Thu deeper than 2010 by 8-10 mb. Too much cloudiness in 2010? Even if this was very similar to 2010, minor differences can be a huge as to sensible wx when it comes to convective potential and the type of svr wx they produce, let alone how intense any given svr wx type may be. Also, I think we may be unimpressed by the SPC DY2 MRGL. Just b/c MRGL says zero about how intense any storm may be and the svr wx it produces. Maybe instead of three well-defined tornadic supercells that occurred on 7/10/89, they may be only one! But for ppl like WxWiz and CoastalWx who are always looking for the absolute max? One honkin' supercell is not enough!

I don't recall that day. Big bust?

Concerning low CAPE and high shear, look at what happened on 4/1/2023 in DE. WxWiz in disbelief and CoastalWx proby "MEH!" LOL. https://x.com/riotrogerriot/status/1642347623733444609 This is a full-blown tornadic supercell, but it doesn't look like one b/c the CAPE was low and shear very high. The CB is tilted over almost 90 deg! 500-1000 CAPE this day, but want to know what the 0-6 km shear was? 100 kt! This storm produced a long-tracked EF3. Isolated storm all by itself in the Delmarva. https://www.youtube.com/watch?v=4esg-DNoO5s https://www.youtube.com/watch?v=FyVPX7-ZHhw Other cells this day in DC area (not svr - I witnessed personally), they were just like this, so ridiculously titled over, they did not look like CBs, just a TCU cloud line. The rain/hail from these storms was *way* downwind (5+ mi) from the rear updraft base (it was hard to tell these bases existed b/c of the extreme tilt!). One my co-workers who lives near BWI reported he just started getting 1/2" hail and no rain falling, or any idea there was a storm near b/c of the odd storm orientation and no LTG/T. Something you'd more typically see in the Plains or Desert SW. Quite atypical for the East Coast, but it shows it can happen. And what do we have coming up for Thu? Quite atypical. "Hope floats" WxWiz!

Yes, this is a significant concern. Too much shear and not enough instability. You can get "cannonball CU" -- the building CU gets sliced by shear and you get part of the CU horizontally shooting downwind abruptly w/ a small cloud trail back to the other part of the CU! However, this go/no go for any CB here "winning" or "losing" is a fine line. If any CB can get established, the mesocyclone should be intense, and then CAPE does not matter nearly as much. It's why you can have as little as 100-200 CAPE and get sig tors. Most often this is in a TC situation, but it can happen in an ET low situation. CB updrafts are maintained extremely well despite low CAPE due to dynamic pressure perturbations induced by the mesocyclones. It also is why when an intense supercell moves into a stable (no CAPE) air mass, it can still produce tors for a little while longer b/c the intense mesocyclone present just doesn't go "poof!" The ante Thursday here is high here either way. It will definitely be a wicked nowcast situation watching storm development and evolving

I would caution this does not always work well. June 2, 1990 has a big tor outbreak in the Great Lakes/Midwest/OH Valley w/ IN getting absolutely crushed w/ 37 tor in the state (more than the 1974 Superoutbreak). 66 tor in this event w/ 7 F4s, and forecasts were big for NY/PA and New England for June 3, and a complete bust. https://en.wikipedia.org/wiki/June_1990_Lower_Ohio_Valley_tornado_outbreak

Timing is ideal and HRRR/RRFS show decent cells/lines! CBs in that kind of shear are likely going to do "something." I put it this way, "to have such a deep sfc low move over srn Quebec w/ those kinds of warm sector wind fields in June?, prove it to me something big will not happen!" We do not have set ups like this very often, so the full range of what can happen we really don't know. And this set up odd in itself b/c through the roof shear and low CAPE, but it not during the cool season! One thing about EMLs. 700-500 *only* can be misleading. Take a look at the IAD sounding 00z 6/14 I attached. 700-500 is crappy at 5.7 C/km, but compress that layer just a bit, and the max is 7.2 C/km...EML! I needed to inform CoastalWx about this, and he learned something new today!