Quincy

If the lower analog domain is used for Saturday, it shows one of those high-end matches that we saw last week. Either way, a consistent signal of significant potential, if the red flags and limiting factors don't win out.

A nicely active May pattern for sure. One that we haven't seen the likes of in at least a few years. The 1991 analog isn't working out too bad at all. I'm holding my breath about getting too amped up for a possible higher-end event, but it appears likely that anyone who doesn't mind a bit of traveling should have three solid chase days FRI-SUN.

I like the challenge too. A lot learned from last week. Shifting targets. Evening surprises. Etc. Keeps it interesting and forces more use of meteorology skills than just relying on "modelology".

Hmm, 00z GFS not lending too much confidence in Saturday.

Like many of the days this week, we may not have a really clear idea on the potential until the near-term, given so many things that could throw a wrench in it. Although the potential is there and with a fairly high ceiling, if things can line up. 

 

00z GFS-based analogs showing a strong signal. Some of the matches were some pretty big days, like 5/23/08 and 4/14/12. Taken with a grain of salt:

Random question, but does anyone know why the SPC has been consistent in putting "Potential Too Low" over the past few days? Especially today, it's thrown me off a little.

It's especially odd since they have 15% probs now to outline in the day 4-8 period (was only 30% in the past). It's perplexing since the Euro and GFS have been in very good overall agreement through Saturday.

May 2013 was a weird pattern -- it has been a while since a potential classic setup comes along in peak season, which certainly seems possible given the looks.

Nino spring/summers seem to have a tendency to go bigger in middle or late season at least the few I've looked at. Think when you put that plus the signs of prior as far as KS/panhandle type targets.. outlook is quite positive for the season as a whole. I guess it'll shut down at some point but the main story has been an active pattern for quite a while.. severe ramped up in late Mar and never fully died off till recently, and even that die off was relatively tame for early season. Some of those April events would have been more memorable if there was just a little bit more surface moisture.

It's been mentioned, but all of the beneficial rain this week should take a big knock out of the regional drought too. Not to mention that bodes well for available moisture later this month.

I know better than to get too excited, but quietly the trends for next weekend have gotten better. Can't help but like the look of the Euro ensemble mean at 168h. I'm sure it will continue to evolve and we need to get through this mid-week mess first.

Some missing pieces (in terms of severe) for the middle of next week and it's a shame. It looks like an active period may result in more heavy rainfall than anything. Although I would suspect at least a slight risk for severe thunderstorms during a couple of those days. The PW values are progged to be on the order of 2+ SDs across much of the Plains, another signal of the heavy rain potential. The Euro shows a general 2-4 inch rainfall event by the end of the week for much of the area. Considering portions of northern Texas have already seen their fair share of rain as of late, it's not's exactly welcome, at least not so soon. Although longer term trends still indicate some persistent drought conditions.

I think there are some encouraging signs. Here is the 500mb mean analog pattern for mid to late May, using the top 5 analogs from the GEFS 6-10 day forecast. It actually lines up very closely to the 00/30 Euro Weeklies projection for the time period, only slightly further east (even better) with the ridge axis.

 

I whipped together a quick May tornado forecast here. A little bit more cautious of an outlook than for April, but I wouldn't be surprised if there was a bigger event somewhere in the second half of May.

I can't be the only one getting concerned about the "jet disappearing into Canada act" (ala May 2009/2012) that seems to be a theme on MR guidance. There may be several days of semi-interesting high CAPE/low shear potential next week, and there's always a chance one of those days could emerge as more significant. But if we're talking amplified western CONUS troughing and large-scale organized threats, it seems we might be waiting until closer to mid-month, at least.

Have to admit I'm getting a bit concerned. I'd much rather have an overall favorable pattern than a couple of days that may or may not produce.

The trend with the ensembles has been to knock the flow relatively zonal, but with positive height anomalies and pushing the jet north later into May. Although the 00/30 EC ENS showed more West Coast troughing by day 15, the ensembles have had poor consistency and verification beyond day 10 over the past several weeks. If you believe the CFS, it also shows signs of death ridging by mid-May.

Looking at some more data throughout today and after the Euro Weeklies come out, I'll be ready to put a May tornado outlook together.

Most ensemble guidance indicates some form of western troughing developing towards the end of the first week of May (possibly with periodic shortwave ejections in advance), looks fairly promising at this time.

It's encouraging now to see this signal prevalent on a majority of the ensemble members, of both the Euro and GFS.

 

Finer details are a long way from being resolved, but after a momentary break in the action, we could see severe threats begin to ramp up again. (I think there is some thunderstorm potential by this Sunday/Monday, but something more significant likely holds off until later next week or the weekend that follows)

After being stuck in model fantasy land, now inside of 10 days we have model support and agreement of some ridging in the east. We'll see if this comes into fruition. If so, we could see some enhanced severe activity into early May.

Say hello to the PAC ridge again ~April 15-19. It's been on the ensembles for quite some time. It's still a bit muddled how the pattern with respect to severe evolves after that, but at least it appears likely the ridging should break down fairly quickly.

Maybe we'll get some early to mid-April action down in Dixie Alley, where they're climo-favored anyway. That area was eerily quiet until April 27-28 last year.

Last call. Still somewhat unsure about the exact placement and intensity of a mesoscale band that will probably drop some 30"+ amounts, but fairly high confidence in the highest amounts from TOL-ORH-BOS with around two feet of snow there. A nail-biter for the western fringe, but I was never buying into the hefty amounts west and southwest of Danbury:

SREF maxing out with the 12 hour snowfall product. Days of lore heading for SNE.

I actually think TOL-ORH should really bang hard on this storm. If 2013 dropped 30"+ in a band, I could see a similar outcome here. Best guess is from the Tolland hills into the Worcester hills and perhaps even northeast Mass.

00z NAM is awfully bullish now for Tuesday as well as Wednesday. Not sure how serious to take it, especially when it's showing a warm front all the way back into Nebraska Wednesday afternoon. Unless the GFS/Euro ramp up, may have to toss the NAM yet again.

It's looking like a relatively small area across southeastern Kansas and far northern Oklahoma will see a somewhat favorable overlap of instability, forcing and wind shear on Wednesday. With that said, as mentioned earlier, there are still some red flags that we may be looking at another underperforming setup.

While the GFS and Euro both show a surface low near the OK/KS border Wednesday afternoon and some backing low-level winds near a quasi warm front, we're just looking at a 1002mb low. Nothing like the more dynamic systems we saw last fall. While there's some moisture, the model consensus is only for mid-60s dew-points. The GFS spitting out some dews around 70 in the warm sector is likely overdone. We're looking at a relatively broad trough with no well defined shortwave energy being focused on one area. While the upper level flow is decent and the risk area is placed on the right-front jet quad, the low and mid-level winds aren't terribly impressive either,

A few pieces there and and a few others likely lacking. Should still be interesting, but again, over a small area and the severity of any storms may be limited by several factors. Thursday looks to have more instability, but the shear pattern becomes more perpendicular to the front. Then, the trend continues to be toward a cold front or elongated low working as the main forcing mechanism.

I'm not 100% sold yet, but here's a look at the 12z GFS-based analogs for Wednesday:

Still need some pieces to come together better than advertised on the Euro/GFS, but can't help but think that Wednesday into Thursday of next week has some potential from Oklahoma/Kansas into the mid-Mississippi valley.

With a fairly deep trough digging, it's going to come down to timing of shortwave energy, surface low development/placement and richness of low-level moisture. Right now, the GFS shows a marginal setup with a strung out low, while the Euro is a bit more robust and shows a nice low-level jet ramping up.

Let's see how the forecast evolves this weekend.

The NAM is advertising some 5-10 EHI values for Iowa, Minnesota, and Missouri tomorrow. That's pretty high for September!

Both the NAM and GFS look highly impressive for northern Iowa into southern Minnesota. Some may discount the NAM based off how it has handled some severe events this season, but even the GFS is spitting out some pretty significant values. Just pull a sounding for north-central Iowa and the GFS is showing over 200 m²s^-2 0-1km helicity with 40+ knots of shear and a 40+ knot LLJ. Even seeing some STP values over 6 there on the GFS. (NAM is maxed out over southern Minnesota with double digit STPs)

 

Caveats: Capping and lack of a trigger. The GFS/NAM combo does show a subtle piece of energy swinging through southern Minnesota, but one has to imagine that the threat near and south of the IA/MA border may be minimal to cap-busted.

As mentioned, the timing for Wednesday/Thursday may be a bit off, but the parameters look awfully impressive for Wednesday. If the shortwave can speed up or we can otherwise get some more forcing in, that could kick off a few monsters. Thursday is probably out of reach, unless the whole thing slowed down. As advertised, Thursday would be a relatively narrow corridor of strong instability, but the kinematic support is lacking, along with an increasingly unidirectional shear pattern.

 

It's into weenie-range, but the GFS/Euro also show a potent shortwave across the Dakotas/upper Midwest by next Monday/Tuesday.

Based on fairly good model agreement at this point, it's looking quite interesting late next week/next weekend as well. A vigorous trough across the NW... The setup is somewhat reminiscent of June 16-18th, although the southeast ridge is a bit more prominent. It's way too early for specifics, but has my attention.

The Euro indicates some severe risk for Sunday into Monday across the Plains and perhaps extending into the lower Missouri/upper Mississippi Valley regions. With an upper level trough digging, an increasing low-level jet and one or more surface lows developing along a front, there could be some potential. The GFS also points at an increasing threat at this time frame. A lot can change, but it's worth keeping an eye on.