jojo762

For posterity..

Would expect some pretty drastic changes to the 20Z outlook with respect to the ENH and MDT risk areas.

Mesoscale Discussion 0251 NWS Storm Prediction Center Norman OK 0133 PM CDT Sat Mar 28 2020 Areas affected...Parts of central/northeast Missouri into southeast Iowa and portions of west central Illinois Concerning...Severe potential...Tornado Watch likely Valid 281833Z - 282030Z Probability of Watch Issuance...80 percent SUMMARY...The initiation of scattered supercells appears increasingly probable during the next few hours. Tornadic potential, including the risk for strong tornadoes, seems likely to increase by 4-6 PM CDT. DISCUSSION...Rapid deepening of the surface cyclone now centered over southeastern Nebraska is ongoing, with an axis of 2-4 mb 2-hourly surface pressure falls now pivoting northeastward, to the northeast of the lower Missouri Valley. To the southeast of cyclone center, a dryline continues to sharpen across southwestern Iowa and western Missouri, and may maintain identity into late afternoon, advancing northeastward just ahead of a surging cold front. Strengthening and backing (to southerly) 850 mb flow ahead of these boundaries is forecast to contribute to enlarging clockwise curved low-level hodographs by late afternoon, beneath a very strong (90-110 kt) 500 mb jet. As this occurs, the environment appears likely to become increasingly conducive to tornadic supercells given sufficient boundary-layer destabilization. Mid/high-level cloudiness and precipitation, to the south of the warm front near the Missouri/Iowa border, continues to slow boundary layer destabilization in the warm sector. However, a tongue of mid 60s+ surface dew points appears to be in the process of advecting north of the Missouri Ozarks, ahead of the dryline, in response to the strong surface pressure falls. As a vigorous upstream mid-level trough and embedded closed low accelerate northeast of the central Plains, broadly anticyclonic mid-level flow will increasingly transition to cyclonic across the region through 21-23Z. The leading edge of stronger difluence aloft may already be aiding convective development near the dryline and warm front, southeast of Shenandoah IA. A further increase in discrete storm development appears possible within the next couple of hours, along/ahead of the dryline to the south. Further development, intensification and northeastward advection of storms now spreading across the Missouri Ozarks also appears possible within the warm sector. Regardless, storms interacting with the warm front probably will pose a risk for tornadoes, while strong deep-layer wind fields and shear within the destabilizing open warm sector will contribute to fast storm motions and potential for long-lived/long track supercells with increasing potential to produce strong tornadoes across northeast Missouri into southeast Iowa and adjacent west central Illinois by 21-23Z. ..Kerr/Goss.. 03/28/2020

Looks like we have CI in NE MO. Just had some radar returns pop in Macon County.

Did the same thing 5/18/17 with a high risk, turned out to be a mostly bad outlook... Different set of circumstances that day though.. EDIT: Also looks like we have CI along the PCF north of SGF.

Feel like that small cell that popped up a bit ago, now in Morgan Co. in central Missouri could bear watching the next few hours if it sustains as it eventually propagates toward Illinois and the warm front.

First TOR warning of the day, just where we all expected; 70 miles south-southwest of LSX.

18Z HRRR continues to show what would probably be a significant tornado outbreak across Iowa and Illinois. *IF* you want to go all in on the HRRR solutions, would seem that the moderate and high-risk tornado delineations are going to have to be expanded to include a larger portion of both Iowa and Illinois, possibly even a small part of eastern/southeastern Missouri and western Indiana.

GFS seems markedly different from CMC/NAM/Euro as far as precip totals go (snow) and location of snowfall to an extent as well, pretty sure we know how that ends up.

Here in Lawrence, KS... pretty confident on seeing some ice Friday evening: freezing rain transitioning to sleet/mixed precip something between .07-.15” of ice looks probable... followed by 4-8” of snow. Kinda sucks because there’s a big basketball game on Saturday here, #3 KU vs #4 Baylor.

*sarcasm*

From the early comments in the main thread looks like we have #MegaSandy2.0 on our hands, fellas.

The damage I’ve seen out of the Abacos is easily some of the worst hurricane damage I’ve ever seen personally, up there with what you’d expect with significant tornado damage imo (in terms of just utter devastation, not in terms of EF-indicators and blah blah blah). Of course, their buildings probably aren’t the most amazing structures ever created - but it is still stunning. Reminiscent of Mexico Beach last year, except on a much more vast scale.

00Z GFS continues the general idea that Friday could be a big day, followed by a conditionally chaseable day on Saturday, with a lull on Sunday followed by a potential big-league severe weather setup on Monday.

As Jeff mentioned next week looks really good. GFS and Euro have had some **remarkable** outputs for Monday or Tuesday next week, like 80kt at 500mb atop massive CAPE and intense LLJ remarkable...(but honestly you should expect it with a seasonally anomalous trough like this)... Still jumping around a bit as to which day will be better. Not sure how much value you should put into outputs like that at Day 7-9 range, likewise its still enough for SPC to mention something about D9 in their outlooks. This weekend *could* be an appetizer for whats to come. As of now, definitely plan on making the 4+ hour drive out to WC/W KS for Friday.

http://atlas.niu.edu/ertaf/ For those who might wonder what he is referring to: Forecast Discussion: The long advertised "forecast of opportunity" has now entered the ERTAF week 2 forecast period. We will continue our week 3 forecast of AA for week 2, with all signals in the analog and dynamic solutions suggesting a rather robust 5-day period of severe convective storms centered on 20 May. In fact, the latest 00 and 12z suites of GEFS dynamic solutions suggest this period maintains a 1+ sigma STDA for 12z-12z sum of CONUS supercell composite parameter for the duration of this 5-day period. While mesoscale details for tornado favorability cannot be clearly determined at this time, the synoptic scale will be supportive of a regime analogous to historical significant tornadoes in May. For week 3, we see many signals that this week 2 AA period could re-load after some breaks between systems emerging on the west coast. Thus, signs would point to at least an 'A' period for week 3, but we will maintain low confidence at this time and upgrade next week if needed. Forecasters: Gensini, Gold, Sirvatka

As far as mid-long-range forecasting goes for chasers and enthusiasts, mid/late May this go-around looks potentially epic for just about anyone who enjoys severe weather. Multiple large troughs (leading to potentially BIG days, and also allowing for surprise "the day before the day" type events.) Opportunities for severe weather appear to start this coming friday as the western CONUS trough begins to eject into a richly moist and unstable western/central plains atmosphere characterized by mid to upper 60s dewpoints and steep mid-level lapse rates, producing CAPE profiles upwards of 3000+ J/KG. Timing of the wave will be critical to how friday evolves. Given an amply strong low-level jet of 40-60kts (and 30-40kts by as early as 21Z), and favorably timed wave on the models, friday seems to have obvious severe weather and tornado potential. Likewise, how Saturday evolves is heavily dependent on several factors: 1. Wave timing (and orientation), 2. convective evolution of previous day, 3. the potential for early-day convection that could washout the atmosphere. If the wave slows down a few hours (which would likely mean somewhat mitigated potential for Friday), Saturday has big time potential written all over it. Sunday appears to be a lull day explicitly on the globals *as of now* which could change as the trough evolves throughout the next few days... Followed by potentially a day or two more of significant severe weather potential into the week of the 20th. Important to not get too bogged down into too many details or specific model runs this far out, just watch for trends. Stay tuned.

Wouldn’t be totally surprised to see the SPC delineate an area for Saturday (May 18) in the next D4-8 outlook. Looks pretty promising on the euro and GFS. Given what models show now, would certainly expect a higher-end ceiling.

And on the CFS, GEFS, and EPS as well. Numerous different "types" of severe setups being shown, which I suppose is typical for late May anyways. Either way, mean S/W flow for a few/several days + favorably progged moisture trajectories = at least several quality chase days somewhere across the Plains.

Surprised by the lack of talk regarding early next week and into early May. Obviously some spread on the ensembles and amongst the global OPs, but early May looks active fellas.

Not very much agreement among the models regarding boundary and jet placement among other things in the Day 6-8 time frame... However, does appear to be an upward trend in severe chances somewhere across the central and southern plains between Sunday-Tuesday next week...

Could probably bump up those snow totals for N OK a bit given expected snow-liquid ratios >10:1... Likely looking at 13:1 to 16:1 ratios across Southern Missouri/Kansas and Northern Oklahoma, with 17:1 to 20:1 ratios closer to the KC metro. Altogether it is looking increasingly likely that large portions of KS and MO will receive 5-10" totals (with some isolated amounts potentially exceeding 10 inches of snow, especially across SE KS and SW MO). Appears that there could be a pretty tight gradient across NE OK and NW AR, where 2-5"+ could fall, extreme NE OK could get closer to 6-8"... Whereas other parts of those regions could receive more nominal snow accumulations. Still should have some pause I suppose about higher snow totals existing over SE KS/SW MO (in addition to northern OK's overall snow potential, as well) given the differing solutions presented by the NAM and CMC (mainly the NAM though, as has been discussed) as opposed to the GFS/Euro solutions.

The eye wall of Florence has absolutely exploded on IR and radar the last couple hours.

18Z NAM completely kills the setup tomorrow with a convective complex that develops this evening over E CO/W KS then meanders it’s way to SC KS/N OK by 12z tomorrow, then NC OK by 15Z... not sure im buying it, but likewise it completely obliterates downstream moisture.

Both 00Z NAM and GFS depict QPF bombs so that’ll probably be what does this in. Different evolution of the MCS on the models though...but for sure looks like a sig severe event for damaging winds and hail.