jojo762

Monday is looking like a classic boom or bust triple point day... should be noted that there is a pretty wide disparity between the ECMWF/UKMET/CMC and the GFS/NAM though... GFS and NAM show what would be a pretty upper-crust supercell environment (with some caveats/possible weak points).

So maybe some severe activity with an isolated tornado threat somewhere in the plains this weekend into early next week. Might get a day with some more concentrated tornado potential (looking at you Monday), but veered LLVL winds and capping could be an issue. LLVL winds being weak or veered and 700/850mb temps being quite warm will be an issue every one of the days more likely than not. Beyond that it’s looking like a large ridge, or at least higher-than-normal 500mb heights will setup across most of the western CONUS and into the plains — some uncertainty as to how this ends up exactly, but probably looking at a lull with some beautiful/warmer weather in the mid to extended period.

FWIW, there seems to be quite a bit of volatility in the 200+ hr range recently... Shifting from ridge fest to trough fest back to ridge fest.

Operational models really did a 180 overnight on the large western CONUS ridge in the mid to long-term... Might be able to anticipate several chaseable/watchable plains severe days in 7 to 10 days.

I don’t know what it is, but there’s been a lot of late-range teaser GFS hours lately. Sigh. CFS as well... For whatever reason, doesn’t seem to be able to hone in on any actual trend toward more activity; there’s a constant wind shield wiper from run to run with regard to the long-range, not that that is necessarily unusual.

If you like LOTS of chaseable plains days, the long-range 12z GFS was your type of run... Not much else can be said besides that it shows a large, lumbering trough with day after day of southwest flow in the extended fairy-tale range atop a very moist PBL.

I know its not within the forum region, but the Southeast sub is boring. 12Z Euro is insane for Sunday in AL/MS. 100-110kt 500mb jet streak atop a 60-70kt LLJ, juxtaposed to 67-71 degree dewpoints and steep lapse rates leading to CAPE values on the order of 2000-4000 j/kg @ 21Z. Insane. 12Z GFS is about 9 to 12 hours faster than the ECMWF (go figure)

I am pretty optimistic about late-April though. Not like that is anything surprising, but still... CFS loves late April/early May, severe wx dashboard is lighting up like a Christmas tree for that time frame.

Looks like the "early next week" trough (cut-off low) got pushed back by about four to five days, even so it is more likely than not that either the trough de-amplifies significantly INVOF the four corners, OR dives south into Mexico, so as far as a central/southern plains threat is considered, this is toast; Dixie Alley is a different matter however. Compounding this, a cold-front crashes across the central and southern plains on Wednesday evening and into Thursday, muting any potential threat regardless of the mid/upper level pattern. So that is a swing and a miss for some early April action. To make matters worse, the pattern becomes... really boring on the global models into at least mid-April. Should be noted, however, that substantial differences exist with respect to the mid/upper level pattern between the 12Z Euro and GFS by day 8+. GFS shows a ridge off the coast of California while the Euro shows a substantial trough approaching the southwestern CONUS.

Nobody has posted in here in quite awhile, so guess i'll try and kick start some 2020 severe season discussion. Looks like a fairly boring pattern will exist until at least early next week, Operational models and Ensembles have been persistent on showing a western trough ejecting into the plains at some point early next week, so that will be something to pay attention to. As of right now moisture return is seasonably impressive on most models -- but timing is an issue in model land-- this will change to some degree given that it is about a week-plus out. Beyond that, it look's like we'll have another few-day period of quiescent weather... Followed by what *could be* an interesting period in mid-April. Stay tuned.

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.

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.