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Central/Western Medium-Long Range Discussion


andyhb
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For the experts...

Look at the 18z NAM at 72, 75, and 78 hours near and just SW of Tulsa. It kind of looks to me like discrete cells could form and get rooted into the warm front and maybe spin up based on the soundings. Supercell composite looks decent as does sig torn. Especially at 72 and 75.

Is that a possibility based on that run?

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4 minutes ago, jojo762 said:

Think my attention is starting to turn to late next week. Both the GEFS and EPS generally agree on showing a substantial trough or two across the central united states in the 4/26-28 time-frame.

I'm with you on this. GFS, EURO, CFS, GEFS, and CIPS all hint at a big trough. 

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8 minutes ago, jojo762 said:

Think my attention is starting to turn to late next week. Both the GEFS and EPS generally agree on showing a substantial trough or two across the central united states in the 4/26-28 time-frame.

Sure but not exactly sure Friday should just be overlooked yet? lol

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1 hour ago, CGChaser said:

Sure but not exactly sure Friday should just be overlooked yet? lol

Probably not... But there are so many things going against it, most notably the crashing front and the possibility of widespread precip (which will also effect northward extent of the warm front)... Still expect at least a couple tornadic supercells on Friday in S OK/N TX. 

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25 minutes ago, okiestormgeek said:

Seems like we were saying that last week about this week. :) 

We were, but that's the nature of Mid/Long-range forecasting... Focusing on the pattern is what's important. We had a big-league trough ejecting into the plains with what the models showed as good moisture return (didn't pan out with the moisture and trough orientation/location). Next week we have several potentially potent shortwaves being progged, with solid moisture return being shown by mid/late week. Which generally lends confidence in increasing chances for severe storms.

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I think there's some huge differences between this Friday's trough and next week's.


The two manifest themselves in different ways. This one more progressive, meaning less room for error. Next week's trough is a large-scale trough with shortwaves moving with the mean flow. These are where your outbreaks come from. Not to say next week will be an outbreak - so much can go wrong with severe. However, I don't think the two are very comparable.

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0z GFS with the best looking potential of the season, with two quality Plains days next Wed/Thur.

While it definitely looks like there will be severe in the Tue-Sat timeframe, potential multiple waves with non-stop convection and meridional flow issues are concerning at this range.

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Looking ahead some...  Appears that  the next best shot at a trough ejecting into the plains will be in the May 6-11 time frame... EPS/GEFS/GEPS generally agree on showing mean western troughing during this time. Perhaps the more important thing to pay attention to is the evolution of the high-pressure that is progged to develop over the Central/Southern Plains shortly after the current wave(s) kicks out east, as this will have a large impact on what actually happens to any potential troughs and S/Ws.

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1 minute ago, jojo762 said:

Looking ahead some...  Appears that  the next best shot at a trough ejecting into the plains will be in the May 6-11 time frame... EPS/GEFS/GEPS generally agree on showing mean western troughing during this time. Perhaps the more important thing to pay attention to is the evolution of the high-pressure that is progged to develop over the Central/Southern Plains shortly after the current wave(s) kicks out east.

That and trough activity over NE

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22 hours ago, mfgmfg said:

Looks like serious flood risk ahead for Fayetteville to St Louis and surrounding areas - Flood Watch is out for a rather large area of MO and AR

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Any thoughts from the forum on the flood risk for this weekend in the Ozarks, especially given saturated soils?

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What a hostile setup for central U.S. severe potential through at least the first week of May and quite possibly through much of the first two weeks.

The relative dearth of severe potential has been consistently modeled for quite some time now. There were some hints about pattern changes into the second week of May a few days ago, but that potential seems to be dialing back as well.

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The pattern favors two cutoff lows effectively shutting down any significant severe threats in the Plains over the next 7-10 days. The lead low works to scour rich, Gulf moisture, as the 12z ECMWF struggles to bring >50F dew-points north of Oklahoma through 240 hours. There are only a few panels in which low to mid-50s dews squeak into parts of Kansas. That's quite a feat to keep the central Plains that consistently dry through the first 7-days of May, especially given excessive, antecedent rainfall across a broad portion of the central United States. Back west, while modeling showed western U.S. troughing for a while, such a trough may result in a meandering cutoff low over Southern California. Such a low remains too far west for any appreciable large-scale forcing across the Plains.

Some analog guidance has hinted at some potential across the southern/central High Plains later in the day 6-10 period, where upslope flow can work to offset otherwise seemingly marginal (at best) low-level moisture. Outside the sub-forum, this pattern could yield some severe potential from the eastern Gulf Coast states into the Carolinas. 

As we know, forecasts for a week out can significantly change. Look out to day 10 and beyond, and sometimes the model progs end up being way off, as patterns evolve much differently than expected. 

Nonetheless, barring some sort of mesoscale accident or extreme model error, this upcoming week looks about as dead as it could possibly be across the Plains with respect to severe potential in May. It's been mentioned before and it's actually fairly common to see a bit of a severe lull in early May. The difference here is that the medium-range pattern looks so hostile for severe, that we may see little to no severe thunderstorm activity in the Plains for quite some time.

The only day of slight interest this upcoming week looks to be on Tuesday, where there could be some modest severe potential across Oklahoma. Such a setup will revolve around a lot of ingredients coming together, as the synoptic scale pattern does not look particularly favorable.

 

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5 minutes ago, WhiteoutWX said:

So who else is excited for the omega death block of doom the next 7-10+ days? Fun times. 

I'm amped. On the bright side we'll be getting some pretty nice weather. Grass and weeds are going to grow at ungodly rates because of all the recent rainfall and succeeding sunshine... ):

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While it is a while out, and a lot will likely change... both the euro and GFS operational runs currently indicate that the cut-off low progged to be over the four-corners region could eject into the plains sometime in the May 11-13 timeframe as a negatively tilted trough... so that's something. Ensembles have been trending toward this type of idea as well. Lots of variables at play and more questions than answers given how far it is out, but this would appear to be our next best shot at meaningful severe potential... enjoy the beautiful weather this coming 7-10 days folks!

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19 minutes ago, jojo762 said:

While it is a while out, and a lot will likely change... both the euro and GFS operational runs currently indicate that the cut-off low progged to be over the four-corners region could eject into the plains sometime in the May 11-13 timeframe as a negatively tilted trough... so that's something. Ensembles have been trending toward this type of idea as well. Lots of variables at play and more questions than answers given how far it is out, but this would appear to be our next best shot at meaningful severe potential... enjoy the beautiful weather this coming 7-10 days folks!

Current trends and analogs suggest severe threats may return by the middle of next week across the southern High Plains, to perhaps as far north as eastern Colorado, as that cutoff low ejects east. Until then, I'll be working extra, unanticipated hours to save up more for prime chase season. 

Even if things don't line up ideally next week, we're getting into the part of the season when it's harder for such troughs to not produce at least a few tornadoes. 

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Tornadoes seem to hate Oklahoma (again) this season. Back in 2014, a grand total of 13 tornadoes it Oklahoma through the whole calendar year, i.e. much below normal for that state.

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tornadoes haven't come much north of I-70 in April

 

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8 hours ago, Chinook said:

Tornadoes seem to hate Oklahoma (again) this season. Back in 2014, a grand total of 13 tornadoes it Oklahoma through the whole calendar year, i.e. much below normal for that state.

April is hit and miss for Oklahoma. It seems like occasionally there are some big early season events, offset by plenty of years with little action in April. The April average of 11 tornadoes for Oklahoma jumps to 28 in May, but you can see the graph for central Oklahoma spikes sharply into May.

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On the other hand, we've seen one of the busiest Jan-Apr tornado periods in recent memory across the Gulf Coast states. Overall, we're still well above average year-to-date, but low severe activity through at least the next 5-7 days will probably move us back to near average in terms of tornadoes.

 

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