Central/Western Medium-Long Range Discussion

[Indystorm]

As Thundersnow posted the current parameters look very favorable for one of the best set ups we have yet seen this year if they come to fruition.  Any analog mentioning 5/3/99 certainly has my attention.

[MattPetrulli]

Honestly seems like a classic case for one hell of chaser convergence. Best analog is May 10, 2010.  

[ClicheVortex2014]

umm I think so... I don't really remember, someone else in here will know. He updated the number today to a 7. Meanwhile Dr. forbes currently has his TorCon at 3.

I was impressed that Forbes has an outlook for day 7... but I guess SPC kinda forced his hand.

 

Looks like a very interesting period for severe weather. I can't wait for NAM to get in range... hope to see some insane nonsense before it floats down to reality. I know I can't be the only one at this point looking at everything and wondering if this'll end the national high risk 'drought'. What GFS has is pretty easily a moderate risk IMO. 

 

I know it's early to be talking about that. Who knows how the models are gonna trend in the next 6 days. But I'm looking forward to reading some AFDs as we get closer.

 

I'm so glad my finals are the day before the event.

[Superstorm93]

All Day 7 risks so far...

 

 

http://tweetimgs.pmarshwx.com/pmarshwx/20160421/20160421022044.png

[ClicheVortex2014]

GFS isn't backing down.

 

This is north-central OK

 

South-central KS

[andyhb]

So if you get rid of that unrealistic decoupling of the boundary layer like the GFS always does at 00z, not much else to say but holy smokes. Depth of the BL moisture could be a bit better on the OK sounding, but man those wind profiles are basically textbook.

[jojo762]

Yeah. This 00Z run of the GFS is the best one yet as far as the parameterized environment goes--pretty insane across the board with everything, nuts to see widespread 6+ 0-1KM EHI's, and widespread 500+ 0-3K SRH. Still feel the trough is a bit too slow tho, and there is a pretty substantial amount of CIN. It's funny because last year, we could hardly get any events with an EML to hold things off, then this year on the first possible big event, we get a big time cap. But feel free to correct me if I'm wrong on those.

[andyhb]

Yeah. This 00Z run of the GFS is the best one yet as far as the parameterized environment goes--pretty insane across the board with everything, nuts to see widespread 6+ 0-1KM EHI's, and widespread 500+ 0-3K SRH. Still feel the trough is a bit too slow tho, and there is a pretty substantial amount of CIN. It's funny because last year, we could hardly get any events with an EML to hold things off, then this year on the first possible big event, we get a big time cap. But feel free to correct me if I'm wrong on those.

 

That low level inversion is not realistic (happens time and time again with the GFS), and it's likely cooling the boundary layer too fast.

[jojo762]

That low level inversion is not realistic (happens time and time again with the GFS), and it's likely cooling the boundary layer too fast.

ah okay, didn't know. Not really well versed in model-tendencies. So that ridiculous cap doesn't really exist. Thanks!

[andyhb]

ah okay, didn't know. Not really well versed in model-tendencies. So that ridiculous cap doesn't really exist. Thanks!

 

There's probably a moderate cap in place until initiation, which is exactly what you need to get supercells vs. a big linear mess.

[thewxmann]

Yeah. This 00Z run of the GFS is the best one yet as far as the parameterized environment goes--pretty insane across the board with everything, nuts to see widespread 6+ 0-1KM EHI's, and widespread 500+ 0-3K SRH. Still feel the trough is a bit too slow tho, and there is a pretty substantial amount of CIN. It's funny because last year, we could hardly get any events with an EML to hold things off, then this year on the first possible big event, we get a big time cap. But feel free to correct me if I'm wrong on those.

 

Cap shouldn't be a big issue, we have a negatively tilted trough with main forcing for ascent arriving well-timed with peak heating. This is almost about as good as a model run gets for a Plains setup.

[brettjrob]

There's really nowhere to go but down from this GFS run for next week. The four-day stretch from Tue-Fri would probably rival a lot of great historical stretches in May/June, and be virtually unprecedented in April for the Plains in modern history.

 

Emphasis on "nowhere to go but down." It's not a matter of whether we fall, but how far.

[Chicago Storm]

There's really nowhere to go but down from this GFS run for next week. The four-day stretch from Tue-Fri would probably rival a lot of great historical stretches in May/June, and be virtually unprecedented in April for the Plains in modern history.

Emphasis on "nowhere to go but down." It's not a matter of whether we fall, but how far.

Change that to Tuesday and Thursday-Sunday and I agree.

[jojo762]

Change that to Tuesday and Thursday-Sunday and I agree.

GFS also hints at some other potentially big things coming in early May too. Hmm...

[andyhb]

There's really nowhere to go but down from this GFS run for next week. The four-day stretch from Tue-Fri would probably rival a lot of great historical stretches in May/June, and be virtually unprecedented in April for the Plains in modern history.

 

Emphasis on "nowhere to go but down." It's not a matter of whether we fall, but how far.

 

I'd argue that the 12z Euro was more impressive than this GFS run (stronger LLJ, stronger flow overlapping the dryline, etc.)

 

Maybe not quite as strong in terms of buoyancy, but still easily >3000 J/kg pooled up against the boundary. The upper jet orientation with this is classic as it looks right now, there's really no meridional concerns with the low amplitude nature of the low latitude ridging out ahead.

[brettjrob]

I'd argue that the 12z Euro was more impressive than this GFS run (stronger LLJ, stronger flow overlapping the dryline, etc.)

 

Maybe not quite as strong in terms of buoyancy, but still easily >3000 J/kg pooled up against the boundary. The upper jet orientation with this is classic as it looks right now, there's really no meridional concerns with the low amplitude nature of the low latitude ridging out ahead.

 

I assume you're referring to Tue specifically, in which case I'll defer to your judgment, since I didn't get a chance to look at the hi-res ECMWF fields.

 

The 4-5 day stretch on the GFS is just unreal for April, though (with Wed being the "down" day whose presence does little to change that fact, in reference to Chicago Storm's post).

 

EDIT: 00z GGEM looks incredibly similar for the whole Tue-Fri period... my goodness. This is a pretty staggering suite of guidance tonight that's leaving me speechless. If the lead time were 72-144 hours, rather than 144-216, it would be hyperventilation time.

[andyhb]

50 kt LLJ over ICT on the 00z Euro at 00z Wed, shear seems to be ramping up here in the last runs.

 

Not to mention there's already 2000-3000 J/kg SBCAPE at 12z Tuesday across a significant portion of OK and KS.

[brettjrob]

As enthralling as these runs are, I despise seeing the H5 ridge axis running through IA-MN-ND. At this lead time, there's still enough uncertainty that the Tuesday trough could start pinching off and send everything into a tailspin, similar to the event this time in 2014. Not saying it will happen by any means. But the Andover comparisons are natural for many reasons, and I can't help but notice that the downstream ridge axis for that setup was through IN-MI. Will try to look at more analogs tomorrow.

[jojo762]

So they did go with the 30% contour. I think since they updated the D4-8 to include two probability contours, this might be the first 30%?

[Superstorm93]

 

 

ON TUESDAY/DAY 6...THE ECMWF AND GFS CONTINUE TO

MOVE A NEGATIVELY-TILTED UPPER-LEVEL TROUGH AND ASSOCIATED MID-LEVEL

JET ENEWD ACROSS THE SRN ROCKIES AND INTO THE SRN PLAINS. THE MODELS

SHOW A WELL-DEVELOPED DRYLINE ACROSS THE SRN AND CNTRL PLAINS

TUESDAY AFTERNOON. TO THE EAST OF THE DRYLINE...SFC DEWPOINTS IN THE

MID TO UPPER 60S F AND STRONG DESTABILIZATION SHOULD BE FAVORABLE

FOR SUPERCELLS. AS THE EXIT REGION OF THE MID-LEVEL JET OVERSPREADS

A VERY MOIST AND UNSTABLE AIRMASS...A SEVERE WEATHER OUTBREAK WILL

BE POSSIBLE WITH TORNADOES...LARGE HAIL AND WIND DAMAGE TUESDAY

AFTERNOON AND EVENING. THE MODELS HAVE BEEN CONSISTENT ENOUGH TO

WARRANT ADDING A 30 PERCENT CONTOUR ACROSS PARTS OF NORTH TX...OK

AND SRN KS.

[Quincy]

So they did go with the 30% contour. I think since they updated the D4-8 to include two probability contours, this might be the first 30%?

In the past, they only did 30%, so it's not completely unprecedented.

[jojo762]

In the past, they only did 30%, so it's not completely unprecedented.

I know that. I was talking about since they updated the Day 4-8. Like I said, I do not think I have seen a 30% since they made it to where there are two probability-categories in D4-8 (15%/30%).

[Chinook]

Sunday could be a regional severe weather threat for areas such as Omaha, Topeka, Kansas City, western Iowa, and Des Moines. 500mb winds will be pretty decent over the warm sector. A dryline will be out ahead of the cold front in central KS, eastern Nebraska.

[Chinook]

The 06z day-2 convective outlook, valid for Sunday: the SPC extended the slight risk to northern Oklahoma, as well as northwest IA. Here is a small piece of SPC's discussion:

--

 EFFECTIVE BULK SHEAR OF 35-45 KT WITH AN ORTHOGONAL ORIENTATION TO THE DRY LINE SUGGESTS DISCRETE SUPERCELLS CAN BE EXPECTED WITH ALL SEVERE HAZARDS.

[SluggerWx]

Still a LONG ways out, but the GFS does show a potentially significant event over the OKC area the afternoon of Sunday, May 8. Worth monitoring in subsequent model runs.

[Quincy]

An ugly pattern coming up for the next week. Even next week's trough ejection may be muddled by continued troughing in the eastern U.S. It's not all that common for a lull in severe weather to start May, but still...

[andyhb]

An ugly pattern coming up for the next week. Even next week's trough ejection may be muddled by continued troughing in the eastern U.S. It's not all that common for a lull in severe weather to start May, but still...

 

While it could obviously screw things up like the wind fields, I'm less inclined to believe it portends a lack of moisture return, especially into the High Plains. We've reached the time of year now where any sliver of the Gulf open to poleward advection for at least a day means there likely will be sufficient BL moisture. If this was March, obviously it would be an exercise in futility.

[SluggerWx]

Mother's Day (Sunday, May 8) through Tuesday still look pretty interesting. A ways to go still, but I know the GFS has hints at something evolving over the plains/Arkalatex region as early as five days ago.

We'll see.

[brettjrob]

While it could obviously screw things up like the wind fields, I'm less inclined to believe it portends a lack of moisture return, especially into the High Plains. We've reached the time of year now where any sliver of the Gulf open to poleward advection for at least a day means there likely will be sufficient BL moisture. If this was March, obviously it would be an exercise in futility.

 

Yeah, I'm torn on whether this next trough will amount to much, as progged. I agree with your sentiment in general that eastern troughing becomes less of a dealbreaker later in the spring with respect to moisture, but I'd feel more comfortable putting up with it in late May vs. early May. In any case, such substantial eastern troughing extending into lower latitudes will almost certainly prevent the next system from being a major outbreak due to the kinematic consequences (e.g., the trough can't eject "cleanly," so you probably end up with meridional and/or VBV issues similar to all this past week).

[jojo762]

While there are still many things to work out, such as moisture quality, timing, etc, late this weekend/early next week continues to look interesting basing purely off of pattern recognition. Something positive is that both the GFS and Euro have started trending toward a less amplified trough (which would result in less meridonial flow) than what they showed a few days ago...That'll all come down to how far east exactly is the EC trough though.