Central/Western Medium-Long Range Discussion

[Ground Scouring]

So we're already going to start with this? Fantastic.

For the record, what do you think is likely to happen this coming Saturday? Honestly, I'd be more interested in your meteorological reasoning than another retort. You could also argue with anyone else who has been (justly) noting the lack of an EML, negative tilts/southerly tracks, etc. Argue with Brett or Jim (wxmann), for instance. A little fairness might be appropriate here.

[SN_Lover]

Lake Oroville for example is 98.14% of what it was last year which isnt that bad, all things considered. 

[Ian]

Am increasingly wondering what this parade of re-curving typhoons might do. 

 

edit: though HM says that's dumb on Twitter. 

[andyhb]

For the record, what do you think is likely to happen this coming Saturday? Honestly, I'd be more interested in your meteorological reasoning than another retort. You could also argue with anyone else who has been (justly) noting the lack of an EML, negative tilts/southerly tracks, etc. Argue with Brett or Jim (wxmann), for instance. A little fairness might be appropriate here.

 

You're asking for fairness now after your behaviour on Saturday while the event was going on? Sorry to disappoint you, but that's not exactly how things work. Brett and Jim absolutely did not conduct themselves the way you did both before and during this recent event, end of story.

 

I think Saturday could be a significant day, large upper troughs like that in May will almost always will afford some kind of severe risk. Also, the GFS has been showing a fairly decent looking EML being advected over the Plain states (not extremely strong, but not negligible either). How is a negatively tilted trough bad for severe weather? It may cause problems in the wind profiles in some locations, but it also generally means a stronger surface low, with accordingly stronger low level flow and stronger mid/upper flow overspreading the warm sector. Positively tilted troughs generally cause a lot more problems in the setup in the Plains.

[andyhb]

I'll also add that in the areas that didn't see cold pool stabilization, the GFS and Euro were both underdoing instability values rather significantly on Thursday, Friday and the weekend.

[Ian]

It's another solid signal either way. Probably doesn't hurt to be a little cautious given what we just saw... But on the same note that was a heck of an active several days. This one seems a little less impressive just trough wise so far but further north and had some other things in its favor maybe.

[andyhb]

It's another solid signal either way. Probably doesn't hurt to be a little cautious given what we just saw... But on the same note that was a heck of an active several days. This one seems a little less impressive just trough wise so far but further north and had some other things in its favor maybe.

 

I actually disagree a bit here just on initial signal, especially from the 12z GFS/Euro. This looks to spread stronger flow over most of the warm sector and has a stronger low level response earlier than the most recent system.

[Ian]

I actually disagree a bit here just on initial signal, especially from the 12z GFS/Euro. This looks to spread stronger flow over most of the warm sector and has a stronger low level response earlier than the most recent system.

Yeah, maybe true. I don't usually dig too deep at this range. I liked the trough consolidation/ progression a bit better from here last go personally.. but it's a solid setup from range. 

[jameswx]

You're asking for fairness now after your behaviour on Saturday while the event was going on? Sorry to disappoint you, but that's not exactly how things work. Brett and Jim did absolutely not conduct themselves the way you did both before and during this recent event, end of story.

 

I think Saturday could be a significant day, large upper troughs like that in May will almost always will afford some kind of severe risk. Also, the GFS has been showing a fairly decent looking EML being advected over the Plain states (not extremely strong, but not negligible either). How is a negatively tilted trough bad for severe weather? It may cause problems in the wind profiles in some locations, but it also generally means a stronger surface low, with accordingly stronger low level flow and stronger mid/upper flow overspreading the warm sector. Positively tilted troughs generally cause a lot more problems in the setup in the Plains.

I know I will take a neutral tilt trough over a positive tilt on most set ups.  Regardless, I don't trust any model at this range progging the lack of an EML. 

[icebreaker5221]

And Nino comes to the rescue! Southern Cali should not be as bad as predicted. 

 

http://www.wrcc.dri.edu/cgi-bin/anomimage.pl?wrc30dPdep.gif

 

Lake Oroville for example is 98.14% of what it was last year which isnt that bad, all things considered. 

 

Probably better for the CA drought thread, since this isn't about the medium-range forecast. 

 

In any event, a small percentage of the state being ~1" above average for the latest 30-day period is just a drop in the bucket compared to the 5-10"+ deficits accumulated this winter.  Also, being slightly below last year when last year was one of the worst drought years ever actually is still pretty bad.

 

But I will concede that a slightly wetter pattern recently is certainly better than the alternative, with some more threats this week.

[MidwestChaser]

It might well come to nothing if we don't have a good EML. The trend toward a neutral/negative tilt with a "pinched" trough (i.e., one farther south with time) is not encouraging, as that would discourage a good EML from emanating over the warm sector. Anyway, we don't need more HP cells causing havoc for both communities and chasers.

 

 

After what you pulled last weekend, read more and post less. It's telling how once you were proven wrong, you ran away for 2 days.

[andyhb]

After what you pulled last weekend, read more and post less. It's telling how once you were proven wrong, you ran away for 2 days.

 

I already handled it, no need to pile on at this point.

[andyhb]

Might add that another thing that could screw this up is if the ULL closes off significantly before the trough ejects. This would cause problems with backing upper level winds and EML advection (shown by the 18z GFS verbatim and some previous Euro runs).

 

Also worth mentioning that the 18z run appeared to suffer from some possible convective feedback in the 81-84 hr period.

[Ian]

Euro weeklies look decent thru week 4. Signal decreases with time but that's typical. Does keep a stronger signal for high heights E/NE US throughout.

[Ground Scouring]

You're asking for fairness now after your behaviour on Saturday while the event was going on? Sorry to disappoint you, but that's not exactly how things work. Brett and Jim absolutely did not conduct themselves the way you did both before and during this recent event, end of story.

 

I think Saturday could be a significant day, large upper troughs like that in May will almost always will afford some kind of severe risk. Also, the GFS has been showing a fairly decent looking EML being advected over the Plain states (not extremely strong, but not negligible either). How is a negatively tilted trough bad for severe weather? It may cause problems in the wind profiles in some locations, but it also generally means a stronger surface low, with accordingly stronger low level flow and stronger mid/upper flow overspreading the warm sector. Positively tilted troughs generally cause a lot more problems in the setup in the Plains.

Regarding the first point, I think my flaw was that I made an outbreak with several tornadoes seem insignificant on the whole, when I was only referring to the original outbreak area in N TX and parts of OK (and even there I was more wrong than right). There turned out to be more visible tornadoes and storm structures than I anticipated, not to mention numerous significant tornadoes (with a count still rising) that definitely caused substantial damage and loss of life. I also should have not overlooked the threat in CO/KS, where there were also significant, long-tracked supercells with strong tornadoes. I really don't know enough to be judging events in progress; even people with more experience and actual background would struggle with a difficult forecasting situation like that which existed on this past Saturday. I can come across as being unwilling to listen, and in fact I am too stubborn and prone to emotional/forecasting swings in many situations. I need to try better/harder to sit back, read, and watch, but sometimes I feel left out when serious questions don't get answered (sometimes understandably, based on my behavior).

 

Regarding this coming Saturday: I must say that the 12Z ECMWF solution, taken ad verbatim, would almost certainly result in a major, quite possibly historic severe outbreak over a wide area, extending from OK/southern KS in the south to NE/SD in the north. What is critically important is that the ECMWF, as early as 96 hours, already begins advection of the first solid EML of the year, with a plume of high-quality inversion spreading northeastward from the Sonoran region over the southern Plains. More than a day and a half before the arrival of the deepening surface low on Saturday, there is already a robust EML in place over the southern Plains, and this EML remains in place through most of early Saturday due to the overall neutral tilt of the 700-mb trough. Moreover, there will be two full days of deep Gulf moisture spreading north, with a fairly strong low-level jet in place by 72 hours. As for the trough itself, the ECMWF has shown a notable shift toward a much broader, consolidated mid-level trough at 96 hours—an important trend as we get within the short range, the ECMWF’s kill zone. If the set-up at 96 hours verifies, then it will automatically have a significant impact by the time the trough ejects on Saturday. Shear is absolutely off the charts for mid May; even considering the ECMWF’s tendency to overdo the strength of the mid-level jet maximum, the pattern depicted would bring H5 winds of at least 55-60 kt into the warm sector Saturday, particularly over OK and southern KS, as a secondary surface low develops over the TX Panhandle. The orientation of the mid-level trough would imply fairly robust to strong backing of the surface winds all along and east of the dry line, extending well north into NE/SD. Such a set-up might also favor dry-line bulges (meaning low-level convergence as the surface low deepens) in OK and southern KS, where the best shear/instability combination seems to be present on the run. There is also no doubt that instability would be strong to very strong if the EML verifies as depicted. The very wide warm sector would also suggest a secondary severe threat along the retreating warm front in NE/SD (although the eventual location/evolution such a threat is more contingent on mesoscale details, such as early convection).

 

All in all, the pattern on the ECMWF shows mid- to late-April dynamics juxtaposed with mid-May thermodynamics. In fact, it does so to an extent that I can’t recall in any previous Plains outbreak on or after 15 May. The overall pattern reminds me a lot of the late-May 1917 sequence, with a series of southern impulses gradually giving way to multiple large-scale, ejecting disturbances. If trends continue, I think that we may be looking at something very special this coming Saturday (and quite possibly Sunday over the Ozarks/upper MS Valley/upper Midwest, depending on how overnight convection and the upper-air pattern evolve).

[Ground Scouring]

Might add that another thing that could screw this up is if the ULL closes off significantly before the trough ejects. This would cause problems with backing upper level winds and EML advection (shown by the 18z GFS verbatim and some previous Euro runs).

 

Also worth mentioning that the 18z run appeared to suffer from some possible convective feedback in the 81-84 hr period.

Since the ECMWF did not close it off too substantially at 96 hours, does that suggest that it has an edge over the GFS within that range, especially given the ECMWF's usual tendency to cut off lows too much/early? I would add that the GFS seems to be trending toward the ECMWF's evolution by Saturday, is it not?

[andyhb]

Since the ECMWF did not close it off too substantially at 96 hours, does that suggest that it has an edge over the GFS within that range, especially given the ECMWF's usual tendency to cut off lows too much/early?

 

Would be best to wait until we get better sampling. The upgraded GFS hasn't necessarily been stellar recently, nor has the Euro at times. I agree that the 12z Euro would have some pretty nasty potential, if we see a consolidation towards its solution, people in the Plains (over a large area) better be paying attention.

[brettjrob]

Major morning convection on the 00z GFS for both Fri and Sat, and the STJ is still carving across N Mexico into TX. I'm certainly taking model QPF at face value this time and assuming an outcome substantially less than the ceiling suggested by H5, rather than falling for the "holy crap, that trough in mid-May without drought concerns can do no wrong" voodoo I did last week. This is the second trough in a row that looks like a borderline-inevitable outbreak at this time of year, and better than most anything we've seen late season since 2010-2011... but this is no ordinary season.

 

Now, obviously, there will still be some tornadoes (at least Saturday), just as there were every day last week.

[andyhb]

Major morning convection on the 00z GFS for both Fri and Sat, and the STJ is still carving across N Mexico into TX. I'm certainly taking model QPF at face value this time and assuming an outcome substantially less than the ceiling suggested by H5, rather than falling for the "holy crap, that trough in mid-May without drought concerns can do no wrong" voodoo I did last week. This is the second trough in a row that looks like a borderline-inevitable outbreak at this time of year, and better than most anything we've seen late season since 2010-2011... but this is no ordinary season.

 

Now, obviously, there will still be some tornadoes (at least Saturday), just as there were every day last week.

 

Will probably start a dedicated thread to this tonight, but yeah the 18z/00z GFS runs would certainly not have too high of a ceiling. The 12z Euro would be very volatile though, whether that goes towards the GFS tonight is the question. The 00z UK is in, although I can't see any of the wind fields on it for that timeframe so that's a bit of a mystery of what everything actually looks like.

 

I'll also add that the hits seem to keep on coming with repeated western troughing on most ensemble guidance/etc. I'd have to think that something bad (or good, for chasers) is going to happen (in spite of the 5 fatalities over the weekend) one of these times if this type of pattern continues. That's not to mention all of the flooding.

[tornadotony]

Major morning convection on the 00z GFS for both Fri and Sat, and the STJ is still carving across N Mexico into TX. I'm certainly taking model QPF at face value this time and assuming an outcome substantially less than the ceiling suggested by H5, rather than falling for the "holy crap, that trough in mid-May without drought concerns can do no wrong" voodoo I did last week. This is the second trough in a row that looks like a borderline-inevitable outbreak at this time of year, and better than most anything we've seen late season since 2010-2011... but this is no ordinary season.

 

Now, obviously, there will still be some tornadoes (at least Saturday), just as there were every day last week.

Yep.  As long as the STJ is prominent, say bye-bye to prospects of a significant EML and widespread favorable thermodynamic profile.  Gotta hope the first days of these systems are prolific like Wednesday was, or else you know what you're getting afterward.

[andyhb]

Well, the 00z Euro looks pretty similar to 12z at first glance through most of the fields. H85 temps/winds in particular are almost identical to the 12z run at 00z 5/17. Will get a look at the morning convection/EML situation a bit later. The 12z run did have widespread favorable thermodynamic profiles across a large chunk of the warm sector at 18z, 00z was partially contaminated by convection (not from the morning).

[thewxmann]

Forget about severe weather, TX and OK are going to be underwater by the end of next weekend. That's going to be the bigger news over the next week.

[NTXYankee]

Forget about severe weather, TX and OK are going to be underwater by the end of next weekend. That's going to be the bigger news over the next week.

Huge concern for that, especially if we get the rain forecasted the next couple days. We couldn't get a drop not too long ago and now the faucet won't turn off and sprung a leak. The small storms this past weekend were efficient rain producers, looks like we have the same amount of moisture to work with once again.

[rolltide_130]

Forget about severe weather, TX and OK are going to be underwater by the end of next weekend. That's going to be the bigger news over the next week.

 

I'm really getting worried about a significant tornado running over a populated area that's been hammered by rain. Seeing as a lot of storm shelters are failing because of water, there may very well be a situation in which they could get pulled out of the ground and thrown, or even more cases of people becoming trapped in them because of floodwater.

[ZackH]

One thing I do like to see is that it is apparent that upper level support will be better this weekend. However... as noted... widespread precip is very probably going to be a major problem... especially the early morning convection. 

[nrgjeff]

This weekend does have a better trough than last models verbatim; that said, last week was a respectable sequence. Memorial Day could repeat yet again after these. Why all the bickering? State of the season remains strong.

 

First, if the EML fails and/or ATMO gets overturned by morning convection, May climo indeed still favors chasers. One would simply modify target and/or philosophy. Shift south if maintaining OFB/DL reasoning. Shift north for broad upslope flow. Saturday worked out great for both.

 

Second, this sequence less midday rain is forecast. Keep in mind morning rain ending is good for OBFs. That could change, but so far it does not look as messy. If upper winds are straight south and/or veer/back no problem. Just target upslope where one would expect 850 winds to be screaming and quite backed.

 

Finally, the ceiling remains high if the short-wave can come out at the right time and with some southwest (vs south) winds upstairs. Last time never looked high risk at any point, due to teardrop trough, but there it at least a path to another MDT for tornadoes on Saturday.

 

Similar thoughts are valid for the trough leading up to Memorial Day. Don't worry, be happy!

[1900hurricane]

I can't say I've really looked at this with great detail, but the way things have been playing out this year does somewhat remind me of 1957. Both this year and 1957 can be described as El Nino springs with the southern plains transitioning from a very bad drought to flooding due to craploads of rain.

[Quincy]

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".

[Ian]

Definitely better than the great lakes vortex that has been around in recent Mays. 

[ZackH]

For what its worth here are the CIPS analogs based on last nights 00z GFS.

 

Friday:

 

Saturday: