Central/Western Medium-Long Range Discussion

[Radtechwxman]

Then why in the corner does it say 12z Thurs current run?? Where it says valid 0z Thurs is actually the time frame I'm looking at. Wed night

[andyhb]

3 minutes ago, StormChaser4Life said:

Then why in the corner does it say 12z Thurs current run??

Because the current run is the one that is running right now, not the displayed one necessarily. Since Wednesday is not in range yet, it defaults to the previous run when you try to display the data for that particular day.

[Radtechwxman]

Just now, andyhb said:

Because the current run is the one that is running right now, not the displayed one necessarily. Because Wednesday is not in range yet, it defaults to the previous run when you try to display the data for that particular day.

I just figured it out. My apologies. Was kinda confusing at first. I'm new to the site. But it has a bar up top showing the progress and shows the run at the bottom. I swear I'm not an idiot. Just had a blonde moment. Lol

[nrgjeff]

Regardless next week still looks fine upstairs. Challenge is to get the moisture. Wind direction and speed with height looks excellent.

Looking ahead, at the weeklies and indices (MJO, AAM), looks like a lull the week of May 7. Of course in May a mesoscale accident is always possible, but appears another East trough will be in the wake of next week's action.

Week of May 14 and/or May 21 could feature a new West trough. Much of that is based on indices. Weeklies have hints of new jet energy chipping away at the West ridge (from the May 7 week). Back when May was weeks 4-6 there was no reason to panic. Weekly's accuracy improves around week 3, and fortunately they now look a little more like late May climo.

[ChrisBray]

Hope you all are enjoying this week.

Looking bleak for the foreseeable future.

[Quincy]

While I agree that the next 7-10 days (beyond Thursday) should be relatively quiet, the pattern isn't exactly bleak. Climo suggests that there's very often downtime in early May anyway, after the atmosphere reloads from late April (or in this case very early May) activity. Based on the OP/ENS Euro, a few weak impulses are able to impact the southern/central Plains in the northwest flow regime highlighted above. While upper level flow may be marginal, don't discount mesoscale features and robust boundary layer heating in areas like Oklahoma and Texas.

Guidance in the longer range, i.e. days 10-14+, is even more encouraging, as that western ridge may shift eastward. We'll see!

[CheeselandSkies]

CFS took a little bit of a dump on the chase prospects for my vacation that I booked on Monday for May 18-27 after several straight runs of it showed at least one trough moving across the central CONUS during that timeframe (what I based my decision on). Still should be at least one opportunity, whether it's good enough to draw me out remains to be seen.

[nrgjeff]

CFS had a bad run as did the 00Z GFS. However the 06Z GFS came back around to Euro Ensembles. Consensus still looks good. Euro weeklies look good. Just hold on Thursday night, lol!

Ensembles/clusters all point to increasing confidence week of May 14. Week of May 21 is likely on the table too. Well, also climo. Week of May 28 and first week of June have excellent climo.

Cannot punt a season based on April, or one quiet 5-days in early May. 2018 is waking up, and I think the ruckus is just beginning!

[CheeselandSkies]

I take it you are Jeff House on Stormtrack?

[bjc0303]

On 5/2/2018 at 11:10 AM, nrgjeff said:

CFS had a bad run as did the 00Z GFS. However the 06Z GFS came back around to Euro Ensembles. Consensus still looks good. Euro weeklies look good. Just hold on Thursday night, lol!

Ensembles/clusters all point to increasing confidence week of May 14. Week of May 21 is likely on the table too. Well, also climo. Week of May 28 and first week of June have excellent climo.

Cannot punt a season based on April, or one quiet 5-days in early May. 2018 is waking up, and I think the ruckus is just beginning!

GWO and MJO would definitely support a surge in activity the back half of May. 

[Thundersnow12]

Victor Gensini and I have 5/14-5/25 blocked off for a trip to the plains, dependent on the pattern of course. 

[Winter Wizard]

Going to be out storm chasing in the Plains from 5/7 to 5/17. Pattern isn't the most favorable, but should still get a few solid chase days in. 

[andyhb]

l'll take an order of the 12z Euro kplzthxbai.

Out there from the 9th to the 14th.

[jojo762]

Fairly significant model variability, but seems like there very well could end up being at least some severe threat over the plains next weekend. 12Z GFS was pretty aggressive for Saturday in particular. 

[Quincy]

It looks like we may be, gradually, moving toward a more active pattern for the central states. With that said, even with some activity in the coming week, I'd be willing to bet that the week finishes at least slightly below average with respect to climatology for severe. That could change if the pattern late this week, that @jojo762 eluded to, looks more significant.

Shortwave energy pivots from the northern/central Plains into the Midwest/Great Lakes around the middle of this week. I don't think Tuesday winds up producing much of anything, but you can't rule out isolated severe in the Kansas/Oklahoma vicinity, especially if boundary layer moisture trends improve. Wednesday is already highlighted in SPC's latest day 4-8 convective outlook, but that targets more of the Ohio Valley sub-forum. Thursday is progged to be a transition day, but details are tough at this point. Maybe it features isolated severe in the High Plains or even along a warm front farther east, but only time will tell.

Friday-Saturday has the potential to feature at least one, if not two noteworthy severe weather setups in the Plains. Details will certainly change, but a positively tilted trough is modeled to swing from the Four Corners region into the High Plains through the period. The setup is not all that different from last week, although the speed of the system looks faster and troughing not as vigorous.

Longer-range trends for the following week (especially mid to late next week) are increasingly encouraging. Perhaps the Lower 48 will finally be moving into a pattern with more consistent/substantial troughing across the western half of the U.S. It's been a long time coming, but in a way, it's better to see this pattern during the second half of May, rather than earlier in the season.

Although it's tough to have much of a detailed look into late May, climatology and ensemble data suggest the signs are encouraging.

[nrgjeff]

I pretty much agree with everything Quincy has above; however, I might not bite yet. Mother's Day chasing requires a particularly good setup to justify the loss of political capital at home.

Looking toward May 16-18 the GFS just tried to resurrect the slow train wreck unfolding on Euro and Cad Ensembles. Trouble is WNW flow which would be OK in June but we're not quite there yet. Ensembles are a little more friendly toward May 21 but that is hour 360.

MJO might finally lumber into a good phase toward Memorial Day, but that train keeps getting delayed. Despite early season troubles, I feel like it is OK to be picky. At the same time it might go nuts sooner.

[bjc0303]

ECMWF, GFS, CMC, and FV3-GFS parallel all introduce western troughing in the 240 hour timeframe. 

GEFS, CMCE, and EPS all introduce western mean troughing about this time period. I honestly cannot help but get pretty excited looking at the Euro EPS mean. The evolution suggests extended southwest flow aloft, with a wide range spatially and temporally of targets. Details will not be clear for a long time, and at this range, even the ensemble could be fooled. Ensembles do exhibit noticeable skill in the 10-14 day window, though (as in skill > climatology). So while things will change, confidence does appear to be increasing slowly on prominent western troughing mid-late next week. This could be a period that helps make up for a lot of the downtime we've had this year.

 

Here is a five day mean of heights centered on May 20th:

 

 

Here is the evolution as a whole on the EPS (mean):

 

After such a bleak opening, there appears to be reason for optimism going forward.

[nrgjeff]

Starting with the ECMWF weeklies yesterday, and through overnight modeling, the forecast has become noticeably more friendly to chasing interests. I'm almost giddy, but pinch myself because it is still the 6-15 day forecast. Weeks 2-3 could be good too if one believes the CFS weeklies. Euro weeklies back off; but, CFS has been better at sniffing out subtle ebbs and flows. Plus, you know, week 2-3 climo.

Focus on the 6-15 day forecast, the following signals are noted. That awful cut-off low in the East Pac is starting to lift out. Still looking for central Pac convection to chill out. Please make way for a new Kelvin wave out of the IO, and favorable MJO. -AAM is forecast to hold on a little while longer. Some models flip to +AAM by week 3 which is not great; however, that late May climo...

Next week timing has been all over the place. 24 hours ago I was thinking late week. Now both the GFS/Euro have storms going most days early week on the returning front (left over from Mother's Day) with a dry line too. Moderate SW flow over a boundary with CAPE, boy I wish that was not week out modelling. Verbatim things calm down May 19-ish but very subject to change. Reload May 21-ish?

At any rate, it looks like the next 2-3 weeks are friendly to chase concerns. This weekend could still yield chase events; but, I try to wait until after Mother's Day for family. Good luck to all!

[Chinook]

Friday (Saturday 00z)- The SPC has a slight risk for severe storms in Kansas. The NAM has this area somewhat capped. The 00z Euro has about 1200 J/kg of CAPE, which is not too crazy. However, the GFS has gone crazy. Usually the GFS is too low with CAPE, right?

 

[Indystorm]

Yes, it is usually the NAM that tends to go overboard on CAPE values on occasion.  Your posted map surprises me.

[Quincy]

The 18z NAM and to some degree, the 12z Euro, show relatively large T/Td spreads throughout the boundary layer. This coincides with both models failing to initiate any convection in vicinity of the strongest bouyancy around 00z Saturday. The GFS, on the other hand, with large CAPE and somewhat less anemic low level moisture, shows precipitation blowing up in north-central Kansas. Another note is that the NAM, which I would lean toward, shows relatively high LCLs (around 2km), which makes sense given the relative lack of quality boundary layer moisture.

With that said, the environment between eastern Colorado and the Kansas vicinity should feature at least some severe threat, given favorable CAPE/shear overlays, glancing effects of upper level energy and convergence along a frontal boundary.

It will take some time to resolve mesoscale details, but I think one can justify the SPC slight risk. Otherwise, anything more substantial or widespread seems conditional, if not unlikely, at this point.

[bjc0303]

This week has looked like a dud for days now, but all signs suggest activity ramping up next week and continuing into the end of May. Could be looking at a prolonged stretch of activity. Finally the season may get going. 

 

Deterministic guidance, as well as ensemble guidance really favor uptick in activity for a large part of, if not the remainder of, May. 

[CheeselandSkies]

Looks like my dart at the calender (May 18-27) might work out. Hard not to sweat each run of the CFS and GFS, even though at 9+ days out most of my vacation is still in model fantasyland. At least the trends are encouraging.

[nrgjeff]

You are golden for a few to several days starting May 18. Possible this coming Sun-Tue has a couple meso-scale accidents, but the midweek flow goes weak; so, I would not consider Sun-Tue a day(s) before the day set-up. Starting May 18 looks great!

Looking ahead the 6-15 day ensemble charts are about as good as one could ask for in late May. 11-15 day always carries a bigger change risk; however, I'm fairly confident in another trough after the May 19 weekend trough. If both troughs offer 2-4 chase days, that's 4-8 chase days in the 10 day period. Odds (even batting .333) favor great chasing success!

[bjc0303]

I know calling things a wedgefest is a meme and all, but the 00z euro dropped and absolute dime on the plains at hour 240 last night lol

[CheeselandSkies]

1 hour ago, bjc0303 said:

I know calling things a wedgefest is a meme and all, but the 00z euro dropped and absolute dime on the plains at hour 240 last night lol

That...is delightful.

[Jonbo]

GFS going a bit bonkers.

[Torchageddon]

13 hours ago, bjc0303 said:

I know calling things a wedgefest is a meme and all, but the 00z euro dropped and absolute dime on the plains at hour 240 last night lol

Did the 00z euro just trash that goodness it showed 2 runs ago?

[nrgjeff]

Overnight deterministic NWP kind of killed the mood. However, Ensembles and Weeklies still look good. Pushing back a weather pattern that eventually happens is not uncommon.

Looking under the hood of both Ensembles and Weeklies, clusters show some excellent 5-day periods - even better than the means. Timing is slightly different on those clusters though. Takeaway is a flexible chase vacation is in great shape. Of course set dates may cause sweating.

Finally, Indian Ocean convection is waking up which is a chaser friendly MJO signal. Still need to get rid of that awful Central Pac. convection though. I think it is on the down trend, but it ebbs and flows. IO also ebbs/flows, but it is making higher highs and encroaching on Indonesia (good). 

I use Kochi U. Japan http://weather.is.kochi-u.ac.jp/index-e.html to check out those regions.

[Torchageddon]

12 minutes ago, nrgjeff said:

Overnight deterministic NWP kind of killed the mood. However, Ensembles and Weeklies still look good. Pushing back a weather pattern that eventually happens is not uncommon.

Looking under the hood of both Ensembles and Weeklies, clusters show some excellent 5-day periods - even better than the means. Timing is slightly different on those clusters though. Takeaway is a flexible chase vacation is in great shape. Of course set dates may cause sweating.

To clarify, what time frame(s) for the deterministic NWP? Just the next 10 days or is that further long range? Mostly interested in the last 10 days of this month.