State of the Chase Season: 2019

[Jeff House]

Monday 12Z NWP continues to point to mesoscale chances Friday through early next week. Modest flow is forecast at 500 mb. LLJ responds most evenings. Moisture starts to return in earnest on Friday. Hard to place surface features a week out, but anywhere from the central High Plains to Midwest has opportunity.

Then around Day 10 a couple runs have more robust 500 mb flow coming into the West. I was going to just blow off the feature on the GFS. However the ECMWF just joined. We'll see what the Para/Beta EC Op does. Plus we got its EPS and weeklies on deck this evening.

Finally the Dashboard continues active around June 20-ish for a few to several days. CFS weekly charts and GFS Ensemble charts both look decent, which lines up with the Dashboard. Note decent in late June is mesoscale more than outbreak, but enough for chasers.

 

[George Sargeant]

Monday 12Z NWP continues to point to mesoscale chances Friday through early next week. Modest flow is forecast at 500 mb. LLJ responds most evenings. Moisture starts to return in earnest on Friday. Hard to place surface features a week out, but anywhere from the central High Plains to Midwest has opportunity.

Then around Day 10 a couple runs have more robust 500 mb flow coming into the West. I was going to just blow off the feature on the GFS. However the ECMWF just joined. We'll see what the Para/Beta EC Op does. Plus we got its EPS and weeklies on deck this evening.

Finally the Dashboard continues active around June 20-ish for a few to several days. CFS weekly charts and GFS Ensemble charts both look decent, which lines up with the Dashboard. Note decent in late June is mesoscale more than outbreak, but enough for chasers.

Fingers crossed, since I'm going to be out there June 13-28...

 

[Dean Baron]

I'm starting to wonder if the Northern Plains will even have a chase season. Typically by mid June the region (WY, MT, SD, ND) will have seen around 30 tornadoes. So far there have only been 5 this year. Also, while Colorado has seen some brief touchdowns, none of them have been quality tornadoes that I'm aware of. The GFS isn't showing anything coming up, although the CFS is a bit more optimistic. I haven't lived here long enough to compare 2019 to previous years. Will there be more storms in July to make up for this quiet period?

Generally, the northern plains stays active on and off through August so there is usually still some good setups even with slow starts. Having said that, this year has been extremely quiet. And for the most part, since 2010 the northern plains has been fairly quiet. Hoping we get a few good setups still this summer but as you mentioned the long range out look isn't real promising.

 

[Quincy Vagell]

The moisture scouring and crashing cold front situation is not only getting old, but it's bordering on obscene. Dew-points in the 40s into northern Arkansas in mid-June? It looks like Tds will crash into the bottom 10% percentile via SPC sounding climatology for several stations from the Plains into Missouri. SGF may challenge daily lows, for example. (not station lows, but sounding lows, as there is a difference)

It does look like this pattern breaks down and shifts back to a more moisture-rich environment across the Central Plains beginning Friday. We should see widespread 60s+ Tds over a broad area this weekend.

Although the pattern over the next 5-15 days looks improved, the trough axis across the northern tier of states is still a bit farther east than ideal. It's still workable. Ensembles blend data as well, so there's no telling if a somewhat deeper trough may dig over the High Plains at some point next week. Stronger upper level flow is progged to eject from the Pacific Northwest into the Northern Plains vicinity by the middle of next week. Moisture should be less of an issue as well.

Nothing screams "major event," but to look at this from a positive mindset, I think the pattern supports a few "diamond in the rough" setups over the next 1-2 weeks, probably between the High Plains/Northern Plains and Upper Midwest. Kansas could get in on the action as well. The pattern and time of year support slower moving storms. Moisture should be there, as you'd expect in mid to late June (even though the next few days challenges that thinking). Less hoards will be out, especially if we're talking about SLGT/MRGL setups north of I-70. If we can work into the Northern Plains, that would place targets, generally, away from flooded portions of the Midwest, as well as KS/OK.

I always liked June. It's a fickle month, but it doesn't take much to squeak out some good events. You just need to get rid of this moisture scouring...

 

[Jesse Risley]

Perusing the 00z/11 CFS, it is good to see some above meager H5 flow return to the Northern Plains by late in the period, particularly through early July (if that comes to fruition). The GFS does seem to be hinting at better moisture return by late next week. As someone who traditionally spends more time out in June and July, there are essentially always several "surprise" upslope days in late spring a summer, particularly in CO, WY, western NE and even into eastern MT. Canada usually has several great chase opportunities on the Prairie Provinces for those willing to find the "diamond in the rough" setups that the northern season generally offers. For those of us that particularly find mid to late season chasing more flexible with our schedules, it's often a case where you will just have to be out there and play boundaries each day and monitor the DCVZ for mesoscale opportunities too.

 

[chrisbray]

12z euro run was epic for next week by the way.

 

[Jeff House]

ECMWF keeps moderate upper flow across the Plains next week. LLJ is forecast to respond most evenings.

Looks like a pair of days is possible Tue/Wed. First one an actual system pushes out over the Northern Plains. Second day might be forests of Minnesota and Wisconsin, but perhaps something can go farther south IA/IL.

Later next week modest to moderate flow is still forecast over the Central Plains and Midwest. I'm a little skeptical, but the LLJ also responds a couple days. Too far out to pick an area of interest attm.

I could see 3-4 subtle days next week. It is not outbreak sequence material, but it is just what June chasers seek. Could be 1-2 gems.

 

[Brett Nickeson]

The Euro continues to trend worse and worse for any severe weather in the plains by continuing to amplify a western ridge that prevents a few subtle shortwaves from ejecting into the northern plains. That possibly leaves a chance for the upper midwest as they bottom out east of the ridge. It's also throwing a moisture-scrubbing cold front in there for good measure by mid-week. In late June. Another moisture scrubber in June.

The GFS differs by a substantial margin, sending through a couple shortwaves mid-week across the central to northern plains with decent - but not great - moisture. The GFS would result in several likely chase days pending mesoscale details.

Experience has taught me that you can plan on a verifiable solution of about 90% Euro and 10% GFS at this point...

 

[Jeff Duda]

Experience has taught me that you can plan on a verifiable solution of about 90% Euro and 10% GFS at this point...

Given that the GFS's dynamical core was replaced by the FV3 operationally as of the 1200 UTC cycle this morning, you will probably want to scrutinize the forecasts more carefully for awhile until you develop a new set of bias corrections.

 

[Quincy Vagell]

I would tend to think that next week should have more chase days than down days. The Euro shows a seasonably robust upper level jet impinging on the central/northern Plains by Tuesday and more or less staying in place across the north-central states through the week.

Tuesday could be a Northern Plains chase, although instability is unlikely to be impressive for mid-June. This doesn't scream a classic moderate shear/large CAPE setup they tend to see in July. Wednesday shifts east, but there are indications that Nebraska/Iowa and possibly Kansas could be in play. Of course, this is about a week out, so details are highly subject to change. Just taking the recent model runs verbatim and the general signal has been fairly consistent.

Late next week/next weekend is more of a question mark. There are signs that a cold front could scour moisture/instability, but don't rule out the Central Plains/High Plains, especially if at least modest instability remains.

It could be worse, a lot worse. Wind shear will be there, we just need some instability. It's mid to almost late June by the end of next week. It shouldn't be too hard to destabilize...

At worst, if things go to junk after Tuesday, I'd still think that the High Plains pulls off a sleeper day or two with isolated supercells and that's in a worst case scenario. Remember, it doesn't take a lot to produce up there when you have modest boundary layer moisture and supercell wind profiles in place.

 

[Quincy Vagell]

Next week still looks to be the beginning of a potentially active period. The axis of troughing through at least Monday is still a bit too far east to get overly excited about, but by Tuesday or Wednesday, there is good model agreement that the pattern turns more favorable in the broad scale. This means that there could still be a few chaseworthy storms between now and then, but threats should be mostly isolated/conditional.

An initial shortwave probably transverses the north-central states in the Wednesday/Thursday time frame. This would tend to favor at least an "enhanced" severe threat with exact placement TBD. In its wake, an array of ensembles, including yesterday's Euro weeklies, keep relatively fast flow in place across the central/northern Plains through next weekend. At the same time, there appears to be a tendency for troughing across the northwestern states with ridging building across the eastern third of the CONUS.

As we've seen, long-range model trends can change. It's possible that the synopically-favorable pattern continues beyond next weekend, but eventually the death ridge will inevitably return. It's the transition period that should provide chasers with a bit of late season optimism.

 

[Marshall Stoner]

Does anyone know if there's something wrong with the GFS as of late? Like really wrong? Compared to the ECMWF it seems to have a cold bias in the long range. It's been a depressingly cool spring/summer up north, but having a trough dig into the NW without any appreciable downstream ridge makes little sense in the latter half of June.

 

[Andy Wehrle]

Does anyone know if there's something wrong with the GFS as of late? Like really wrong? Compared to the ECMWF it seems to have a cold bias in the long range. It's been a depressingly cool spring/summer up north, but having a trough dig into the NW without any appreciable downstream ridge makes little sense in the latter half of June.

Operational GFS has been *ahem* "upgraded" with the FV3 core, which has a pretty significant cold bias.

Although, it's really not that far off. Not getting out of the low 60s on Father's Day is ridiculous. This needs to stop.

 

[Marshall Stoner]

Operational GFS has been *ahem* "upgraded" with the FV3 core, which has a pretty significant cold bias.

Although, it's really not that far off. Not getting out of the low 60s on Father's Day is ridiculous. This needs to stop.

Would you say the cold bias grows with time? Like is looking at 240h+ completely useless now? I know it's always been useless at that range for predicting synoptic setups, but before you could sometimes get reasonable run-to-run consistency in the evolution of the longwave pattern at that range. Now every GFS run is different while the Euro is at least being consistent in showing a warming trend for the Easturn US.

 

[Andy Wehrle]

Would you say the cold bias grows with time? Like is looking at 240h+ completely useless now? I know it's always been useless at that range for predicting synoptic setups, but before you could sometimes get reasonable run-to-run consistency in the evolution of the longwave pattern at that range. Now every GFS run is different while the Euro is at least being consistent in showing a warming trend for the Easturn US.

I don't know enough about the details of it to say with certainty, but I'd suspect so.