State of the Chase Season: 2019

[Dean Baron]

It looks like people's prediction of a more active second half of May might be coming true. Finally starting to see some big potential towards the end of the GFS's range (albeit still a long ways out) starting around the 17th. Looks like the jet stream could still be digging out of the SW beyond the GFS's range. If this actually verifies, it could be a very active end to the month. A long ways out so it's hard to get too excited, but when trying to plan a multi day trip it is encouraging to see some signs of life finally in the deterministic models.

 

[Andy Wehrle]

The 11-15 day forecast looks excellent this morning. Some GL troughing is noted, probably due to West Pac. However, the IO induced jet extension is on track. Should favor the Southwest trough as well. So, by late May we don't stress over GL troughs. We chase Southwest troughs coming into the Plains. I'm feeling great about May 17+.

You do if you live in the GL and would like it to not be 50s and showery when it's almost June...and would also like some local/regional setups to chase.

 

[Warren Faidley]

Still on track for insane RH levels to remain in place per the latest model runs. Seeing all the severe in the old strongholds of MAF and LBB bodes well for a normal season. Strong signals with the latest GFS runs of major jet action for the rest of May.

 

[Marshall Stoner]

You do if you live in the GL and would like it to not be 50s and showery when it's almost June...and would also like some local/regional setups to chase.

Might have to wait for a La Nina spring for that. Good instability in the southern GL is hard to come by without a strong SE ridge. Gulf-Coast riding mega-MCS always does a number on instability east of the Mississippi. By late June we can generate good instability locally over the corn belt, but by then you have to prey the dynamics haven't gone to shit.

 

[Todd Lemery]

GFS and CFS are coming into agreement on the 17th-22nd period. There’s enough moisture returning from the gulf and the 500 and 850 winds come to life, especially starting the 19th. A couple of lows sliding through during that time period equals smiles. I did notice relatively uncapped air in the middle of the period, but it’s starting to look up.

 

[Dan Robinson]

Agreed, cautiously optimistic for some action starting in 7 to 10 days. Still a little early to fret about it, but the meridional nature of the flow shown without that really nice diffluent zone of a negative tilt is a little meh. But certainly much better than a ridge or NW flow! As it stands there should be a couple of decent days in the mix.

 

[Devin Pitts]

Euro/EPS is still pretty consistent with lighting things off starting the weekend of the 18th, as it has been advertising for a bit. GFS/GEFS has been flip flopping quite a bit, but overall trending towards it as well. Starting to look like I timed my chasecation pretty well this year as I head out Friday!

 

[Paul Knightley]

Deterministic and ensemble output from the main global centres are pretty consistent with the notion of a powerful Pacific jet developing through mid-late week next week...models are not that great at handling the eventual collapse of such a jet into a tough/series of troughs - and so we should still expect to see shifts in timings/locations of any eventual collapse.

However, as others have said, later next week/through the weekend/into the w/c Mon 20th May, it seems fairly plausible that some form of trough/circulation will translate from the W Coast into the mid-section - but it's too early to say whether this will be in the form of a stronger southern stream (and consequential risks across the southern Plains) or a larger trough, which might open up a more classic multi-day dryline then front set-up.

Beyond that - well, given the uncertainties in the evolution due to what I've mentioned above, it's very tricky...if that is the collapse of the jet then we should expect a more blocky pattern to develop - then, it depends on how this is orientated - if we have a ridge over the SE states then we could have a slow-moving trough to the SW - meaning some multi-day High Plains fun - on the other hand, we could get a trough-ridge-trough pattern, which would be not such good news.

 

[Dan Robinson]

The last few runs of the GFS, Euro and ensembles are very encouraging - long-term SW flow, multiple ejecting shortwaves, moisture staying in place. Would be a 2004-like pattern if it verifies.

 

[Warren Faidley]

The last few runs of the GFS, Euro and ensembles are very encouraging - long-term SW flow, multiple ejecting shortwaves, moisture staying in place. Would be a 2004-like pattern if it verifies.

I have to agree. The model **trends** are quite encouraging, with a smorgasbord of possibilities over an extended period including an interesting negative-tilt trough / dryline fiesta possible next weekend. It would also appear the svr. potential might cover a wide range of locations from north to south depending on your desired flavor of storm modes. You have to figure sooner or later a good season will return and this might be it.

 

[Devin Pitts]

I try not to get hung up on individual GFS runs at this range, but that 12z GFS run this morning was something else.

 

[Marshall Stoner]

The scenario of the northern stream clipper in the Tuesday/Wednesday time frame carving a deeper SE trough has gone out of favor in both GFS and Euro. Still not 100% confidence, but the trend of that system coming out weaker makes me happy.

 

[Warren Faidley]

Yes, we have officially reached the point where every model run is anxiously awaited!

 

[Alex Elmore]

Analogs of the GEFS members point to a favorable pattern starting around the 19th when looking at temperature anomalies. 9-11 day average (5/19-5/22) and 12-14 day average (5/22-5/25) below (CIPS Analog Extended Threat Guidance).


The CIPS experimental probability guidance is also starting to get in range of this potential pattern (Day 7 and Day 8). The guidance is based on the mean GEFS. (CIPS Severe Weather Probability )


Finally, Victor Gensini's SCP analysis page of the GEFS members shows promise when looking at the 5/18-beyond period as well (Extended Range Severe Weather Environment Forecasts )


Hopefully this ends up being a good period for those of us with chasecations in that range.

 

[JamesCaruso]

I’m pretty bummed out personally because I am definitely going to miss this next trough which should kick off the action on the southern Plains this Friday 5/17; SPC has today introduced a Day 6 risk in classic chase country. I can’t possibly get out there before 5/23 and per GFS the Plains look to be under a ridge around then. The next trough ejects a closed low up toward the Great Basin and does not dig into the Plains. Memorial Day Weekend doesn’t look too good right now except maybe in the northern Plains which is not my favorite stomping grounds. Of course, that’s not a particularly reliable range for the GFS so I will try not to worry too much, although either way I have to imagine my trip starts at an unfortunate time and I won’t be able to avoid a lull after this next trough. I just hope the lull is a short one. I will take comfort in the posts above mentioning “long term” and “extended” favorable conditions, surely those comments can’t refer to just one good week, I mean in 2013 there were two straight great weeks and everyone thinks that season sucked.