State of the Chase Season: 2016 Edition

There is some interesting output around for those heading out mid-late May, as others have mentioned. For example, ECMWF ensemble output is suggesting a western USA trough towards day 15, and GEFS suggests something similar. Of course, the big questions are how much ridging will occur ahead of it, and will this ridging lead to a deep incursion of continental air into the Gulf? There are also quite a few question marks surrounding the reliability of the models, even ensembles, at that range in the current regime - that is, of repeating blocking episodes around the N Hem.
My view is that if the current deep incursion of continental air into the Gulf is not repeated, the slow but sure moisture return will lead to events mid-late month. Moisture is key, of course - once it's in position, even modest looking waves a few days away can turn into sizeable chase days, and back to back chase days if they're somewhat slow moving.
 
Thought I would try to get some activity going again in this thread, since there have been no posts for about a week.

Curious as to what you all think about the next couple weeks. Personally, I had a three week window carved out from 5/14-6/4 for a chase vacation, but can only be away for two of those weeks - so it was going to be either 5/14-5/30 OR 5/21-6/4. Right now I am leaning toward the later trip, more for work-related reasons than anything, but doesn't look I would be missing much next week anyway. Obviously too soon to know much about the following week but the GFS appears to offer some rays of hope for a more favorable pattern.
 
The week of May 22 is starting to look promising, at least the broad North American weather pattern. Next week should have a local set up or two, but I would favor the May 22 week.

Weekly models have struggled with it for some time, but have started to consolidate. The issue may have been the MJO. Current convection over the Date Line is correlated with cool anomalies over much of the US including the West (good) and Midwest (bad). Recently the Indian Ocean has started to flare up which is bullish for US storm chasers. If the Indian Ocean becomes the dominant MJO forcing, the US signal is trough West ridge East (quite bullish). Lag time is about 10 days give or take. Back to the models: CFS, Euro weeklies and 11-15 day forecast all line up fairly well now for the week of May 22.

An 11-15 day regional forecast carries considerable risk of change, but there is some value at the continental level. Details will not be apparent for another week, but the coveted trough West ridge East pattern is forecast the week of May 22.
 
I'm sticking with the NCEP Ensembles this time of year for long range guidance.

http://www.esrl.noaa.gov/psd/map/images/ens/ens.html

The time frame of May 22 is indeed looking good and could bring several days of favorable upper level flow -- although I'd be surprised if the currently forecast system arrives as strong as the GFS is showing. Once the rh settles in, it's a typical late May and early June drought pattern of chasing out west into NE Colorado.
 
Too late to edit my previous post but another positive factor in the latest 12z GFS forecast is uninhibited northern transport of quality Gulf rh several days in advance of the (22nd) system. I know the GFS can often overdue moisture this far out, but climatology says it's late May.
 
To echo Jeff's thoughts, the pattern does look good beginning the 22nd for at least few promising chase days. Since we're looking at an ensemble mean (EPS), there are questions about how the western trough ejects. There is concern too that central U.S. ridging and a small cutoff low across the Southeast may complicate things a bit, but it will be late May and barring some drastic change, severe will accompany the trough. This may also be more of a central to even northern Plains threat based on ensemble depictions.
 
I just looked at the 12Z GFS, and I don't see a single chase setup within a day's drive of Illinois. Obviously that could change with the next run, but it's still kind of depressing. What month is it again?
 
kevin-palmer said:
I just looked at the 12Z GFS, and I don't see a single chase setup within a day's drive of Illinois. Obviously that could change with the next run, but it's still kind of depressing. What month is it again?
Click to expand...

The GFS hasn't been looking great for the Plains either - it wants to put a blocking ridge in the middle of the country to hold back the western trough late next week. But ensembles (NCEP and especially ECMWF) at least try to flatten the ridge. As long as the GOM stays open, there's hope towards the end of the upcoming 10-day period. Also, CPC outlook is generally favorable with a western trough, eastern ridge and wet in the middle
 
Still some significant differences in next weekend's/weeks's forecast between the GFS and Euro, but per 12Z models it's looking a bit better for chaseable days than in runs past. GFS initially has a high amplitude ridge over the central US and a quasi Omega block going on, keeping the initial part of the trough from ejecting out into the plains and trapping it west and north. That eventually breaks down and a final shortwave passes through the central plains Monday and Tuesday. The Euro looks much more favorable for multiple chase days, with a lower amplitude ridge over the plains and multiple short waves rotating around the parent trough starting Saturday. The Euro also deepens the trough during that time and digs it a bit further south which I would have to imagine leads to more favorable setups this time of year. I'm more encouraged for the 21st to 25th than I was yesterday at this time.
 
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