For the northern areas, yes. If you watch Trey’s video though, the further south you went, the slower and almost stationary the boundary was.
In addition to this, it’s also possible to have a cold front that is subtly forced if the cold front doesn’t bring a strong temperature gradient with it. This was discussed in Trey’s video on the 5/31/85 outbreak, where the cold front was so diffuse that even with its modest eastward progression the forcing was subtle enough for discrete development.
You pretty much nailed it. It actually was true with the 3/14 system! Per Trey’s video, the Arkansas cells formed on the cold front, but it was a very weak temperature gradient. I think 70s on one side to mid 70s on the other around Arkansas. As you went north, it was a stronger gradient, hence the linear mode to the north.
I believe it was you who said that were storm mode ever-so-slightly different during the first half of the day on 3/15, we might've been dealt the outbreak of a lifetime. Considering the radar presentation the day-of, I would concur.
I’m really looking forward to Trey’s breakdown. Mississippi definitely got the brunt of it. If that big line of crapvection showers weren’t there, I feel like all of Mississippi would have been in play vs just the southern portion. Imagine that kind of radar presentation spanning the entire state.
It was my personal closest call in a long time that evening, so definitely memorable for me. This outbreak was also a great example of both how it takes 10,000 factors to come together perfectly to get "the outbreak", but when certain conditions are favorable, storms can overcome even the most meager of environments (i.e. every cloud in Alabama spinning by evening).
That was quite the HRRR run. While this run was initialized at 0Z (so the night of the 14th) each model run after that tended to linearize and beef up that rain shield more and more.
It's crazy to think if they had initiated later and storm mode cooperated a bit more, we would be having a much different conversation.
Can't remember what was happening at that point, though I do remember as the confluence band moved into AL, DPs and CAPE still weren't that great so that likely prevented a good bit of development.
Hmm I was just gonna comment on why 3/14 wasn’t high risk.
I don’t think it’s the fact that they don’t buy it, I’m sure it’s more of the fact that many forecasters saw more potential “flies in the ointment” on March 14 rather than March 15 before the event began. I seem to remember many people calling for a much more linear mode on March 14th than what actually happened in the higher risk contour. OMEGA is also still in its infancy, relatively speaking, so it would make sense to err on the side of caution when forecasting until we’ve seen OMEGA make more accurate predictions in the future. That will fully cement it as a much more trustworthy tool IMO.
Hindsight is 20/20 as always, but I do feel like the SPC jumped the gun with the 2 day high-risk for 15th. The outlook did verify, it wasn’t a bu$t at all, but you had a lot of flies in the ointment build in between that issuance and the morning of the event. To @slenker ‘s point though, CAMS weren’t showing discrete supercells for the 14th until the morning of if I recall. Everything was just being depicted as a giant line until then. Still think they could’ve went high when the CAMs latched onto that solution for the 14th though.
Concur. Worth remembering that the 14th basically went the opposite of the 15th on models; it really didn't look overwhelmingly impressive until the day-of, and I do think there was genuinely just some extra focus put on the 15th because of how insane it looked - those kinds of soft biases can effect anyone, including seasoned forecasters. That being said, the D2 High Risk was certainly an interesting choice, though at the time I still understand why they pulled on it. Their placement was good, too - a lot of us were concerned it wasn't far enough north, but it was right where it needed to be.
