We have a unique set of new diagnostic variables for this years experiment in an attempt to extract information about individual hazards. One of those is 0-3km hourly maximum updraft helicity (UH). We decided to add an activity to do tornado probability for the full and 3h periods on Thursday in addition to forecasting the risk in TX in the regular framework.
The forecast challenges this week can easily be summed up by Fridays forecast Moderate risk in Oklahoma and the extension of increased risk through IL. That was our area of focus. We had the full complement of model guidance, and some experience from days prior about how difficult it is to have confidence in making good areal forecasts and then putting the probabilities in the right 3 hour time windows.
Thursday morning we awoke to a line of thunderstorms across central OK. Eastern CO had what appeared to be a cold air dam and to the east southeast appeared to be situated a deformation zone. Given the stronger deep layer shear, this small area of convection intensified an a southward moving supercell developed around 12 UTC. This cell and its previous incarnation had dropped a bunch of hail (drifts near Blanchard, and larger hail with the supercell).
I couldnt stop watching the news, maybe because I want to see these dedicated rescuers have a small victory by finding survivors. Especially at these schools. Schools. We don’t know if these estimates are accurate. [Update: They were not.] We can only hope that some of these families find their loved ones amidst this chaos.
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So you think you can forecast?
The atmosphere always has a surprise in store. After much debate about the goodness of the previous days crazy heat burst forecast and the subsequent realization that one occurred in Madison WI, we had some good discussion about what makes a good forecast. These issues always arise. Define good? Is there really one metric that just sums it up? What do people expect from the forecast? Does the forecast add value? Add value relative to what?
This was a #seetext kind of day. It was hard to get folks motivated, myself included. This was due to many factors including supercomputer issues and a whole lot of uncertainty in whether storms would form in areas with decent moisture and shear. But after a bit of digging into the maps a few areas presented themselves, including NE and IA into WI, and south Texas. After a bit of debate we decided to tackle the interesting situation along the front and remnant convection in IA and WI.
Unlike Dorothy and Toto we were whisked away to Montana … far from climatology for this time of year.
Efforts centered on diagnosing how this low CAPE low moisture environment would yield severe storms and if those storms did indeed arise if they would be severe. The shear was plentiful and the mountains, and accompanying upslope flow, appeared sufficient and necessary for storms across ID and OR. Montana was its own temptation and indeed I have been thinking all day about model cancer given the robustness of model storms there. Multiple lines of what appeared to be squall lines with UH tracks were present.
Well the end of the first week was pretty tough. I think we almost have all the bugs out of the system, managed to pull off a live-blog on Thursday and now here we are with a weekly summary. We managed to learn a few things relating to our goals already, and some of them will not surprise you.