Saturday, March 3, 2012

From near the hot seat

I was job shadowing. I went to bed last evening after having seen the model forecasts for the outbreak. They were convincing with the usual caveats. It was a fairly large Moderate Risk but I figured that when I awoke the High Risk would be issued and it was. The environment was favorable for a significant severe event.

The whole point of job shadowing (for me) is to prepare for the upcoming Hazardous Weather Testbed Experimental Forecasting Program. We will be replicating, to some extent, the forecast process for defining the threat of severe weather probabilistically. So it is very helpful to watch the forecast team execute on big days.

The forecast environment was great for supercells. High bulk wind shear, deep and low. Storm relative helicity was, at least for the models, in a favorable range for tornadoes. Observed wind profiles from the radar (VAD) were favorable ... even at 9am when the first watch was being considered in what look liked elevated run-of-the-mill storms in an uncapped, warm advection regime. And within 20 minutes the first TOR warning was issued and within the hour the first tornado emergency went out for north of Huntsville, AL. That was the big hint of the day ... its going to be big. And the atmosphere had no plans on being subtle.

The forecast process was quickly shuffled to the team and products were being disseminated for nearly the entire shift. If it wasn't an Discussion going out it was a Watch. It wasn't stressful but I am pretty sure that it wasn't until an hour and a half before shift ended that everything that needed to be covered in a watch or MD was covered...at least for now. Even when shift ended storms that had done nothing for the last hour (no warnings and seemingly, benign severe wise, started producing tornadoes in southern AL.

We were busy doing surface analysis from AR to SC and MI to FL to keep track of the evolution of the warm sector, looking at any number of supercells producing the latest nasty looking circulation or debris ball. We watched a supercell pair wreak havoc for quite a while.

I think what was disorienting for me was that I never had a clear picture of what the radar would look like from a forecasting perspective. The scenario of supercells and line segments was evident but before I could form any conceptual model of the outbreak we had storms all over the place. It was the sheer size of the areas being considered and the ongoing nature of the threat that was distracting because I am not used to that. I am not a forecaster as much as a researcher. I simply lack that experience.

As soon as shift started Corey said to me: "Its all about boxology." meaning that today was all about planning for non-stop watch issuance (this is something I am realizing now even though I thought I understood then), planning for when and how the outbreak would start and evolve, respectively, and planning for the size of Watches so that you capture what you need to capture and give yourself time to draw up the next one in between coordination calls. And when I think about it now, that process was smooth, exacting, purposeful and skillful. They make it look easy but it takes quite a lot of experience and skill to pull that off.

The Huntsville storms were of concern only 45 minutes into shift. FYI: Famous last words always start with "I think you have at least 2 hours to get setup". That was watch 1 and within the next hour the next watch was out. Then storms started going on the dryline in MO. So that meant it was time for watch 3 to be drawn up, coordinated and issued around 1600 UTC (all times approximate). By 1730 UTC the MO storms had supercell characteristics.

The next wave hit in LA by 1830 UTC but these were not doing much but were along a cloud line feature that connected to the de-evolving threat from Huntsville area to Greer earlier. We expected this to change as the storms in MS and AL initiated seemingly anywhere north of the cloud line. So we had nearly 4 areas going strong and the next watch was out by 1930 UTC and another shortly thereafter.

It was at this point that I stopped taking copious notes. There was simply a lot to look at and keep track of, plus I ate lunch for 25 minutes. It was simply keeping tabs on all the storms, their trends, and making sure every area that needed a watch had one. Monitoring the latest observational data, peering from a far at all the supercells, and in all cases hoping that the spawned tornadoes would stay out over unpopulated land.

Keep in mind that this is a narrow perspective on that day. The outlooks were issued at 1630 and 2000 UTC, more than 13 severe weather MDs, many more winter weather MDs (I am jealous MI of your blizzard but I was blissfully unaware), and countless media calls. Shift change came about at 2200 UTC and those words were used again: "I think you are covered for a bit." And by 2220 UTC the next watch went out the door.

All told I think 6 watches with another 14 severe weather MD's went out that shift. For the convective day it was another 8 watches with another 10 MDs through the next 2 shifts. And that does not count the 2 watches from the previous evening of a long-lived supercell that started in MO and went through to IL-IN.

It was a great experience on a day where a lot of folks had a negative experience. So the stats are still coming in. Roughly 98 tornado reports (not individual tornadoes). 35 fatalities, maybe more. Whole towns are gone. Many more damaged. The damage assessment teams are out from multiple local NWS offices in which multiple teams per office are out trying to rate the tornadoes damage and estimate their strength.