J Gontesky
EF0
I've written up my thoughts in a sort of Post Mortem on this storm and posted them to my blog and will cross-post them here. I'm trying to do better at assessing my failed forecasts to learn from them rather than skip right on to the next event. I've focused all along on the impact this storm would have on the Kansas City area and surrounding communties and continue to in this post-analysis.
In most respects*, this was one blown forecast for this area. The much-anticipated spring snowstorm never materialized for the Kansas City region with only a dusting to two inches falling across the area. To the credit of forecasters across the region, this was a particularly difficult forecast from the start, with a strong low and models that were all over the place. The low was slated to undergo several transition periods, which it did in fact do, just not quite as forecast. Most notably, the surge of warm, dry air that intruded in the middle layers of the atmosphere during the daylight hours Monday was stronger and more pronounced than any of the models had anticipated, right up until the RUC picked up on it only about 3-6 hours out. This dry slot was beautifully visible in the 24-hour water vapor loop. By that time, the seeds for a bust had been sewn: the forecast was out there, the snow had shut off, and the damage had (or hadn’t, depending on how you look at it) been done.
Secondly, the movement – the speed and the track – of the upper level low through KS did not come to fruition as anticipated. In both aspects, the models were not far off, but off by just enough to matter. As others have mentioned in previous posts as this event was ongoing, in terms of speed, the upper level low stalled out in SW KS for about 6 hours midday Monday; a seemingly minor detail that was not anticipated by the GFS or NAM (even the RUC didn't grab ahold of this stall until the low started inching NE again!). The GFS was the first to hint at this stall in its morning run, but even then it late in the game. Hindsight shows that this slowdown, while only barely indicated by the GFS, was a detail that should have served as a hint of what was to come. In analyzing model run after model run, as I did with this system, I normally pride myself in having a good grasp on the trend, the run-to-run changes. But in this case, it is clear that this trend was not given its proper recognition. The trend was nothing new either: even going back 5-7 days when the storm system first came into the sights of the models, it was progged to be a Sunday/Monday event – a full 24-36 hours earlier than what would eventually verify. Not only did this slowdown displace a good deal of the moisture westward and northward, it also served to zap the dynamics, using up the lift in a dry atmosphere through the NE KS, NW MO area, thus further decreasing the significant snowfall potential for this area.
By the time the upper level low started moving again late in the afternoon Monday, it tracked slightly farther north than had been anticipated, placing the highest snowfall totals north of the KC area, in a swath from north-central KS through SC and EC Nebraska and even into Central IA. Widespread reports of 25â€+ were common through central NE, forcing the closure of hundreds of miles of I-80, not to mention the closures of schools, businesses, and the rest of the usual impacts a massive snowstorm of this scale will bring.
*: One aspect of this storm that verified relatively well was the QPF: Here in NE KS, a total of 1.13†of liquid equivalent fell between Sunday morning and Tuesday morning. As early as Thursday, significant precipitation was forecast, with a 1-1.5†QPF forecast several days out. While this isn’t the headline making news (in fact, this aspect has gotten virtually no media attention through Tuesday morning), it is certainly a headline with respect to the looming drought for this region. Additionally, as hinted at by the forecasts, some borderline-convective sleet showers did verify yesterday afternoon, dropping a 1-2 tenths of an inch of sleet at a time in a series of short, pronounced bursts each lasting 4-6 minutes. Over 0.4†of liquid equivalent was received in a relatively short window Monday afternoon (~2-5pm) which included several of these bursts.
In most respects*, this was one blown forecast for this area. The much-anticipated spring snowstorm never materialized for the Kansas City region with only a dusting to two inches falling across the area. To the credit of forecasters across the region, this was a particularly difficult forecast from the start, with a strong low and models that were all over the place. The low was slated to undergo several transition periods, which it did in fact do, just not quite as forecast. Most notably, the surge of warm, dry air that intruded in the middle layers of the atmosphere during the daylight hours Monday was stronger and more pronounced than any of the models had anticipated, right up until the RUC picked up on it only about 3-6 hours out. This dry slot was beautifully visible in the 24-hour water vapor loop. By that time, the seeds for a bust had been sewn: the forecast was out there, the snow had shut off, and the damage had (or hadn’t, depending on how you look at it) been done.
Secondly, the movement – the speed and the track – of the upper level low through KS did not come to fruition as anticipated. In both aspects, the models were not far off, but off by just enough to matter. As others have mentioned in previous posts as this event was ongoing, in terms of speed, the upper level low stalled out in SW KS for about 6 hours midday Monday; a seemingly minor detail that was not anticipated by the GFS or NAM (even the RUC didn't grab ahold of this stall until the low started inching NE again!). The GFS was the first to hint at this stall in its morning run, but even then it late in the game. Hindsight shows that this slowdown, while only barely indicated by the GFS, was a detail that should have served as a hint of what was to come. In analyzing model run after model run, as I did with this system, I normally pride myself in having a good grasp on the trend, the run-to-run changes. But in this case, it is clear that this trend was not given its proper recognition. The trend was nothing new either: even going back 5-7 days when the storm system first came into the sights of the models, it was progged to be a Sunday/Monday event – a full 24-36 hours earlier than what would eventually verify. Not only did this slowdown displace a good deal of the moisture westward and northward, it also served to zap the dynamics, using up the lift in a dry atmosphere through the NE KS, NW MO area, thus further decreasing the significant snowfall potential for this area.
By the time the upper level low started moving again late in the afternoon Monday, it tracked slightly farther north than had been anticipated, placing the highest snowfall totals north of the KC area, in a swath from north-central KS through SC and EC Nebraska and even into Central IA. Widespread reports of 25â€+ were common through central NE, forcing the closure of hundreds of miles of I-80, not to mention the closures of schools, businesses, and the rest of the usual impacts a massive snowstorm of this scale will bring.
*: One aspect of this storm that verified relatively well was the QPF: Here in NE KS, a total of 1.13†of liquid equivalent fell between Sunday morning and Tuesday morning. As early as Thursday, significant precipitation was forecast, with a 1-1.5†QPF forecast several days out. While this isn’t the headline making news (in fact, this aspect has gotten virtually no media attention through Tuesday morning), it is certainly a headline with respect to the looming drought for this region. Additionally, as hinted at by the forecasts, some borderline-convective sleet showers did verify yesterday afternoon, dropping a 1-2 tenths of an inch of sleet at a time in a series of short, pronounced bursts each lasting 4-6 minutes. Over 0.4†of liquid equivalent was received in a relatively short window Monday afternoon (~2-5pm) which included several of these bursts.
And our spring break is next week, so we only have three days of school and then a week off. It's pretty sweet. B) 
