Confidence is increasing for a two-day Plains run happening next week as the first big upper trough of the spring moves through the center of the country. The basic ingredients for a typical spring tornado event should be in place: strong southwesterly flow aloft turning to south-southeasterly at the surface, deep moisture in the low levels and both a dryline and warm front region to work with. Models have been in good general agreement about the juxtaposition of these surface and upper features for Monday the 8th and Tuesday the 9th. Though this pattern is still too far in the future to start picking even general targets - or even saying with any certainty that a Plains trip is happening at all - it's good enough to start talking about.
The GFS model is moving the trough eastward faster, showing a setup in Kansas/Oklahoma on Monday, and another in Missouri/Arkansas on Tuesday. The Euro model is slower, keeping the strong upper support over the Plains for at least one more day (Wednesday). The difference between the models, as it stands now, would mean either a 2-day trip or a 3-day one.
There are a couple of potential scenarios that would work against a Plains trip. One is the potential for tornadoes in the Midwest. As I've mentioned before, any half-decent tornado risk in the Midwest region is enough to keep me here locally, even if a better tornado setup exists simultaneously in the Plains. It's fairly common for a big system to produce tornadoes both in the Midwest and in the Plains - sometimes on the same day, sometimes a day apart. With the Plains being so well covered by hundreds of expeditioners, the novelty of a Midwestern tornado all to myself is the more appealing prospect, even if the chances of success are much lower for any given event here.
The second factor is this being a mid-week event, I will need to take days off from work to make a multi-day Plains run. There is usually no need to take off work for Midwest expeditions.
Beyond the end of next week, there isn't enough consistency and agreement between models to speculate on the pattern.
The following table charts the probability of a Great Plains weather expedition for the indicated date ranges:
2013 Plains Storm Expeditions - Probabilities as of April 2
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