Plains storm chase forecast update No. 6: for April 16
Signals are showing in long-range models (GFS and Euro) for both a dominant western troughing pattern and in-place deep surface moisture to finally emerge by next week. This system, if it materializes as shown, would be worthy of the first Great Plains expedition(s) of the season. As the larger trough sits out west, it would be poised to send several "shortwave" impulses across the Plains, each which has the potential to produce an outbreak-type scenario.
GFS model 500mb winds forecast for Saturday, April 23
The only caveat I've noticed is for the tendency of the first incoming shortwave to fail to really "dig" southward, instead dealing a glancing blow to the southern Plains. That being said, at worst we'd be looking at a spatially smaller event biased more toward Nebraska. Even so, the general western troughing pattern is shown to persist afterward, "loading up" to send more impulses across the Plains. It's definitely a pattern that storm chasers like to see.
These new model forecasts have me fairly optimistic that the first Plains expedition will happen before the end of April. As with all model forecasts a week out, changes either good and bad are inevitable in future runs. However, consistency and agreement are on our side right now.
It turns out that the less-than-favorable system that is swinging through the Great Plains right now nonetheless produced a series of photogenic tornadoes in Colorado and the Oklahoma panhandle. I don't necessarily regret not chasing that one, as relatively few systems of this caliber will produce. I go on chase trips purely based on systems that show a high probability of seeing tornadoes. The lower-probability systems sometimes will produce, but one must chase a large number of them before you get one like Friday. I get my fill of the lower-probability systems right here at home in the Midwest year-round.
The following table charts the probability of a Great Plains chase expedition happening during several indicated date ranges in the near future:
|2016 Plains Chase Expeditions - Probabilities as of April 16|