|Wednesday, April 28, 2010 - 12:24AM CDT
4/29-31 forecast update
With both the 00z NAM and GFS models in now, I feel it's safe to make some new predictions on how the upcoming few days may go chase-wise. The chances for a Plains trip on Thursday have without question dropped significantly. For the Kansas dryline play, instability is shown as much weaker, capping stronger, low-level wind fields not as backed (less convergence) and precip not breaking out until well after dark. Those are some pretty serious negatives considering that the target area is roughly 8 to 10 hours away from St. Louis, and that's without adding Friday to the picture. Friday looks like a potential event much closer to home, around the MO/KS border eastward into the lower Midwest. On Friday, convection is shown widespread; upper winds are great; lower level winds are not awesome, but doable; and moisture will be in place. It's hard to look at what Thursday's setup has become and get excited about driving that far, only to have to jump back east for something close to home the next day. Saturday may bring a possible play in southern Missouri and northeastern Arkansas.
Again, we're dealing with models - but at this point we're only two days out. With two major models in agreement this late in the game, confidence in what they're showing for Thursday is fairly high. As always, I'll be on standby for a run westward if things change before then, but now I'm thinking more of passing on Thursday in favor of Friday and beyond in the Midwest.
In the week following this one, the GFS and Euro have flip-flopped some, with a high-latitude western trough/zonal flow pattern that will be too far north for good Plains observing if it happens as depicted. As such, lower chase probabilities for next week. After that, I see no consistent pattern that would warrant anything other than a 50/50 chance of observing beyond May 10th. This table's percentages reflect expeditions that include trips to the Great Plains, so a Midwest-only trip is 'off the radar' here.
|2010 Storm Expeditions - Probabilities as of April 28|
|April 28-May 4||50%|