Chris's Corner - Heading into Fall

Now we get to our main focus: the Arctic cold outbreak for early to middle next week. There is becoming strong confidence on this event per the gefs mean with relatively low spread among the individual members. A classic cold outbreak setup with the upper longwave trough axis retrograding westward into the plains late this weekend and then deepening into the MS and Ohio River valleys for early next week. This will be coincident with a 1050mb area of high pressure at the surface driving southeastward into our region beginning on Sunday night and lingering (albeit with some modification of the airmass) into Wednesday.

Monday through Wednesday look really cold--about 25 to 30 degrees below normal--where many areas may not get above freezing for all three of these days! Early morning min temperatures look to be in the teens, possibly single digits in spots. All of these values are supported well by gefs ensemble members with relatively low spread. When factoring in the winds, wind chills may dip below zero, particularly during the early morning hours. Quantifying all of this, if realized, it will be the first time since 1991 that we have seen an airmass this cold in the first half of November, nearly 30 years. (1991 was the last time stl and cou saw 3 consecutive days of below freezing Max temps in the first half of november)