We've been tracking a storm system for over a week now that threatens to bring the first blast of winter to central Kentucky this weekend. It appears that things are coming together just as predicted. A major blast of cold air is coming and temperatures will fall to the 20s by Sunday morning. Ahead of this, rain will change to snow by Saturday morning and could possibly dust a few cars and trees and Halloween decorations before it's done, especially along and east of I-75. This will be my final update on this storm. Get ready because it's about to get COLD!! I'll leave you with the latest forecast discussion from the fine folks at NWS Louisville:
Latest GFS, NAM, and ECMWF are in pretty good agreement showing an deep upper low diving SSE across the eastern OH Valley Friday night. The GFE 18z ensembles showed the trough aloft being 3 to 4 standard deviations below normal which is significant. With this system will come cold air advection and dynamic cooling aloft. The model- indicated pattern suggests possible development of a winter-like deformation band within a tight isotach (lines of constant wind speed) gradient in the left exit region of a 300 mb jet streak diving south over the lower OH Valley. In these types of patterns, a definitive mesoscale band of wintry precipitation normally occurs assuming temperatures within the moist layer and at the surface are sufficiently cold. In this system, the models suggest all this to occur, which would suggest a band of snow over the eastern half of the forecast area, especially east central KY late Friday night. Model soundings show moisture extending up to between 500 and 600 mb, and cold enough in the moist layer for ice crystal formation which would stay as mostly snow as it fell to the ground. If this verifies, then scattered rain showers during the day Friday likely would diminish or end in the evening, with a band of some snow developing late at night which would move quickly southeast and end by Saturday morning with up to an inch or so of snow possible mainly across the Bluegrass, and especially on grassy areas.
The Euro model has sort of taken on the look of the GFS that I posted last week (below). Imagine that. Low pressure near the Great Lakes may drive a sort of "back door" cold front through here Friday night and into Saturday morning with much colder air arriving. Both models take us below freezing Halloween night and into the first morning of November. The question is, will any precipitation accompany this front? It's still a little early to tell, but there remains a small chance that we could see a few snowflakes early this coming weekend, especially in eastern Kentucky.
Here are the temps and precip predicted by the European model. Notice the freezing line dropping into Kentucky by 8:00PM Halloween and then the precip shield which is depicted as getting really close to the Bluegrass that night. Interesting... just something to watch.
As we wait to see how El Nino is going to shape up for winter and what impact it may have on our temperatures and snowfall, we are currently soaking up the final nice days of the year in Kentucky. Sunshine has returned after a week or two of ICKY weather and by the weekend we’ll see the 70s for highs come back for several days…well into next week. Ahhh… enjoy it!! The leaves are peaking at this time as well, which will make for some absolutely delightful days to finish out October.