Light snow is flying across central Indiana this evening, but “light” is the key word here. For most, a dusting is all we’ll muster with this initial wave of energy.
As we move into the first half of the weekend, a more vigorous disturbance will track across the region. We’ll notice snow breaking out across southwest Indiana around lunchtime before the area of snow grows in overall coverage and intensity through the afternoon into the evening hours.
With a cold surface and temperatures in the mid to upper 20s as the snow falls, expect slick roadways across the region Saturday afternoon into the evening. While winds aren’t expected to be particularly strong, the “open country” may experience a few issues with blowing and drifting snow due to the dry, powdery nature.
Most of central Indiana, including Indianapolis, can anticipate 1″ to 2″ of snow with this event Saturday, but there will likely be a couple of 2″+ reports. Snow will diminish from southwest to northeast after midnight.
Attention will then shift to additional snow and severe cold early next week… More on that in the AM.
Most of the concentrated rain should come to an end around dark Thursday. By that time we forecast a general 1/2″ to 1″ to fall in area rain gauges.
The basis of our late-December forecast is built from the MJO, or Madden-Julian Oscillation. We note the MJO is expected to rumble through Phase 4 before heading into Phase 5 around Christmas. Phase 4 (image 2 below) is a warm phase and correlates well to what the week ahead will provide. However, Phase 5 (image 3 below) is a colder phase and could “up the ante” for the potential of wintry weather around Christmas.
If the MJO amplitude remains, it’ll roll into Phase 6 to close the month and open January. Here’s how that would correlate in the temperature department:
The upcoming week will run milder than normal- lining up perfectly with MJO Phase 4.
The first of our targeted holiday storm systems will come at the tail end of the warm Phase 4 and will likely deliver a wind-whipped rain in here as early as Wednesday night and Thursday morning. However, as the storm pulls northeast along the Ohio River, it’ll deepen on its journey into the eastern Great Lakes region. This will help pull colder air into the region, likely resulting in rain transitioning to snow Friday. Given the path of the storm, this doesn’t favor some sort of prolonged backlash snow event, but it could be enough to result in accumulating snow across eastern Ohio Valley sections and downwind of the snow belt regions of northern IN, OH, and MI.
The pattern, as a whole, appears to be one of transition to close the month and open January and it’s not really until we get to mid-January where we think all of the drivers “align” to create more of a lock and hold cold pattern. With that said, a stormy late December pattern can present problems, even in the midst of relatively mild times. We’ll be here to dissect the storms as they come throughout the holiday season…
While this will support a 5-10 day period of temperatures of 5° to 10° above average (milder overnight lows, and a few days with highs at or above 50° are a good bet during the period, as well), the stage is already being set in motion for a return of colder conditions around the Christmas holiday. While admittedly, transitional periods can be “finicky,” there’s support from other pattern drivers behind a wintry return between the 12.22 and 12.24 time period. Furthermore, data suggests that there will be plenty of storminess to boot.
We expect the mean ridge position to set up shop over the Pacific northwest. This will result in a warmer than average regime across the west. At the same time, the trough will be pushing back into the east. As the cold air settles back in, we expect a rather active time of things during the period. This certainly doesn’t mean we’re talking snow storms, but it does appear likely that at least one or two systems of interest loom. We’ll have to deal with the challenges that will come from one or both as time draws closer.
II. Highs today will come tonight (mid-to-upper 50s) ahead of the cold front. Once the front moves through, colder air will return for the second half of the weekend. As wrap-around moisture combines with the colder air, light snow showers will develop late Sunday night into Monday morning (shown below). This won’t be a huge deal.
III. The next item of interest will come from a clipper system Thursday. This won’t only serve up another round of light snow, but also help to reinforce the unseasonably cold air. Highs will return to around freezing to close the week with lows in the 20s.
IV. That leads us to what comes next weekend. While it’s still far too early for any sort of specifics, we’ll simply say to keep a mental note in the back of your mind for the potential of a more disruptive winter event coming out from the southern Plains into the Ohio Valley. We’ll certainly have to fine tune things and “hone in” as we progress through the upcoming week. From this distance, prospects range from nothing more than a light snow to a “plowable” storm. Unlike this weekend’s storm, there will be a limit to how far north next weekend’s storm will be able to track…