As we look ahead to Halloween, the pattern continues to look mighty “interesting” to say the least. A deeply negative EPO (East Pacific Oscillation) will take the drivers seat and potentially lead to some early wintry “fun and games” as we close out the month and head into early November.
Ensemble data, centered on Halloween, is in excellent agreement with respect to the overall upper air pattern. That said there are subtle differences in the handling of the southeast ridge.
These seemingly subtle differences at 500mb can mean a world of difference in terms of the resulting weather we deal with here at the surface.
We’re confident there will be a rather significant weather event on or around Halloween, but caution we’re far from being able to provide details around the specifics. The early thinking is that a storm system provides a round of showers and thunderstorms just before the holiday with sharply colder conditions pouring into the area on Halloween, itself, with the threat of the first lake effect snow outbreak of the year heading into next weekend. Stay tuned. Run-to-run differences within the operational suites will be significant in the days ahead. It’s far too early to latch on to any one particular solution.
Regardless, with high latitude blocking in place, a colder than average period of weather is likely as we move through early November. The brunt of the cold, relative to normal, should be featured across the central Plains.
More on the longer range November pattern in the days ahead. Our official November Outlook will be posted over the weekend.
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…
II. Another push of unseasonably cold air will pour south into the region behind this storm system and set the stage for a potentially interesting time of things when a new storm system approaches a bit later in the week…
III. A very complex storm system will impact the area Thursday. While there are many details that are yet to be worked out, someone across the mid-south into the Ohio Valley will likely get a “plowable” snow out of this event. Initially, available cold air will be marginal, but with an expected strong upper level low, this storm system is likely to “manufacture” its’ own cold air and result in a swath of heavy, wet snow to the north and northwest of where the upper low tracks. Stay tuned.
Behind this storm, you guessed it- cold air will reinforce itself across the region heading into next weekend!