I. Another quiet, pleasant mid-summer day is on tap thanks to high pressure. Though very warm, humidity will remain low today. We should add another 90 degree day to the books later this afternoon.
II. A cold front will move into the Ohio Valley Wednesday and we expect a couple of lines of thunderstorms to move across central Indiana during the day. The first line will likely be in a weakening state as it approaches central Indiana around lunchtime tomorrow, however, we expect a second line of showers and t-storms to move through the heart of the state tomorrow evening.
The Storm Prediction Center includes northwest IN in a ‘Slight’ risk of severe weather Wednesday.
III. While dry conditions (and cooler temperatures) will return here for late week and into the first half of the weekend, all eyes by this time will be centered on soon-to-be Barry. Conditions still seem favorable (sea surface temperatures and upper level wind environment) for a disturbance currently over SW GA to strengthen into a named tropical system over the northern Gulf over the next 24-48 hours.
While confidence remains low concerning potential inland impacts from the eventual remnants of Barry (always the case with tropical systems), there seems to be an opportunity for two paths as of now.
“Path A” would essentially be a scenario where Barry gets trapped under an upper level ridge to the north, resulting in raining himself out over Texas next week. “Path B” would curl Barry north and northeast into the OHV, spreading a swath of heavy tropical rains well inland. Stay tuned.
IV. The other headliner will be a return of significant heat next week. While Barry may (or may not) have a say in cooling us down late next week, there will be a renewed stretch of 90 degree warmth that develops Sunday into at least the middle of next week. Longer range data continues to trend hotter and we’ll have a look at the updated European Weeklies later today or Wednesday.
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…