COLD AIR BACKING OFF
The polar branch of the jet stream has retreated and a warm up is underway entering the end of the workweek. Temperatures late Thursday have jumped nearly 20-degrees since early morning lows in the teens.
The storm-track has moved north allowing the air to become more mild with the low pressure tracking into southern lower Michigan, we are moving away from the arctic air. Snowfall potential shifts north for now along and north of the low that is tracking along the polar jet stream.
MILDER DOESN'T MEAN NO SNOW
As the cold, polar branch jet stream retreats the more moist, southern branch will migrate north. This connection to a more rich resource of moisture will aid in clouds and even some rain chances here as early as Friday evening. A few spotty showers may migrate into south and southeast Indiana late day.
The southern and northern jet stream split often leads to an overall trend to milder temperatures but it also creates some problems for sophisticated computer model forecasts in the medium and longer range.
A split flow implies that the two are separate jet streams. From time to time these two can merge or marry and create a more formidable storm system. There is some speculation that moving forward, the arctic air looming in the upper Midwest could get pulled down.
For instance, Saturday's system while fueled by southern stream energy, could mix the colder air and some northern stream energy to create a period of light snow or snow showers by evening.
Next week, the scenario is becoming more interesting as the overnight computer models are still trying to resolve what to do with a system Monday and Tuesday.
Once again the two jet streams are split, so there is still quite the spread in solutions, but the trend is there for something more organized. Sounds vague and it is, but it warrants close watch.
Are you hopeful for some snow? Are you a "snopeful" kind of person? I know they're out there and are pining for a snow. Sure adds to the seasonal feel but snow has been lacking again this December as well as the past five Decembers. We've had five straight December's with less than 5" of snow. We average 6.9" of snow in December and so far this month, a mere trace.
For those of you waiting on some snow, the outlook is not entirely bleak, especially given the set-up entering the weekend and much of next week. We will hawk over the data and keep you in the "snow" as to when those chances will rise!