Nice Start to Weekend Turns Active and Continues into Next Week

A major cool shot has gripped the Ohio Valley Thursday night through Saturday morning with temperatures in the night falling into the mid 30s to low 40s with highs struggling to reach the low and mid 60s. Add a bit of a breeze and clouds, it felt down right cool. Heading into mid September more and more days will take on the look of what most of the area experienced Friday but at the same time the fall season is young, so sunshine and a few 80s can still occur.

Active energy streaming from Canada into the Lakes Keeps Weather Active; Courtesy of NCEP

As the fall progresses into winter the jet stream becomes much more of a player on the weather field. In the summer the jet stream often sets up a home over southern Canada and the far northern reaches of the United States but as Autumn deepens, solar insolation decreases, and cold air pools grow southward the jet stream follows suit. This weekend and next week will be a prime example of this such thing. Saturday will feature some sun and dry conditions but by late Sunday afternoon clouds and showers will be heading for the region and continue into Monday. By Monday evening dry weather returns for a day before another ripple of energy rotates in late Tuesday into Wednesday. Just to add a sticking point to this Thursday appears dry but by Friday a third piece of energy rotates in and a chance of showers will be back in the forecast. This is exactly what you get when colder air and a more active jet begins to take a hold on the pattern.

A bit more on the weekend temperatures for Saturday should climb into the upper 60s to low 70s on subtle east winds and partly sunny skies. Overnight lows with a bit of added cloud cover will prevent the temperatures from dropping into the 30s but mid 40s to low 50s will be common place. For Sunday the classic Ohio Valley split will be in place. By as early as predawn Sunday a few showers and thunderstorms are possible over the western reaches while the eastern reaches wake up to mostly sunny skies. As the day progresses clouds will increase and lower from west to east and by sunset on Sunday the entire region runs a risk of seeing a few showers. Temperatures on Sunday should be a couple of degrees warmer thanks to a south wind funneling in moisture. Sunday’s threat is not expected to be widespread and continuous but if you have outdoor plans, especially over southern and southwest Indiana and western Kentucky keep an eye to the sky. As the school and work week kick off Monday, showers and a few thunderstorms will continue to be in the area for most of the day. Temperatures will remain mild with low and middle 70s for highs and lows starting off generally in the upper 50s to middle 60s.

Some questions have been asked if this is normal for September across the Ohio Valley region and my answer to that question is “No.” In general September is a very sunny and mild month but this September has been anything but normal. After a torrid start with middle 90s to lower 100s in less than 48 hours many areas saw 35 to 45 degree drops. So we started off the month in an unusual fashion. Take also into the equation the frequency of systems darting through the country and providing some rain threats for our area. Again, something that is not typical for September. Then to add just for good measure, a few days of September have been perfectly normal.

Potential Next Weekend for Another Cut Off Low Sitting Across the Midwest; Courtesy of NCEP

Taking a glance into the following weekend, some models are beginning to show another upper level low transitioning into a cut off from the main jet stream. The low starts off in the Missouri Valley, drifts it into the far southwest Ohio Valley before pushing south towards the Gulf. Features like this are hard to pin down a week in advance but the very fact we have had a couple of these systems develop over the last few weeks the chances that something similar to this will be around for next weekend. Bottom line in all of this the continued active pattern with frequent storms and generally below level temperatures.

Briefly to the tropics, nothing is imminent right now but there is mischief out off the southeast Coast that can slowly develop into a disturbance. This is not suggesting a storm will develop but with troughing over the Ohio Valley and up into southeastern Canada with subtle ridging beneath the trough, often times a system can slowly develop from a washed out cold front or on the southwestern edge of a remnant trough. We are getting to that time of year so one must at least keep an eye on that possible scenario.

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By Weather Specialist Josh Ketchen