Sunday, June 11, 2023 5:30 P.M.

The Kentucky part of our area is under a Severe Thunderstorm Watch until 11 P.M. Should it be?

The original Watch issued by the Storm Prediction Center did not include the Louisville area. The original watch’s northern boundary covered pretty much of the southern half of the commonwealth. It’s pretty marginal, but a couple of isolated severe storms could hit southern KY this evening, especially near the Tennessee border.

Meanwhile, the Louisville office decided to include numerous counties in northern KY to the original Watch. Bad decision. Radar trends and model forecast trends continue show no threat of severe storms within at least 50 to 75 miles of the Ohio River. The local office invented a risk that doesn’t exist.

3:45 P.M. Wed. April 5, 2023

It appears the Storm Prediction Center is catching on to the reality of the current system over the central U.S. For 6- 8 hours they had Tornado Watches covering a vast area from Louisiana to Michigan. As of this time the number of tornadoes reported has been 0. There have been about 50 severe storm reports scattered throughout that area.

The most recent Watches covering the situation have been downgraded to Severe Thunderstorm and even that may be stretching it a bit. As mentioned earlier today, the thunderstorm line is moving into a less favorable environment, so I wouldn’t expect much, if any, severe weather this evening. Computer models continue to weaken the system for the next few hours.

Between 4 and 5 p.m. a weakening line of showers will spread northeast along the Ohio River near Louisville. Most of this activity will be over southern Indiana, but parts of northern Jefferson County could get some rain as well.

The main line of storms should push across the metro area between 5 and 6 p.m. Heavy downpours are likely as well as strong gusty winds. An isolated severe storm warning is possible, but not likely.

Wed, April 5, 2023 Noon

Severe Storms Center is paying a lot of attention to today’s situation. At Noon, they have Tornado Watches in a solid line from Louisiana to Michigan. Right now, conditions are ripe hundreds of miles to our west.

But, this is a dying weather system spawning the current storms. As weather patterns ease during the afternoon, strong/severe storms should have a harder time forming. As the cold front slowly moves eastward this afternoon/evening, it will be losing it’s supporting wind field and instability.

As a result, severe storms should become more isolated along the front as the threat diminishes. The primary line of thunderstorms is expected to move through Louisville metro between 5 and 7 P.M.

5 P.M. Monday, Jan. 30, 2023

General situation shows a large cold air mass over the midwest slowly dropping southward. Temperatures today have been slowly falling and will continue tonight as temperatures drop into the upper 20’s by morning. Meanwhile, a small upper level disturbance in the jet stream flow will move rapidly ENE over the area tonight. It’s not much of a system, but it does have enough moisture to bring us some icy weather tonight.

That’s where the forecast trouble starts. The lower atmosphere (up to 5,000 feet) is definitely cold enough to support an inch or two of snow overnight along the Ohio River. But, it’s not that simple.

There’s a pocket of slightly above freezing air roughly between 5,000 and 10,000 feet above us. That will be slowly cooling overnight but should still stay slightly above 32 degrees. That’s the fly in the ointment.

The primary consequence will be that some of the snow falling through this warm layer will melt, then refreeze into sleet before hitting the ground. That sets up a very subtle balancing act between snow and sleet for our overnight entertainment.

In general, the whole atmospheric column will be slowly cooling, so snow becomes the most likely result as time goes on. The onset is trickier. Everything depends upon just how thick that warmer air is and how much cooling it will get from evaporation of precipitation aloft.

The models are consistant on two things. First, the amount of moisture falling will be small. Probably between .1″ and .2″ of water. That would be a 1″-2″ snowfall but only about a quarter-inch of sleet. Second, the location of the maximum precipitation will be about roughly 30 miles north and south of the Ohio River.

After putting all those variables into a big pot and letting them simmer, here’s what I think will happen tonight. Precipitation should begin around 8 P.M. in Louisville. At first, it’ll be mostly sleet with a little snow mixed in. As the night goes on, the mix will gradually change to mostly snow with a little sleet mixed in. Any significant snow/sleet will end by 3-4 A.M. The Louisville area should end up with a snow/sleet total of up to one inch.

North of Louisville snow totals could get up to 1″-2″. South of Louisville will see a snow/sleet accumulation up to one-half inch.

By morning rush hour, treated roads should be in fairly good shape with icy spots. Meanwhile, non-treated roads should be mostly snow/ice covered.

Mon. Jan.30, 2023 12:30 P.M.

Forecast models are all over the place with tonight’s forecast. However. it now appears that we’ll see an accumulation of snow tonight. At this point it looks like an accumulation of about 1″ – 2″ around the Louisville metro area with slightly higher totals over southern Indiana.

If that pans out, school kids could see a free day tomorrow. However, as pointed out above, forecast models are unusually scattered for an event so near in time.

More later…there’s a lot to digest.

Today’s models can’t seem to agree on snow tonight, but rain is a sure bet.

First, a note on Sunday’s snowfall. Sunday’s weather events gave yet another reason why weather is so fascinating. Both the event itself and the (lack of) forecasting it. Rain was the models’ choice while also giving hints that there could be some snow at the start. But nothing like the 1″+ we had around the county. And that’s about the only place snow fell.

As the rain moved in, a sudden intensification of the precipation brought colder temperatures AND snow into Jefferson County and almost nowhere else.

Weather can be so much fun!

Tonight

Meanwhile, tonight’s system will be much stronger and almost all signs point to rain. This morning, the GFS was the only model predicting snow at the start with a quick change to rain. Now, other models are drawing closer to the snow start followed by rain. Temperatures with this system are about 3-5 degrees warmer than Sunday’s, so if any snow falls, it’ll melt quickly.

Snow and/or rain should begin around Midnight or shortly after. By 2-3A.M. any chance for snow will be gone. After that, periods of rain will continue during the morning then fade away by late afternoon. Winds will pick up during the afternoon with gusts probably topping 35 mph.

Snow flurries will be likely tomorrow night and Thursday.

Stuff:

The northernmost point of Brazil is closer to Canada than it is to the southernmost point of Brazil.

11 P.M. UPDATE

Now looks like an hour or two of snow/sleet will be mixed in with the onset of rain around daybreak. Any minor accumulations on grassy areas will fade away during the morning.