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.

6 P.M. Monday 6/6

Storm cluster weakening

Satellite, radar and lightning data all have shown a rapid decrease in storm intensity in the northern half of the convective system moving across the region.  A couple of severe storms could still pop over far southern KY, but the rest of us will receive a good soaking this evening.

Friday, Jan. 28, 2022  5 P.M.

Heaviest snow showers locally have been over the western three-fourths of Jefferson Co. KY.  Both SDF and LOU have reported heavy snow much of the past hour.  In IN, Floyd and Harrison Co. seem to have picked up some quick accumulations.

Heaviest snow between 5 -6 P.M. will move into Bullitt Co. and Spencer Co.  Jefferson County (especially the southern half) will continue to see moderate to heavy snow showers.

Noon  Wed. Jan. 19, 2022

The GFS still has about a half inch of snow for us (Louisville area) while four other models now agree than any significant snow will once again fall over central KY.  Looks like the area from Bowling Green to Lexington to Ashland is in for another 4″+.

More later.

Substantial Snowfall possible

Wed., Jan. 12, 2022  4:30 P.M.

GFS forecast this morning generates 8+ inches of snow for Louisville from late Saturday through Sunday.  Other models have wide-ranging solutions to a developing storm over the region – from mostly rain to rain/snow mix to just a little snow.

With many complexities working into various model’s ideas, it’s far too early to know how this system will ultimately come together.  But it will be fun watching the next few days as various ideas come and go.  The model BLEND (a combination of many U.S. models with others from Canada, Europe and Australia) currently predicts 2.5 to 3″ from this system.  BUT, the same model predicts ZERO measurable precipitation during that time.  See how confusing this stuff can get?

Meanwhile, as we move on, more and more clarity should come into view.  At least I hope so.  Personally I’m hoping the GFS comes through – as it often does.

La Nina

As mentioned a week or so back, the “unloading” of cold arctic air from Canada is well underway.  As usual in La Nina winters, the bulk of the cold air has moved far more east than south,  We’ve seem some below normal temperatures, but our neighbors over the Great Lakes and northeastern states have seem some really cold weather.  This trend is showing signs of lasting another two weeks or so.  But the warm part of La Nina should return in February.

Stuff

In Gainesville, Georgia, it is illegal to eat fried chicken with a fork.

4:30 P.M., Wed. Feb.17, 2021

Heavy snow stays south and east of Louisville

The latest winter storm to come our way just can’t seem to get its act together.  Sure, there’s energy aloft and moisture available, but all the ingredients for heavy snow here are just not lining up.  Along and south of a line from Bowling Green to Lexington to Morehead, snow accumulations of 4″-6″ or more are likely.

But, we’ll be on the northern fringe of the system where the upglide (lifting motions) will be weak.  The Louisville area will get 1″-3″ of new snow.  That should break down to about 2″-3″ from Louisville into our bordering counties south and east.  Southern Indiana will have a diminishing trend from the Ohio River north and west.  Starting at about 1″-2″ near the river and dropping off to near zero 30-40 miles away from the river.

Light snow will continue tomorrow morning before fading away during the afternoon.  Little or no additional accumulation.

Stuff:

I found this little tidbit really amazing…

British mathematician Kit Yates has calculated that the estimated 2 quintillion coronavirus particles floating around the world would fit inside a single Coke can.