Category Archives: forecast

Rainy Sunday

Saturday, Jan.21, 2023 6 P.M.

I’ve been watching the models’ handling of the next two storms headed our way. Both have been indicating a cold rain for tomorrow and for Tuesday night/Wednesday. The second on will be much stronger (for us).

Yesterday, words like snow, sleet and freezing rain started entering the forecast. A deeper dive into the weather data made me believe those words shouldn’t be there. The atmospheric setup just isn’t cold enough.

A storm developing over Texas tonight will advance ENE over the Gulf Coastal states tonight and tomorrow before turning up the Atlantic Coast tomorrow night. With the storm staying so far to our south, we’ll be on the northern fringes, so rain totals will be on the light side.

Models agree that the rain/snow line will be at least 30 miles north of the Ohio River. So, don’t be surprised if we see a little wet snow mix in from time to time. Basically, though, we’re expecting just a cold, rainy morning. Then rain will slide eastward by early afternoon.

Models also point to another (mostly) rain event by midweek, so snow lovers are probably in for another disappointment with that system.

Meanwhile, global models are pointing toward below normal temperatures here for the next week or two. So, we’ll see additional snow chances ahead.

Snowy, blustery night ahead

Thursday, Dec. 22, 2022  5 P.M.

The action begins this evening

If you’ve followed this blog recently,  you’ve heard about how very slow changes in the atmosphere can add up over time.  Also, we’re seeing today how these little changes can take you away from the original “solution” only to move back to the original forecast before the storm arrives.  Such as the evolution of the snow amount forecast from last week until today.

Last week, the early indications were for about 2″ to 4″ from the system arriving now.  By early this week the forecast for snow was down to about an inch or two.  Then, this morning, the forecasts started climbing. Now we’re up to about 2″-3″ for Louisville while 3″-6″ appear likely over southern Indiana.

Yesterday,  I mentioned that the changeover from rain to snow would be about an hour or two later than the previous estimate.  Too bad I didn’t think too much about that, because it seems to be the reason for the increased snowfall forecasts.  This is a developing storm.  It just recently got it’s act together and will intensify rapidly overnight. The extra time before the onset of the snow allows the storm to gather more moisture.  Little changes can make big differences.

Forecast summary

Rain this evening will change to snow around 8-9 P.M.  Winds  will increase to 20-30 mph with higher gusts overnight.  Temperatures will drop from the upper 40’s now to near zero by morning.  Louisville’s snow total from 2″ to 3″.  Areas north of the Ohio River could reach 6″ of snow.  Hazardous road conditions due to ice, snow and blowing snow.

Tomorrow will remain very cold as temperatures remain in the single digits in addition to strong winds continuing.  A mix of clouds and sunshine with flurries possible.

Christmas Eve and Christmas will remain quite cold.   High Saturday about 15 and 20 on Sunday.  Skies should be sunny to partly cloudy.

Merry Christmas!

Enjoy Saturnalia


Cold air, snow arrive tomorrow night

Wed., Dec.21, 2022

Little change from yesterday.  Based on the latest model runs, only a few minor tweaks are needed.

Some light showers will develop tomorrow morning.  Southerly winds will warm us to the upper 40’s by mid afternoon.  More rain should arrive by late afternoon.  It appears the rain to snow changeover will be an hour or two later (8 to 9 P.M.).  Then temperatures drop about 20 degrees in two hours as stronger winds bring in the colder air.  Any appreciable snow should be over by Midnight to 1 A.M.

Snow accumulation stills looks to me to be 1″ to 2″.  But the models are trending lower.

Biggest concern is still the cold/wind.  Temperatures should drop to the low single digits by Friday morning then stay in the single digits all day.  Saturday should reach the mid teens and Christmas  will get all the way up to near 20.

Very Cold Air Still On The Way

Tuesday, Dec. 20, 2022

Little change in the forecast since yesterday’s post.  The Super Christmas Storm of ’22 is still expected, but primary effects will cover the north central states from Colorado to northern Missouri to near Chicago.  The cold air behind the storm center will produce heavy lake effect snows across the Great Lakes Friday and Christmas Eve.

That part of the storm will make a lot of news through the weekend.  But, the main action will stay hundreds of miles away from us.  Nevertheless, we will not be spared from the storm entirely.  Rain will develop Thursday with temperatures in the 40’s.  The cold air sweeps rapidly into the area during the evening  (7 to 10 P.M. ?) as the rain changes to snow  for an hour or two.  An inch or two of snow is expected.

After Midnight, strong winds will be howling through the area over night…slowly diminishing Friday.  In addition, snow showers/flurries during the day could add an additional inch to our snow total.  The temperstures will slowly moderate through the weekend.  Friday’s high should be in the high single numbers rising to the mid teens Saturday and around 20 on Christmas.

Very Cold for Christmas Weekend

Snow should be on the light side

Dec.19, 2022  4:30 P.M.

When I started forecasting weather for the Louisville area in 1969, I had one major point of emphasis about weather forecasting:  Don’t ever believe a weather forecast for more than 3 days ahead.  Weather forecasting has improved significantly since then, so,maybe, that could be extended by a day or two.  But the point is, we do not have perfect forecast models.  Nor can we measure weather parameters – humidity, temperature, winds, etc – precisely.  And, to make matters worse, when we measure our weather data, it’s at random spots on the Earth.  Forecast models are set to run on a precise computer grid.  The data is seldom measured at the grid points, so sophisticated smoothing systems have  been created to fit the data to the grid.

Thus, before forecast models even begin computing, we have three significant areas of known error sources within the system.  I am amazed at how well the longer range forecast models perform…most of the time.  But as good as the modern models are, they are not perfect!

So why do professional forecasters continue to believe them?   Why so much hype 7 to 10 days before an event is due to happen?

I can’t answer those questions, even after 50 years of trying.

This week

We are currently in one of those major “hype” situations.  The major outbreak of arctic air set to arrive Thursday night has been predicted to arrive “in 7-10 days” since before Thanksgiving.  So after many misfires it’s actually going to happen.  Since last week, the models have been predicting some pretty dire weather for much of the nation east of the Rockies.  The local outlook was for 4″-6″ of snow, very strong winds and a possible flash freeze in addition to frigid temperatures.  Keep in mind, this forecast was for at least 7 days ahead,

No matter!  The hype machine jumped into full gear.  By the weekend all the talk centered around a massive pre-Christmas storm of legendary proportions right here in Louisville.  But, as should be expected, the forecast models slowly made “adjustments” to the forecast.  Those incremental changes have greatly altered the forecast and possible consequences for us.  Even the most extravagent hypists should have it figured out by now.

This being Monday and the actual event is likely Thursday night, I expect more changes to occur during the days ahead.  Nevertheless, here’s what I’m currently expecting later this week:

Slowing warming temperatures tomorrow through Thursday midday.  Rain should move in Thursday afternoon and change over to snow Thursday evening.  Snow will last 2-3 hours with accumulations around 1″ – 2″.  Very windy, with temperatures dropping into the single digits by Friday morning.  Friday remains cloudy, windy and cold with snow showers and flurries.  Additional accumulation up to an inch.  Temperatures will reach only the lower teens.

Note: the possibility of a Flash freeze Thursday is much lower now than earlier thought.

Severe storm chance very low this evening

Possible severe storms stay north of Louisville

Wed. June 8, 2022 5 P.M.

Storm Prediction Center did a good job of narrowing in on the severe storm threat area over southcentral and southeast Indiana.  However, they pushed their Tornado Watch box too far south.  Or did they?  More on that later,

Back to the current weather, the primary factors for severe storms have already moved east of I-65, so damaging weather threat is generally over for the Louisville area.  However, a weak wind shift line/cold front is trying to form over southern Indiana.  That will give us about a 30% chance for a thunderstorm around 7-8 P.M. tonight.  Then a little cooler, but much drier day tomorrow.

Tornado Watch?

As mentioned above the Storm Prediction Center pinpointed the severe threat today very well.  In fact the boundaries for the Watch they issued did not include extreme southern Indiana or  metro Louisville.  Their southern boundary was about 40 miles NORTH of the Ohio River near Louisville, where it should have been.

So what happened?  In recent years local Weather Service offices have been given the leeway to “alter” the SPC Watches.  So today they decided to change the prediction to include the Louisville area.  Seems to me we saw another case of CYA this afternoon.

To the uninitiated, CYA is a long-running acronym for “Cover Your A–”

Good job SPC!  Not so good, locals.

Widespread severe storm outbreak this evening/tonight

Biggest part of damaging weather will stay south of Louisville

Wed., April 13, 2022  4:30 P.M.

The atmosphere  is set to produce a significant severe weather outbreak over the next 6 hours, or so.  Wind fields are very strong (more so than usual).  The moisture/heat component is high enough locally, but remains much more conducive to severe weather several hundred miles south of here.  The Storm Prediction Center is highlighting the northern half of Alabama, western half of Tennessee and the southwestern corner of Kentucky as the area of highest risk of the “big three” severe storm events – hail, high winds and tornadoes.  Tornado Watches cover most of that area at this time.

While locally, we’re not in nature’s “bulls eye” but we are still under some risk, especially for strong wind gusts.  A squall line/cold front will quickly cross the area this evening.  Our highest threat for severe storms here will be between 8 P.M. and 10 P.M.  Thunderstorms should produce strong to severe winds and heavy downpours.  An isolated “spin-up”  tornado or two will be possible, especially south of Louisville.  Note:  Spin-ups tornadoes sometimes occur in the area of “kinks” along the line of thunderstorms.  They usually last only a few minutes and fall on the low end of the tornado family – F0 and F1.

Even though 8 to 10 P.M. will be our highest threat time, additional thunderstorms/heavy rain will not leave the area until around Midnight.  Some minor flash flooding could occur

Quick update on tonight’s snow forecast

Friday, March 11, 2022  Noon

In reference to yesterday’s blog, as expected the NAM still seems to have the better solution.  The GFS and other models now pretty much agree with the NAM.  On the large scale picture the result should be overall less snowfall for eastern KY and the Appalachian region than previously expected.

For Louisville area, my latest idea is this.  Rain/snow arrives in Louisville area around 6-7 P.M.  Snow becomes dominate from 8 P.M. until Midnight.  Only flurries after that.  Temperatures remain around 32 degrees during the snow so major roadways will only see minor accumulations due to above freezing surface temperatures.  Snow accumulations  on grassy areas should be up to one inch in metro area with higher accumulations south/east of Louisville.  Highest accumulations (2″ – 4″) along central I-75 and east.

Mostly sunny tomorrow with high around 30, but back to near 50 by Sunday.

Winter makes a brief comeback

Thursday, March 10, 2022  6 P.M.

All week the models have been predicting a seasonably cold air mass to reach our area late tomorrow.  They were expecting a quick drop in temperatures from the 50’s during the afternoon, then dropping to near 30 by Midnight.  Meanwhile, the cold air would be able to squeeze some snow out of our relatively dry air.  Snow forecasts averaged about an inch.  Cold air would stick around Saturday with a strong warming beginning Sunday.

Then, this morning’s models started to upgrade the situation(s).  I use the plural because this morning the GFS and NAM models had two distinctly different solutions on how this situation will play out.  The primary headline is that they both end with the same large scale solution – a large spring snowstorm dropping 4″-6″ over southern  and eastern KY tomorrow night then sweep along the Appalachians with 5″-8″ of snow Saturday.

Without getting into too much explanation, while getting to the big picture the GFS paints a snowier picture for us near the Ohio River.  The GFS puts about an inch of snow for far southern Indiana.  About 40 miles either side of the river it predicts about 1″-2″ of snow.  Sliding south and east of Louisville you quickly get to 3″, then 4″+.

The NAM, on the other hand, keeps the band of heavier snows farther south of the Ohio River.  It predicts about 1″ for Louisville (lower north of the river, more south of the city).

As I’ve mentioned before, normally the GFS is a little better than the NAM.  In this case, however, I like the NAM’s solution – about an inch of snow tomorrow night from about 8 P.M. until 1 A.M.

We’ll give it another look tomorrow.

Storm updates

4:15 P.M. Thursday, Feb. 17, 2022

Better news!

Some big changes from earlier.  Wind gusts will be much weaker than previously expected.  Louisville area and Southern Indiana wind gusts will most likely stay in the 30-38 mph range.  No longer a serious damage threat here.

However, wind gusts up to 40-45 mph will still be likely until about 8 P.M. over southern and eastern KY.

Another change…the prospect for severe thunderstorms over southern KY has dropped to a very low level.

For the Louisville area, periods of heavy rain will move through the area for the next hour or two.  Rain will end over the area between 6 and 7 P.M.  Then cold weather moves in overnight.