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Evolution of a forecast

Heavy rain, strong winds tomorrow

6 P.M. Friday, January 10, 2020

A major storm system will move across the area tomorrow.  We’ve seen several similar systems over the past few months and the results should be about the same as the previous ones.

But, first, let’s look back at how the forecast has evolved this week.  The hype was out early – Monday I heard “potential” for 5″-7″ rains (Thursday through Saturday), major severe storms outbreak Saturday, high winds and flooding were added to the mix.

By Tuesday, the rain potential was down to 3″-5″, but all the other dire circumstances were still in play.  Wednesday, the rain potential forecast was down to 2″-3″ and rain for Thursday was out but still a 90% chance for rain Thursday night and Friday.  The bad-news vibe for Saturday was still there.   Wind gust forecast was now up to 50-55 mph.

Thursday was a nice day, but the bad news would start Thursday night – it didn’t.  But, Friday would be a rainy day setting the stage for Saturday’s deluge.  Also, the rain forecast was now down to 1″- 3″.

Friday.  The  total rain forecast is now down to 1″-1.5″.  Wind gust forecast is still calling for a few gusts to 45 mph in Louisville area.  My current forecast expects a few showers in the area until 10 P.M. followed by dry windy weather later tonight through tomorrow morning.

This is a good reminder about the scourge of hype that has infected meteorology and the media.  This is not new – there was plenty of it during the time I was working.  It just seems to be getting worse.  The same thing holds for the “climate crisis.”  There is no climate crisis.  So many dire claims; no verification.  Supposedly, in the past 30 years, or so,  42 specific “predictions” of things that would happen before 2020 have been made. So far, none of the 42 has happened.  But, I digress.

Tomorrow

Here’s what I expect tomorrow.  Partly cloudy, windy and warm in the morning.  Temperatures will reach a record high in the low to mid 70’s.  Winds will gust into the 30-40 mph range by late morning. That’s the easy part.

The GFS has the cold front/heavy rains pushing through between Noon and 4 P.M. while the NAM is four hours later.  Let’s compromise and say 2-6 P.M.  During that time heavy rain is likely.  Thunderstorms are possible, but a pretty low risk.  Wind speeds and gusts will be lower during the afternoon than they were in the morning.

After the heavy rain  moves east, winds will pick up again into the 30-40 mph gust range and temperatures drop rapidly to near 40 by Sunday morning.

Notes:  The NAM predicts the center of low pressure with this storm to move/form right over Louisville tomorrow afternoon.  The GFS hints at it.  IF that happens, you’ll notice two results.  1).  Rainfall will be less than currently predicted.  Total rainfall would probably be less than one inch.                                                                                                                                                                    2).  Winds will be weaker than expected.  Morning gusts in the 25-35 mph range.  Evening gusts in about the same range.

Either way, not to much to be worried about.

Odd

Thursday, August, 8, 2019

We’ve had some crazy pretty forecasts this summer, especially before our weather turned dry over the past six weeks.  Meanwhile, the recent dry weather has  us hoping for some needed rainfall.  And,  the National Weather Service has given us some hope for tomorrow and tomorrow night.  I just have no idea where their forecast came from!

They’ve got a 50% chance for both time periods.  The models I’ve seen have dropped rain chances to less than 10%.  So, what’s up?  I have no idea.  I don’t see any rain tomorrow or tomorrow night.  But, I’d sure like to get a good, soaking rain.  I just don’t see it happening soon.

Remember back in May and early June how 50% forecasts brought us many heavy rain episodes?  Seems to me the forecast probabilities were too low then, and too high now.

 

 

Derby Day update

3:15 P.M.

Radar indications are now projecting the heaviest period of rain at Churchill Downs should be between 3:45 and 6 P.M.  Rain should lighten, perhaps even end, by Race Time.  Either way, it looks like the track condition will be either sloppy or muddy.

Horse race reminder:

No one ever bets enough on a winning horse.

Derby Weather

Sat. May 4, 2019

Another rainy one!

Although it won’t be as bad as last year, we’ll still have our second wet Derby in a row.  After giving us a little hope yesterday, the models have settled back into a slower developing southern system.  That keeps us wet most of the afternoon into the evening.

Here’s how it shapes up:  cloudy this morning followed by periods of light rain most of the afternoon.  Then, the worst part of the forecast.  Expect a period of heavier rain (perhaps even some thunder/lightning) between roughly 5 to 7 P.M.  After the Derby, rain tapers off during the evening.  Temperatures remain in the 60’s all day.

In spite of the weather, I hope you have a Derby winner!

Glimmer of hope fading

Friday, May 3, 2019

Models backing off from earlier trends.

After giving a promise of rain fading away by early afternoon with models runs from earlier today, tonight”s NAM family has taken most of the hope away.

Forecast now holds rain (mostly light) in Louisville throughout most of the afternoon.  Earliest end to rain now looks like 5 P.M. with a 40% chance it’ll still be raining lightly by Derby time.  Two years in a row!

Derby forecast looking better!

Friday, May 3, 2019

Latest data shows heavy rains heading south of us

After several days of increasingly gloomy forecasts for Derby Day weather, this morning’s product suite shows a definite trend toward better weather for tomorrow.

Models are now shifting the storm path to a more southerly route.  That means less rain locally and a quicker departure during the early afternoon.  Good news on both fronts.

Assuming this model shift is real, here’s my latest Derby Day forecast:  Light rain during the morning fading away to out southeast by early afternoon.  Some sunshine could show up by late afternoon.  Temperatures will be in the low 60’s during the rain but warm into the low 70’s by late afternoon.  Derby time:  mostly cloudy with a temperature near 72.  Track should be “good.”

Of course, remembering what happened last Derby Day, the above may not be the “last word”.   But the most recent trends are looking much better.

Now, the horses!?   Next question, please.

As a rule                                                                                                                                                             Horses are cruel                                                                                                                                              You bet their number                                                                                                                                       They barely lumber.

Not so interesting after all

Sunday, April 14, 2019  2:45 P.M.

Cooler, drier air takes over

Thunderstorm chances have dropped to near nil as the atmosphere has rapidly drier this afternoon.  Still a chance for some showers over the next few hours as cooler air rushes in. Showers, if any, will be scattered with only about 30-40% areal coverage.

Winds, which did gust once to 40 mph at SDF have remained mostly in the mid to upper 30’s and will slowly diminish for the rest of the afternoon. Temperatures will also begin a rapid drop.

Stuff

Forrest Mars, the inventor of M & M’s, was allergic to peanuts.  Thus, he never got to taste his invention.

 

Interesting situation for a couple of hours

Sunday, April 14, 2019  12:30 P.M.

Thunderstorms possible

Sudden heating and increasing dew points for the past few hours have pushed us into an interesting weather pattern for the next 2-3 hours.  A rather diffuse low pressure system has been over us this morning (it brought us the overnight rain).  The low is now moving northeast into northern IN/MI.  That’s why we’ve seen the rapid increase in winds.  But, low level moisture is now dropping!  Also, in the wake of the low, a cold front is now marching from west to east across southern IN and KY.  The front should pass the I-65 corridor between 2 -3 P.M.

Ahead of the front scattered thunderstorms are popping up. Due to the decreasing moisture, no solid line of storms is expected.  But, some isolated storm or two could generate some gusty winds, perhaps (but not likely) even up to 50 mph.  Any thunderstorm threat locally will be over by 3 P.M.  Stronger storms, even a severe storm or two, could pop up over eastern KY later this afternoon.

About those winds…

1).  We are under a Wind Advisory this afternoon.

2).  National Weather Service Definition of a Wind Advisory is sustained winds of 31-39 mph for at least an hour and/or wind gusts of 46 mph to 57 mph.

3).  The current NWS forecast predicts wind gusts up to 40 mph.

4).  The current Hazardous Weather Advisory and Weather Advisory say gusts to 45 mph.

5).  Go figure!  Why issue an Advisory for something they aren’t forecasting?

6).  And, the prediction isn’t even going to happen.  The strongest wind fields are over eastern KY (east of I-75).  Locally, our wind gusts should top out in the mid 30’s.

Stuff

Q is the only letter of the alphabet that does not appear in any state name.

 

New time estimate

1:45 P.M. Thursday, March 14, 2019

1).  Signs  are showing the upper atmosphere and the lower atmosphere are beginning to “uncouple.”  Basically, that means that the “sweet spot” for severe weather production is fading away.

2).  The general weakening will allow the system to slow its eastward progression.

3).  Best time for Louisville now looks to be 4:30 until 6 P.M.

4).  Strong gusty winds (non thunderstorm) will continue.  Thunderstorm winds could be strong (50 mph or so), but tornado threat is lowering.