Looks like a White Christmas!

1 P.M. Thursday, Dec. 24, 2020

Short-term models are predicting a significant outbreak of snow showers/flurries this afternoon and evening.  With temperatures in the 20’s, snow will accumulate and slick roads will develop.  With the cold air around, the light, fluffy snow could accumulate to several inches this evening.  Water content will be very low, but dry snow accumulation features plenty of air to fluff it up.  The low water content, however, should allow roads to stay  in fairly good shape.

Snow should begin in Louisville area by mid afternoon.  Accumulating snow will end before midnight.  The whole area should get about an inch of snow. However, systems like this usually form some heavier “cells” of snow showers.  If one of these hits you, 2″-4″ inches will be likely.

So as an estimate:  within a 40 mile radius of Louisville…                                                                        up to 1″ – near 100%                                                                                                                                        1″-2″ –   about 50% of the area                                                                                                                      2″-4″ –  about 20%                                                                                                                                            4″+   – about 5%

Since yesterday, I found the traditional greeting for the season

Lo Saturnalia   (lo is pronounced    “yo”)

Saturnalia is the reason Christmas is celebrated on Dec. 25th

 

Very cold for Christmas

6 P.M. Wed., Dec. 23, 2020

Rain likely tonight…probably ending 2-3 A.M.  No snow, as cold enough air won’t arrive until daybreak.

Mostly cloudy, windy and cold tomorrow – some flurries possible .

Tomorrow night continues with mostly cloudy and cold with flurries possible.

Best chance for snow will be Christmas morning as an upper air system tries to wring out some moisture.  Some minor accumulations (less than an inch) possible.  Christmas day will be very cold with highs mostly in the low 20’s

Note:  Snow is likely over eastern KY (mostly along and east of I-75) tomorrow into Christmas Day.  Around an inch near Lexington but the far eastern mountainous areas could see 2″-4″.

Happy Saturnalia!!!  (The real “reason for the season.”

11 P.M. update

11 PM Dec. 15, 2020

Evening models  have shifted everything about 30-40 miles farther north than earlier.  That puts the Louisville area into the little or nothing snow category.  Meanwhile, 1″-3″ inches of wet snow remains likely in all but extreme southern Indiana.

 

Snow is in the air!

Tuesday, Dec. 15, 2020

Seems like the thoughts of snow have brought me out of hibernation.  So, here come some thoughts on yet another one of our rain/sleet/snow situations…

In general, an active upper air trough will swing out of the Rockies through the Ohio Valley to the east coast by late tomorrow.  Ordinarily, that would bring us some rain under the current temperature setup.  But, this system features a big twist.  A big lobe of energy has dropped into the far southern part of the system.  That piece of energy will gradually take control and become the primary driver of the spectacular nor’easter expected to drop a foot or two of snow from West VA, PA and to New England by tomorrow night.

Meanwhile, we’ll be left with a dying system over the Ohio Valley.  Thus, total precipitation will probably amount to a quarter-inch or less.  But, in what form will it fall?

One important thing – all models agree that temperatures around 5000 feet above the surface will stay below freezing.  That definitely keeps snow in play.  Also important is when the dying upper air system trudges up the Ohio River, temperatures in the lower atmosphere will warm.  That pushes the odds for rain/drizzle higher.

Forecast

Put a line about 20 miles south of the Ohio River.

If you live south of that line, you’ll see a rain/snow mix after 3 A.M. changing to rain after an hour or two.  By daybreak, it’ll be rain/drizzle through midday.  Possible flurries late afternoon/evening.

For the rest of us,  here’s how I think it’ll work – Clouds will thicken this evening while local temperatures drop into the mid thirties.   Around 3 A.M. some snow should begin.  Mixed with rain and/or sleet, it’ll continue until about daybreak.  Little accumulation on roadways, but grassy areas could see 1″-2″ locally.  Up to 3″ farther north of the river.

After daybreak, we’ll see periods of light snow, rain and mostly drizzle through the morning.  No additional accumulation is expected.  In fact, most of the overnight snow should melt away.  Snow flurries will be likely again as colder air arrives late afternoon into the evening

 

The Land of “I”

Sunday, June 28, 2020  8 P.M.

Disappointing rain, so far.

Weather Service has really cranked up the rain probabilities recently and continues them well into the week.  The best chances for wide spread rains, however, seem to be over.  Lots of rain yesterday, last night and this morning.  Soaking, even flooding, rains fell over central Indiana and most of Kentucky, but not here.  Along and north of I-64 there was about a 60 mile wide area with very little rain.  Plenty of rain north and from southern Jefferson County southward.  But most of us missed out.  Never good news during the growing season.

Meanwhile, NWS continues with 70% – 80% most of the time tonight through Tuesday. I’m hoping they are right, but to me the situation isn’t nearly that clear cut.  The rains of the past 36 hours had some pretty good upper dynamics, but that support has faded.  We still have lots of moisture and a fading warm front hanging around, but with upper dynamics weak I’d drop the rain chances to the 30-40% range – more scattered showers/t-storms than widespread.

I’d still love for some worthwhile rain to hit my lawn and garden.

Now, to that strange headline above.

The Land of “I”

I have a lot of concerns.  The one I’m going to discuss here is nothing new.  It has, however, reared it’s ugly head to much greater extremes and ruinous results during the current presidential regime.  It’s been revealed that our PIC (Prevaricator In Chief) has some really nasty genes.  (True, that was well known before the election, but too many Americans failed to grasp the reality.)

Our PIC has been the embodiment of, and promoter of, the “I” generation.  The “I” generation has only one concern – themselves.  Whenever PIC speaks, the words “I” and “me” are constantly being expressed.  Anybody remember hearing the word “we”?  Doesn’t ring a bell to me.  PIC’s “thing” has been this MAGA  nonsense.  That won’t work with I.  “I” has made America worse before and, especially, after PIC took over.  (A side thought…maybe Joe Biden should campaign using the slogan – Make America Great Again! )

Let’s take a look back.   World War II.  The era that produced what Tom Brokaw named the Greatest Generation.  Along with help from many nations, the United States led the battle to defeat the evil empires of Germany and Japan.  Millions of Americans joined together to produce the greatest military victory this world has ever seen.  It was a huge sacrifice – rationing, shortages, blackouts in addition to the battle casualties.  It was an effort enabled by Americans working together – WE.

After World War II, Americans continued to work together.  WE were the leaders of the world.  WE beat polio.  WE made the Russian missiles leave Cuba.  WE won the Cold War.  It’s impossible to mention all the WE moments Americans achieved.  But, somewhere along the way, WE started to fade and “I” started becoming important.

Looking back, I think things started unraveling during the Vietnam War.  WE became divided over the war.  But, when the war ended, WE never fully recovered.  Additional wars have further divided Americans.  Each time, the “I” factor grew.

But, the change hasn’t been only about war.  Front and center – the Anti-vaxxers.  What could be more simple than taking a shot to eradicate a dangerous disease from the world?  It’s obvious to WE vaccines are a good thing.  But “I” says no.  ‘I” will not vaccinate my child.  I don’t care if your kids get sick.

In this time of great uncertainty, the “I” movement has really become emboldened – and PIC has been cheering them all the way. Don’t do simple things like stay at home or wear masks – that’s your right.  Don’t care about WE who don’t want covid 19.  WE can’t peacefully demonstrate because “I” will send in the troops to clear the way for my photo at a church “I” haven’t been in since Inaugural Day.  And on and on…

“I” has been slowly growing in the U.S. for decades, but the trend has accelerated since PIC took over.  He has clearly demonstrated that “I” only weakens us.  Only WE can get America moving in the right direction again.  My hope is that WE will find something to unite around to get us moving in the right direction…before it’s too late.

Huh?

Wednesday, June 10, 2020

Latest NWS forecast reads like this:

Detailed forecast for

Jefferson County

Late This Afternoon
Breezy. Partly cloudy. Slight chance of showers and thunderstorms early in the evening. Some thunderstorms may be severe with damaging winds and large hail early in the afternoon. Southwest winds 15 to 25 mph. Chance of precipitation 20 percent.
It is confusing, at the least.
Missed opportunit
Although we did see some showers yesterday, rain totals were small.  Today’s missed opportunity was our last chance for awhile, and that’s bad news.
 A strong upper air ridge will be building over the mid U.S. and will provide a long stretch of dry weather.  Temperatures are expected  to remain near-to-below normal, so it won’t be heat wave conditions,  but the ground will be drained of moisture quickly.  Early in the growing season is a bad time to have a dry spell because dry areas tend to feed on lack of moisture and grow.  Normally, summers tend to get drier as we get into July and August.  That usually bodes poorly for the growing season.  If these trends continue, we could be in for a hot, dry late summer.
Stuff
1).  Coronavirus  cases in the U.S. are growing again as we reopen.  However, deaths from the virus are continuing to fall – about 1000 per day lately.  Seems like the older generation (people like me) is sticking by the masks and quarantining while the younger ones are less severely ill from the virus.
2). Cudos to our Prevaricator In Chief.    Must give credit where its due.  When he ran for President, Mr. Trump  (PIC) ran on two big issues.  1).  Build a wall.  2).  Make America Great Again.  Well, he has succeeded at both.  First, he imagined a great wall to keep the “good guys” (us) in while keeping the bad guys (Latin Americans) out.  He got his wall, but it didn’t quite work out as he imagined.  Instead, the much smaller wall around the White House is designed to keep the good guys (concerned Americans) out while keeping the bad guy in – hiding in his bunker.  Yes, PIC the world is laughing – not at us, but at you.
Then there’s MAGA.  Frankly, I never quite understood this slogan.  At least for the past 200 years when compared to the rest of the world, America has always been great.  We’ve had our problems, but we’ve been slowly improving over time.  But, when faced with a crisis, our PIC has really come through.  Yes, we’re NUMBER 1 – in a big way!  By huge margins,  we lead the world in coronavirus cases and fatalities!  Yes, we are NUMBER 1.

Muggy, showery weather continues

Tuesday, May 26, 2020  11:30 A.M.

More showers, t-storms today

Big disconnect today between the NWS forecast and the models’ forecasts.  NWS has just a 20% chance for afternoon/evening showers and thunderstorms.  Models, however, are the most favorable for showers/t-storms they’ve been for quite awhile.  They indicate at least a 60% – 70% chance you’ll have rain at your house this afternoon/evening.  Man vs. machine…we’ll see how it works out!  Personally, I’ll go with the machines.

Computer models, part 3

Tuesday, May 5, 2020  6 P.M.

Current weather:  A strong upper air disturbance over upper midwest now will rotate southeast toward Kentucky tonight.  This system will provide some reasonably potent lifting motions over the lower Ohio Valley late tonight.  Not much moisture is available, but additional periods of light rain/drizzle are likely late tonight into tomorrow’s morning rush hour.

We’ll get to see some sunshine as tomorrow wears on, but temperatures will remain unseasonably cool.  The below normal temperatures will likely continue through the next week or two.

Computer models, part 3

The past two posts have told the story how weather forecasting and computers have been wedded since the beginning of electronic computing.  Today there are computer models/projections for just about everything.  Even one that predicted Secretariat to win the Super Derby last Saturday.

We all know that weather forecasts certainly are still not perfect, even though meteorologists have been at it the longest.  Other forecast models have the same problem, but do get better with age.  That leads us to the Coronavirus Models,  Unlike sports, weather, economics, etc., the available data on pandemics is pretty sparse.  Luckily not many pandemics occur.  Nevertheless, models have been built and put into action.  As expected we are hearing a variety of conflicting reports.  Pandemic modelling is a relative new field…its going to take some time for the model errors to shrink.  But with more data rapidly becoming available, improvement will occur.

Early talk of millions of deaths possible in the U.S. were simply “potential”.  They assumed no precautionary steps taken.  When precautions/restrictions went into effect across the country, the oft-quoted University of Washington model predicted 100,000 to 240,000 fatalities.  Our PIC (prevaricator in chief) just laughed that off.  Meanwhile, as the volume of data escalated, a few weeks later, UW lowered its prediction to 60,000.  Subsequent revisions went to 68,000 and then to 76,000.  All the recent revisions have been ridiculously low.  I’ve been watching the case/death numbers closely.  They just didn’t mesh with the predictions.  For example, Monday UW estimate was still in upper 70,000’s.  Just following the daily data, it was obvious we’d exceed that this week.  But, then, yesterday…

Kudos to the New York Times

For some (obvious) reason, it appears that PIC and his gang have been withholding information from an internal government forecast model.  That model predicts total U.S. deaths at 135,000.  To me, that number seems about right.  But with the recent rush to reopen the country, even that number could be low.  Thanks to the Times for breaking this story.  PIC, however, will likely just discard it as “fake news.”    (The only thing worse for PIC was if Jeff Bezos’ Washington Post had broken the story.)

Computer models, part 2

Monday, May 4, 2020  6 P.M.

First, our local weather

A weak low pressure system will work its way across the southern plains tonight and across Kentucky tomorrow.  It’ll bring us some rain tonight (after Midnight) into tomorrow.  Any rain after mid-morning tomorrow will be very light.  Total rainfall is expected to be in the quarter inch to half inch range.  Cooler air filters in tomorrow and we’ll see below normal temperatures likely through the weekend, at least.

Computer models and forecasting, part 2

After the Army built the first eniac  (computer) from 1943-6, the Navy decided to build a second one in cooperation with the private sector.  A group of mathematicians and meteorologists was chosen to complete the project.  Why meteorologists?  Two reasons: first, the earliest computers had no what we now call “software.”  The machine had to be built to solve one single problem.  It would have no other use since the “software” had to be built into the machine,  Second,  the project leader was  John von Neumann, a mathematician.  Von Neumann, however, was familiar with Richardson’s work from the 1920’s.  (previous post)

He figured the team had an already-solved problem.  All they had to do was build the machine to perform the calculations.  Thus, he reasoned, meteorology had the problem and a pre-existing method to solve the problem.  That would save a lot of time.

In reality, Richardson had made some mistakes and faulty assumptions.  The meteorology team spent a lot of redoing the physics and methodology before the machine could be built.

Finally, in 1950, in a large lab at Princeton University, eniac produced the world’s first non-military computer “output” – a 24 hour numerical weather forecast.  It took the machine 24 hours to produce it.

Within two years, the computer time dropped to two hours.  The world of “computer weather forecasting models” accelerated from there.  Improvement has been immense.

Other models:

Computer modelling has expanded over the years.  Virtually anything you can think of is under the scrutiny of various models.  Weather has had 70 years working on the problem and we still make mistakes.  Same goes for other models you may hear mentioned.  Which brings up today’s most talked about model – the coronavirus model.  The conversation continues tomorrow.

non-Derby Weekend odds and ends

Sunday, May 3, 2020  5 P.M.

Summary

Weekend forecasts for Louisville were reasonably good although temperatures were several degrees higher than predicted yesterday. If this had been a “business as usual” Derby Day, I wonder how many bad sunburns the infield crowd would have suffered.  Today’s temperature forecast was far worse than yesterday’s.  The expected showers finally arrived, but rain so far has hardly been worth the effort.  We’ll still maintain a chance for a few more light showers until about 8-9 P.M.

Looks like a nice day tomorrow with mid 70’s highs, then a good shot at a more significant rainfall tomorrow night into Tuesday.

Below normal temperatures will prevail from midweek through the weekend.

Forecast Models

Homo Sapiens (that’s us) evolved, we believe between 200,000 and 300,000 years ago, but did not  develop language skills until about 50,000 years so.  So, we’ve been trying to predict the future for at least 50 thousand years.  The first scientific numerical attempts, that I’m aware of,  were by Lewis Richardson in the early 1920’s.  He used equations developed by Wilhelm Bjerknes ( the Farther of modern meteorology) to create a numerical “model” of the atmosphere.  He then extrapolated the input data forward in time.  He produced a 6-hour forecast for two cities in Europe.  Sounds pretty simple, but there are an enormous number of calculations required to move forecast data horizontally and vertically through the atmosphere, even for just six hours.  Working off and on, Richardson took six MONTHS to complete his 6-hour forecast!

The numerical prediction did not produce realistic results.  But, the concept was proven correct. But the huge number of calculations needed proved it was not feasible at the time.

Jump ahead two decades.  During World War II the military wanted some way to speed calculations needed during battles.  Started in 1943 the project ended in 1946 by calculating (very rapidly) trajectories for canon balls by a machine called eniac  (electrical numerical integrator and computer).

Story continues tomorrow