Flash Flood, Tornado Watches tonight

Thursday,March 19, 2020

Flash flooding likely: severe storms iffy

A fairly strong upper air disturbance will come across the lower Ohio Valley tonight.  Lucky for us, it’s focused mostly on Indiana.  With this upper system, we’ll see two clusters of thunderstorms overnight.  With the rains of the past two days, periods of heavy rain, especially over southern IN, will pretty much guarantee widespread pockets of flash flooding over northern KY and southern IN.  If you live in a flash flood-prone area, you know the drill.

The first cluster of thunderstorms will be over the area this evening.  The southern side is weak and will provide plenty of rain to west and central KY and initiate some of the expected flash flooding.  But no severe thunderstorms.

The first cluster of storms will be more noteworthy over the southern half of Indiana.  Severe storms are moving over southern Illinois and will race eastnortheastward.  Heavy downpours are likely and a few severe storms will be possible between, roughly, 8 P.M. and Midnight.  Primary threat will be strong winds and possibly some hail.

The second cluster of storms will move through the area between about 2 A.M. and 8 A.M.  This one is much stronger and is likely to produce an outbreak of severe storms from Arkansas, southeast Missouri and southern IL this evening.  By the time this cluster arrives in the Louisville region, it is likely to be weakening.  Plus, atmospheric instability will be diminishing. Also, the strongest dynamics will remain north of our area.

The result will be a very noisy night north of the Ohio River.  Flash flooding will probably become  a serious problem.  Storms will be strong, but probably not severe.  Along and south of the Ohio River, the primary line of thunderstorms most likely won’t arrive in Louisville until 5 A.M. or later.  They will not be very strong, but deposit enough rain to make a very messy rush hour before the exit the area by 8 A.M.


Recent trends looking good for us

Strongest storms will stay south and west of Louisville

Thursday, March 12, 2020  4:45 P.M.

Latest radar trends and short term forecast models are strongly indicating that we’ll get plenty of rain this evening, but severe weather will not reach the Louisville area.  Severe storms are forming along the approaching cold front over western KY and dropping rapidly southeast.  That area of severe storms is heading toward central Tennessee.

Meanwhile, area of showers and non-severe thunderstorms has been expanding over  SW IN and is moving our way.  Cold front may produce some gusty winds as it passes through the Louisville area between 6:30 and 8:30 this evening.  Our biggest problem will be with heavy rain and possible areas of flash flooding.



Two rounds of thunderstorms this evening

Thursday, March 12, 2020  4 P.M.

Cluster of rain/thunderstorms in the area now is not showing any signs of severe weather,  Instability is very low, but the dynamics are quite strong.  Nevertheless, severe weather is not expected with this area.  However, stronger storms appear likely later this evening.

Current showers/t-storms are forming along a warm front slowly pushing north.  Once we get into the warmer/moister air south of the front, we’ll have the potential for slightly higher instability for a few hours.

During that time, a cold front will be moving over southern IN/western KY.  That system should pass through our area between 6 and 8 P.M.  The front is already creating severe weather to our west.  Instability should still be weak, but the wind fields will be strong enough to create a strong wind threat – possibly severe (58 mph or more) in a few areas.  Atmospheric structure favorable for tornadoes should remain south and west of Louisville.

After 8 P.M., threat for severe weather will move south and east of Louisville area.

Even less snow tomorrow

Fri., Feb. 7,2020

Weak Clipper brings a little more snow

A weak Alberta Clipper dropping into the Ohio Valley tonight and tomorrow morning will leave a minor calling card in its wake.  Available moisture is lacking and the clipper does not appear strong enough to force much lifting this far south.  The clipper’s path is expected to pass over southern IL/IN.  That sets up central IN for a possible 1-3″ accumulation tonight and early tomorrow.

Meanwhile, south of a clipper’s path, not much happens.  In reaction to the clipper moving north of us, we’ll see southerly winds tonight.  That’ll hold temperatures in the low to mid 30’s.  Precipitation south of a clipper’s path historically is little or none.  So, even though some light snow is possible late tonight and tomorrow morning, accumulation will be in the “little or none” category.  Probability for measurable snowfall is about 50%.

Tomorrow morning marks the last snow chance for about a week, at least.

Grasping at more straws

Thursday,Feb. 6, 2020

Light snow possible late tonight

Snow chances have been few and far between this winter.  We started with tad about an inch of grass-only snow in November and haven’t been able to match it since.  However, we’ll see two chances over the next two days.  Best chance for breaking past one inch will come Saturday morning.

A strong upper level trough is passing over today, but so far is having trouble with surface development.  That problem should end tonight as a major surface storm will be developing/accelerating northeastward along and just east of the Appalachians tonight.  Latest forecasts have the storm path a bit farther east than earlier models.  That’s bad news for the Louisville area.

We were expected to be in the western edge of snowfall from this system.  Now, it looks like we’ll be “really” on the edge.  Far southeastern KY could get up to 6″ overnight.  As you head northwest from there, snowfall will lessen.  Bowling Green, Lexington and NE KY should be in the 2″-4″ range.  E-town, Bardstown, Shelbyville, and Henry County will likely be in the 1″-2″ zone.  West of that, snow will fall off quickly. SE Jefferson County could get up to .5″ while downtown will probably get a dusting.  North of the Ohio River…little to nothing.

In the Louisville area, snow is likely to begin about 3-4 A.M. and probably be over around 7-8 A.M.  Any accumulations will be on grassy areas.  Roads should be wet, but icy conditions are likely on some bridges and overpasses.

As the upper trough moves eastward tomorrow, a (probably) weak Alberta Clipper will run southeastward along the backside of the trough.  Models are projecting another area of light snow with the clipper and put us in its projected path.  I’ll check back on that tomorrow.


Together, Kobe Bryant and LeBron James played in every NBA Championship Finals from 2008 until 2018.  But, they never played each other.

Shaky forecast models

Wed., Jan 22, 2020 4 P.M.

Flip flops are the latest model fashion

Two weeks ago, the models were forecasting a major pattern reversal over North America.  Winter was finally on the way.  Seven days ago, the models had reversed themselves – abnormally warm weather would remain well into next month. Now, the models have undergone a “reversal reversal.”  In other words, the forecast again favors below normal temperatures taking over during the next 7-10 days.  This time, however, the Euro model is even colder than the GFS.

It’s all very confusing, but here’s what’s most likely for the next few days.  A deepening upper level low will push from the southern Rockies tonight to a position right over top the IN/KY by late Friday.  Ahead of the storm we’ll be mild with periods of rain from late tomorrow into Friday.  As the low moves over us rain showers will probably change to snow showers Friday night into Saturday.  It’ll be too warm for any accumulation on roads, but some minor accumulations are possible on grassy areas.

After that, warming will be back early next week followed by rain, then colder.  GFS and Euro predict another storm with rain to snow next Fri/Sat, but forecasts that far in advance this winter have met with pretty poor results.  We’ll see.




Is the GFS messing with us again?

Thursday, Jan. 16, 2020

Not again?!

Today’s GFS is really cutting back on its pattern-reversal forecast.  Today’s runs push any cold phase arrival back a week, at least.  It’s quite a bit weaker than last weeks storm, but another west coast storm is developing and heading toward a northern cut across the central U.S. Saturday.  Following that, Sunday thru Tuesday will be the coldest days we’ve seen in almost a year.

That was supposed to be start of a long term cold period. But, now the GFS is predicting yet another major west coast storm moving into the central Plains the next weekend.  Even after that, it’s holding off on a pattern shift.

The Euro model has been a little hesitant on the magnitude of any pattern change for the past week.  Now, it too is backing off.

The GFS has been doing this to us for six months.  I’m still hoping that one of these times, it’ll actually happen.

Winter’s return still on target

Wed, Jan. 15, 2020

This morning’s showers surprised me as I thought the return to warm air would be dry.  But the yoyo weather will continue – warm today, colder tomorrow, and warmer with periods of rain Fri/Sat.  Then, Sunday wintry weather arrives.  We’ll see below normal temperatures for at least a couple of weeks.  The GFS has lost the weak clipper system it was earlier predicting for Tuesday night. Now it’s developing a snow to rain event for Wednesday night and Thursday.  Updates will follow.

Australian Fires

Due to geographical location, global wind patterns and ocean currents, the West Coast of North America and the East Coast of Australia are both prone to seasonal forest fires.  This is nothing new – it’s been going on for thousands of years.  Many are putting the blame for this year’s higher than normal fire destruction on “climate change.”  Good try, but climate change has been going on forever, just like the fires.  Might other things be involved?   Of course.

1).  Forest maintenance –  Like the U.S., Australia bans removal of undergrowth from forest floors.  Undergrowth removal eliminates the majority of the fuel for fire growth and rapid spread.  Seems to me that undergrowth removal should be priority #1.  But, it’s banned.  The result is more fires, much more land burned, rapid spread of fires, more wildlife and human deaths…   (But, it keeps some environmentalists happy.)

2).  Population – Since 1950 Australia’s population has jumped from around 8 million to about 25 million today.  As in the U.S., Australians have built many homes in forested areas amplifying the potential death and damage fires can create.

3).  Humans-  So, we’ve got forests primed to ignite, and many more people living in them.  Then you add in the fact that humans are pretty careless.  In the U.S., an estimated 85% of all forest fires are caused by humans.  I’m guessing it’s about the same down under.

4).  Malicious humans.  A large number of forest fires are intentionally started by arsonists.  U.S. numbers say 21% of our forest fires are arson.  As of yesterday, about 155 people have been arrested on arson charges in Australia.  An additional (approximately) 300 have been arrested for fire-related offenses.

Forest fires have been occurring for as long as Mother Earth has had forests.  Climate change has been happening even longer than that.  But, since we homo sapiens arrived about 200,000 years ago, life for forests has become much more hazardous.

Note: The graph below portrays the areal coverage of Australian fire damage for the past 100 years.  This year  (so far) ranks #3, but 1975 was ten times higher than this year!

Note 2: In 1975 the big climate issue was global cooling and the beginning of the next Ice Age.  So, I wonder if that year’s fires were blamed on that.

Note 3:  One hectare equals 2.47 acres.

Fig. 1. Yearly fire season (June through May) hectares burned by major bushfires in Australia since the 1919-20 season (2019-20 season total is as of January 7, 2020).

Winter arrives (finally) next week.

9 P.M. Tuesday, Jan. 14, 2020

Mild weather continues a few more days

I don’t know how many times over the past six months, our forecast models have predicted a reversal in the upper air pattern over North America, but it’s been often.  Only once (November) did it actually happen.  Now, it’s seems like it will reverse for a second time, starting Sunday.

The shift to west coast ridge/east coast trough is underway.  The strong northwesterly winds aloft will definitely put us into below normal temperatures.  When pattern reversals occur, they generally persist at least 2-3 weeks.  But, this has been unusual winter, to say the least.  When the “cold phase” hit us in November, it lasted about 3 weeks before the “warm phase” took over.  And the warm phase has been around ever since.  Since November 25, we’ve only had six days with below normal temperatures.  For those keeping score, that’s 45 above normal days and only 6 below.

So, are we going to have a “3 week” winter, or will be longer?  Good question.  Answer unknown.

Old rule of thumb:  After 3 weeks, if the upper air winds over us are stronger than when the cold regime began,  it will persist another 3 weeks.  If the winds are weaker than originally, the warm regime will return quickly.

Rest of this week

Official forecast gives Louisville a chance for rain tomorrow.  I’m not buying that although some light rain will be possible over southern KY.

Another midwestern storm is likely late Friday, but it’ll be much weaker than last week’s storm.  We’ll probably see periods of rain from Friday into Saturday.

Then, winter arrives Sunday!  Next chance for snow comes from a weak clipper next Tuesday.