Tuesday, Feb. 5, 2019

Possible flooding late this week

Winter rains are the perfect setup for flooding.  The Ohio’s been running quite high for the past few weeks.  Smaller rivers have had frequent up and downs recently, as well.  During the winter our soil is almost always saturated.  So heavy rains have nowhere to go except to run off into nature’s rain-collecting system.  The next possible flooding system is knocking on our door right now.

A strong upper air trough will be working its way eastward from the Great Plains into the Ohio Valley.  Ahead of the system, huge amounts of moisture are rapidly moving northeast from the Gulf of Mexico.  As the system slides our way, a series of smaller upper air disturbances will race from southwest to northeast ahead of the surface cold front.  Each one will bring along the opportunity for rain.  Light to moderate rain tomorrow (mostly during the morning), then heavier rain tomorrow night and Thursday.  Rain should end Thursday night.

How much rain?

Models today are a little less generous with rain than they were a couple of days ago.  Nevertheless,  they are still high.  Both the GFS and NAM are forecasting 1.5″ to 3″ for much of southern IN and northern KY.  They also suggest as much as 4″ over southern KY.

With water levels already elevated, I’d expect many area rivers and streams could reach flood level by Thursday evening.  The Ohio River should not reach flood stage.

Cold air arrives again Friday, but only for a brief stay.  It won’t be anything like last week.

Stuff

Of the millions of birds which migrate from the north into the United States for the winter, 35% never make it back to their nesting grounds.  Of all the millions of birds which migrate southward from the United States each fall, 25% don’t make it back. (Audubon Society)

Thursday, Jan. 31, 2019

Possible light snow tonight.

The last Alberta Clipper for awhile (for us) will race across Il and IN into Ohio by early tomorrow.  This one continues to show up pretty weak, but will put down a swath of 2″-4″ snows across northern parts of IL, IN and Ohio tonight.

Clippers have been an almost daily feature recently.  I’ve pointed out that it’s rare to get precipitation south of the surface path of the clipper.  An exception was the small amount of rain earlier this week.  That clipper was much stronger than the current one.  As warmer air moves northeastward into the Ohio Valley tonight, it may squeeze out a little snow.  Then, again, based on our position relative to the clipper, history isn’t too fond of that idea.

The models’ stories

Both the GFS and NAM run about 50-50 on the chance for a measurable amount of precipitation.  Overall, the NAM is a little more aggressive toward snow.  The ultra short term models (HRRR and RAP) are drier.  Neither one predicts a measurable amount of precip. but both do open the door for a dusting of snow.  Also, neither the HRRR or RAP predicts rain tomorrow – contrary to the ongoing NWS forecast.

And the winner is…

The HRRR and RAP have outperformed the bigger GFS and NAM during the recent cold weather outbreaks.  This will be that last clipper for awhile as the upper air parent trough is shifting eastward to allow for warming trend.  Meanwhile, I’ll stick with the little guys one more time.

Clouds increase tonight and temperatures slowly rise into the mid to upper 20’s.  If anything falls from the sky it’ll be snow (or possibly sleet).  Any precipitation should exit east of Louisville by 8 A.M. tomorrow.  Then, warmer air pushes temperatures into the 40’s during the afternoon.  If any snow falls overnight, should be only a dusting – may a few spots may even get a generous dusting.

Then, thoughts of snow will disappear for at least a week.

Think snow!

Stuff

Chicago’s “bean” looks great even in the snow!

By the way, the bean’s official name is “Cloud Gate.”

Photo by Tyler LaRivieve/Chicagoist

Monday, January 28, 2019

Month ends on a very cold note

A cold front crossing central IN/KY now is producing scattered very light showers.  The showers will move east of I-65 by 7 P.M. Maximum rainfall should be .02″ to .03″.  Much of the area should get only a trace of rain.  The rain will exit the area several hours before near freezing temperatures arrive, so no snow is expected this time

After 7 P.M. the Arctic air pushes in to set the stage for a very cold end to January.  Tomorrow won’t be too bad as temperatures remain in the 20’s all day.  Morning low will be around 20 with an afternoon high in the mid 20’s.

Wednesday will be the coldest day with a morning low near 8 degrees at the airport but afternoon highs only in the mid teens.

Thursday starts with a low only a couple degrees on the plus side of zero, but with afternoon temperatures rebounding into the 20’s  Warming continues Friday.

Snow?

With the cold air in place we’ll continue to see chances for flurries/light snow here as weak upper air disturbances pass overhead.  At this time, it looks like our best chance for a dusting will be Tuesday night into early Wednesday

Stuff

Light pillars are rare.  They require ice  crystals and man-made light.  Enough ice crystals for the pillars to appear usually only happen with clear air and very cold temperatures –  such as sub-zero cold.  Mia Stalnacke of Kiruna Sweden sent this photo to http://www.spaceweather.com recently.

The orange pillars  are created by sodium vapor lamps while the blue-white ones are from LEDs.

Thursday, Nov. 24, 2019

Daily chance for flurries/light snow

Now that cold air has reestablished itself, the open question remains – what about snow?

Helping to bring in  the new cold air mass is a brisk northwesterly jet stream flow from northwestern Canada into the central and eastern U.S.  Little pockets of even higher energy move along with this jet on a roughly daily basis.  One is passing over us tonight and will bring only clouds.  If it were a little stronger, it might squeeze out some flurries or light snow.  That’s another big question.  How strong will they be?

Being small, these Alberta Clippers (as we commonly call them) are hard for the computer models to resolve well.  As of now, the system due tomorrow night looks a little stronger – some flurries and very light snow possible.  Story looks about the same for Saturday night.  The GFS especially likes the chances for light snow from a Clipper Sunday AND one on Monday night/Tuesday.

Meanwhile, it’s far too early to get a handle on Sunday and Tuesday’s Clippers.  If the Tuesday storm works out similar to the GFS model’s forecast, the coldest air of the season will follow.  We’re almost certain to get that “single digit” temperature that has been talked about a couple of times recently.  Perhaps even a trip down to near zero.  But, that’s next week – plenty could change.  Meanwhile…

Tonight

Back to current times, the clouds should hold most of the night, but skies should clear by sunrise.  Westerly winds appear likely to stay above 10 mph.  Those two features should be enough to keep temperatures in the lower teens.  Probably it’ll drop to 12-13 here in Louisville.  A few degrees colder west of Louisville since skies will clear earlier there.

Lots of sun tomorrow, but not much warming.  Highs in the mid 20’s.

Stuff

Here’s another cool aurora shot from spaceweather.com