Author Archives: wx

Colder air returns

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5 P.M. Thu. Feb. 7, 2019

Fireworks fizzle out

Ideas about some exciting weather between 4 and 5 P.M. certainly proved to be wrong.  That squall line died out quickly so all we got was more rain – minus the winds and flash flooding.

Threat of anything bad happening is over.  Rain should end just after 9 P.M. but amounts won’t be high enough to trigger river/stream overflows locally – flooding is far more likely over Indiana at least 30 miles north of the Ohio River. Remaining rainfall should be less than one-third of an inch.

Temperatures will be dropping quickly tonight into the 20’s by morning.  And the cold air will bring some wind gusts to 30 mph or so this evening – weakening after Midnight.

Action-packed late afternoon

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Thursday, Feb. 7, 2019  2:30 P.M.

Very windy squall line approaching

Between roughly 3 P.M. until 4 P.M. a fast-moving squall line will pass through the Louisville Metro area.  We’ll see brief, intense rainfall along with wind gusts of 40 mph or greater during that time.  That could create some minor damage and possible power outages.  It’ll be quick.  As the cold air arrives this evening, winds will remain strong with gusts over 30 mph.

By 4:30 P.M., colder air will begin working its way into the area.  Temperatures will fall into the 50’s by 7 P.M. and drop all the way into the 20’s by morning.  They’ll only reach the mid 30’s tomorrow afternoon.

Rains projected for us earlier this week have fallen far short of predictions.  However, the brief heavy rain this afternoon should create some short-term flash flooding in the usual flood prone spots, but that should clear rapidly.

The Flood Watch we are under will most likely expire without any stream and river flooding.  Additional rains this evening are not likely to push rivers/streams over their banks.   We are not out of the woods yet, since another extended period of rain is likely early next week.

Good news

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Wednesday, Feb 6, 2019  11:30 A.M.

Lessening threat for flooding

Morning runs from the GFS and NAM both are lowering the rain estimates for the next 36 hours.  Since yesterday, radar rainfall estimates are under 1/2″ for southern Jefferson County rising to about .75″ along and north of the Ohio River.  Heaviest rain so far has been over southcentral IN.

Heaviest rain will shift into southern KY this afternoon as rain diminishes (for awhile) for northern KY and southern IN.  Periods of rain return tonight and tomorrow.  Now appears like the total will run between 1.5″ and 2″ for most of Louisville area with higher totals over southern KY.

 

Very wet weather for a few days

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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)

Happy Groundhog Day

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Sat. Feb. 2, 2019

Early spring has arrived

We’ve now completed the cycle created by the Sudden Stratosphere Warming we began talking about about a month ago.  The breakoff vorticies from the polar jet stream have retreated northward to allow warmer air to take over.  The last segment of the polar vortex to hit the U.S. was extremely cold for the Great Lakes and northeast but moderated quickly as it pushed southward.  We didn’t even drop to zero ( 3 was the lowest), so it certainly wasn’t even close to “record breaking” as it was to our north and east.

With the polar jet now back home, the next few (maybe, many) systems to produce our weather will arrive via the Pacific Ocean, so they’ll be warmer.  And, with a little help from the Gulf of Mexico, probably wetter as well. The first will arrive Monday night.  Then, a large slow-moving system could provide periods of rain from Wednesday through Friday.

The GFS isn’t even hinting at decent snow chances for the next couple of weeks.  We’re going back to the West Coast Cold – Eastern U.S. Warm pattern that was prominent from late December to early January.  Get out your raincoat and put away the snow shovel for awhile.

The Groundhog

Punxsutawney Phil was rudely awakened from his hibernation around daybreak today.  His handler then read a statement “supposedly” from Phil.  The guy in the funny top hat announced that we’ll have an early spring.

The GFS and the seasonal model both say the same thing – early spring.  I consider that a far superior source for weather data.

Transition to warmer weather is underway

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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

Cold bottoms tonight

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Wednesday, Jan. 30, 2019

Major warming this weekend

At least the winds have calmed.  Bitter cold air temperatures again tonight with a low  0 to -2 at the airport and most areas outside the Watterson will be below zero tomorrow morning.  We’ll see more clouds again tonight keeping temperatures from dropping too far below zero.  Could be a snowflake or two, but no accumulation this time around.

Afternoon temperatures tomorrow will climb into the upper 20’s.  Models are really downplaying the weather system due in the area tomorrow night into Friday.  Current indications are for some light snow beginning late tomorrow night then changing into rain Friday morning.  Looks like not much of either snow or rain.  More on that tomorrow.

Stuff

According to Boeing, more than 80% of the world’s population has never flown on an airplane.

Snow tonight!

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Tuesday, January 29, 2019

Colder air brings some snow

While most of the weather talk today concerns the minus 10 to 20 degrees below zero wind chills expected tomorrow morning, the models are getting a little friendlier toward the cold blast bringing some snow as well.

It won’t be much, but at least we’ll probably see some actual snow on the ground by morning.  The GFS likes the idea of a bit of snow.  The NAM, not so much.  Both of the short term (24 hours or less) models, the HPPP and RAP like the idea a lot.  The latest blast of Arctic air will arrive this evening.  From roughly 9 P.M. until 1 A.M. some light snow/flurries will accompany the cold air.  Accumulations along and north of the Ohio River should be from a dusting to a half-inch.  South and east of Louisville will probably range between one-half to one inch.

In any event, the winds will be over 20 mph tonight, so the snow will be blowing around a lot.  Roads will see most of the snow blow off.  If crews put salt on the roads, it will make matters much worse – lots of icy spots.

Temperatures will bottom around 5 degrees tomorrow mid morning and only reach the lower teens tomorrow afternoon.  Most of us will see near zero temperatures Thursday morning.

Another chance for light snow arrives Thursday night.

Scattered showers early this evening

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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.