Energy-packed atmosphere, but…

Friday, July 20, 2018 Noon

…we’ll probably get lucky.

Unusually strong summer system is dropping southeast from the western Great Lakes and should trigger numerous strong-to-severe thunderstorms this afternoon/evening.

Morning rains set up the higher moisture, now the upper dynamics have plenty to work with.  Lucky thing for us is that the next big surge of upper energy is approaching rapidly and probably won’t get enough heat energy to kick off storms until it is either right over us or to our east.

Storms should start organizing between 2-3 P.M. near I-65 and move rapidly southeast.  Some scattered severe activity is possible in the I-65 corridor, but these storms will get better organized and much more dangerous east of I-65.  Widespread severe weather is likely over the eastern half of KY this afternoon/evening.

Luckily, most (if not all) of the damaging weather will be east of the Louisville metro.

Watch the skies this afternoon.

Timing update

Thursday, May 31, 2018  5:45 P.M.

Development to our west is still slow.  Primary development, as expected, will stay south (where the energy is) with heaviest storms over western TN.  A weaker bit of energy may still work its way up the Ohio River tonight, but that looks like it’ll be later than I originally thought…probably arriving around 11 P.M. to Midnight.  No problems with this system, if it arrives.

Comment:  This has been a really bad month for Louisville area forecasters.  It’s only fitting that the  current NWS forecast seems destined to join the faulty list.  My guess is they haven’t taken into account the changes caused by this afternoon’s storm system.

Storms possible again tonight.

Thursday, May 31, 2018 5 P.M.

Severe wind gusts ripped across the area this afternoon as winds gusted as high as 59 mph at Standiford Field.  Many reports of 50+ mph came in from around the state.  That cluster of strong storms is continuing to create trouble over southeastern KY.

Meanwhile, to our west what was expected to be the “big event” tonight is having a tough time organizing.  No surprise there.  This afternoon’s big cluster of storms has used a huge amount of the potential energy expected to fuel tonight’s storms.  So, no “big event” is likely tonight.  A line/cluster of thunderstorms could develop into our area around 9 P.M. until Midnight. But they won’t be very strong, even if they do reach us.  No additional severe weather is expected tonight  It appears that tonight’s outbreak may stay south of KY.  Lots more energy available over TN.

Two rounds of heavy thunderstorms possible today

Thursday, May 31, 2018  Noon

After a largve production of heavy/severe thunderstorms in the central plains overnight, two distinct developments today as that energy moves east.

1).  A pulse of upper energy is moving rapidly eastward and is creating a developing strong cluster of storms over southern Illinois. This system is expected to expand eastward across southern Indiana and extreme northern Kentucky over the next few hours.  Some severe thunderstorms are likely this afternoon.  Primary threat will be brief, strong gusty winds.  Smaller threat will be hail.  If everything develops as expected, the cluster of storms will move through the Louisville area from about 2 P.M. to 3:30 P.M.

2).  The “main event” from the midwestern system is expected to develop later this afternoon and reach our area tonight.  Best time for us looks like 8 P.M. until Midnight.  Again, strong, gusty winds will be primary threat.  This time, however, the storms are expected to be more widespread.

NOTE:  How this afternoon’s storms play out could have a significant say in how tonight’s system develops. I’ll have an update on that later.

Update to rain chances

3:30 P.M. 5/26/2018

Rain/thundershowers over southern IN have remained weak and are not showing any indication of dropping into KY.  So, there will still be a slight  chance for a shower later today or tonight, but most, if not all, of  the Louisville area will stay dry through the weekend.  But, it’ll be hot!  Have fun!

Hot Holiday Weekend

Sat. May 26, 2018  12:30 P.M.

Up to an hour of rain and possible thunder late this afternoon appears to be the only weather disruption we’ll see this long weekend.  Memorial Day weekend is often referred to as the “unofficial beginning of summer.”  This year, however, it’ll be more like the middle of summer, especially tomorrow and Monday.

This afternoon, I expect a narrow line of showers/thunder to form over southern Indiana by around 2 P.M.  They will drift slowly southeastward through the Louisville metro between about 4 P.M. and 5:30 P.M.  It should not be a solid line, so not everyone will see rain.  Even those who receive rain won’t get much, probably less than a quarter inch.

The rest of the weekend will be hot, humid and dry.  Only a scant chance for a thunderstorm tomorrow and Monday.  Highs both days will be near 90 degrees.  (heat index: low 90’s)

Beautiful evening

Tuesday, March 20, 2018

On my previous post I gave two reasons why I wasn’t expecting to see much snow tonight.  The second reason has been my downfall to getting this forecast correct.  The weak secondary upper has formed, BUT it formed too far east to disrupt the flow of wrap around moisture westward into Ohio Valley.  The result?  More snow than I expected.

As of 8 P.M. we already have two inches on the ground.  The snow should become very light over the next hour or two, then continue overnight.  Louisville area should have 2″ – 4″ by morning.  Deeper snows north and northeast of the city.  Lower totals south of the metro area.

Another “iffy” March snow forecast

Tuesday, March 20, 2018  2 P.M.

Another big nor’easter is on track to pound the eastern U.S. from northern West Virginia, north Virginia and northern Maryland northward into New England.  4″ to 8″ of snow will be likely over a large area while some spots could record a foot of snow, or more.

Meanwhile, we’ll be on the back side of this big snow-maker.  The computer forecast models are predicting about a 2″ – 4″ snow in about a 100 mile wide swath from southern Indiana and extreme northern KY  northeastward toward Lake Erie. That swath could reach 6″ or more over east-central IN and northwestern Ohio.  The Louisville National Weather Service’s forecast includes Louisville in that 2″ – 4″ snow area.  But, don’t count on that much snow here.  I have two good reasons for predicting why our Louisville snowfall total should be lower.

First,  the western side of Northern Hemispheric storms is a weaker precipitation-maker than the warmer eastern side.  The northwest side of these systems has to “wrap around” moisture from the active eastern side of the storm. That’s a hard job to pull off. Nevertheless, it does work.  Whatever moisture that does make the wrap around is rather small, but efficient.  As it reaches the northwest quadrant of the storm, it encounters colder air which squeezes out some moisture.  Little, if any, moisture can get far enough around to reach the southwestern quadrant of the storm.  The problem here is that the Louisville area will be in the Southwestern quadrant of the system by Midnight-2 A.M.

Second,  several models are predicting a weak low pressure to form west of the primary storm center.  This development is expected over east KY and West Virginia.  When that happens this evening, it will interfere with the wrap around precipitation mechanism of the parent storm.  So, we have another problem with the potential snowfall here.

With all that to consider, here’s my forecast:  a light rain/snow mix will begin during the afternoon rush hour and quickly  turn over to snow this evening.  Periods of light snow will continue overnight changing to flurries by daybreak.   Temperatures will remain in the 30″s all night, so roads should remain mostly wet with just a few slick spots.

How much snow?

Louisville area: !” to 2″ on grassy areas

South of Louisville: less than 1″

Southern Indiana: 2″ to 4″ north of the Ohio River.  4″+ over south-central counties northeast to the Ohio border.


March 11 evening snow update

Significant changes in past few hours.

Models have been running the precipitation farther north this evening.  It now appears the southern one-quarter of KY will stay snow free.  Heaviest snow band looks to be between a few miles south of I-64 to southern KY.  Basically, Bullitt Co and south.

Also, models are predicting faster movement of the storm (should leave Louisville area by 3 AM.  Faster movement means lower precip. totals for us.

Another change:  Models are now predicting colder temperatures overnight.  That means slightly more accumulation of snow AND possible road problems for Louisville.

So, for Louisville area:  some rain, but mostly snow.  Louisville could see an inch of snow on grassy areas with some slush on roads.  Major roads, however, should have few problems

Another close call

Sunday, March 11, 2018  4 P.M.

Majority of snow stays south of Louisville

As expected (at least by readers here), Friday’s weak Alberta Clipper failed to generate much snow around the metro area.  Today a strong Clipper is approaching our region and will pass through tonight.  This time, however, the storm has its eyes focused on central and southern Kentucky.  You guessed it…little, if any snow for the Louisville area.  Another missed opportunity in a winter highlighted by misses.

Once again, temperatures will play a big role in tonight’s weather.  Surface temperatures locally will stay above freezing during the precipitation event, so no problems are expected with area roads.  They will stay wet, even if we do get a small amount of snow.  In fact, most major roads will be dry before the morning rush hour.

But, let’s talk about central/southern KY

Starting about 20-30 miles south of I-64 on down to the Tennessee border, SNOW will be the primary factor.  Sloppy, wet snow (probably beginning as rain) appears likely for about 4-6 hours tonight.  Time frame should be roughly Midnight until 6 AM EDT.  Most of the southern two-thirds of KY should receive from 2″ to 4″ of snow – mostly on the grassy areas.  Some spots could get as much as 4-7″ of snow.  That would be enough for the heavy wet snow to break some tree limbs and/or power lines.

Louisville area summary

Light rain will move in during the evening.  Rain will mix with, or change to, snow around Midnight.  Precipitation should diminish by about 3-4 AM.  Snow accumulations, if any, should be less than one-half inch – on grassy areas only.  No traffic problems are anticipated.