Very Active Weather Expected This Weekend

wxornotBG 4/28/17: Severe Weather Concerns

Posted by Landon Hampton on Friday, April 28, 2017


Well, this is certainly not the easiest forecast that I have ever had! Actually, this may be one of the harder forecasts I have ever had to work in my time at wxornotBG or at WKU.


I will be focusing largely on today’s severe weather threat today, as the models have trended in favor of developing severe weather this afternoon and evening.

*Me to the models trending towards severe weather today*

The large scale environment that is preconditioning everything and is setting this up is not easy to diagnose right now. Whatever is going to help force the lift for this weather is going to be subtle and not easily predictable. This was the largest question yesterday; would we get enough lift? That question is slowly being answered this morning, and it looks like it is going to be a hesitant yes.

That dashed line is what is expected to be our primary forcing this afternoon. It is subtle, but still there. h/t

With the trend towards a very subtle, yet discernible wave in the mid levels of the atmosphere, we have our potential source of forcing. I am trying not to place too much weight into the HRRR, but the 3km NAM shows the presence of a similar feature, but doesn’t develop widespread convection.

The large scale pattern, as difficult as it is to assess, is largely why this threat even exists. Because of a deep longwave trough set up across the central Plains, we have enhanced westerly flow across this portion of the country. This allows for wind shear to increase, and thus, severe weather chances to increase.


This isn’t the only factor, though. Remember that cold front yesterday morning? Yeah, that is now moving rapidly northward as a warm front. The air mass south of it contains a lot of moisture for storms to work with, and will help to create a very unstable atmosphere this afternoon.

That is plenty of instability to develop severe weather this afternoon. h/t

In addition to this, the winds in the lower and mid levels of the atmosphere look to favor storms potentially rotating. But, as I said before, this forecast hinges on a lifting mechanism. If some of the primary convective models are wrong about strength, timing or placement of the recently shown shortwave feature, this forecast is up a creek without a paddle very quickly.

Me watching this forecast unfold like:

However, if storms go, expect the threats for large hail, damaging winds and isolated tornadoes. As such, the SPC has placed us in an Enhanced Risk this afternoon.

The current SPC Day 1 outlook across the region. Warren county is split by the eastern edge of the Enhanced Risk. h/t SPC

Timing on this looks to be largely after lunch. The warm front looks to move through in the early afternoon hours, with our forcing mechanism following closely afterwards. Additionally, the warm front may stall across our region because of this same convection, and may lead to several rounds of severe weather and heavy rainfall as well. That is something we’ll have to keep an eye on.

The HRRR develops thunderstorms this afternoon across the region. These will be capable of all severe weather types. h/t

That may change, so keep it tuned to wxornotBG this afternoon for the latest. Also: look for highs to jump into the mid and upper 70s this afternoon, with very muggy conditions developing.

Tomorrow and Sunday just feel so far away from now because of this forecast, but they are in this forecast as well!


Tomorrow just looks terrible, to be honest. Dewpoints look high and temperatures look high as well. This will create a mid-summer feeling environment during the afternoon hours. Expect mostly sunny skies, with the possibility for an afternoon storm or two. Highs should be in the upper 80s.


Sunday looks like another potential severe weather day. A deep trough will be moving towards us, and will bring with it strong wind shear. Additionally, models are developing instability along and ahead of the surface cold front associated with the overall system. There is still a lot that can happen between now and Sunday, but I am expecting a severe weather threat at the very minimum. The SPC has us in a marginal risk for now, but I expect that to change.

The SPC’s convective outlook for Sunday. We are currently in a marginal risk. h/t SPC

Expect highs on Sunday to roll up into the mid 80s, with breezy conditions likely as well.

Forecast Summary

Today: Partly cloudy skies, with severe thunderstorms possible this afternoon. All threats on the table. Highs around 78°F. Overnight, look for storms to move out, with partly to mostly cloudy skies remaining. Lows around 67°F.

  • Bus stop: ⛅️  52°F
  • Lunch hour: 🌤  68°F
  • School is out: 🌤/⛈  78°F
  • Evening time: 🌤/⛈  75°F

Tomorrow: Partly to mostly sunny, and hot. Isolated storms are possibe,  with highs around 88°F. Overnight, look for partly cloudy skies, and lows around 70°F.

  • Wake up: 🌤  68°F
  • Lunch hour: 🌤  82°F
  • Evening time: 🌤/iso’t ⛈  87°F

Sunday: Partly cloudy, with clouds increasing. Look for thunderstorms to approach by the evening, with severe weather possible. Highs around 86°F. Overnight, look for storms to exit, with lows around 55°F.

  • Wake up: 🌤  70°F
  • Lunch hour: 🌤  80°F
  • Evening time: ⛅️  ⇾ ⛈  85°F

Folks, that’s all I got for you! Be sure to follow @wxornotBG on Twitter and like Landon Hampton on Facebook for the latest info on this afternoon’s severe weather threat. Happy Friday!s