Thundersnow Chances Are Good Overnight

I hope you enjoy this video of thundersnow. This is a possibility in our area overnight. As the storm intensifies overnight the mid level instability will increase significantly. On top of this we will already have lots of moisture,  lift and cold air in place. To put this all in simple terms we will have all of the ingredients not only for a winter storm but also for thunderstorms. Thundersnow is very rare and assuming it develops it will likely be scattered in nature. With all of that said we think the best chance for thundersnow will be between 2 and 5 am overnight tonight. Thundersnow has a tendency to put down very heavy snowfall rates which can reduce visibility to near zero at times.

I talked to a fellow Purdue graduate this afternoon that spent several years researching thundersnow and forecasting it. He is currently working for the Storm Prediction Center in Norman, Oklahoma. Here are his thoughts on the potential for thundersnow in our area.

“Ross, good to hear from you! I am in Norman nowadays working for SPC. You have a nice setup so far from what you have explained. As with any thunderstorm, you need substantial lift (such as from frontogenesis; plenty of dynamical lift I’m sure is occurring from what I have seen with model plan view/sounding perspectives), moisture, and instability (elevated instability either CSI/CI; plenty of ways to assess this and CAPE is certainly one of them). Of course the final ingredient with winter precipitation is an atmosphere cold enough to support snowfall (which is definitely the case, although I heard that there is a sharp transition zone where sleet could mix in). I don’t want to just say that there is a silver bullet but you might see what sort of midlevel lapse rates are showing for that area of NW AR (anything over 6.5 C/km would be a bonus). Also take a look at the trends in forcing and destabilization with the RUC possibly. With these well developed upper level systems, you will more than likely see a good trowal airstream signature (look at theta-e maybe in the 700-500mb layer). I hope this helps and let me know if you have any observations of TSSN! Good luck!”

This is very technical but summing all of this up, it takes many ingredients for thundersnow to occur and all of them are forecasted in our area late overnight tonight. The big one is the lapse rates between 500 to 700 mb. They need to be 6.5 or greater and the models are forecasting them to be between 7.5 and 8.0 between 3 and 4 am. On top of this there will be sufficient moisture, cold air and intense lift. In theory, thundersnow seems like a very good possibility…now lets see what happens.

Ross Ellet

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32 Responses

  1. I wouldn’t be at all surprised by t’snow tonight-I’ve only experienced it twice before!! Starting to feel like one of those Spring snow storms that dump lots o’ snow-a rather heavy sleet/snow mix started a few min. ago-33 in downtown Mens; still warmer at the airport…

  2. Would it be possible to see snowfall rates as high as what was going on in that video of over 4″ per hour?

    • Yes that would be extreme but very possible with convective snow!

      Drew Michaels

  3. Is all that precip weakening in Oklahoma supposed to happen? It looks like its falling apart.

    • This upper level low is set to intensify overnight….that shield will likely strengthen in intensity.

      Drew Michaels

  4. What time will the changeover occur near Altus?

    • I think Altus may be on the bubble the rest of the night with a mix of rain, sleet, and snow. You should be getting some decent sleet right about now.

      Drew Michaels

  5. where is the low located?

    • North Texas and southern Oklahoma near the Red River.

  6. I know you have been asked this question alot but what time do you think the changeover will occur in Coal Hill

    • I think you guys will see a mix of rain and sleet throughout teh night. It may not change completely over to snow.

      Drew Michaels

  7. Drew,
    3″ here NE of Pea Ridge so far, latest 12 & 24 hr RUCs are hinting at quite a bit for us…

    12hr. (through 10am tomorrow) has 8″ more

  8. 00z has another 1.75″ liquid qpf; good grief….overstating? or is this including some sleet tomorrow late morning/afternoon?

    • I think it could be a little of both…this low is going to deepen tongiht and we sit right on the pivot point…we may be in this stuff through tomorrow morning. At that point the warm layer starts to work back in from the east and that may switch it to rain and snow. Some decent totals are going to happen in our area.

      Drew Michaels

  9. So the Coal Hill area may not see much snow?

    • Probably guys are right on the critical line. A wintry mix is most likely what you’ll deal with.

      Drew Michaels

  10. So when we wake up tomorrow there will probably be quite a bit on the ground?

    • Yes it several inches of snow should be on the ground!

      Drew Michaels

  11. 2 inches now in Fort Smith…ridiculous heavy blowing snow still! Roads are all covered here. They are slick!

  12. So its looking like Clarksville going to miss out for the most part. Do u expect that warm layer aloft to start to erode for here or do u think it will stay mostly all rain for here?

    • I think that warm layer will stick around in your area….rain and sleet would be my guess.

      Drew Michaels

  13. Could the Coal Hill and Clarksville area still get 2” or 3” of snow?Also do you think it would be out of the question to see some isolated places get 4” or 5”of snow in South Johnson CO?

  14. Drew,There is barely any snow on the backside of this thing.Is it gonna intesifie?Also I saw that you increased the snowfall forecast area wide,is there gonna be less dry air or less warm air?

    • Dan,

      We’re still on the north side of the low which is yielding very heavy snow along the border of Arkansas and Oklahoma. Those areas are in a pivot zone…all of the snow and precipitation is rotating around it causing major accumulations. The back is forecast to intensify overnight.

      Drwe Michaels

  15. Snowing heavily in Mena at 10:40; ground is now covered!I guess we will get 2 or 3″-who knows. Drew, you know I always end up all excited when it finally snows here!!! Even when I’m ready for gardening…

  16. Drew,

    We’ve got just over 5 inches here in north Fayetteville as of 10:45pm, with this intense band still hours away, what do you think we can expect here? The NAM was predicting around 18 inches earlier today with the GFS predicting 12, can we expect something around these totals if the temperature stays at or below 32 degrees for the rest of the night?

    Also, because of this blog post, I will be staying up all night in hopes of experiencing Thundersnow. Haha.


    • Travis,

      You pose a very good question. I think spots in Washington county will have achance to see over a foot of snow into tomorrow. The tricky part will be tomorrow afternoon. There’s a warm layer at 5,000 ft that’s forecast to move west into northwest Arkansas. That could cause some snow and rain tomorrow afternoon which would melt some of the snow. We’ll see!

      Drew Michaels

  17. Heavy snow In Mena at 10:55-beautiful, big flakes. Around freezing but the ground’s still warm so it would take a lot to cause driving issues here. I’ll keep watching…

    • I appreciate the reports!


  18. 1 inch around Vian with heavy snow/blowing snow 29 degrees.

  19. Drew,Im not sure if my question went through eairlier.I really need to know an answer to this question.Is it possible for the Clarksville area to see 2 or 3 inches of snow and sleet,your snowfall map said that earlier I think.Did I read that right?

  20. its 2:42 am and i have 5 1/2 inches on the ground here in sallisaw and its still coming down hard.

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