Rare "High Risk" for Tornadoes/Severe Storms Midwest & OH Valley Today...

A rarely issued (especially for November) "High Risk" of tornadoes and severe thunderstorms has been issued by the SPC for today in the Midwest and Ohio Valley region.

As we mentioned yesterday, please stay very alert in this region today.  Storms will be fast moving, and due to the threat of extensive and intense wind damage with any severe storm, I highly recommend that you treat a Severe Thunderstorm Warning just as you would normally treat a Tornado Warning today, taking the same sheltering action when in harms way.

Thunderstorms will get underway by mid morning near the Western edge of the outlook areas, and race East/Northeast this afternoon and evening.  The highest risk of tornadoes is within the "High" risk area, with widespread wind damage the primary threat otherwise, and extending throughout the "moderate" and "high" risk areas.

If you or someone you know will be attending the Ravens/Bears game in Chicago today, please make sure to identify sheltering options as you enter the stadium and move there quickly if your smartphone app indicates that a Severe Thunderstorm or Tornado Warning has been issued for that location.

Below is a forecast radar image from the high resolution HRRR model valid at kick-off (12 Noon CST):

If this model verifies, and there is a good chance it will, several possible supercell thunderstorms will be approaching the stadium from the West at kick-off.

The situation will evolve rapidly from midday, with a squall line forecast to develop across much of the moderate/high risk area by 3pm CST:

The highest tornado potential will be with isolated storms that form initially from mid to late morning, and then isolated cells ahead of the line this afternoon.  Widespread, potentially significant, wind damage can be expected with all severe storms today, and especially as the more solid line forms this afternoon.

Thunderstorms will be very fast moving today across the entire threat area, so there will be little reaction time available.  If a warning is issued for your area, please seek immediate shelter.

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Regional Severe Weather Episode Likely for N. MO, S.E. IA and W. IL Tonight....

For good reason, a lot of attention is being paid to the expected severe weather episode across the Tennessee and Ohio Valley region for tomorrow.  As I mentioned in a post earlier this morning, that event has the potential to impact a large number of people with widespread, damaging winds and a few tornadoes.



With all of the attention being paid to tomorrow, I'm afraid that another event that appears to be taking shape for late this evening and tonight is being flat overlooked or quickly "brushed over".  Below is the latest WeatherGuidance severe weather outlook for this evening and tonight:

I am particularly concerned because 100% of the associated threat will take place after dark, and a significant portion of the threat will take place after Midnight, into the pre-dawn hours of Sunday.



Below is a forecast radar image from the high resolution NAM computer model, valid 8:00 PM this evening.  While it's important not to take the indicated storm positions literally, you get the idea that there will be isolated to scattered thunderstorms beginning to develop over northwestern Missouri around or shortly after that time period:

Jump ahead to 12 Midnight CST, and quite a cluster of strong to severe storms is depicted over southeast Iowa, northeast Missouri and west-central Illinois:

As these storms initially form late this evening and early tonight, large hail will be the primary threat.  As we move on in time toward and after 12 Midnight, a risk of tornadoes will also increase, as low to mid level wind profiles become more favorable for such development.

As I pointed out earlier, it is important not to take the forecast radar positions literally, so in general, folks across the Northern third of Missouri, the Southeastern third of Iowa, and west-central/northwest Illinois should be particularly alert for thunderstorm development late this evening and tonight.



If you live in or near the green shaded area on the top image, please make sure that you have a way to receive weather warnings overnight tonight, and have a sheltering plan in place before you go to bed, that way you can move there quickly if threatening weather is observed or a warning is issued for your area.

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Significant Severe Weather Episode Likely Sunday Across the OH/TN Valley Region...

Late fall is known for an occasional outbreak of severe weather, and unfortunately it looks like tomorrow will be just such a case.  While the threat of severe weather will exist generally along and East of the Mississippi River, the most widespread and potentially dangerous situation appears to be taking shape for much of the Ohio and Tennessee Valley region, as indicated in yellow on the above image.



By far, wind damage will be the primary threat from this event.  The potential exists for widespread, significant wind damage, particularly within the yellow shaded area on the image above.



A few tornadoes will also be possible, particularly early in the event when a few isolated storms may form along or ahead of the main line.  All storms, as well as any tornadoes, will be very fast moving, which will further increase the risk of people being caught off guard if they're not paying attention to the weather.  The primary risk will occur from afternoon into the evening, then spreading East overnight.



Below is the NAM forecast model depiction of what the radar may look like at 3:00 PM CST tomorrow:

As you can see, the model is already depicting a line of severe thunderstorms along the cold front by that time, but if you look closely toward the Southern end of the line, you'll see a few isolated cells, as well as a few isolated cells ahead of the line over Indiana and Kentucky.  While it's important not to focus on the exact locations of where storms are depicted by the model, it does give us a good idea as to the overall scenario that is likely to take shape.  Any isolated storms that form would need to be watched closely for tornado potential.

In addition to the "traditional" tornado threat associated with any isolated supercells that are able to form ahead of the main line, this is likely to be a situation where numerous "spin-ups" will occur along bowing segments within the overall line of storms throughout the event.  While any tornado touch downs with these line segments are likely to be brief, the associated wind damage potential will be intense.

If you live across the areas indicated above or have travel plans into this region on Sunday, especially from midday Sunday into the afternoon and evening, please stay aware of the weather and be ready to seek immediate shelter if you find yourself in a dangerous situation.  Storms will be very fast moving, so there will be little time to react in many cases, unfortunately.  Due to the potential for intense damaging winds, I also recommend treating a Severe Thunderstorm Warning as you would a Tornado Warning, especially in the yellow shaded area on the top image.

For more information from 'The Original Weather Blog', including shorter, more frequent posts during rapidly changing weather events, please be sure to follow me on facebook and twitter:

 

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