Several rounds of storms upcoming…

Three rounds of strong to potentially severe storms are expected across parts of Middle Tennessee over the next 5 days, along with the risk for more heavy rain and possible flooding.

 

ROUND #1: Tonight/Thursday morning 11pm-10am

– Low threat of damaging winds

– Main risk area far west & south Middle Tennessee

QLCS storms should be winding down as they reach our area well past midnight.  Meager instability, however, combined with strong low level shear will present a shot at a rogue QLCS tornado.  These tornadoes will be the quick spin-up type and we won’t have a lot of lead time on these.  Be sure to have some sort of wake-me-up device handy.

 

ROUND #2: Friday evening/Friday night 6pm-1am

– Damaging winds, large hail, a couple tornadoes all possible

– Heavy rainfall and localized flooding also possible

– Main risk area northwest Middle Tennessee

Atmosphere will become very favorable for strong/severe storms Friday.  A warm front is poised to lift northward of us early Friday putting much of the midstate in a very unstable warm sector.  Dew points roaming through the 60s and 2500j/kg MLCAPE (instability) will provide ample fuel for these storms.  However, due to a lack of a trigger mechanism and a weak cap, convective development won’t happen until the afternoon.  PWATS (atmospheric moisture content) will be 1.5 to 1.6, meaning any substantial storm will provide torrential downpours.  Given our rains over the weekend, these additional rains could promote flooding.  This will need to be watched.

 

ROUND #3:  Sunday/Sunday night

– Damaging winds, large hail, a couple tornadoes all possible

– More heavy rainfall and flash flooding also possible

– Main risk area all of Middle Tennessee

Sunday offers a shot at some severe storms, but the chances are much more limited than Friday.  PWATs will still be high, so torrential downpours and additional flooding is a possibility.

QPC forecast

(H/T to OHX WCM Krissy Hurley and this morning’s discussion authored by Sam Shamburger)

Legit or bust…

I need to preface this post with this.  Anything that flows from my fingers onto this virtual parchment is my own opinion and is wholly separate from any opinion held by government agencies or school districts.

So, it appears as though we have folks moaning and groaning about another apparent “bust”.  I’m reading stuff like, “The SPC highlighted us and NOTHING HAPPENED.”  “Has the SPC lost it’s mind?”  Both of these statements – and similar beliefs held by others – are rooted in ignorance.  I’m willing to bet none of the offending principals realize what the SPC risk outlooks are or what they’re supposed to mean.  If they won’t take it upon themselves to learn, let me educate them.

The SPC outlooks are meant to describe what COULD happen given the atmospheric conditions present, not what WILL happen.  These outlooks are refined throughout the day in response to ever-changing atmospheric and weather conditions.  These “ever-changing atmospheric and weather conditions” equate to any number of variables within the atmosphere the weather models can’t see due to resolution limitations.  These variables that change during the day of an event are called microscale features.

Take, for example, our last event where “nothing happened”.  The outlook was issued according to what the SPC forecasters saw on the vast number of weather models employed by NOAA.  These forecasters have forgotten more weather than you, me, or any other armchair meteorologist has learned.  They are the best of the best.  The weather models, even the short range suites, have a hard time picking up on microscale features.  Atmospheric mixing is a microscale feature.  It cannot be picked up by medium-range modeling.  Could the forecasters envision a scenario where mixing could be a possibility?  Sure, but these guys and gals don’t operate on possibilities.  They make a forecast based on actual data in front of them.

The factors that dictated today’s event were picked up very early in the forecast cycle.  The threat outlooks were changed accordingly as the data changed.  I think one would agree that that is a reasonable response.  The idea that not everyone would see a storm was realized very early on.  The atmospheric conditions favored scattered activity as opposed to a linear event.  That’s why your “Twitter-ologists” used the term low probability/high impact events.  The SPC modified the risk areas as a response to this morning’s model data.  Remember, it’s not what WILL happen, but what COULD happen.

Unfortunately, that low probability/high impact event turned into a high probability event as a tornado more than likely touched down (will need to wait for survey teams to confirm) in Bedford Co and made a mess of a person’s farm.  You won’t hear him crying wolf about an apparent bust.  The forecast verified.  I believe that part of Bedford Co was included in a MODERATE risk with a 10% tornado chance happening within 25 miles of a point.  Guess what…it verified for this farm owner.

Now, let’s discuss schools for a second.  You will NEVER hear me give an opinion one way or another against a school making a decision to close schools.  As a parent of two, given the choice of having my child in school or with me during a severe storm, I want him with me.  The school district cannot have buses caught out on the roads when tornadoes are a possibility.  There is simply no mechanism available for a school bus full of children to find adequate shelter when out on a route.  Not to mention the liability risk the school district would incur if the unthinkable happened.  Let’s not forget, our educators are more than likely parents, too.  They deserve to be with their children just as much as you deserve to be with yours.  There was an incident at Plaza Towers Elementary School in Moore, Oklahoma back in 2013.  A tornado struck the school during the normal scheduled day and seven children were killed when a wall fell on them.  I don’t want to be the parent running towards a destroyed school scared to death wondering if my child is hurt.  The schools have days built into the schedule for inclement weather.  Inclement weather just doesn’t mean snow.

I know my opinion might be dissenting to one of your own, and I’m fine with that.  It’s my opinion and I own it.  I’m not going to bump you off of your opinion.  You and I both know that’s a fools errand.  Just know that when a forecast “busts” because YOU didn’t get a storm doesn’t mean it busted for the farm owner who lost a barn, or the guy who had a roof blown off his house, or the lady whose grandmother was injured when her mobile home overturned.  The world just doesn’t revolve around you…it revolves around all of us.