Tomorrow’s Severe Threat: Potential But Not A Guarantee!

6:30PM Thursday 3/1/12

Happy first day of meteorological “spring.” The astronomers would yell at us for saying that, wouldn’t they!

What a nice day today and a chance for folks hit by storms Wednesday start the clean up process. Now we look ahead to tomorrow’s severe weather potential.

First off, it does look like some storms may arrive toward daybreak or in the morning with some hail or perhaps a wind gust, but these do not look to produce major severe weather concerns at this time. It’s later in the day where things get a little hairy, potentially.

I know Jay has touched on this in his weather forecasts tonight on WLKY… the fact that this is not a guaranteed forecast of severe weather for tomorrow. I’ve had an opportunity this afternoon to look hard at the data on this storm as well as read some of the thoughts of fellow meteorologists. I can tell you — there is a lot of hype being placed on this event.

The question, is it hype-worthy?

SPC Moderate Severe Risk Friday

The map you see above is courtesy of the reliable Storm Prediction Center in Norman, OK. They are really the experts from far and wide that have the tools to look ahead and forecast severe weather potential. As you see, they have an enhanced risk of storms over our viewing area for tomorrow, extending southward as well.

Their thoughts on paper:

   WITH STORM MODE LIKELY TO BECOME A MIX OF SUPERCELLS AND COMPLEX
   LINE SEGMENTS...THREATS FOR BOTH DAMAGING WINDS AND SEVERAL
   TORNADOES APPEARS EVIDENT...ACCOMPANYING THE LIKELIHOOD FOR LARGE
   HAIL.  A COUPLE OF STRONG TORNADOES WILL ALSO BE POSSIBLE -- MAINLY
   DURING THE MID TO LATE AFTERNOON HOURS IN AND NEAR THE MODERATE RISK
   AREA.

Some additional thoughts from various National Weather Service offices across the region:

LOUISVILLE: If supercells do manage to pop in the LMK CWA, they will go
severe very quickly and will rotate easily, with tornadoes, damaging winds,
and large hail all in play.  Since there is still some uncertainty, though,
it is important to stay tuned to the latest weather information as this
event unfolds.

INDY: THE PRESENCE OF THE DYNAMICS/SHEAR/HELICITIES AND JET
STRUCTURE ALOFT ALONE ARE SUPPORTIVE OF THE SEVERE WEATHER THREAT.
ENTIRE FORECAST AREA REMAINS UNDER THE GUN FRIDAY AFTERNOON AND
EVENING BUT GREATEST CONCERN FOR SIGNIFICANT SEVERE AT THIS POINT
LOOKS TO BE SOUTH OF I-70 AND SPECIFICALLY OVER SOUTHERN COUNTIES
WHERE INSTABILITY AND HELICITY VALUES WILL BE ENHANCED IN THE
VICINITY OF THE DEWPOINT BOUNDARY.

NASHVILLE: STRONG LONG TRACK TORNADOES...DAMAGING WINDS AND LARGE
HAIL ARE ALL POSSIBLE. SPC CONTINUES TO POST A MODERATE RISK FOR
SEVERE WEATHER OVER THE MID STATE. THIS EVENT LOOKS MORE
WIDESPREAD AND SUBSTANTIAL THAN THE SEVERE THREAT WE HAD
YESTERDAY...PROBABLY THE BIGGEST OUTBREAK OF TORNADOES SINCE
APRIL 27, 2011. THIS EVENT COULD BE ONE OF THE GREATER IMPACT
EVENTS IN THE PAST FEW YEARS. THE PUBLIC SHOULD BE STRONGLY ADVISED
TO TAKE THIS THREAT VERY SERIOUSLY.

As you can see, many meteorologists looking at the parameters in place for tomorrow have some significant worries that this could turn out to be a big severe weather day around our part of the country.

And they are right! If storms were to form, they would be dangerous. We have a lot of available POTENTIAL energy that would be released if storms popped up. Plus, a strong cold frontal boundary is moving into the region, which would serve to lift the air. Combine that with wind energy which is very strong… and it appears that at least a broken line of convection would be realized along this front because it is so sharp.

Indeed! This Model Pops Storms On The Front

The NAM model shown above does pop storms on the boundary west of us in the late day period and pushes it through our region toward evening rush. If this line indeed develops, the concern runs high for strong wind gusts, hail, and perhaps a tornado.

However some models poke a layer of warm air into the mid levels of our atmosphere by 4PM… which would essentially put a lid on our atmosphere and keep storms from developing. This would be a very hostile environment and keep storms from thriving on an otherwise warm and wind-energized air mass in place.

FROM PADUCAH NWS:
PER SOUNDINGS AND THE LACK OF UPPER LEVEL SUPPORT...THE CAP MIGHT BE
STRONG ENOUGH TO SUPPRESS CONVECTION INTO THE EARLY TO MID AFTERNOON
HOURS. THE LONGER IT CAN REMAIN INTACT...THE FARTHER EAST THE FRONT
WILL PROGRESS BEFORE CONVECTION BREAKS OUT.

Bingo. The weather service in Paducah sums it up well, just underscoring the problems with saying that there is a guarantee that severe weather develops – we have to see them develop first!

A couple more points to make. There will be a wave of wind energy that passes through around 1PM as the warm air just arrives as well as the moisture. If some storms can develop on this leading edge of the jet streak passing by, we could see severe weather develop early in the afternoon and race northeastward. Afterward, I see a break where it looks like we are unable to see storms from 2 or 3 until 4PM… awaiting the front. The jet streak I mentioned will be moving over and perhaps northeast of us by then, which promotes sinking air in the low layers and a decreased storm threat. Plus, with storms developing to our south, a distinct potential for our storms to get disrupted exists.

I don’t want to sound wishy-washy or look like I’m going back and forth. I just want to share with you the difficulties of severe weather forecasting and how important we feel it is to not alarm you about storm threats, but instead keep you informed with the latest data and see what happens. I will say this, I don’t think it’s wise right now to say anything “absolute” about this system… saying things like we will see tornadoes -or- severe weather will occur only serves to panic folks… and I really think it is critical to reserve these comments for when we absolutely know and feel that storms are going to happen.

For now think of it this way. Any storm that develops will likely turn severe tomorrow afternoon because of the reasons I discussed above. BUT also keep in mind that for us to realize severe weather, storms will need to develop in that air mass in the first place! And I don’t think anyone can guaranteeyou at this point that will happen.

So keep an eye on the forecast here at WLKY… you know Jay, Matt, Susanne and myself will keep you informed. We just ask you keep checking back for updates, but don’t get alarmed… yet. We’ll have more data this evening to look over and have a better look at how this may all play out.

Until then, I’m interested to hear your thoughts about this discussion!
–Jared