Updated: Potentially Active Severe Weather Episode Mid-Week For Central/Southern Plains

The potential for severe weather on Wednesday and Thursday is becoming more clear with the addition of new weather data to the forecast. Let me preface the rest of this post with two points. 1.) I’ve included for your convenience some severe weather safety links at the bottom of this post and 2.) it’s my hope that the information I’m sharing will alleviate some of the unnecessary anxiety and stress that is so often fostered by attention hungry fear mongers in social media. Having said that, let’s take a look at this week’s severe weather potential.

Updated 7:20 PM CDT: There is a Slight Risk tonight for parts of Kansas, Missouri, and Oklahoma with a pending watch from the Storm Prediction Center. If any storms for tonight, they could have an effect on the atmosphere in such a way that Wednesday’s severe weather outlook could be changed.

It’s no surprise that the Storm Prediction Center added an Enhanced Risk to Wednesday’s severe weather outlook. As is often the case, as more data become available, it’s easier to put the pieces of the puzzle together. Here’s a look at Wednesday’s SPC severe weather outlook. While some severe weather scenarios are almost textbook, this forecast challenge has become more daunting as the days when storms are likely has drawn closer.


Day 1 SPC Categorical Outlook 7 April 2015Tomorrow’s severe weather setup is a very complex scenario. The next two days will certainly be no small challenge to any meteorologist. As of this post, SPC forecasters feel that storms may form much earlier than usual. This will have a significant effect on where and when any additional storms form later in the day. From the SPC discussion, “STILL..DEEP LAYER
SHEAR SHOULD BE STRONG ENOUGH FOR ORGANIZED CONVECTION…INCLUDING SUPERCELLS AND AN EVOLVING STORM CLUSTER…IN THE PRESENCE OF SIZABLE CAPE.” In other words, in spite of the fact that storms may form early, there are ingredients available for them to become potent supercells. It’s possible that if storms form early, it could be in the north-central Oklahoma/south-central Kansas border region…but that is subject to change. As the afternoon progresses, peak heating occurs, and several other elements fall into place making the atmosphere more volatile, there will be, “AN INCREASED RISK FOR SUPERCELLS CAPABLE OF PRODUCING VERY LARGE HAIL AND A COUPLE OF TORNADOES. INITIALLY ROUGHLY NEAR THE CENTRAL AND EASTERN KANSAS/OKLAHOMA BORDER AREA…THIS ACTIVITY IS EXPECTED TO SPREAD NORTHEASTWARD/EASTWARD TOWARD THE LOWER MISSOURI VALLEY…BEFORE GRADUALLY WEAKENING WEDNESDAY NIGHT.” Now, let’s take a look at the SPC’s severe weather probability map.


SPC Probabilistic Outlook 1 7 April 2015As I’ve stated in previous posts, the purpose of the probabilistic map is to give people in the shaded areas an idea of their chances of seeing some kind of severe weather within twenty-five miles of a point. For parts of Kansas, Missouri, and Oklahoma shaded in red, there’s almost a one in three chance of some kind of severe weather occurring fairly close to any specific area. In the “hatched” area that’s outlined in black, there’s a higher probability of storms with a bit of extra power to their punch. The main thing to keep in mind is that if you are properly prepared for severe weather and aren’t doing anything foolishly risky, you’ll be just fine. If you live in a mobile home or will be working in a large room with a wide span roof, a barn, outbuilding, or outdoors (all typically areas that have an increased danger and are particularly vulnerable to even weak tornadoes or strong straight-line winds), you might consider planning today where you would take shelter if you’re in a warning. Outside of the red shaded area is our 15% and 5% probabilities regions which cover a large part of the southern plains to the Ohio valley. Keep in mind that storms may be very isolated in the 5% area, but can still pack quite a punch. So, to wrap up Wednesday’s outlook in lay terms…current SPC forecasts convey the possibility that some storms may get an early start. If they do form, expect them to be severe. Later in the day, the atmosphere will be primed for even more robust storms to form. Expect all modes of severe weather (aka: large hail, damaging straight-line winds, flash flooding potential, and tornadoes), numerous severe thunderstorm and/or tornado watches, and many warnings issued by your local National Weather Service office. Perhaps most importantly and once again, I can’t emphasize enough the importance of following official sources of watch and warning information.


Day 2 SPC Categorical Outlook 7 April 2015Thursday’s severe weather outlook will be just as challenging as Wednesday’s…perhaps even more difficult…but the same hazards will be possible, especially in the Slight and Enhanced Risk areas. From the SPC discussion, “WHILE RESIDUAL CONVECTION/CLOUD COVER COULD ALTER THE LOCATION OF — OR EVEN HINDER DEVELOPMENT OF — THE NEXT ROUND OF AFTERNOON/EVENING STORMS AHEAD OF THE ADVANCING SYSTEM…IT APPEARS AT THIS TIME THAT AMPLE DESTABILIZATION WILL OCCUR AHEAD OF THE FRONT IN THE WAKE OF PRIOR PRECIPITATION. In a nutshell, in spite of widespread storms Wednesday that will have used up a lot of “energy,” the atmosphere will have plenty of time to re-charge its batteries for another round of rowdy weather. This time, the focus will be from northeastern Texas to southern Wisconsin and southwestern Michigan. The Enhanced Risk introduced yesterday by the SPC still holds. In fact, population wise, there will be almost three times as many people in the Thursday Enhanced Risk area as there were on Wednesday in spite of the fact that it is a slightly smaller area. Now, let’s take a look at Thursday’s probability map.


SPC Probabilistic Outlook 2 7 April 2015Once again, the purpose of this map is to convey to you the probabilities of severe weather in or close to where you live. It’s not meant to scare or alarm anyone but, knowledge being power, to inform you so you can prepare for the possibility of storms and take necessary precautions if you’re in a warned area. The current thinking is that the highest probabilities will exist for much of eastern Missouri and most of Illinois…including the St. Louis and Chicago metro areas and surrounding suburbs. From the SPC discussion, “EXPECT SUPERCELL MODE TO EXIST — AT LEAST INITIALLY — WHICH THUS SUPPORTS INTRODUCTION OF AN SIGNIFICANT SEVERE-WEATHER AREA AND ENHANCED CATEGORICAL RISK ACROSS ILLINOIS/EASTERN MISSOURI AND VICINITY…WHERE LARGE HAIL AND DAMAGING WINDS APPEAR LIKELY ALONG WITH A FEW TORNADOES.” Just like Wednesday, supercell thunderstorms will exist with all the trimmings. Regardless of where you live in the Marginal, Slight, or Enhanced risk area, prepare accordingly for the possibility of all modes of severe weather. Friday could be active as well from Georgia to the DelMarVa region and Saturday in western Texas…but with two rather significant days of severe weather already on our doorstep, we’ll cross those bridges if/when necessary.

Before I wrap this up, I’d like to pass along some helpful information from the Storm Prediction Center. This graphic is an excellent resource and clearly explains the new severe weather risk categories.

SPC Outlooks Graphic 2Here are some more helpful links:

Let’s meet again tomorrow to take a look at the day’s severe weather setup. It’ll be a much briefer post than this one, and will only focus on tomorrow’s severe weather probabilities. Once again…follow only official National Weather Service sources of watch and warning information along with the broadcast meteorologists of your choice…plan accordingly if you are in a watch…take proper precautions if you are in a warning…and you’ll be just fine. It comes as a surprise to many…but regardless of what these storms throw at you…if you take the necessary safety precautions you’ll come through smelling like a rose.

See you good folks later…



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