How Wisconsin Weather T-Storm Outlooks Work
By Justin Poublon
May 13, 2019 - 12:13 PM CST | 781 0
Severe Weather Awareness
We are preparing for the 2019-2020 severe weather season. It's been slow so far with only 3 severe reports. Tornado Awareness week in mid-April was poorly timed. The severe weather season has started much later in spring the last 5+ yrs. In 2019 we hope to get people thinking about severe weather at the right time (not during a snow storm). Mother nature has a way of balancing things out. The law of averages and climatology suggests an uptick in severe weather could be just around the corner for late May and June. Seems like a perfect time to have the following discussion about severe weather prediction.
Wisconsin Weather T-storm Outlooks
You might be familiar with Storm Prediction Center Convective Outlooks? These are outsourced forecasts which have become widely used by the NWS & TV media. Before 2013 we used SPC outlooks too but they failed us at the worst times. We discovered that severe weather forecasting is best handled at the state level and that someone needed to step up take leadership and responsibility in Wisconsin. Since then we've taken t-storm forecasting very seriously since then spending years developing and perfecting our outlook system which we call "T-storm Outlooks". Last year we gave the system finishing touches and are now ready to share as an independent alternative to the SPC!
T-storm Outlooks are based on the interpretation of severe weather parameters with no spatial requirement. The system is designed to be flexible fitting the demands of individual storm events. We can forecast down to 2-3 counties or out to the entire state. Outlooks are created using our Storm Event forecasting system, then disseminated through the variety of services we offer here at wisconsinwx.com such as the Member Forecast. We have five zoneable t-storm threat levels: General, Strong, Severe, Significant, and Target. They escalate from General to Significant. Target is a bullseye or special marker to denote specific areas and can be used at any level. More detail below:
T-storm Outlook Criteria
Below is a detailed explanation of what our thunderstorm outlook types mean.
GENERAL (A)- Just a t-storm, rumble of thunder, embedded thunder. Lightning. Not too concerned. May produce heavy rain.
STRONG (B) - stronger than average. Storms that can briefly reach severe criteria, contain hail, gusty winds, or even a tornado. It's designed to be flexible. Not something you should ignore, but not something you should get totally worked up over either. We don't want to waste your time. Over the course of the season we may issue a "Strong" forecast 30+ times. Stay weather aware and don't be surprised if a warning gets issued.
SEVERE (C)- Thunderstorms fully capable of severe weather (hail >1" or wind >=58mph or tornadoes). When we use the "Severe" zone, you should take it more seriously than strong or general. We are activating your awareness and getting your attention. We take great responsibility and consideration at this level. A "Severe" forecast may only occur 15 or less times per year.
SIGNIFICANT (D)- Think worst of the worst. April 10, 2011 or May 30,1998. There is an obvious significant or widespread threat which needs to be respected. In the history of Wisconsin Weather (2013 to present) we haven't issued one of these yet. "Significant" zones will only be foretasted with the highest level of responsibility & consideration. If you see one of these, be ready.
TARGET (D)- Where we predict the biggest impact will be. Usually smaller in coverage spatially because we using it to add precision. It's NOT an enhancer of risk or extra bonus modifier, it's a combination of gut feeling (intuition) and model interpretation that comes with many years of storm chasing. In storm chasing it's referred to as "The Target Area", where the morning prior we can often identify where a tornado will occur down to the city. It bridges the gap between logic and intuition. It's a level of personalization you cannot find anywhere else!
In our system, "Strong" t-storms are capable of weak tornadoes. We assume all thunderstorms will produce heavy rain and lightning by definition. Severe criteria of hail (>=1") or wind gusts (>=58mph) are defined by NWS.
Thank you for reading. Please let us know if you have any questions!