Monday, June 16, 2014

Updated Severe Weather Discussion for Thursday, June 19

This is an updated severe weather discussion for Thursday, June 19.

This discussion will utilize only analog guidance, as there are some things that need to be clarified with the method as a whole (those caveats will be discussed as we move along). The image above shows tornado, damaging wind and hail reports from the top 15 dates whose conditions match up the best with those forecasted on Thursday. When atmospheric conditions similar to those on Thursday set up, the result is typically a severe weather event in the Midwest, as the image above shows. The hardest hit areas include Minnesota, Iowa, Wisconsin, Illinois, Indiana and Missouri. Phrased better, these states should be prepared to be affected by potentially significant weather conditions this Thursday if analog guidance verifies.

If we look at a probability map from the top eight most severe analog dates, we see that the analog guidance suggests that there may be a 60% or greater chance of severe weather in Illinois, Wisconsin, Iowa, and extreme southeast Minnesota. These percentages are definitely threatening, although considering most recent model guidance, these percentages may actually be too high, not only due to recent developments, but the natural tendency of the CIPS system to seemingly overestimate these events.

Use caution when utilizing this graph. This image shows the percentage of the top 15 analog dates that had a long-track tornado occur, where a long-tracked tornado is defined as a track over 30 kilometers. As you can see, this risk is anomalously high over north central Iowa, where nearly half of the chosen analogs had long tracked tornadoes occur. This may all seem frightening, but the caveats we discussed with the last image stand here as well- I don't think things will be this bad.

The threat for severe weather on Thursday will be examined in the next discussion.


1 comment:

Anonymous said...

Any idea about St. Louis for Thursday? Any severe?