The National Weather Service (NWS) Storm Prediction Center (SPC) significantly escalated tomorrow’s tornado risk in Indiana with an outlook it issued at 1:30 p.m. ET today, April 1.
Approximately the southern three fourths of the state (shaded yellow on the Tornado Outlook map, above), which now includes Lafayette, Muncie and Fort Wayne, has at least 10% probability of a tornado within 25 miles of any point on April 2, according to the revised SPC outlook. A 10% probability is as much as 50 times what’s normal in Indiana at this time of year.
The same area also has a 10% or greater probability of a “significant” tornado, as indicated by black hatch marks on the Tornado Outlook map. NWS defines a “significant” tornado as one containing tornado wind speeds of at least 111 mph, capable of doing EF-2 damage on the enhanced Fujita scale.
All of Indiana continues to have a chance of hurricane-force straight-line thunderstorm winds tomorrow.
The red shading on the Severe Wind Outlook map above indicates that the entire state has at least a 30% chance of damaging thunderstorm winds or gusts of 58 mph or greater within 25 miles of any point tomorrow. The black hatch marks on the map indicate that the entire state also has at least a 10% probability that any severe thunderstorm that forms could have “significant” damaging winds or gusts of 75 mph or stronger, which could do as much damage as a weak tornado.
For most of Indiana, a 10% probability of significant damaging thunderstorm winds is 100 times what’s normal for this time of year.
As if the thunderstorm wind and tornado risks weren’t enough, the entire state also has an elevated risk of large hail, some of which could be two inches wide or larger. Northern Indiana (shaded in yellow on the Severe Hail Outlook map, above) has at least a 15% probability of one inch or larger hail within 25 miles of any point. The remainder of the state (shaded red) has at least a 30% probability of one inch hail. Black hatch marks on the Severe Hail Outlook map indicate at least a 10% probability of “significant,” two-inch hail.
The SPC outlook indicates a warm front will move through the state tomorrow, bringing warm, moist air and the atmospheric instability that severe storms require. A cold front with storms in front of it will then move in. Those storms could reach Indiana by late afternoon. Timing is important, because severe storms will be most likely where the warm front has had time to bring in that warm, moist air and any sunshine that occurs has had time to warm the earth’s surface. The warmer and more humid the air gets tomorrow where you are, the more likely severe storms will be.
If you’ll be in Indiana tomorrow, it is imperative that you have multiple, reliable ways to receive NWS watches and warnings, including severe thunderstorm warnings (because some thunderstorm winds could do as much damage as a weak tornado). Remember that emergency managers use the term “outdoor warning sirens” for what people commonly call “tornado sirens” because the sirens are not designed to be heard indoors. Also, most communities don’t activate sirens for severe thunderstorm warnings, even if the thunderstorm has hurricane-force winds.
Here’s a link to a blog about the top five ways to get severe weather warnings. If you don’t have a NOAA Weather Radio receiver, you have time to buy one, which I highly recommend doing.
As with Sunday’s weather, you might get lucky. It’s possible that none of these bad things will happen where you are. It’s wise, however, to be prepared, because the NWS says the probabilities are unusually high for the entire state.
