The STP (Significant Tornado Parameter) has a bullseye right over Bloomington. STP = 1.6 for Monroe County tomorrow.
Here's a look at the Supercell Composite
Here is the (very long) discussion from the NWS;
NEAR TERM /Rest of Today/... Issued at 956 AM EDT Wed Mar 13 2019 Isolated to scattered light showers north of I-70 will continue to move east across the area and then out of the area by late this morning setting up for a dry afternoon. Still looking at mostly cloudy skies but with southerly flow highs should still climb into the 60s. Made some minor adjustments to the PoPs for the next few hours based on radar reflectivity trends but otherwise no appreciable changes made. Previous discussion follows... Table setting day for central Indiana and the Ohio Valley as the intense surface low currently organizing over Colorado strengthens and kicks out into the High Plains later today. Convection associated with storm system currently extended from western Kansas south into west Texas and will progress E/NE throughout the day steadily before moving into the region in a weakened state this evening into the overnight. Initially though...the focus will be on the area of showers over the mid Mississippi Valley. Residual dry air and subsidence through the boundary layer was creating a more hostile environment for rain to overspread the forecast area currently but the arrival of better lift and forcing aloft into the region over the next few hours will enable a steady top down saturation of the column through daybreak. Hi-res guidance brings the focus of most of the rain through the morning to areas mainly near and north of I-70 with the associated area of lift shifting northeast by early afternoon. The afternoon will see the initial transition for the region into the warm sector with model soundings and RH progs suggesting some sunshine and breezy southerly flow. Temps...spring-like feel expected for today...especially this afternoon as temperatures rise into the 60s with clouds scattering and southerly winds advecting warmer air into the Ohio Valley. Generally took a split of the model guidance with a closer lean to the cooler MAV as the MET guidance looks a bit aggressive with warming later today. && .SHORT TERM /Tonight through Friday Night/... Issued at 354 AM EDT Wed Mar 13 2019 Forecast challenges focus on impacts from gradient winds and severe storms Thursday as the weakening surface low tracks into the western Great Lakes by Thursday evening. While some murkiness lingers within the details which lowers confidence a bit...remain concerned about a period of high impact weather for central Indiana on Thursday. The initial axis of prefrontal convection that will expand east from the High Plains this morning should be located in the vicinity of the Mississippi River by early evening. While the focus for stronger convection will remain southwest of the forecast area from mid evening into the early overnight...expect scattered showers will overspread the region with some embedded thunderstorms as model soundings show elevated instability present above an expanding shallow inversion. Surface flow will be gusty with a strong 850mb jet nearing 70kts moving through the area late tonight...but the presence of the strengthening inversion should keep most of the stronger winds aloft from reaching the near surface layer through daybreak Thursday. The bulk of the hi-res guidance shifts most of the prefrontal convection set to impact the region tonight east of the area Thursday morning which when coupled with the dynamics present over the area later in the day...raises the ceiling for potential severe weather ahead of the occluded boundary during the afternoon. The initial low level jet will shift east of the area Thursday morning but a second jet will swing around the base of the upper low over the Plains and nose back into the region by the afternoon. Further up in the atmosphere...mid and upper level diffluence will increase with the presence of stronger jets in both layers over the Ohio Valley. 100+kts noted at 500mb Thursday afternoon is particular impressive. BL shear will steadily increase across the area into the afternoon and while strongest helicities in the 0-1km and 0-3km layer will be focused east of central Indiana...values remain more than sufficient to support severe convective development. With all of the factors present above...confidence is higher in a 2- 4 hour window during the afternoon where storms can develop and may quickly become severe as they rapidly move east. The key to whether the severe threat is isolated or more substantial will come down to available instability and moisture return in the dry slot between the prefrontal convection and the occluded front. Hi-res guidance has shifted more ominously in the direction of a potential greater threat with MLCAPE levels rising to near 1000 j/kg with dewpoints climbing into the mid and upper 50s within a narrow axis over the forecast area by 18-19Z. And while lapse rates aloft are a bit lower than would be desired to support a greater severe threat...there does appear to be enough of a steepening within the 700-500mb layer overlaid on the instability axis over the region. Should this come to fruition...the hi-res solution suggestive of a broken but potentially potent line of convection developing in the Wabash Valley around midday and moving east through the afternoon is becoming a real possibility. All severe threats would be on the table...damaging winds most prevalent considering the screaming winds aloft which any stronger cell would be able to tap into. However...the presence of long curving hodographs courtesy of the stronger low level helicity levels supports a tornado threat and wet bulb zero values at 6-7kft also present a hail risk. As mentioned above...there is still some detail that model runs later today and tonight will hopefully clear up...but the threat for severe storms is higher than it looked to be Tuesday. Stay tuned. Not to be lost in the growing severe threat is the continued concern for strong gradient winds outside of any convection due to the intense flow aloft. Remain reasonably concerned that there could still be periods Thursday where stronger boundary layer mixing can occur and support peak gusts rising into advisory criteria at a minimum. Again...the convective development could scuttle a more widespread and prolonged high wind threat and with some clarity still needed...will not introduce any headlines as of yet. Will however highlight the high wind and severe potential via an SPS. Brief postfrontal clearing Thursday evening will occur before clouds expand back into the region as the cold pool overspreads the lower Great Lakes. A trailing upper level wave and surface trough on the back side of the departing system Friday morning may bring a few light rain showers to primarily the northeast half of the forecast area on a brisk and noticeably colder day. Rain will end by Friday evening with skies slowly clearing from the west overnight as high pressure builds in. Temps...the possibility of some sunshine developing ahead of any convection Thursday raises the potential for temperatures to warm into the lower to possibly mid 70s over parts of the forecast area. Low level thermals support a model blend for highs. Will lean a bit closer to the cooler MET guidance for Friday highs which may end up being close to 30 degrees colder than Thursday highs. An overall model blend will work fine for lows through the period. && .LONG TERM /Saturday night through Wednesday/... Issued at 253 PM EDT Wed Mar 13 2019 Generally quiet weather is in store for central Indiana through the long term. Below normal temperatures are expected with an upper trough in place over nearly the eastern half of the U.S. Small chances for rain or even a brief rain/snow mix will slide through central Indiana through the period as weak upper waves make their way through the upper trough. High confidence in below normal temperatures, with low confidence in precipitation chances.
Well, shoot.
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