####018006810#### FXUS63 KIND 160707 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 307 AM EDT Fri May 16 2025 .KEY MESSAGES... - Strong and Severe Thunderstorms are expected this afternoon and early evening across Central Indiana. - All Severe modes are in play today, including damaging straight line winds, large hail, and isolated tornadoes. - Warm and humid with highs in the mid to upper 80s. - Cooler and quiet for the weekend, additional precipitation again next week && .SHORT TERM (Today and tonight)... Issued at 307 AM EDT Fri May 16 2025 Synopsis: Strong low pressure was found over the eastern Dakotas with a frontal boundary stretching east across northern MN, then southeast to lower Michigan and western Ohio. This was resulting in a warm and humid southwest flow over Indiana. GOES16 shows mainly a few high clouds in the wake of the convection that has pushed east to Ohio. Water vapor imagery shows a tropical plume of moisture streaming from the Pacific, across TX to KY and TN, while dry air and subsidence from MO/IL/WI was swirling into the upper low over the northern plains. Today and this evening - * Strong Storms, some severe, are expected this afternoon and evening * Damaging Straight line winds, Isolated Tornadoes and Large Hail possible. An active weather pattern is set up for today. Broad cyclonic flow around the deep upper low over the northern plains is expected to continue drive the weather across Central Indiana. We will remain within the warm sector, with moderate southwest winds in place across our area through the day, due to the moderate pressure gradient in place. Furthermore plentiful lower level moisture appears in place as dew points across area were in the middle and upper 60s. Looking aloft, models suggest a short wave pivoting around the upper low pushing across IL and nosing toward Indiana by late afternoon. A tight gradient in place aloft suggests strong dynamics with this feature. By late afternoon and into the evening models suggest a LLJ of 40-50 knts across the area. Further support for convection is found within the forecast soundings where steep lapse rates are displayed with convective temperatures in the middle 80s and afternoon CAPE values over 2400 J/KG. Helicity values also appear favorable for rotating updrafts, particularly across the southern half of Indiana late this afternoon and evening. HRRR continues to suggest thunderstorm development with this wave and instability initializing over IL late this afternoon, before pushing across Indiana during the 22Z to 02Z time frame. Although an isolated tornado cannot be ruled out anywhere in Central Indiana this afternoon and tonight, the best chances for tornadoes will be along and south of a Sullivan-Bloomington-Greensburg line, while straight line winds and hail appear to be the larger threat across points to the north. This situation will evolve as the day progresses and these areas could change in later analysis. Thus today is a day in Central Indiana where people will need to stay weather aware, listen for watches and warnings, have multiple ways to get weather information and ensure your are familiar with your safety plan. Overall, low pops to no pops will be used this morning, with near categorical pops late this afternoon and early evening when storms are expected. Highs again should be at or above persistence, in the mid to upper 80s. Tonight - In the wake of the storms by mid evening, cyclonic flow will remain in place, however the flow aloft will shift to westerly and mid level subsidence is seen flowing into the system. The arrival of westerly winds will allow dew points to fall to the 50s, resulting in a cooler and less humid air building across Indiana overnight. Models show ridging building across the northern plains states late tonight, leading to lee side subsidence over IA to build across IN as the night progresses. Thus skies should become partly cloudy in the wake of the storms overnight. Given the start of the change in air mass, lows in the the middle 50s will be expected. && .LONG TERM (Saturday through Thursday)... Issued at 307 AM EDT Fri May 16 2025 An exiting low will move off to the NE at the start of the period. Behind the low, broad riding across the central plains will initially dominate this weekend. Pressure gradients between the system will keep wind gusts to around 25-30 mph during the afternoon on Saturday but will be much calmer for Sunday. A more active pattern is then expected for much of the work week as an upper low, with a couple of short wave, moves through the region. Models are struggling to determine the details at this time as different solutions show varying tracks and strengths to the system. Confidence on temperatures is also low as it will depend on what side of the low central Indiana ends up with. Despite the uncertainties, it does look like there will be a good amount of moisture to work with, so could see a threat for multiple days of heavy rain, and temperatures probably below normal for much of the week. Towards the end of the long term and into the holiday weekend, a ridging pattern may set up to bring from the rain expected next week, but it is still too soon to have much confidence in this yet. && .AVIATION (06Z TAF Issuance)... Issued at 1221 AM EDT Fri May 16 2025 Impacts: - VFR conditions for much of the period. - MVFR to IFR conditions expected on late this afternoon and early evening with Thunderstorms - High confidence for afternoon and evening Thunderstorms, possibly severe. Discussion: Another active weather day is in store for Central Indiana. Strong low pressure over the upper midwest will provide SW winds and today and keep the TAF sites within the warm sector, bathed in warm and humid air. Strong SW flow aloft today along with a moist and unstable column will lead to thunderstorm development this afternoon. HRRR brings an area of thunderstorms across Indiana during the 21Z-01Z time frame. Have used a VCTS window to account for this. Some gusts of 40-50 knts will be possible due to the strong flow aloft. During this window, MVFR to IFR Conditions will be expected with the passage of storms. VFR should return in the wake of the storms as high pressure begins to build into the Ohio Valley. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Puma LONG TERM...KF AVIATION...Puma