FXUS63 KIWX 141650 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 1250 PM EDT Tue Apr 14 2026 .KEY MESSAGES... - Isolated storms are expected this afternoon, especially along the US 24 corridor in Indiana. This evening and overnight, additional severe thunderstorms are expected. All hazards are possible. - Locally heavy rainfall is possible tonight into Wednesday which may result in some renewed areal and river flooding concerns. - Above normal temperatures will continue into this first part of weekend before a cold front brings below normal temperatures. && .UPDATE... Issued at 821 AM EDT Tue Apr 14 2026 Quick update to the grids to increase pops this morning based on current radar trends. The outflow boundary that was responsible for the uptick in overnight showers/storms has accelerated south, ending the threat of convection with that feature for the time being. An area of showers and storms was working through NE IL into NW Indiana with some new development ahead of it. It still remains uncertain how far east this will make it before weakening. No severe threat is expected with this activity, with locally heavy rain and maybe some gusty winds the main concern. Pops are highest in the west with a decreasing trend eastward with everything done by 18Z (if not before). Most likely the afternoon and early evening hours will be precip free as it will take time to destabilize once again. The outflow boundary is likely to modulate back north and could be a focus for some isolated storms. However, the greatest concerns still exist later this evening into the overnight hours with some signals indicating a somewhat increased threat for damaging winds as the upstream convection races east. Something to sort out in the afternoon package. && .DISCUSSION... Issued at 322 AM EDT Tue Apr 14 2026 A complicated forecast over the next 72 hours with several rounds of convection possible. Severe weather is possible each day through Thursday, with greatest confidence in scattered severe storms tonight. A convective complex is ongoing this morning across Wisconsin to the Lake Michigan vicinity with an associated outflow boundary extending from northeast Iowa to far southeast Wisconsin. This convective system has shown signs of both downwind propagation (eastward across east central Wisconsin) and upwind propagation (southeastward across south central Wisconsin). A strong low level jet feeding into this boundary should help sustain additional convection and southeast push of the outflow to southern Lake Michigan this morning. The tendency over next few hours may be for increasing trend in stronger cores to be displaced further behind outflow boundary due to some stronger downstream MLCIN across the southern Great Lakes. May need to watch for potential of isolated severe gust across primarily southern Lower Michigan this morning where more of a forward propagation may be favored, but a higher confidence potential does exist across NW IN/southern Lower MI for some 40+ mph wind gusts this morning. There have been some instances of small scale circulations developing at leading edge of the line across SE Wisconsin in QLCS type setup. If forward propagating system can reach southern Lower Michigan this morning cannot completely rule out similar evolution where westerly 30-35 knot 0-3 km shear vector has a more favorable orientation, but more limited instability with southward extent and more likely more parallel orientation of shear vectors to line through time may limit this potential. Another thing to monitor for today could be possibility of some small scale convectively enhanced short wave kicking northeast out of eastern Missouri this morning which could interact with the southward dropping outflow boundary across northeast or east central Illinois. Timing of this interaction would probably be late morning/midday period in unfavorable timing in terms of peak diurnal instability, but may need to watch for some uptick in convection across far west/southwest late morning given steep mid level lapse rates in place. Overall forecast thinking has not changed greatly for the primary severe weather threat period tonight. The outflow boundary will likely stall from NE Illinois into portions of IWX forecast area this morning, with instability recovery likely by late afternoon as this instability gradient is advected back northward via stronger low/mid level flow associated with convectively enhanced short waves to the southwest. Some isolated stronger storms are possible in vicinity of this instability gradient as it lifts north, but the possibility exists for weak CIN to hold. By this evening low level flow will back some to the southwest in response to a progressive wave across working across the Upper Midwest. This should yield a pocket of strong 925-850 mb moisture convergence from eastern IA into southern WI this evening which looks prime for convection initiation. Some lower confidence still persists in how convection will evolve tonight, whether a coherent cold pool and southeast propagating convective system occurs, or if storms remain just slightly elevated north of the composite boundary. Supercell wind profiles will likely be in place again by this evening as a stronger mid level jet lifts across northeast IL late afternoon with a wind/hail threat. Best combination of shear/instability still looks possible across NW IN/SW Lower MI where all severe hazards would appear more likely, although helicity profiles more favorable for tornadoes may be displaced west across northern IL where shear may be augmented by the low/mid level jet. As mentioned, still uncertainty with details in convective mode tonight, but overall key themes from previous forecast remain intact. Some heavy rain potential may materialize later tonight as potential outflow with southern Great Lakes storms could become more favorably oriented parallel to veering low level westerly flow. It is difficult to get into too much detail regarding severe potential for Wed/Thu as this be highly dependent on previous day's convective evolution and hard to resolve smaller individual smaller scale waves in this pattern. This situation is a complex one as stubbornness of longwave ridging to break down across eastern CONUS results in multiple upstream short waves shearing out as they encounter this ridge, and also an added increased susceptibility to convectively enhanced short waves from southern Plains/lower MS Valley. Instability profiles will likely be more limited for Wednesday and Thursday, although at least Wednesday should still feature respectable wind shear profiles that could allow for at least an isolated severe threat. Some small increase in instability is possible Thursday as upper ridge finally appears to be broken down by stronger mid level wave, but shear profiles may become a bit more marginal by this time. The extended period of above normal temperatures will continue through the first part of the weekend. Medium range guidance is starting to come into a little better agreement in timing frontal passage with next more substantial longwave trough for first part of the weekend. Much too early for details, but some strong/severe threat could accompany frontal convection Saturday depending on timing. May also need to watch for periods of strong synoptic winds this weekend in both pre-frontal and post-frontal environments. Cooler, below normal temperatures should build in for second half of weekend into next Monday, but residence time of this cooler air looks to be limited. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1243 PM EDT Tue Apr 14 2026 An outflow boundary, depicted on satellite as the interface of mid- level cirrus and sprouting fair-weather cumulus, will be the focus for isolated severe thunderstorms this afternoon. These storms may drift into KFWA near 00z. Not enough confidence in this scenario to move beyond PROB30. Additional TSRA, likely in a weakening state, is anticipated later in the period as a line storms drops southeast from MI. MVFR ceilings may linger beyond daybreak Wednesday. At KSBN, greater confidence in the timing of TSRA there which does pose a gusty wind threat. This will need to be monitored. Additional showers and perhaps a thunderstorm are possible near daybreak Wednesday as activity departs Illinois. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...None. && $$ UPDATE...Fisher DISCUSSION...Marsili AVIATION...Brown