Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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686 FXUS63 KIWX 260445 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 1245 AM EDT Wed Jun 26 2024 .KEY MESSAGES... - Mainly dry overnight with a few showers and storms possible just prior to sunrise over northwest Indiana. Showers and storms become more numerous by midday. - Hot weather not expected through the weekend. High will be mainly in the upper 70s to mid 80s. - Next system is expected to bring chances for rain & storms late Friday into early Saturday night. && .UPDATE... Issued at 914 PM EDT Tue Jun 25 2024 Stable bubble and low level CIN persists across much of the area this evening due to effects earlier convection. Main area of thunderstorm development this evening has been in the vicinity of very strong instability axis draped from southwest Iowa into west central Illinois into southeast Wisconsin. Hi res guidance trends over past few hours have backed off on extent of convection through the early overnight locally. This trend appears reasonable as lagging upper forcing back to the west will likely provide little opportunity to overcome MLCIN limitations locally. By late tonight, more substantial upper trough should approach the western Great Lakes allowing weak low level convergence axis to shift across eastern IL/northwest IN. This should allow for weakening of stronger mid level lapse rates which are aiding in capped conditions this evening. While this may be supportive of more showers and thunderstorms, instability magnitudes should be tempered as a result. Have updated grids to reduce PoPs this evening into the early overnight, but an additional decrease may be needed given current trends. && .DISCUSSION... Issued at 252 PM EDT Tue Jun 25 2024 The initial round of storms has moved south along the outflow boundary where convection was becoming more scattered. Large CAPE values were indicated by SPC mesoanalysis from around 4000 to 5000 J/Kg south of the boundary from east central IL to west central IN. Massive hail cores were indicated in this area with 70 dBz to over 30K feet per radar. West of the forecast area over nrn IL and far southern WI, an EML was helping to produce extremely large CAPEs in a long band of >6000 J/Kg and a core over 6500 J/kg per SPC. Capping at the base of the EML should hold storms in check until late this afternoon and this evening per HRRR. Have reduced storm coverage over the forecast area into early this evening given the above reasoning. It still looks like a more marginal storm threat tonight, although locally heavy rainfall is possible along with possible subsequent flooding of mainly urban area. Otherwise, a break in the stormy weather is expected until late Friday when a pair of upper level systems are forecast to reach the area per GFS. BUFKIT soundings given a strong signal for the potential for heavy rain with precipitable. water values over 2.0 inches. && .AVIATION /06Z TAFS THROUGH 06Z THURSDAY/... Issued at 1238 AM EDT Wed Jun 26 2024 Clouds are streaming in off a decaying complex of thunderstorms moving through central IL. Showers are noted upstream over Wisconsin, drifting southeast, in the vicinity of a cold front there. This cold front will move through the TAF sites later today. Forecast soundings depict an ample environment for thunderstorms, but not nearly as robust as the storms less than 24 hours ago. Confidence is medium for the timing and there is some guidance that misses KSBN all together; low confidence on that solution. Ceiling trends will need to be monitored at KSBN early this morning with FEW036 in the 0354z observation. However, upstream observations are generally VFR and the in-house blend suggests only a 30% chance of MVFR ceilings early this morning. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...None. && $$ UPDATE...Marsili DISCUSSION...Skipper AVIATION...Brown