


Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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505 FXUS63 KIWX 090548 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 148 AM EDT Wed Jul 9 2025 .KEY MESSAGES... - Seasonably warm & humid conditions will persist, with daily maximum heat index values in the upper 80s to around 90 degrees. - An active weather pattern will return on Wednesday, resulting in frequent for showers and thunderstorms over the next several days. - Severe weather chances are expected to remain low. However, locally heavy rainfall may become a concern this weekend. && .DISCUSSION... Issued at 130 PM EDT Tue Jul 8 2025 An active weather pattern will return to the area over the next several days with the passage of numerous mid and upper-level disturbances. A well-defined short wave trough axis will traverse the area this afternoon and evening, with numerous showers and storms likely developing upstream across IL. Most high-res models suggest this activity should dissipate or at least weaken significantly prior to reaching our western zones after 00z w/ the loss of diurnal instability, but nonetheless a few light showers will remain possible through the night across the entire CWA. Isolated to widely scattered storms will be a possibility again during the late afternoon and early evening hours on Wednesday with a subtle ripple in the flow / weak vort max on the back side of the aforementioned trough. After a brief lull during the day on Thursday, models suggest a rather complex pattern evolution w/ two highly energetic southern and northern stream disturbances interacting over the central plains. While the exact evolution of this pattern remains a bit muddy at this time, precipitation chances should increase markedly especially from Friday night through Saturday. Forecast vertical profiles appear extremely moist with very tall/skinny CAPE profiles, supporting a threat for locally heavy rainfall which is highlighted in the latest WPC Days 4/5 excessive rainfall outlooks. At this time, this does not appear to be a widespread heavy rain event though w/ the latest NBM spectrum suggesting only around a 20% chance of exceeding 0.5 inch QPF across much of the area despite a few deterministic runs hinting at much more robust totals. Otherwise, seasonably hot and humid conditions will persist w/ the more substantial humidity arriving in time for the weekend which may help push heat indices into the lower 90s. && .AVIATION /06Z TAFS THROUGH 06Z THURSDAY/... Issued at 145 AM EDT Wed Jul 9 2025 A convectively enhanced short wave will continue to track across northern Indiana this morning with some scattered showers and isolated thunderstorms. Instability is a limiting factor however, with CIN for near sfc based parcels persisting. Confidence at this time is too low for inclusion of showers at terminals overnight, but trends will continue to be monitored through the daybreak. The best chance may be at KSBN where remnant MCV feature across NE Illinois could speak some early morning showers/isolated storms. Broad upstream upper trough will take a baggy sfc trough/cool front into northern Indiana today with a diurnal uptick in showers and embedded storms expected. This potential appears to affect both terminals and will continue idea from previous forecast in PROB30 mention through mid/late afternoon at KSBN, and mid afternoon through early evening at KFWA based on frontal timing. Drier low level air will eventually seep into northern Indiana tonight behind this front. This setup could yield some patchy shallow fog development across NE Indiana early Thursday morning but this will be addressed in next TAF issuance. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...None. && $$ DISCUSSION...Hammer AVIATION...Marsili