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Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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048 FXUS63 KIWX 120957 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 557 AM EDT Fri Jul 12 2024 .KEY MESSAGES... * There remains chances (20-30%) for widely scattered showers and storms today, best chances during the afternoon. * Periodic chances (20-40%) for thunderstorms Saturday night through Tuesday. There is the potential for severe storms, especially later Sunday night through Tuesday. * Hot and humid conditions are expected Sunday and Monday, dependent on storm chances. && .DISCUSSION... Issued at 251 AM EDT Fri Jul 12 2024 A broad upper trough axis, currently over Lake MI and IL, will track toward Lake Huron by this evening. Broad ascent on the southern flank, and building SBCAPE up to 1500 j/kg, will likely allow for widely scattered showers and storms to once again increase in coverage today. Focus will be near a subtle quasi-stationary low level boundary and outflows, best chances (20-30%) over east/northeast portions as a well-defined vort max pivots east through the lower Great Lakes. Similar to yesterday, any convection should remain disorganized and transient given poor mid level lapse rates and weak flow through the column. Subsidence and drying then builds in Friday night into most of Saturday behind the departing upper wave with dry/seasonable wx anticipated. Did continue to carry a low PoP over western IN Saturday afternoon as weakening elevated convection over IL could work in advance of an approaching warm front. A building instability reservoir does fold in on the northeast fringe of a building thermal ridge with hot/humid conditions and periodic storm chances Saturday night through Tuesday. Warm front and associated impressive MUCAPE gradient does lift through in this transition Saturday night into Sunday morning with initial chances for convection, best chances north as a weakening MCS may accompany a convectively aided disturbance tracking east-southeast through the Great Lakes. A capped and muggy airmass follows in behind the warm front into Sunday afternoon with heat indices possibly nearing advisory levels (100), dependent on potential convective cloud debris and boundary layer recovery if a more organized MCS tracks through in the AM. Additional episodes of convection (strong to severe potential) remains on the table later Sunday night through Tuesday, though confidence on timing and impacts on temps are always of lower predictability in these "ring of fire" west-northwest flow summer regimes (hence the broadbrush chance PoPs through the period). This pattern breaks down beyond Tuesday as an upper trough drops into the Great Lakes forcing the active boundary and instability off to the south. && .AVIATION /06Z TAFS THROUGH 06Z SATURDAY/... Issued at 555 AM EDT Fri Jul 12 2024 Weak flow will persist over the area with nearly saturated conditions at ground level at the onset. Light fog was in the VCNTY of the terminals and may briefly encroach upon the terminals early this morning. Otherwise, little if any winds should be the rule. Kept VCTS at FWA given the diurnal favorability for convection there. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...None. && $$ DISCUSSION...Steinwedel AVIATION...Skipper