Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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958 FXUS63 KIWX 221824 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 224 PM EDT Sat Jun 22 2024 .KEY MESSAGES... * Relief from the heat arrives later tonight through Monday, but briefly returns on Tuesday when afternoon heat indices may once again near 100 degrees. * Showers and scattered storms expected to move in tonight with some potential for wind gusts in excess of 50 mph late evening into early overnight hours, best chances in nw IN and sw MI. * There are chances for thunderstorms Tuesday into Wednesday, though confidence regarding timing and intensity is low at this time. && .DISCUSSION... Issued at 224 PM EDT Sat Jun 22 2024 No changes in thinking from the previous forecast. Shortwave and associated deepening sfc low tracking east through the northern Great Lakes will drag a convective outflow and synoptic cold front southeast through the area tonight into Sunday. This will bring rain/storm chances and at least a brief reprieve from the heat. Dry, hot and somewhat breezy conditions will persist this afternoon into most of the evening given a capped/dry airmass with 700 mb temps near 10-11C. Attention late this evening into early Sunday turns to a line or cluster of deep convection organizing over eastern IA, southern WI and northern IL during the late aftn hours. Expectations are for this activity to undergo a general weakening trend with southeast progression as it outruns more favorable flow/forcing into much less downstream instability. With that said, if a more organized upstream convective segment is realized, the potential for isolated severe wind gusts would exist for areas mainly northwest of US 24 in the 03-07z window. Non-severe gusts in the 30-50 mph range appear more likely however with what should become an outflow dominant convective line. Opted to hold with likely to categorical PoPs otherwise along the pre-frontal feature early Sunday given ample pooled moisture. The main cold front then follows through Sunday morning into early Sunday afternoon with additional non-zero chances for scattered showers/storms. A turned over airmass and weakened frontal convergence behind the early AM composite outflow limits chances/coverage however. Drier and cooler air (seasonable) does settle in Sunday afternoon, and more into Monday when sfc high pressure briefly builds in with pleasant wx. Return flow quickly ramps back up in response to the next round of Upper Midwest and Northern Great Lakes height falls. This will allow a frontal system, first as a warm front and strong low-mid level theta-e advection late Monday night into Tuesday, followed by a cold frontal passage Tuesday night or Wednesday to potentially impact the local area. This type of evolution points to several MCS`s during this time which will no doubt modulate the positioning/timing of these frontal features and degree of heating/destabilization. Confidence in temps and shower/storm chances remain very low as a result at this forecast range. Higher confidence however in seasonable temps and dry conditions to follow for the second half of the week. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 121 PM EDT Sat Jun 22 2024 We`ll start the period with VFR conditions as high pressure keeps the area dry. However, a cold front arrives around midnight and this may provide showers and thunderstorms to the area. At this point, feel more confident in SBN getting thunderstorms and perhaps some MVFR VISBY reductions (in a tempo group). FWA appears more likely to receive showers as the line looks to become outflow dominant and lose its strength between SBN and FWA. Either way, have more confidence in a deck of MVFR CIGs starting just after 10z at SBN and around 12z at FWA. Moderation back to VFR will be possible in mid to late morning as the front continues to sink southward. Winds, initially southwesterly with gusts up to 25 kts today, will veer more westerly and northwesterly behind the front on Sunday with gusts up to around 25 kts once again. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for INZ005>008-012>015-020-022-023-103-104-116-203-204-216. Excessive Heat Warning until 8 PM EDT this evening for INZ009- 017-018-024>027-032>034. OH...Excessive Heat Warning until 8 PM EDT this evening for OHZ001- 002-004-005-015-016-024-025. MI...Heat Advisory until 8 PM EDT this evening for MIZ078>081-177- 277. MARINE...None. && $$ DISCUSSION...Steinwedel AVIATION...Roller