Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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190 FXUS63 KIWX 211841 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 241 PM EDT Tue May 21 2024 .KEY MESSAGES... - Potential of strong to severe thunderstorms remains for late tonight, mainly west of I-69, but confidence is decreasing. The greatest threats are damaging wind gusts. - Warm and muggy conditions to be replaced by somewhat cooler and less humid air later this week into the Memorial Day weekend with some additional chances for showers and storms. && .DISCUSSION... Issued at 223 PM EDT Tue May 21 2024 A robust cumulus field has blossomed across the area today in the warm sector south of a front that is positioned just north of the MI/IN border. A few isolated showers or storms could pop up along this front, but have only kept a slight chance for this afternoon with soundings showing a capping inversion that will limit convection. The bigger concern is the potential for severe weather late tonight. Convection is ongoing ahead of a surface low across portions of Iowa into Wisconsin. CAMs show a QLCS developing upstream with the greatest tornado potential across Iowa, but there is less confidence into the southern Great Lakes given expected tendency to some outflow dominance through time, and the fact 0-3km shear will be more marginal with eastward extent compared to upstream across the MS Valley. The main shortwave will lift up into northern Michigan, while a second wave farther south will push across central Illinois into Indiana. As these waves diverge, some of the CAMs are also showing a split in the line of storms, meaning that our forecast area is less favored for severe weather, except for maybe the northwest corner. The latest SPC Day 1 Outlook maintains a fairly sharp gradient in severe potential from Enhanced Risk far northwest to Marginal Risk across southeast which falls inline with above factors and the gradient in convective environment expected through time. Given strong DCAPEs, some concern does exist if integrity of linear convection is maintained to have some damaging wind gusts late evening/early overnight across the west/northwest. Hail looks to be a lower end threat, and focused probably extreme west/northwest. The cold front stalls just east of the area Wednesday morning, and so there could still be isolated to scattered showers and storms, but the risk of severe weather is low. Broad trough remains over the region going into Thursday, so while the better moisture and energy will be to the southeast, the is still a chance of storms in our area south of US 24. Although transitory ridging moves in on Friday, with will also bring increasing moisture up from the south and a continued chance for mainly afternoon convection. A cold front comes through Friday night with the potential for moderate to heavy rain, and then Saturday should be dry and noticeably cooler with highs in the 70s. The more moderate temperatures will persist through Memorial Day as will periods of showers and thunderstorms. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 108 PM EDT Tue May 21 2024 Low pressure, currently over far northwest Iowa, will lift northeast through the TAF period. Showers and thunderstorms will develop ahead of a cold front later today, arriving over KSBN in a weakened state after 00z. The latest high resolution guidance are split whether or not this line survives to KFWA, but the general concensus seems to be "barely". So, I`ve offered -SHRA in lieu of -TSRA. Given the weakening trend in forecast guidance, I`ve trended a touch higher for forecast ceilings, favoring VFR ceilings through the TAFs. The cold front finally passes through near 12z offering a subtle wind shift toward about 220-240 degrees. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...Small Craft Advisory from 8 PM this evening to 5 AM EDT Wednesday for LMZ043-046. && $$ DISCUSSION...Cobb AVIATION...Brown