Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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018 FXUS63 KIWX 130021 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 821 PM EDT Wed Jun 12 2024 .KEY MESSAGES... - Chances severe storms late Thursday & Thursday evening with strong gusty winds and large hail. - Hot & humid Sunday through Wednesday; highs around 90 to 95 with afternoon heat indices 95 to possibly as high as 105. - After Thursday, storms will again be possible during the afternoons and evenings Sunday through Wednesday. && .UPDATE... Issued at 749 PM EDT Wed Jun 12 2024 A lake breeze-enhanced narrow convergence zone from north of KRZL to near KGSH to KOEB is associated with some cumulus with modest vertical growth. Other than this low level convergence, not much else from a synoptic standpoint in terms of forcing. Over next hour or two cannot discount at least potential of an isolated shower along this axis. Looking upstream, an MCV tracking across southern Wisconsin/northeast Illinois has a small area of decaying convection associated with it, along with an outflow boundary. Heading into the non-favored diurnal hours this evening in terms of instability, would expect a continued weakening trend with a low end chance of a few showers affecting far NW portions of the area late evening. By late tonight, westerly flow will strengthen that should allow for more notable positive low level theta-e advection from the Mid MS Valley. This will result in some potential of isolated showers and thunderstorms late tonight into early Thursday. && .DISCUSSION... Issued at 1233 PM EDT Wed Jun 12 2024 Surface high pressure stretching the length of the Appalachians will keep the region mostly dry through tonight. However, a progressive westerly flow aloft could bring another weak wave across the northern portion of the forecast area later this evening with a few showers or storms. Another disturbance will then move into Michigan around sunrise tomorrow, but is generally expected to remain north of the area. The bigger concern is a storm system developing over the great plains that will move in late tomorrow afternoon and evening. Wind shear will be favorable for organized linear convection with around 40 kts of bulk shear. Moisture and instability will also be on the rise with dewpoints in the mid 60s. The highest CAPE will be across northwest Indiana into southwest Michigan topping 2000 J/kg surface based. CAMs are in decent agreement bringing storms in from the Northwest as early as 4 PM EDT. SPC keeps a slight chance of severe storms across this area with the greatest threats being wind and hail, although cannot rule out a few isolated tornadoes. The severe threat should end before midnight when the convection then transitions into more of an MCS with a marginal risk of excessive rain. Upper level ridging starts to shift eastward from the plains on Friday and then builds on Saturday. It will therefore be warm and dry to start the weekend with highs in the low to mid 80s. Heat and humidity increases on Sunday and highs will be in the 90s. A shortwave could also bring some storms Sunday afternoon or evening. Moisture increases further on Monday with southerly flow, and heat indices will climb to near 100 degrees. Pop-up afternoon convection will also be possible. Similar conditions are expected on Tuesday and Wednesday. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 749 PM EDT Wed Jun 12 2024 A weak lake breeze combined with southerly flow on western periphery of Mid Atlantic anticyclone has allowed for a narrow axis of sfc convergence across northwest/portions of north central Indiana. Best low level moisture pooling along this convergence axis appears to have shifted just east of KSBN, and would expect any early evening isolated shower development to not affect the terminal. MCV remnant convection across southern Wisconsin will also need monitoring this evening. This convection has been in a decaying state and would expect this trend to continue into a non- diurnally favored time late this evening as it reaches southern Lower Michigan. A few showers are possible late evening/early overnight across far northern Indiana on southern periphery of this vort max, but will not include with 00Z TAFs given expected weakening trend. Additional isolated showers are possible late tonight/early Thursday as westerly flow upstream strengthens allowing for uptick in low level theta-e advection. Greater potential for storms to affect terminals still appears to be late Thursday afternoon into Thursday evening as an axis of moderate instability noses into northern Indiana an advance of a stronger short wave. Best chances of storms appear to be in the 22Z-03Z period, and will handle this period in greater detail with next few issuances. Some of these storms may have some strong thunderstorm outflow winds associated with them. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...None. && $$ UPDATE...Marsili DISCUSSION...Cobb AVIATION...Marsili