Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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450 FXUS63 KIWX 161933 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 333 PM EDT Sun Jun 16 2024 .KEY MESSAGES... - Areas close to Lake Michigan may see showers and thunderstorms between 10 pm and 4 am. Gusty winds and heavy rain will be the main concerns. - An Excessive Heat Watch remains in effect due to an extended period of hot and humid conditions. - Widely scattered afternoon and evening thunderstorms are possible Monday and Tuesday. && .DISCUSSION... Issued at 226 PM EDT Sun Jun 16 2024 The main story of the upcoming forecast period remains with hot and humid conditions already starting today and expected to further intensify, especially in the second half of the week with afternoon/evening heat indices in the 95 to 100 degree range and limited cooling during the overnight hours. Extensive coordination with surrounding offices as resulted in a continuation of the Excessive Heat Watch with the reasoning to be explained below. Regardless of what headlines may or may not exist, the extended period of heat and humidity will still pose an issue to those working or playing outdoors, those without adequate means to cool off (both day and night) and those with health problems made worse by the hot and humid conditions. Afternoon temperatures have climbed into the upper 80s with some potential for far SW areas to still touch 90. A large gradient in dewpoints was also in place across the area with upper 40s far NE to mid 60s SW. Overnight lows for tonight and much of the upcoming week will end up in the lower to middle 70s, making for rather unpleasant sleeping. While many areas will remain dry into at least Monday morning, far NW locations may see a chance for showers and thunderstorms later this evening into the overnight hours as a well defined mcv heading towards the Quad Cities, continues to move ENE and force additional showers and storms across northern IL. SPC upgraded to a slight risk ahead of this feature with the marginal risk being expanded slightly to roughly a DeMotte to South Bend to Kalamazoo line. Models are varying somewhat on the strength of storms as they pass over Lake Michigan and enter SW Lower MI/far NW Indiana and move ENE. Some models also expand the precipitation further south to at least US-6 and maybe even a bit more. For the moment have limited pops to slgt chc to chc and will defer any further increases to the evening shift. Gusty winds and heavy rain will be the main concerns. While the hot and muggy conditions are fairly straight forward, finer details in cloud cover, chances for showers/storms and mixing out of dewpoints with drying ground conditions lead to challenges in upgrading the watch to a Heat Advisory or Excessive Heat Warning. The greatest concerns for the heat still exist moreso Wednesday and beyond as the cumulative effects of the heat as well as lack of rain chances all lead to greater impacts. Weak disturbances and subtle forcing mechanisms could help spark widely scattered showers and thunderstorms during the afternoon and evening hours of Monday and Tuesday. One mechanism could be any boundaries that may be left over from the convection tonight. While it will be unstable and generally uncapped, hard to assign more than a slgt chc to maybe chc of convection at this point. Any storms that manage to form will not move much and with the moist conditions will produce very heavy rain and maybe locally gusty winds. Models do key in on a disturbance working north Monday night that may help increase chances for showers and storms, but think models may be overdone somewhat with general consensus of offices being to keep pops silent or slgt. Chances for showers and thunderstorms may increase over the weekend as the ridge axis orients more west to east and sinks some. Best chances may exist Sunday but if these don`t pan out, then the potentially dangerous heat will persist. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 132 PM EDT Sun Jun 16 2024 With a southeast CONUS mid level ridge to our southeast, an MCV was noted on morning satellite images and this is expected to graze our northwest between the timeframe of 3 to 7z. How far eastward it can get is still in question and agree with the sentiment of the previous shift with its prob30 for TSRA. Inside the 9hr window with this issuance, will look to include a VCSH mention during this time frame to still keep it on the radar so to speak. Otherwise, VFR conditions are expected, especially at FWA, where more confidence in capping/ dry air winning out remains away from the forcing of the MCV. Winds become increasingly more southwesterly from southerly behind a warm front passing through tonight. Gusts to 15 to 20 kts cannot be ruled out during the peak mixing time frame of the afternoon. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...Excessive Heat Watch from Monday morning through Friday evening for INZ005>009-014-017-018-024>027-032>034-104- 116-204-216. Air Quality Alert until midnight EDT tonight for INZ020. OH...Excessive Heat Watch from Monday morning through Friday evening for OHZ001-002-004-005-015-016-024-025. MI...Excessive Heat Watch from Monday morning through Friday evening for MIZ078>081-177-277. Air Quality Alert from midnight tonight to midnight EDT Monday night for MIZ078-177-277. MARINE...None. && $$ DISCUSSION...Fisher AVIATION...Roller