Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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366 FXUS63 KIWX 160921 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 521 AM EDT Mon Sep 16 2024 .KEY MESSAGES... - Warm and dry conditions will persist this week with highs in the 80s. - Very low humidity values are expected this afternoon and Tuesday afternoon. Care should be taken with any fires. && .DISCUSSION... Issued at 256 AM EDT Mon Sep 16 2024 Another day where a persistence forecast is difficult to beat as unusually strong mid/upper ridge remains locked over the Great Lakes and Northeast thanks to pair of troughs over the western CONUS and north Atlantic. Thermal profiles will be very similar to yesterday and continue to lean on higher BC guidance given recent "overperformance" of high temps under sunny skies and very dry/well- mixed boundary layer. One minor change for today is that slight backing of low level flow to more easterly direction will advect an even drier airmass into the area. Low/mid 40s surface dewpoints over drought-stricken Ohio will advect into our area and afternoon RH values will likely drop even lower than yesterday with values around 20 percent possible. Wind gusts remain below 15 mph and 10-hour fuels remain relatively moist but finer fuels are drying quickly and care should be taken with any fires today. Tue will be very dry as well, particularly west of I-69. Forecast confidence remains low with respect to tropical system now developing off the Carolina Coast. The primary circulation has developed a bit further south than previously expected which seriously calls into question its ability to reach our area with even any remnant/light showers. Primary issue seems to be California upper low (just now getting better sampled by upper air data) which is deeper and slower than previous runs and limits its influence on the tropical system allowing resident ridge to hold firm. While some guidance members suggest a few showers reaching our far east late Tue/Wed this seems unlikely given incredibly dry/stable airmass in place and southward displacement of primary vort max. Latest NHC forecast also seems to favor the 00Z GFS which shows the tropical system stalling over the Appalachians Tue/Wed. Latest NBM came in entirely dry for our area but I did keep a slight chance mention in our far east Wed afternoon given prior forecast and low confidence. As previously discussed, any rain would be light and isolated anyway with no impact on worsening drought conditions. Temps during this period will be a bit lower with more cloud cover anticipated, though still expect low/mid 80s. Dry conditions return for the end of the week as broadening upper low drifts east and flow backs more E/NE, advecting drier air back into the area. Highs will also climb back into the upper 80s. There are some hints that the western CONUS trough will eventually make headway into our region early next week with an associated cold front and chance (albeit still low) for rain. Still plenty of time for forecast changes at this time range though. && .AVIATION /12Z TAFS THROUGH 12Z TUESDAY/... Issued at 518 AM EDT Mon Sep 16 2024 An upper level ridge was still over the region and was centered near Detroit early this morning. Large scale subsidence associated with this high will continue to prevent nearly all clouds from forming during this TAF period. Otherwise, low level east flow will persist with east to east/southeast winds around or under 10 kts. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...None. && $$ DISCUSSION...AGD AVIATION...Skipper