511 FXUS63 KIND 101847 AFDINDArea Forecast Discussion National Weather Service Indianapolis IN 247 PM EDT Wed Sep 10 2025
.KEY MESSAGES...
- Gradually climbing temperatures through the week with near 90 degree highs by Saturday
- Mostly dry weather outside of breif rain chances this weekend may lead to continued expansion of drought conditions into next week
- Dry fuels and low RH values each afternoon may lead to an elevated fire threat, but light winds should limit the overall threat
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.SHORT TERM (This evening through Thursday)... Issued at 247 PM EDT Wed Sep 10 2025
A combination of near surface high pressure and the passage of mid level shortwaves will make for a somewhat uncertain evening forecast of portions of central Indiana. This afternoon should remain rather mundane with a well mixed PBL and temperatures in the low 80s. However, focus shifts towards the passage of an amplified mid level shortwave this evening. Overall moisture content is lacking, but there is a narrow layer between 800-600mb of moisture convergence over southern IL and IN that could be enough for sporatic showers and even an isolated thunderstorm to develop after 22Z. This should generally be defined to the Vincennes, Shoals, and Washington regions with overall QPF below a tenth of an inch.
Even with a small sub-region receiving rain chances, the wave arrival should lead to broken mid level cloud cover over much of central Indiana this evening. These clouds will become more diffuse over NE central Indiana later tonight into tomorrow morning, of which could lead to a diurnal cooling boundary with NE portions of the area falling into the mid 50s and SW portions remaining in the low 60s.
Tomorrow will begin the arrival of longwave ridging from the west, of which will bring a warming trend and dry weather through at least early Saturday (more on this in the Long Term Section). Low RH values tomorrow afternoon and dry fuels will support an elevated fire threat. More details on this threat can be found below in the fire weather discussion.
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.LONG TERM (Thursday night through Wednesday)... Issued at 247 PM EDT Wed Sep 10 2025
Saturday Through Tuesday.
Forecast confidence remains low this weekend into early next week with a wide range in potential outcomes, well depicted by model spread in the 3 major ensemble guidances. The general synoptic pattern has a building ridge across the Central US, but the variance is associated with the potential for for ridge-riding diabatic shortwaves. While there will be some moisture return into the Ohio Valley by Saturday, instability values will be fairly meager, but a strengthening jet across the Upper Midwest will increase shear and create a favorable environment for thunderstorm organization. At this point, confidence is fairly high in at least some thunderstorms across the Great Lakes region, but confidence is low that any reach as far south as central Indiana.
The lack of confidence in Saturday to Early Sunday`s forecast provides cascading impacts for the rest of the long term, and therefor forecast confidence continues to decrease Sunday into Monday. General consensus in the overall airmass will remain warmer than normal, with the potential caveat of lingering upper level cloud cover. Currently leaning towards a more persistent pattern with the upper level ridge helping to push the aforementioned low pressure further east into the Northeastern states, but will have to continue to monitor forecast trends.
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.AVIATION (18Z TAF Issuance)... Issued at 107 PM EDT Wed Sep 10 2025
Impacts:
- None
Discussion:
VFR conditions are expected through the period.
An mid level wave will be moving through the Ohio Valley later today through tonight providing scattered to broken cloud cover between 10- 15kft. There is a low chance that some 4-6kft clouds reach KBMG this evening.
Winds will be less than 10KT through the period, starting off easterly, before turning more southerly Wednesday.
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.FIRE WEATHER... Issued at 247 PM EDT Wed Sep 10 2025
The lack of any significant rainfall since late August has resulted in abnormally dry and minor drought conditions to develop across Indiana. With little to no rain in the forecast for the next 7 days, confidence is increasing in an slightly elevated fire weather danger each afternoon as daily min RH values fall into the 25 to 35% range. The major factor keeping the fire weather threat lower is the lack of wind. Despite deep mixing, very weak low level flow should keep winds under 10 mph through the period. If no appreciable rainfall is observed this weekend, the fire weather threat may continue to increase and persist into mid month. Will continue to monitor the extended forecast for increasing fire weather concerns.
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.IND WATCHES/WARNINGS/ADVISORIES... None. &&
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SHORT TERM...Updike LONG TERM...White/Updike AVIATION...Updike FIRE WEATHER...White
NWS IND Office Area Forecast Discussion