417 FXUS63 KIND 092313 AFDINDArea Forecast Discussion National Weather Service Indianapolis IN 713 PM EDT Tue Sep 9 2025
.KEY MESSAGES...
- Gradually climbing temperatures through the week with near 90 degree highs by Saturday
- Dry weather outside of low 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 Wednesday)... Issued at 252 PM EDT Tue Sep 9 2025
Quiet weather conditions are expected through the period as surface ridging and a dry airmass remains in place. The center of the surface high pressure has shifted well northeast of the Ohio Valley which has allowed for winds to become more south or southeasterly. This along with plentiful sunshine helped temperatures warm well into the 70s today. Some locations could reach or briefly exceed the 80F mark over the next few hours. Deep mixing into an anomalously dry airmass aloft is promoting low dewpoints in the 40s though, making it feel comfortable.
A few upper waves moving through during the short term period will provide an increase in mid-high clouds at times. Expect very dry air in the lower levels to prevent any precipitation. High resolution guidance was blended into the forecast for dewpoints during peak heating as they more accurately simulate diurnal mixing. Low RH values each afternoon and dry fuels supports an elevated fire threat. The one caveat is winds remain light which should greatly limit the threat for fires to spread. More details on this threat can be found below in the fire weather discussion. Mostly sunny skies on Wednesday will continue the warming trend. Look for highs to reach the low-mid 80s.
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.LONG TERM (Wednesday night through Tuesday)... Issued at 252 PM EDT Tue Sep 9 2025
Wednesday Night and Thursday...
Models suggest strong ridging in place aloft over the plains while a quick moving short wave on the lee side of the ridge is expected to push across Indiana on Wednesday Night. Best forcing looks to pass during the evening hours. This system appears to be somewhat moisture starved. Time heights show some low and mid level saturation as a weak surface boundary passes, but subsidence remains in play aloft and the majority of the column appears to remain dry. Thus will expect some passing clouds on Wednesday Night into Thursday as this wave passes. Overall, there appears to be a non- zero chance for rain but confidence for any rain remains too low to be significant.
Thursday Night through Tuesday...
A warm and dry pattern will continue across Central Indiana through this time. The upper flow will remain highly amplified with the previously mentioned strong upper ridge over the plains building east to the Ohio Valley on Friday. This upper ridge is expected to persist across Indiana through Tuesday, gradually shifting from north-south orientation to a southwest-northeast orientation. The impact of this will allow for a strong surface high to set up over Quebec by Friday...shifting south to the east coast by late in the weekend, warmer and more humid air will begin to arrive across Central Indiana. Forecast soundings through the period suggest a dry column, with convective temperatures in the upper 90s along with minimal CAPE. Thus precipitation is not expected through the period due to a lack of forcing and moisture. Thus partly cloudy days and mostly clear nights along with above normal high temperatures will expected. Look for high temperatures mainly in the middle to upper 80s through Monday.
As mentioned in earlier discussions, this dry weather may leading more threatening fire weather and drought conditions in the weeks ahead.
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.AVIATION (00Z TAF Issuance)... Issued at 713 PM EDT Tue Sep 9 2025
Impacts:
- None
Discussion:
VFR conditions through the period.
An upper level wave moving through the region will lead to a modest increase in mid and high cloud cover overnight, which should help to prevent fog despite light winds.
Convective temperatures may be reached Wednesday, allowing some scattered fair weather cumulus to develop around 5kft.
Winds will be less than 10KT through the period, becoming easterly or possibly calm in spots overnight, before turning more southerly on Wednesday.
No obstructions to visibility are anticipated.
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.FIRE WEATHER... Issued at 259 PM EDT Tue Sep 9 2025
The lack of any significant rainfall over the last several weeks 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 elevated fire weather threat each afternoon as daily min RH values fall into the 20% range. Lowered afternoon dew points each day through next Saturday to the NBM10th percentile to account for such dry conditions and afternoon mixing bringing down even drier air to the surface. The one 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 kts through the period. It is worth noting that CPC has placed the majority of the Midwest and Mid Mississippi Valley in a slight risk for extreme heat for Sept 15-18th. 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...Melo LONG TERM...Puma AVIATION...Nield FIRE WEATHER...Melo
NWS IND Office Area Forecast Discussion