textproduct: Indianapolis

KEY MESSAGES

- Scattered to numerous showers and storms at times today

- Locally heavy rainfall possible today

- Above normal temperatures expected through Thursday.

- Mainly dry weather expected from Thursday onward.

FORECAST UPDATE

Issued at 1033 PM EDT Wed May 27 2026

Showers and storms have moved out of Central Indiana this evening as high pressure settles into the region from the north. Satellite imagery shows mainly skies already with a few observations around Indiana and Ohio indicating early signs of patchy fog development. The main focus with this evening's update will be the fog potential later tonight for portions of the region. Confidence on where and when fog develops is only marginal as it will be a race against the incoming drier airmass. Observations across Northern Indiana already show dew points in the 50s while most of Central and South Central Indiana is still quite saturated near the surface with dew points in the mid 60s to near 70. Thinking tonight could be a scenario where the best time for fog development will be earlier in the night, around midnight to 5am, before drier air pushes south. Winds are already near calm in spots and clearing skies should allow for good radiational cooling and resultant fog development. Thinking the best threat for fog and dense fog will be the counties along the I-70 corridor and southward, any location where heavy rain fell earlier today. Fog may persist toward and just after sunrise along and south of I-70, while drier air to the north helps eradicate any fog a few hours earlier. Will be monitoring the fog threat tonight and updating the forecast as needed.

DISCUSSION (This evening through Wednesday)

Issued at 250 PM EDT Wed May 27 2026

Today through tonight...

Surface low pressure located roughly over Knox County, per visible satellite imagery, is slowly moving eastward today. A surface trough extends from the low eastward into Ohio. This has been the source of numerous showers and thunderstorms this morning. Shower activity had largely diminished earlier this afternoon, however, as upper- level support exits eastward. Nevertheless, showers have once again begun slowly intensifying as sunshine warms the boundary layer leading to some weak instability.

ACARS soundings out of IND show meager lapse rates but rich moisture throughout the column. A deep warm cloud layer has lead to high efficiency rainfall production, and heavy rainfall rates have been observed (2 to 3 inches have fallen in a few localized areas). Though shower/storm activity is less numerous than earlier, some very localized totals of 1 to 2 inches are possible this afternoon.

Guidance shows surface low pressure weakening and drifting east this evening, taking any lingering showers/storms with it. Clearing skies are expected tonight as high pressure builds in from the north. This process may take some time, and low-level moisture from today's rainfall may take most of the night to scour out. If skies clear soon enough, and dry air from the high doesn't arrive until morning, then fog may develop tonight. Locally dense fog is possible.

Thursday through early next week...

Long range guidance continues to depict an Omega Block pattern developing aloft with ridging centered over the central CONUS and central portions of Canada. Meanwhile, surface high pressure builds into the region from the north. This will promote dry weather conditions late this week through early next week. Expect another warm day Thursday in the low 80s with highs then holding nearly steady in the mid to upper 70s through early next week.

A few models have hinted at the ridge retrograding slightly, allowing for a shortwave to move in aloft early next week. These solutions are outliers, but this will continue to be monitored as this could impact temperatures. Precipitation still appears very unlikely during the period.

AVIATION (00Z TAF Issuance)

Issued at 750 PM EDT Wed May 27 2026

Impacts:

- Showers and storms exiting the region to the south - Clearing trend this evening, leading to patchy fog overnight - Winds becoming light out of the N/NE overnight

Discussion:

Satellite and radar imagery shows convection moving south and east of all TAF sites across Central Indiana as high pressure moves in from the north. Watching the progression of the drier airmass advecting in with the High as there will be a fog threat during the overnight hours before the drier air arrives. Thinking the best threat for any fog will be in the Wabash River Valley and those areas which received heavy rainfall earlier today in Central and South Central Indiana. Fog may develop as early as midnight however confidence is low in exactly where fog may develop first. Added fog to the KIND and KBMG TAFs around and after 06z, but would not be surprised if some fog began developing earlier. This is a low confidence fog forecast as fog should begin to dissipate as drier air moves south overnight. Still wanted to mention it in the forecast as widespread rainfall has left the near surface layer fairly saturated this evening.

Expect winds to diminish to 5 kts or less out of the N/NE after sunset and potentially go calm at times overnight. During peak heating of the day tomorrow, NE winds of 08-12 kts is expected with gusts 12-18 kts at times. Expect VFR cigs and vis during the day tomorrow.

IND WATCHES/WARNINGS/ADVISORIES

None.