HUM 20260718

Update No. 1

Posted 6:45 am on Friday, 17 July 2026

Summary of Changes from prior message:

• The updated NWS briefing expands the severe-weather concern from Saturday alone to include both Friday and Saturday, with more specific timing of 3:00–10:00 PM each day.

• A new Marginal Risk—Level 1 of 5—has been added for today, with damaging winds and locally heavy rainfall capable of isolated flash flooding.

• A few strong to severe storms are possible Friday afternoon and evening, while Saturday retains a Slight Risk—Level 2 of 5, with damaging winds and locally heavy rain possible during the afternoon and evening.

Additional Information:

• Canadian Wildfire Smoke: Ohio EPA has issued a statewide Air Quality Advisory through midnight Friday. Southwest Ohio is expected to reach the Unhealthy for Sensitive Groups range because of fine-particle pollution from Canadian wildfire smoke; brief hourly conditions could be worse.

• Air-Quality Impacts: Haze, reduced visibility, and respiratory irritation are possible. Children, older adults, outdoor workers, and people with heart or lung conditions should reduce prolonged or strenuous outdoor activity and monitor for symptoms.

• Overall Risk: Clinton County is within a Marginal Risk—Level 1 of 5, meaning isolated, generally short-lived severe storms are possible.

• Damaging Wind: Clinton County is within the 5% wind-probability area. This represents a 5% chance of severe wind—58 mph or greater—within 25 miles of a point during the outlook period.

• Tornado: No tornado probability area is identified over Clinton County, indicating the probability remains below SPC’s 2% contour threshold.

• Large Hail: No hail probability area is identified over Clinton County, indicating the probability remains below SPC’s 5% contour threshold.

• Significant Severe Weather: No hatched area is present, meaning SPC is not currently highlighting an elevated probability of winds at least 75 mph, hail at least two inches, or significant tornadoes.

• Storm Character: Stronger storms are expected to be multicell clusters rather than organized supercells. High atmospheric moisture and instability could support isolated damaging gusts and locally heavy rainfall, but weak wind shear should limit storm organization and duration.

Friday Weather Graphic:

Saturday Weather Graphic:

- - - - ORIGINAL HEADS UP MESSAGE (HUM) - - - -

Posted 6:40 am on Thursday, 16 July 2026

This is your Heads Up Message for Saturday, 18 July 2026. Remember, this remains a Day 3 outlook. Forecast timing, storm coverage, and potential impacts may change before Saturday.

SUMMARY

Clinton County is within a SLIGHT Risk—Level 2 of 5—for severe thunderstorms Saturday, with a few severe storms possible during the afternoon into the evening. Damaging wind is the primary concern and could affect trees and power lines, temporary outdoor structures, vertical amusement rides, and unsecured decorations or equipment.

THREATS

• Damaging Winds – Primary concern. Stronger storms may produce wind capable of downing tree limbs and power lines, causing isolated power outages, and damaging tents, canopies, inflatables, signs, vendor displays, vertical amusement rides, and other temporary structures.

• Frequent Lightning – Expected with any thunderstorm. Lightning may interrupt outdoor activities even when a storm does not become severe. Lightning can occur before the heaviest rain reaches an event location.

• Large Hail – Secondary concern. The Storm Prediction Center indicates that large hail may be possible with initial storm development across Ohio before storms organize into clusters with a greater damaging-wind threat. NWS Wilmington currently identifies damaging wind as the primary local concern.

TIMING

• Saturday morning: No primary severe-weather window is currently identified, but organizers should review updated forecasts before event setup or opening.

• Saturday afternoon: Primary period of concern for Clinton County. Thunderstorms may begin developing, and a few could become severe.

• Saturday evening: The severe-weather risk may continue as storms organize into clusters and move south and east.

• Exact arrival time remains uncertain. Outdoor events should be prepared to act during the afternoon rather than waiting for storms to reach the immediate area.

FORECAST CONFIDENCE

NWS Wilmington currently lists medium confidence in the damaging-wind threat but notes uncertainty regarding the exact timing of storms. A Slight Risk means scattered severe storms are possible; it does not mean every part of Clinton County will experience severe weather.

Confidence should improve as Saturday approaches and newer forecast information becomes available.

CONSIDERATIONS FOR EVENTS

• Assign someone to continuously monitor weather conditions, alerts, and forecast updates during the event.

• Review weather-related event messaging in advance, including what may need to be issued, who has approval authority, and who is responsible for distributing each message.

• Clearly identify who has the authority to pause activities, close attractions, or direct attendees to shelter.

• Identify sturdy shelter locations and determine how long it will take to move attendees, vendors, staff, and volunteers. Tents, canopies, picnic shelters, and similar structures do not provide protection from lightning.

• Establish action points before the event begins, including NWS warnings, thunder or lightning nearby, and manufacturer or operator wind limits.

• Review shutdown, lowering, and securing procedures for vertical amusement rides, inflatables, stages, elevated equipment, tents, and canopies. Allow enough time to complete these actions before winds arrive.

• Secure or remove decorative lawn ornaments, signs, flags, umbrellas, temporary fencing, vendor displays, trash containers, and other loose outdoor objects.

• Determine how weather instructions will be communicated to attendees, including those in parking, camping, livestock, vendor, or activity areas.

• Do not wait for rain to begin before seeking shelter. Outdoor activities should remain suspended until at least 30 minutes after the last thunder is heard.

BOTTOM LINE

The current severe-weather concern is focused on Saturday afternoon into the evening, rather than the entire day. Outdoor activities do not necessarily need to be canceled at this time, but organizers should remain flexible and be prepared to pause operations, secure vulnerable equipment, and move people to sturdy shelter with adequate lead time.

Clinton County EMA will continue monitoring forecast updates and will provide additional information if the expected threats or timing change significantly.