Outlook for Cobb County & region: isolated storms, heat index in 90s

A split image with thundercloud on the left, scorching heat in an urban setting on the right

The National Weather Service issued a hazardous weather outlook for Monday, June 17, 2024, for Cobb County and other parts of north and central Georgia.

Isolated thunderstorms are possible across the region, and the heat index is expected to be in the 90s.

In this article, you will learn:

  1. What is in today’s National Weather Service alert
  2. What counties are included in the alert
  3. What is meant by the terms “isolated” and “scattered”  
  4. What is meant by the heat index
  5. About the National Weather Service and what it does

What is in the statement?

The statement gives the following details:

This Hazardous Weather Outlook is for portions of North and Central Georgia.

.DAY ONE…Today and Tonight…

Isolated thunderstorms are possible this afternoon and evening

across the northeast Georgia mountains. Widespread severe weather

is unlikely.

Hot weather continues today, with heat index values expected to

reach 92 and 97 degrees in the afternoon. Precautions should be

taken to ensure adequate hydration and access to cooling.

.DAYS TWO THROUGH SEVEN…Tuesday through Sunday…

Isolated thunderstorms will be possible on Friday and into the

weekend.

What counties are affected?

The following counties are included in the hazardous weather outlook:

 Banks, Barrow, Bartow, Bibb, Bleckley, Butts, Carroll, Catoosa, Chattahoochee, Chattooga, Cherokee, Clarke, Clayton, Cobb, Coweta, Crawford, Crisp, Dade, Dawson, DeKalb, Dodge, Dooly, Douglas, Emanuel, Fannin, Fayette, Floyd, Forsyth, Gilmer, Glascock, Gordon, Greene, Gwinnett, Hall, Hancock, Haralson, Harris, Heard, Henry, Houston, Jackson, Jasper, Jefferson, Johnson, Jones, Lamar, Laurens, Lumpkin, Macon, Madison, Marion, Meriwether, Monroe, Montgomery, Morgan, Murray, Muscogee, Newton, North Fulton, Oconee, Oglethorpe, Paulding, Peach, Pickens, Pike, Polk, Pulaski, Putnam, Rockdale, Schley, South Fulton, Spalding, Stewart, Sumter, Talbot, Taliaferro, Taylor, Telfair, Toombs, Towns, Treutlen, Troup, Twiggs, Union, Upson, Walker, Walton, Warren, Washington, Webster, Wheeler, White, Whitfield, Wilcox, Wilkes, Wilkinson

What is meant by “isolated” and “scattered”?

The NWS defines “isolated” as follows:

A National Weather Service convective precipitation descriptor for a 10 percent chance of measurable precipitation (0.01 inch). Isolated is used interchangeably with few.

“Scattered” has the following definition:

When used to describe precipitation (for example: “scattered showers”) – Area coverage of convective weather affecting 30 percent to 50 percent of a forecast zone (s).

Isolated thunderstorms and scattered thunderstorms are two terms used to describe different distributions of thunderstorm activity within a particular area. The main difference lies in the extent of coverage and how the thunderstorms are spatially distributed:

  1. Isolated Thunderstorms:
    • Isolated thunderstorms are relatively rare occurrences that happen sporadically and are generally confined to a limited area.
    • These thunderstorms are often characterized by being few and far between, with significant gaps between individual storm cells.
    • Typically, isolated thunderstorms cover less than 20% of the forecast area.
    • Despite their isolated nature, these storms can still be intense and may produce heavy rain, lightning, gusty winds, and possibly hail.
  2. Scattered Thunderstorms:
    • Scattered thunderstorms are more widespread than isolated thunderstorms and cover a larger portion of the forecast area.
    • In a scattered thunderstorm scenario, numerous individual thunderstorms develop, but they are not continuous or widespread enough to be classified as a “line” or “cluster” of storms.
    • Scattered thunderstorms generally cover between 30% to 50% of the forecast area.
    • Although scattered thunderstorms are more widespread, they still leave considerable gaps between storm cells, and not everyone within the forecast area will necessarily experience a thunderstorm.

In summary, isolated thunderstorms are fewer in number and more localized, covering a smaller area with significant gaps between storms, while scattered thunderstorms are more widespread, covering a larger area with numerous individual storms occurring somewhat randomly across the forecast area.

What is the heat index?

The NWS defines the heat index as follows on its website:

The heat index, also known as the apparent temperature, is what the temperature feels like to the human body when relative humidity is combined with the air temperature. This has important considerations for the human body’s comfort. When the body gets too hot, it begins to perspire or sweat to cool itself off.

Chart from NOAA showing relationship between relative humidity and temperature in heat index

About the National Weather Service

The National Weather Service (NWS) is a part of the National Oceanic and Atmospheric Administration (NOAA).

The NWS describes its role as follows:

“The National Weather Service (NWS) provides weather, water, and climate forecasts and warnings for the United States, its territories, adjacent waters and ocean areas, for the protection of life and property and the enhancement of the national economy. 

“These services include Forecasts and Observations, Warnings, Impact-based Decision Support Services, and Education in an effort to build a Weather-Ready Nation. The ultimate goal is to have a society that is prepared for and responds to weather, water and climate events.”

>>> Read all the Cobb County Courier climate and weather coverage by following this link.