"Isolated" vs. "Scattered" Showers

Published: May. 8, 2007 at 9:54 PM CDT|Updated: Dec. 28, 2007 at 12:27 AM CST
Email This Link
Share on Pinterest
Share on LinkedIn


What's the difference between  scattered and isolated showers?


From a technical perspective--and in "weather talk"--isolated and scattered showers do indeed have different meanings.

The term "isolated" refers to showers that are few and far between, and the National Weather Service (NWS) defines "isolated" as displaying between 10% to 20% coverage.  In other words, when the forecast calls for "isolated" showers, only 10% to 20% of the forecast area will receive measurable rainfall within the forecast period -- most neighborhoods stay dry.

"Scattered" refers to the range of 30% to 50% coverage.  So, even with "scattered" showers, half or less of the neighborhoods are expected to "get wet."  For 60% and above, the terms most frequently used are "likely" and "numerous."  At 90% to 100% coverage, we often simply say something like "expect showers."

So .. in the simplest sense, if I call for "isolated showers" over the WAFB viewing area, statistics say that the chance of rain actually occurring in YOUR neighborhood is 20% ... or about 2-in-10 (assuming that my forecast is correct).

I've taken to using the term "spotty" for rain chances under 20%, although the "purists" will say that the term has not been "approved."  But I think it provides a mental picture that DOES distinguish it as being even less likely than "isolated."

Note that NONE of those terms reflect anything about the AMOUNT, intensity, or duration of the rain event -- they only apply to the extent of areal coverage.

Hope this helps!

Jay Grymes
Chief Meteorologist
WAFB Storm Team