Questions about sleet

Well, if it’s any comfort, U.S. meteorology professionals don’t use the word “sleet” in any official machine-readable report format (which use numeric codes for reporting precipitation type in a observation).

NOAA uses World Meteorology Organization code tables which never uses the word “sleet” to decode any precipitation type. The two phenomena discussed here are called “rain and snow or ice pellets” (code 23) for the one type of sleet, and “ice pellets” (code 79) for the others. (Plus some other codes for variations in intensity and content of snow, ice, and liquid rain.)

“Sleet” does not appear in the code table, almost certainly because of the ambiguity in customary usage.

https://www.nodc.noaa.gov/archive/arc0021/0002199/1.1/data/0-data/HTML/WMO-CODE/WMO4677.HTM

Living in an area that is prone to all of them, the practical difference that sleet and rain don’t cause problems with traction. Sleet acts as pebbles, so the roughness doesn’t slip – it’s only slightly more slippery than wet pavement.

Snow is more slippery. The flakes slide more easily so you have to be more careful.

Freezing rain is a bitch. It turns everything into a skating rink and driving is extremely dangerous until it’s melted. It also often causes black ice – a clear coating of ice on the the road that you can’t differentiate from wet pavement. It may be in certain patches, surrounded by wet pavement so you find yourself skating suddenly.

We had a lot of sleet yesterday in the DC area. Sidewalks were covered, buy easy to walk on. I was walking on a dead end street, so I decided to go onto the road. It turned out to be black ice, so I slid. I made the quick decision just to keep sliding until I hit a small pile of snow. Dunno why I didn’t figure that out until my late fifties.

Sleet is just hail that never had the makings of a varsity athlete.

I was in my 30s when I figured out that if I started to lose my balance on ice or snow, I needed to squat down as far as I could, and lean forward a little. I might end up sliding pretty far, but I wouldn’t take a tumble.

I don’t think I heard the term “wintry mix” until fairly recently (within the last two decades at least). ‘Sleet’ was always one of those words I saw in print more often than I heard anyone actually use it, and I wondered what it was as a kid. Its lack of popular use (compared to ‘snow’, ‘hail’, and ‘rain’) and uncertainty of meaning may be why ‘wintry mix’ has come about here.

Rain, hail, snow, all easy to identify. When little frozen bits fall from the sky they could have started as raindrops and frozen on the way down, or snow that melted and refroze on the way down, or little bits of ice forming in the clouds to small to be hail and too dense to be snow, or any of the options thawing and freezing multiple times on the way down from the clouds.

If it’s not rain or snow or hail I’ll probably just call it sleet.

It’s also possible for falling water to be super-cooled - that is, it’s below the freezing temperature of water but it’s still liquid because… well, physics I probably can’t explain well but such conditions are possible.

As soon as super-cooled water hits something it instantly turns to ice.

This can also account for an ice coating/sheet.

To further complicate things, super-cooled water can co-exist with conditions that produce sleet, freezing rain, and snow. So definitely it can be part of a “wintry mix”.

Same. But it is fairly obvious what it means: a mix of frozen and unfrozen water.

Growing up, i distinguished among:
Snow – flakes, of varying types with other names, mostly depending on the temp.
Slush – snow mixed with cold rain, or snow that has partially melted as it fell
Sleet – bits of ice with cold water
Dry sleet, or ice – bits of ice without any melted parts, which was quite uncommon.
Hail – a mythical frozen thing I’d read about, that was a larger ball of ice with layers
Freezing rain – mostly water that froze when it landed

For what it’s worth, any rain heavier than a light drizzle actually forms as ice and melts on the way down. It just takes way too long to form large drops of liquid water (longer than it takes to precipitate).

Here’s what they taught us in elementary school (Northern Virginia, early 1960s):

Rain: water coming out of the sky
Snow: fluffy white stuff coming out of the sky
Sleet: tiny ice pebbles coming out of the sky
Hail: bigger ice bits coming out of the sky

Not from elementary school, but more or less contemporaneous:
Slush: a mixture of snow and water on the ground
Freezing rain: really cold water coming out of the sky that freezes when it hits the ground

More recently:
Wintry mix: a mixture of two or more of snow, sleet, and at least one kind of rain as defined above

When my wife and I lived in Bristol VA/TN which is at about 1700 feet above sea level, we saw hail a few times a year, I’d guess. It would generally be pretty spherical up to about penny- or nickel-sized, but if it got any bigger than that, the shapes would get more irregular. And it wasn’t just a winter thing; some of the bigger hailstorms we had were well into spring.

But everywhere else we’ve been, hail has been a rarity. Not quite mythical, but more like a once-a-decade event.

I’ve never heard anyone but me say, “it’s slushing outside”. But everyone knows what slush is, and sometimes it falls from the sky, and “it’s slushing” seems descriptive to me.

I would call tiny ice pebbles “sleet”, but I expect sleet to be wet and nasty, not just little bits of ice. Probably because it pretty much always IS wet and nasty when it falls here. I suppose the new term is “wintry mix”, but we used to just call that “sleet”.

Oh, and I’ve now seen hail a couple of time. But when I was young I never had, outside of photographs in my weather book.

I’ve only seen hailstorms in the middle of summer, as far as I know. Either that or I’m not paying attention, but hail I associate with warm weather.

“Sleet” to me is frozen rain. It’s pin-prickly and annoying as hell if you’re running in it.

Where? Location might make a difference re timing of hailstorms as well as frequency. I really don’t think we had any hailstorms in Bristol as late as May, and certainly not in summer. But mostly in early to mid spring, March and April, now that I think about it.

So don’t run in it! :laughing:

Chicago. It’s something I associate with severe thunderstorms.

Same here. Hail is a mid-to-late summer thing here in Saskatchewan, with strong thunderstorms.

That’s why there is specialised crop insurance for hail damage. One bad hailstorm can wipe out an entire year’s crop, right at harvest time.

For some reason I want to call it that too. It’s those very tiny ice pebbles or snowflakes that are white and fall very slowly, but are completely round unlike a snowflake. I’m not sure if they are actually tiny ice pebbles or just snowflakes that are so small you can’t see any structure. I think I may think it as sleet because it isn’t obviously ice or snow and so I assumed it was sleet as the only other option.

For me, sleet does not fall slowly. It comes down at pretty much the same speed as rain. What you’re describing to me sounds to what I would call “powdery snow” (which is not, looking it up, the same as what skiiers call “powder.”) This may just be a personal way I use to describe it and is not widely used beyond my lexicon. I think what you’re describing is listed in Wikipedia either as “snow grains/granular snow,” though I don’t remember coming across those terms in the wild. I use phrases like “powdery snow” or “big/fluffy snow” to describe the flakes or lack of flake structure.

Actually, now that I think of it, I’m probably describing something else. I’m talking about teeny tiny snowflakes that look like they have no form, but they do accumulate. Are you describing something that happens on the verge of freezing temps? I’m thinking of snow in frigid temps, when flakes tend to be quite powder-like with smaller -to-non-discernible flakes.

We were grateful here over the past couple of weeks of succeeding winter storms when the freezing rain turned to sleet. Made for much better traction.