How in the world can it rain below 32 and snow above 32??

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frigidice77

How in the world can it rain below 32 and snow above 32??

#1 Postby frigidice77 » Sun Dec 05, 2010 1:48 pm

I have heard of a time before where it was raining at 26 degrees in nebraska.Freezing rain lower than 26. Also what about snow above 36 degrees. How is it possible?
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#2 Postby RL3AO » Sun Dec 05, 2010 1:50 pm

If you have a thin layer of cold air near the ground but the rest of the lower atmosphere is above freezing, the rain won't have time to refreeze before hitting the ground. With snow its the opposite. Warm air near the ground but snow doesn't have enough time to melt before making it to the ground.
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#3 Postby JonathanBelles » Sun Dec 05, 2010 2:29 pm

It can be raining as low as 25 degrees and snowing as high as 45 degrees if the themodynamics and moisture contents in the atmosphere above you are just right.
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frigidice77

#4 Postby frigidice77 » Sun Dec 05, 2010 2:34 pm

Your kidding right about the snow with 45 degrees.
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#5 Postby Extremeweatherguy » Sun Dec 05, 2010 3:04 pm

frigidice77 wrote:Your kidding right about the snow with 45 degrees.
It is extremely rare, but yes it technically can snow at such warm temperatures. For a technical explanation to why this is the case, see the link posted below.

http://www.sciencebits.com/SnowAboveFreezing
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#6 Postby vbhoutex » Sun Dec 05, 2010 3:34 pm

frigidice77 wrote:Your kidding right about the snow with 45 degrees.

I have seen snow at 40f, and sleet at 47f. I've seen rain right at 32f but as it cooled the atmosphere it changed over to snow.
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#7 Postby frigidice77 » Sun Dec 05, 2010 4:04 pm

Wow very interesting facts about snow and rain. I learned a lot today. Lol.
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Re: How in the world can it rain below 32 and snow above 32??

#8 Postby PTPatrick » Sun Dec 05, 2010 10:27 pm

I have seen in snow at 50 here in Denver...but it was with a very unstable airmass, and the temperature litterally plummeted in to 30s as the snow fell. Snow above freezing is quite common at higher altitudes such as here in Denver. It just often doesnt stick. On the other hand, "freezing" rain is rare at altitude, simple because we are "above" the layer of the atmosphere that is often below freezing when the uppers are warmer. We are in what is the warmer layer(usually above 850 mb) so to speak. We do sometimes get freezing fog and drizzle though, but that is different than freezing rain.

Freezing rain does often occur in mountain valleys. Cold air settles in mountain valleys...to the extent that I have seen it be in the mid 20s at 7000 ft in the frazier valley, and 35 up toward berthoud pass. In that particular situation, precip was falling as sleet and freezing rain in the valley, rain around the pass, and oddly enough, snow further east in the foothills on the other side of the moutains. It was a crazy drive :) I believe a warmer moist air mass moved inf rom the SW in that case and displaced cold air west of the divide, while cold canadian air stayed east of the divide.

Bottom line, the atmosphere changes temp as you go up, and while to an extent, higher is usually colder, it isnt always the case.
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#9 Postby TeamPlayersBlue » Mon Dec 06, 2010 1:58 pm

Ive seen snow in Houston at 40F when i was 9 years old. (1994 i think) Huge flakes too
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#10 Postby Gladstone » Wed Dec 08, 2010 3:37 am

"Warm snow" is not uncommon in the Mid-Atlantic during late March or early April. I spent about 45 years in the Maryland suburbs of D.C. and have several times seen snow with temps 40F or more (it comes down in huge flakes.)

On the other side, I recall living in Georgian Towers on Colesville Road in Silver Spring, Maryland in the late '70s when we had a heavy rain with a temp of 27F. It was just awful.

Tim in NC
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Re: How in the world can it rain below 32 and snow above 32??

#11 Postby wxman57 » Wed Dec 08, 2010 8:23 am

Let's see if I can explain it using a metaphor of common, everyday items. Consider the ground outside to be where you observe whether it's snowing, sleeting, or raining. Now, consider your freezer (in your kitchen) to be way up in the clouds where the precipitation forms.

It's 95F outside and you go to your freezer, crack open a few ice trays, put them in a glass, then go outside and throw them on the ground. You now have ice on the ground but it's 95 degrees! How can that be? It's because as the ice traveled in your glass from the kitchen to the outside surface it didn't have enough time to melt, even though the temperature was well above freezing.

That's how we get snow on the ground with the temperature well above freezing. Because just above the warm layer at the surface, the temperature is well below freezing where the precipitation forms. Because the air aloft is below freezing, the precip forms and falls as snow. But when the snow encounters that thin warm layer near the surface, it just doesn't have time to melt before you see it reach the ground.

It's just the opposite when you observe rain when it's below freezing at the ground. Consider another example where it's 25F outside and you go in the house to get another glass of ice. But your freezer has been unplugged for days and the ice in the ice trays is all water. You dump the water in your glass and go outside and throw it on the ground. Does it fall as ice? No, because ice takes time to freeze when it encounters sub-freezing air. It hits the ground and THEN freezes (freezing rain).

Don't assume that the temperature of the air column above you is the same or colder than the temperature at the ground. You can have temperatures near or below freezing at the ground and temperatures near 70 at a height of 1000-2000 ft up.
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Re: How in the world can it rain below 32 and snow above 32??

#12 Postby Stephanie » Wed Dec 08, 2010 7:55 pm

Those were great examples wxman57! Thanks! :)
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