Freezing rain in 20-degree weather?

[RegGuheert]

There is a weather alert for freezing rain starting tonight and going through Christmas. At the same time, the forecast is for the temperature not to go above 32 F during that same period. How can this be?

 

My understanding has always been that freezing rain is the result of air temperatures above 32 F with ground (or snow, in this case) temperatures at or below 32 F. If all the air above the ground is below 32 F, then I expect to get snow. If there is warmer air (above 32 F) above lower air which is below 32 F, then I expect to get sleet. Again, it doesn't make sense to me to get freezing rain if the air temperature is below 32 F.

 

Any meteorologists out there who can enlighten me on this seemingly-contradictory forecast? Perhaps a web link that could explain this? Or is the forecast simply wrong? In any case, I will be watching to see what type of precipitation we get and at what air temperature.

[G5052]

If the drops pass through a warm air layer above, and then go through a cool layer, they may still fall as rain.

 

I hate freezing rain because it makes the roads so scarey and tends to cause power outages. Give me snow anytime, although it took three days for us to really be able to get out after the recent storm.

[RegGuheert]

If the drops pass through a warm air layer above, and then go through a cool layer, they may still fall as rain.

Thanks! Makes sense. I guess it depends on the size of the raindrops and the amount and temperature of below-freezing air through which it passes. Still, it's 6 F right now and they are saying it will be about 22 F when the freezing rain starts tonight. At 22 F, I suspect falling rain would freeze quite rapidly. We'll see...

I hate freezing rain because it makes the roads so scarey and tends to cause power outages. Give me snow anytime, although it took three days for us to really be able to get out after the recent storm.

Yes, I'll take snow or sleet any day! I remember when Quebec got nearly 2 inches of freezing rain about 10 years ago. It was so heavy that it tore down even the giant structures holding up the high-voltage power lines. Many people had no power for a month in 0 F weather. Absolutely horrible!

 

They are forecasting a quarter inch here, which will make travel nearly impossible if it happens. We've asked the grandparents to postpone their visit until after Christmas. It should be just the nine of us for Christmas! :001_smile:

[G5052]

I actually had knee surgery yesterday and my DH is disabled, so we're just going to hunker down for awhile if it's nasty out!

[RegGuheert]

I actually had knee surgery yesterday and my DH is disabled, so we're just going to hunker down for awhile if it's nasty out!

Wow! I hope you have a speedy recovery!

 

I'm thinking your little avatar pony will be needing knee surgery soon if he keeps up that pace for long! ;)

[Carrie12345]

I live in an area notorious for its ice storms. Makes for incredible photo ops, but what a pain!!!!

 

I still don't completely understand how it all works, and I was surprised to hear the weather man telling me 1" of rain can equal various depths of snow, depending on the temperature and moisture in the air. It's something I'm going to have ds research after the holidays. ;)

[lionfamily1999]

I'm just hoping they're wrong as usual.

 

They were right about the snow.... ish.... we had MUCH more than they thought. Now, I just hope the freezing rain goes back to the snow they'd originally forcasted :p

[Mandamom]

I live in an area notorious for its ice storms. Makes for incredible photo ops, but what a pain!!!!

 

I still don't completely understand how it all works, and I was surprised to hear the weather man telling me 1" of rain can equal various depths of snow, depending on the temperature and moisture in the air. It's something I'm going to have ds research after the holidays. ;)

 

Here's a link to a chart

 

http://www.cbs3springfield.com/weather/classroom/weathercharts/6550997.html

 

 

 

http://www.hpc.ncep.noaa.gov/research/snowfcst/snow.pdf

This is some information about winter storms in general that someone might find interesting.

[MeanestMomInMidwest]

I don't know *how* it happens, but it happened to us last night. Air temps slightly above zero, rain hitting the windows (and everything else). Everything is covered in ice. Last night my poor dog slipped and fell on the front stoop. The de-icer couldn't keep up.

 

Today it is beautiful, but I'll be staying off the roads (and sidewalks, steps, etc.).

 

ETA: Here's a definition of freezing rain that kind of explains how it happens

Freezing rain: Rain that falls into a shallow layer of subfreezing air at the ground (usually only several hundred feet deep) and freezes upon impact to form a coating of glaze on exposed objects.

Edited December 24, 2009 by MeanestMomInMidwest

[RegGuheert]

http://www.hpc.ncep.noaa.gov/research/snowfcst/snow.pdf

This is some information about winter storms in general that someone might find interesting.

Wow! Now there is a technical slide set! Looking through it, Slide 13 seems to be the best answer to my question. That slide implies you would need a lower cold layer below about -10 C (14 F) to have the rain refreeze into sleet or snow. That is quite a bit colder than it is forecast to be here.

ETA: Here's a definition of freezing rain that kind of explains how it happens

Freezing rain: Rain that falls into a shallow layer of subfreezing air at the ground (usually only several hundred feet deep) and freezes upon impact to form a coating of glaze on exposed objects.

That agrees with the link that Mandamom provided.

 

I've learned something new today! Thanks, Ladies!