What is a re-freeze and how is it going to impact Houston when the snow clears out? – KHOU.com

Next up in 5Example video title will go here for this videoNext up in 5Example video title will go here for this videoHOUSTON — The Houston area woke up to a winter wonderland Tuesday morning, and while people had fun playing, sledding and taking photos in the snow, we’re not done with winter weather.Preliminary snowfall reports show 2-4 inches of snow fell between Monday night and Tuesday morning. By Tuesday afternoon, the low-pressure system that brought the snow to Southeast Texas moved to the east, taking most of the moisture away from the region.RELATED: How much snow did Houston get? | Here are the Southeast Texas cities with the most snowfallAnything left on the ground is either going to re-freeze or stay frozen overnight. A Winter Storm Warning remains in effect until Tuesday at 6 p.m. There was even a Blizzard Warning in effect from Beaumont to Lake Charles.By the afternoon, snow will stop falling, temperatures will climb to at or just above freezing and the snow on the ground will turn to slush.Overnight, as temperatures drop to below freezing again, that slush will re-freeze and cause issues on the roads and sidewalks.RELATED: Southeast Texas covered in snow! Your best pictures and videos from across the areaWhile the wind calmed down a bit on Tuesday, around 11 a.m., the air temperature remained at 29 degrees, but with the wind, it felt like 14. Due to the wind, most feel-like temperatures across the Houston area were in the teens and low 20s.That brings in a strong possibility for ice to form overnight. Local leaders are still advising people to stay off the roads if possible.When the precipitation freezes on the ground, it makes it very dangerous to drive. That’s what’s expected to happen overnight from Tuesday into Wednesday as the air temperatures remain in the teens and 20s and feels-like temperatures, due to the wind, could reach single-digits.RELATED: How does this snowfall compare to the snowiest days on record in Houston?The KHOU 11 Weather Team issued Weather Impact Alert Days for Tuesday and Wednesday due to the hard freeze. By Wednesday afternoon, temperatures should reach the low-40s. Another hard freeze is expected Thursday morning, but by that time roads should be dry and ice free.Temperatures are expected to warm up in the latter half of the week and the weekend.Black ice is one of the most dangerous conditions for drivers when the weather gets cold. The reason is quite simple — it’s really hard to see.Black ice is almost perfectly clear with no trapped air pockets. It is only black because of the paved road underneath.A couple of conditions have to be met for black ice to form. First, the water has to fall gently. A heavy, splashing rain will create bubbles and swirls in the ice. So heavy fog, misty rain or even condensation from a vehicle’s exhaust can all create black ice.The other big condition is pretty obvious — it has to be cold enough to freeze. But black ice is often so thin it can form when the air temperature is above freezing.That is especially true in the early morning hours before the sun can warm roadways. Bridges and underpasses are the biggest culprits. Cold wind can whip around bridges bringing down the surface temperatures and underpasses often don’t get enough sun to warm the roadway.So what do you do if you hit black ice? It may be counter-intuitive for drivers. If you feel your wheels slipping, take your foot off the gas, resist the urge to slam down your brake pedal and coast until you get traction again. If you start to skid, steer into the skid instead of away from it.Road crews treated thousands of roadway miles ahead of the winter storm but Houston Public Works Director Randy Macchi said that just because some roads were pre-treated, doesn’t mean it’s safe to drive.”You need to stay off the roads. That’s the most important thing. All the brine does is it lowers the freezing point of the water and as we expect tonight and tomorrow and through the next few days, the temperatures to be exceptionally low, it will freeze,” Macchi said.The region’s roadways were treated with a salty solution called brine to help prevent ice from building up.But how does it work?  Meteorologist Chita Craft said it is similar to when crews salt the ground before a big freeze. It’s a mixture of salt, water and sodium chloride, but in a liquid spray so that they can cover more ground at a lower cost.First understand when water is in its liquid state, like rain, the molecules are loosely packed.Whenever water reaches the freezing point of 32 degrees or below, molecules are then packed more tightly. On roads, this causes a big problem.Wet, icy and slushy roads reduce traction between a car’s tires and the road surface. If a driver were to hit the ice, their car could suddenly go into a skid, which is a scary situation.That’s why there is a need to break up these molecules to limit ice or slush on the roads.Salt or the brine solution does not necessarily melt ice or snow with increased heat. It merely brings the freezing point of water to lower temperatures. At the molecular level, the salt molecules get in the way of the bonding water molecules helping it not to freeze.The regular freezing point of water is 32 degrees. Adding sodium chloride lowers that freezing point to 15 degrees.Wrapping your outdoor pipes is important to keep them from bursting and flooding your home. We have a list of stories to help guide you.RELATED: Wrap your pipes before the Houston area gets hit with a hard freezeRELATED: No pipe covers? These simple household items can save your pipesRELATED: Yes, leaving faucets dripping during freezing weather can help prevent pipes from burstingDon’t forget the irrigation system for your sprinklers needs special attention, like the bell housing or backflow preventer. So, turn the water off and let it drain. You can get specialty covers or an old blanket can do the trick. Just make sure you secure it with tape or something else.

Source: https://www.khou.com/article/weather/houston-ice-snow/285-5246c095-00ac-4f3f-b6f8-078c9bfe211b