Howdy everyone and thank you for continuing on with module 10. Now in this video we're really going to be switching gears and talking about something totally different than what we're use used to thinking about here. We're going to start thinking about cold winter storms. What is a winter storm exactly? I know us in Texas, especially in College Station, we're not really used to winter storms. Well, winter storm is a combination of heavy snow, blowing snow, and or dangerous wind chills. And there are many different types of winter storms. Here's just a couple of them that we're used to hearing. Um there's blizzards, ice storms, lake effect storms, snow squalls. Now, blizzards are where we have these dangerous winter storms. And in a blizzard, we're combining blowing snow and wind, which results in extremely low visibility. So that's what makes it a blizzard. It's this extremely low visibility. Now ice storms, which are more common here in Texas than blizzards. This is when we get an accumulation of at least a/4 in of ice on exposed surfaces. And a/4 in of ice doesn't sound like a lot, but this is ice, guys. This is this is quite a bit. So that causes um a pretty bad day as we know here in Texas in 2021. Now, we have lake effect storms that we don't really get in Texas, but these do impact pretty large areas of our country. This is where we have cold, dry air that moves over large bodies of water. And here in the United States, this typically occurs around the Great Lakes. We have cold, dry air coming from Canada, moving over those large body of water like Lake Erie, Lake Ontario. That's going to add moisture to our air and then dump it out as snow over the land. So those regions that live along the Great Lakes, they get these huge lake effect storms. And I mean huge storms. And then we have these snow squalls, which are brief intense snow showers that are accompanied by strong dusty winds. This is kind of similar to our squall line thunderstorms in a way that they do occur in these these lines and they are pretty intense and they do have those strong gust fronts as well. Now, how do they form? Well, kind of similar to our thunderstorms, except for here, we need the air to be cold. So, three ingredients are necessary to make a winter storm. We need our cold air. And this means it needs to be below freezing temperatures, not just in the clouds, which can happen with thunderstorms, but it has to be below freezing temperatures near the ground as well. Now, even though we're talking about cold air, we still need lift. So, we still need to rise that air in some way. We need air to rise because we need the air to rise to form our clouds and precipitation. And usually with these winter storms, the way we can lift our air is due to orographic or frontal mechanisms. Remember the orographic and frontal um mechanisms from I think two modules ago. I would definitely review that if you don't. Um but usually this happens when a cold dry air mass usually coming from Canada here in the United States um ends up moving south and it interacts with a warm moist air mass usually coming from the Gulf of Mexico and they collide and that's whenever we get the warm moist air rising up but we're still we still have that cold air that's being involved. So that's where we're going to get the uh winter storm forming. And then of course moisture. Can't form clouds or precipitation if we don't have moisture. So three ingredients, cold air, still need lift, and still need moisture. So here's that graphic I showed a couple modules ago that really helps um me understand the difference between all these different precipitation types, especially the winter precipitation types. Now, rain occurs as snow up in the clouds, but it falls into a large mass of warm air as it's falling to the ground and it melts um and it stays as rain, right? But freezing rain occurs when that snow melts and it hits cold air and it freezes as soon as it hits the cold surface. Sleet occurs when snow melts but refreezes fairly quickly on during its descent and it because it's traveling through a large um area of cold air and then snow just stays snow throughout its entire descent. It never it never reaches warm air so it never melts on the way down. Now, most winter um wintertime precipitation starts out as snow in the clouds because the top layer of the storm is usually below freezing. Now, snowflakes are just collections of ice crystals that cling to each other as they fall toward the ground. And precipitation continues to fall as snow when the temperatures remain at or below 0 degrees C from the cloud all the way to the ground. And there are different types of um snow or different types of intensities of snow that we receive. You probably heard these terms before or maybe not because we're in Texas, but we have snow flurries, snow showers, snow squalls, blowing snow, blizzards. What do all these terms mean? Well, usually when we see snow flurries in the forecast, this is referring to light snow falling for short periods of time. Usually get little to no accumulation, but you might see a light dusting at least um in the morning. It melts usually when the sun comes out. Snow showers are usually uh a little bit more intense. They fall at varying rates and they usually have brief duration. So, you can get some accumulation with snow showers. Now, our snow squalls, we already went over this one. This is brief intense snow showers. These are also accompanied by the strong gusty winds. You can get a significant accumulation possible. We most commonly see these types of snowfalls in the Great Lakes region because of those lakes um lake effect storms. Blowing snow is just blowing snow. It's wind driven snow. And wind driven snow reduces visibility and causes drifting. So this can be from snow that is falling. So it's actively snowing. But you can even get blowing snow when it's not actively snowing. If you have loose snow on the ground and it gets windy, it can pick that back up and cause kind of a lot of problems, especially for travel. Then we have our blizzards. Um, these were when winds are very high, so over 35 mph with snow. So 35 mph at least. That's going to cause blowing snow while it's actively snowing reduces visibility a lot to at least a/4 mile or less and for at least 3 hours. So that's whenever you get the blizzard condition um definition there. Sleet occurs when snowflakes only partially melt when they fall through a shallow layer of warm air. Um these slushy drops refreeze as they next fall through a deep layer of freezing air right above the surface and eventually reach the ground as frozen raindrops that bounce on impact. Now, sleet usually bounces when it hits a surface and does not stick to objects. However, it can accumulate like snow and cause a hazard to motorists. Freezing rain occurs when snowflakes descend into a warmer layer of air and melt completely. And when these liquid water drops fall through another thin layer of freezing air just above the surface, they don't have enough time to refreeze before they actually reach the ground. But because they are super cold, they instantly refreeze upon contact with anything that is at or below 0 degrees. Um creating a glaze of ice on the ground, trees, power lines, or really any object. And a significant accumulation of freezing rain lasting several hours or more is called an ice storm. Now, norers um thrive and pick up on strength from cold air. Uh these are very very similar to hurricanes, which is a topic of our next module. But unlike hurricanes, these things need um cold air to thrive instead of warm air. And these most commonly occur in the eastern United States. So like the New England area between October and April because we have lots of moisture and cold air available during that time. And northeasterly winds are what's driving these storms up the east coast along the Gulf Stream. And the Gulf Stream is what's giving it that warm water, that warm moist air. Um, and these can dump huge amounts of rain and snow. They can also produce hurricane force winds. So again, very similar to hurricanes. And they too also create high surfs and storm surge and cause severe coastal erosion and flooding. Now I don't know if you've heard about bomb cyclones, but I think it was 2022 was the first time I ever heard this term thrown about. These are types of norers that form rapidly and have fast developing low pressure centers and they rapidly strengthen. These are like those hurricanes that strengthen really quickly before they hit the coast. Um, very similar except for this. These are big winter storms. And just some examples of norers. Um, we had one in 2011. This happened in October um when there were still many leaves on the trees. So that added that added even more problems because we had record-breaking snowfall in many areas of New England during this storm. We saw a maximum of 32 in of snow, which still having leaves on the tree added to the weight. So having that much snow, leaves on the tree, high winds caused many of the trees to snap and be uprooted quite easily. And that caused 3.2 2 million people to lose power. Many of these outages lasted up to 11 days. 39 people were killed and it cost about 1 to3 billion in damage. The following year in 2012, we saw another noraster. And this one um was especially notable because it happened only one week after Hurricane Sandy hit the same areas impacted. So, they were already just kind of coming out from that Hurricane Sandy. They haven't even begun to recover yet and got hit with this nor easter. This one saw maximum snowfall of 13 inches, maximum wind speeds of 75 miles per hour. It was hurricane force, so it was almost like getting hit with two hurricanes. And four people were killed with this event. Then of course, probably the biggest example of winter storms would be the 2021 wintertorm Yuri, the Texas freeze. I didn't live in Texas at the time, so I didn't experience this, but I understand that a lot of you in this class have experienced this and have lots of different kinds of experiences with this storm. Some of you had um a really bad time, some of you not as bad of a time. So, our experiences differ widely and same is true for a lot of disasters. But in case you're not from Texas or you haven't experienced this, this happened in 2021 between February 10th and 19th about and we saw temperatures as low as -2° F in Dallas. So that is not normal for Texas at all. This led to um power grid failure and ultimately 240 human deaths. 240. 65% of that was just due to cold exposure. You have no power. You have no way to heat your homes. 158 deaths were by hypothermia. Three deaths were by frostbite. These are things you don't really think about in Texas. You're not prepared for, but they do happen. And when the power grid fails, all of our safety nets kind of go with it. Not only did humans die, but thousands of livestock died as well. That doesn't get a lot of attention, but that caused a lot of problems. not just um financial problems, but this was people's livelihoods that were taken away as well. 80 to$130 billion in damage. Now, how in the world did that happen? Everyone says, "Well, global warming didn't exist in 2021, right?" Well, that's not exactly true. Let's explain the polar jetream and the polar vortex. You guys remember when we talked about the jetream uh a few modules ago, maybe it was last module. Uh those jet streams occur in between these atmospheric circulation cells and they kind of contain air masses. So air masses don't cross these jet streams. So this is where our polar jetream typically is. Remember this figure, polar jetream? Well, they kind of keep all the cold air where they belong and they don't cross that jetream. They don't. But we know that jet streams can move and dip and they do quite a lot. So here's our polar jetream. It's found in the troposphere. This exists year round. Um the jetream gets strongest during the winter. It's responsible for regular winter weather in our northern states. Um but we have this polar vortex. Here's our polar vortex. And polar vortex is a region of the stratosphere around the poles and it's it gets contained by this polar jetream. It doesn't cross the jetream. So it usually stays pard of 50° latitude or so. We very rarely see it south um south of that. And this polar vortex does not exist year round. It begins forming in August and it gets really really cold in the middle of u winter. And the temperature decreases greatly in this region because we're not getting as much sunlight during those times of the year. Then we have the sudden stratospheric warming theory where sudden stratospheric warming causes this polar vortex to break down during the winter and that leads to the polar jetream that contains this polar vortex to become unstable. See, it's starting to move a lot and that's due to the the increased temperature seen in the in the stratosphere. So we don't things are warming in the pool. So we don't have as big of a temperature difference between the air on this side of the jetream and the air on this side of the jetream. So it starts to weaken. It starts to become unstable. And that's what ultimately led to the polar jetream um dipping as far south as Texas, allowing that polar vortex to sneak on in to an area that is not prepared. So yeah, even with winter storms, we should kind of still care about global warming because the strength and stability of our jet streams, especially our polar jet streams, is controlled by the temperature gradient. How how different are the temperatures in between the two atmospheric cells. The greater the temperature difference is, the stronger the jet streams are. But as we warm the poles, because the poles are getting warmer faster than the tropics, we see less of a temperature difference. So, our jet streams are actually getting weaker, and that's going to allow those cold air to sink farther south than it typically does, and we could see more winter storms like 2021 in Texas in the future. Another example, 2022, we had a bomb cycle. This was the first time I heard the term used. I don't know if it was the first time it ever was used, but this is just the first time I heard it used. Um here we had air pressure dropped to 24 millibars within 24 hours. Remember when pressure is changing quickly that means our winds are going to move quickly. So this created very high winds. Um we also saw temperatures dropping 26° in Montana in 3 minutes. So huge drop in not just air pressure but a huge drop in temperature as well. And this storm impacted 60% of the US population. And this produced extreme conditions because of those high winds. So we saw wind chills of -58° F, heavy snow, storm surges along the coast, ice fog, which is frozen fog. I mean, you probably never seen that here in Texas. Strong winds and ice bombs. Yes, you read that right. Ice bombs. Ice falling from the sky from large structures. And this bomb cyclone killed 55 people in the United States and four people in Canada. So I mentioned windchill. What is windchill exactly? Windchill is the temperature that your body feels. And the higher the wind speed, the faster your body loses heat. And it actually makes you feel colder. So when it's cold and windy, those windchills can get very low very quickly. Now, what can we do to mitigate against winter storms? Probably never thought we would have to think about this, but 2021 is a great example as to why we need to think about this. Here in Texas, a lot of our pipes burst. Um, so we were not only were without power, but a lot of folks were without water. So that's because a lot of our water lines, they're not buried as deeply as they are up north. Up north, we bury our water lines below the frost line, so we don't have this happening. And then we insulate all our water pipes in our homes that are not underground. And we don't really do that here in Texas, right? So maybe we should start thinking about doing things like that. Maybe we should insulate our water pipes. One thing you can do if you're not able to insulate your water pipes is allow your faucets to drip during cold weather. If you know that the weather is going to be below freezing for an extended period of time, put all your faucets on a drip. Open all your cabinets to allow heat in there. That will help prevent your pipes from bursting. If you're going to be going out of town during the winter season, if you're going back home and you're leaving your apartments, um, leave your faucets dripping while you're away. Very, very slow drip. It doesn't have to be dripping a lot. Just a slow drip just to get water moving. Moving water is harder to freeze than water that's still. Also, keep your roof well maintained. I don't know why it says rude. Keep your roof well maintained. Um, winterize your home by insulating walls and attics. Caulk and weather strip doors and windows. Clear your gutters. Trim your trees. Maintain heating equipment and chimneys. This will help make your home more efficient at heating. And stock up on non-p perishable food items. A lot of people probably realized that during the winter storm as well. Grocery stores were empty. Um it was hard to travel. Roads were treacherous. So stock up on non-p perishable food items at home so you don't have to leave. Uh dress warmly and stay dry. Um I always recommend keeping a shovel, ice scraper, blanket, flashlights, water, and food in a vehicle. This is something that I always did up north. Um, and you probably don't do that in Texas very often, but I still have my ice scraper and I still keep all of these things in my car. Even in Texas, um, those things can come in handy in the winter if you're ever caught off guard if you're going on a long road trip. So, those are some things that you as an individual can do to mitigate against winter storms. And that's all I got for you guys. Um, thanks for listening in. I think we have one more video to go for this wild weather module and we're going to switch things up a lot again. We're going to turn up the heat. I'll see you there.