Since it is winter in the Northern Hemisphere, we thought it would be a good idea to explain a little bit about the variety of winter weather watches, warnings and advisories. During these cold months, you’ll probably hear some of these terms in the weather forecast, but we will give you a better idea of just what they mean.

The first thing to keep in mind, is that the National Weather Service sets its watch, warning and advisory criteria depending on location or region. For example, snow in New York City is not as big a deal as it would be in a city in the south, where bad winter weather conditions are less frequent. This mostly has to do with what are considered typical types of winter weather for a specific area, and what people are accustomed to dealing with. While 3 inches of snow in New York might be a nuisance, 3 inches of snow in Dallas or Atlanta might cause much bigger problems because people there may not be used to that kind of weather.

Watches and Warnings are issued by National Weather Service regional offices, and they go by county, and usually cover a wide area, often including several states.

Here are a couple of watches and warnings you will hear a lot over the winter, if you live in a snow-prone area: Winter Storm Watches, and Warnings. The difference between a Watch and a Warning is straightforward. A Watch means conditions are favorable for dangerous weather conditions. A warning means winter storm conditions are imminent or occurring.

First off, here’s the NWS definition of a “winter storm”: 5 inches or more of snow or sleet in a 12 hour period, or 7 inches or more of snow or sleet over a 24 hour period. There are a few other elements that could come into play, like enough ice accumulation, mainly freezing rain, to cause damage to trees and power lines, or a life-threatening or damaging combination of snow and ice, with gusty wind.

Now here are a few you might not be familiar with. For example, an “Ice Storm Warning”. Those aren’t much fun, and they’re issued when a quarter inch or more of ice accumulation is expected. Usually, that will be freezing rain, which is precipitation that falls as liquid, and freezes when it hits the surface. A quarter inch of ice is heavy enough to cause tree damage and power outages, not to mention very hazardous driving and walking conditions.

You have probably heard the term “Blizzard Warning”. So, what exactly is that? A Blizzard Warning is a bit different from a Winter Storm Warning, mainly because focuses more on wind and visibility. Basically, winds of 35 mph or greater, and visibility of a quarter-mile or less, constitute a Blizzard Warning.

There is a prevalent misconception that a Blizzard Warning means it will be extremely cold, or there will be heavy snowfall. However, there is no temperature requirement for a Blizzard Warning, and snow does not actually have to be falling. Snow that is already on the ground, combined with the wind, could meet the low visibility requirements for a Blizzard Warning.

The next one does have to do with cold, and that is a “Wind Chill Warning”. It means wind chill temperatures of minus 25 degrees or lower are expected in the next 12 to 36 hours. During a Wind Chill Warning, you should either stay in a warm place, or have the right type of clothing to protect yourself completely against the cold. Even though it may be sunny, wind chill can cause frostbite on exposed skin, and possibly hypothermia, quite quickly.

Those are the biggies. Now, you might hear the word “Advisory” associated with hazardous winter weather. That means the dangerous winter conditions we talked about are likely, but not bad enough to meet the criteria for a warning. But that does not mean it won’t be dangerous. And again, that depends on where you are located. An advisory for snow in New York might qualify as a warning for a place like Atlanta.

This is a lot to remember. But when you hear the words “watch”, “warning” or “advisory” in a winter weather forecast, you should pay close attention to the forecast so you’ll know what to expect and figure out how the conditions will affect your situation.

Always have enough food, water, medicine, protective clothing on hand, and a well-maintained vehicle to get you through any weather trouble.

The National Weather Service website has all of this detailed out, including current maps showing you where the rough spots are.

Sources:

National Oceanic and Atmospheric Administration / National Weather Service

https://www.weather.gov/lwx/WarningsDefined

https://www.weather.gov/bgm/WinterTerms

One of the biggest questions this time of year is: “Will we have a White Christmas?” Lots of people dream of a White Christmas, as the song goes. And, just about everyone has their own idea of what that is.

For some, it means it has to actually snow on Christmas Eve or Christmas Day, with enough accumulation to completely cover the ground. Other folks are satisfied with just some snow on the ground, even if it isn’t snowing. And, there are people who are happy just to see a few flakes fall from the sky.

Well, believe it or not, there is, in fact, a scientific definition of what counts as a White Christmas. According to the National Weather Service, a White Christmas is defined as having one inch or more of snow on the ground Christmas morning. So, it doesn’t actually have to be snowing. That’s the official word, anyway. But, if you have your own standards, that’s cool too.

With the big day coming up fast, we have some predictions on where to expect a White Christmas, based on the official definition. 

As you probably expected, the southern states won’t have any snow on the ground Christmas morning. No big surprises there, however, thanks to a cold front that’s expected on Christmas Eve, it will at least be a cool Christmas Day for most of the southern tier of the country. Now for the snow, and we’ll go from west to east.

There will be at least 1 inch of snow on the ground in the Sierra Nevada and Cascade mountain ranges, as well as the Northern and Central Rockies, including the Tetons and Bitterroot Ranges.

There’s a big storm brewing in the Northern Rockies, and that’s expected to bring snowfall to the Northern Plains and the Great Lakes. That should give those areas enough snow to call it a White Christmas.

That same storm will bring a lot of rain to the eastern third of the country from coastal New England down to the Gulf Coast. But, cold air will come in behind it, providing a chance for at least an inch or more of snowfall for the Appalachians, the Ohio Valley and up through western Pennsylvania and New York State. And there’s also plenty of snow on the ground from the last storm over much of New England, with more expected.

As for the rest of the country, the higher elevations of the Intermountain West should have enough, but the lower areas will be dry. And the chances of a White Christmas are low for most of the Central Plains and the middle Mississippi Valley, eastward into the Carolinas and the southern parts of the Mid Atlantic states.

Remember, that’s where we expect a White Christmas by the official definition.

Now, for the really important news. We’ve checked the weather conditions at the North Pole, because Santa is getting the sleigh packed up and the reindeer fed for the long trip. It’s clear and cold up there, and the Elves are hard at work. And Donner is in the gym, for a last-minute workout, because he had a little too much pumpkin pie over Thanksgiving.

The weather for Santa’s journey should be fine, with that big winter storm over the northern states getting out of the way just in time.

As you probably know, it’s dark all the time at the North Pole during the winter months because of the Earth’s tilted axis, which causes the seasons. But, not to worry. Santa always has plenty of light thanks to the North Star, and Rudolph’s nose, which we understand is operating at full power. 

And remember, the good folks at NORAD will be tracking Santa again this year online at https://www.noradsanta.org/!

Whether you have a white Christmas or not, we wish you a merry one, and a happy, safe holiday season.

Officials at the North Pole, the home of the legendary Santa Claus, say the world’s most famous elf has rarely encountered a season quite like this one.   After consulting with sleigh scientists, this year’s trip around the world will be similar but remain within seconds of the total flight time in 2019.   

The traveling team of reindeer and elves along with Santa Claus will wear masks and carry plenty of “Santatizer”.  However  the additional weight on board will not be enough to slow dropping off packages and toys.  

“During the Spanish Flu of 1918-1920, Santa Claus was extra careful on his deliveries,” said Odds Bodkins, head of Physics at the University of The North Pole.   “He’s never late for a delivery, no matter what occurs in the world.”    

St. Nicholas has approximately 31 hours to finish his work because there is an overall difference in the Earth’s rotation and time zones.   He visits over 1600 homes per instant, flying at nearly 1800 miles per second which is more than 8000 times the speed of sound.   Bodkins says “most reindeer can only run at 40 miles per hour, because they haven’t consumed the magic dust needed for high speed flight.”

Snow is the one ingredient that assists in Santa’s quick take-offs and landings.   The reduced friction with ice or snow on the ground allows the sleigh to quickly get airborne.    While not every location worldwide has snow, any additional snow will make this year’s journey easier.

“Air traffic control at the North Pole has much better technology than in year’s past.   After a software upgrade, the crew can guide Santa into a strong tailwind which accelerates the overall flight time,” Bodkins said.   

The sleigh is expected to depart the North Pole at around 3:00am Central Standard Time on Christmas Eve.  

A beloved tune during the holiday season is “The Christmas Song”.  It was sung by some of the greats:  Mel Torme, Nat King Cole, Bing Crosby and Perry Como.  And even more recently by Christina Aguilera and Michael Buble. “Chestnuts roasting on an open fire. Jack Frost nipping at your nose.”  Wait.  Who is this Jack Frost character?  And why is he nipping at our noses?  Is he the one that leaves the icy, feathery, pattern on the ground when we get the first near-freezing temperatures of the autumn season?  In this week’s Meteo Monday, we are talking about frost! We will explore the history of the mythical nose-nipper and discuss how frost REALLY forms! 

Jack Frost, much like his counterpart Old Man Winter, is a personification of wintry weather. He is often depicted as a mischievous character that brings in the cold and with that, we get frost, snow, and freezing temperatures.  Jack Frost first made his appearance in English Literature in the 1700s. The book “Round About Our Coal Fire” or “Christmas Entertainments” was published in 1734. It is here that we see one of the first references of Jack Frost. “This time of year being cold and frosty generally speaking, or when Jack Frost commonly takes us by the nose…” From that point on, the frigid fellow has made an appearance in many books, articles, comics, cartoons, songs, television shows, and movies.

Now, let’s take a look at what frost actually is and how it forms. Per the National Weather Service (NWS) Glossary, frost is described as “the formation of thin ice crystals on the ground or other surfaces in the form of scales, needles, feathers, or fans”.

How do you know when it’ll be a frosty morning? It all comes down to the dew point. Dew point is the way you measure atmospheric moisture. It is the temperature to which the air must be cooled, to reach saturation.  This is how you get dew. If this happens with surface temperatures below freezing, but the temperature within 4-5 feet of the ground is above freezing, the dew freezes on contact. And thus you have frost. Just because the surface temperature is below freezing doesn’t mean you’ll get frost. The temperature must fall to the dew point. Frost typically occurs under a clear sky, with light winds. 

Frost can damage sensitive plants and crops. During the growing season (which varies across the country), the NWS will issue frost advisories if a widespread frost is expected across the area. A frost advisory will be issued when air temperatures are between 33-36℉.  If the temperature is expected to drop below freezing, during the growing season, a freeze warning will be issued instead.

Local topography can also play a role in frost formation. Cold air is heavier than warm air, which will allow it “sink” down into valleys. Valleys will be cooler than the surrounding hill-tops, and therefore frost would be more likely to occur in the valley.

Sources

https://www.weather.gov/arx/why_frost

https://www.weather.gov/ctp/wwaCriteria

https://w1.weather.gov/glossary/index.php?word=Frost

https://writinginmargins.weebly.com/home/a-brief-history-of-jack-frost

https://upload.wikimedia.org/wikipedia/commons/9/98/Round_about_our_Coal_Fire%2C_or%2C_Christmas_Entertainments%2C_4th_edn%2C_1734.pdf

https://en.wikipedia.org/wiki/Jack_Frosthttps://w1.weather.gov/glossary/index.php?word=Dew+Point

Many people know that around December 21 of each year, the Winter Solstice arrives. However, it wouldn’t be 2020 without something out of the ordinary happening! This year during the solstice we are in for a treat, with what many are calling “The Christmas Star.” The conjunction of Saturn and Jupiter will be responsible for this “star.”  It is, however, not actually a star.

These two Jovian Gas Giants will appear to merge into one “star”  on the evening of December 21, they however still remain millions of miles apart. The fact that this is occurring on the winter solstice is just merely a coincidence. Conjunctions of planets like this can happen on any day of the year. Henry Throop, an astronomer with NASA said, “The date of the conjunction is determined by the positions of Jupiter, Saturn, and the Earth in their paths around the Sun, while the date of the solstice is determined by the tilt of Earth’s axis. The solstice is the longest night of the year, so this rare coincidence will give people a great chance to go outside and see the solar system.”

If you want to view the conjunction, all you have to do is find an unobstructed view of the southwest sky. When you look up, you’ll see what looks like a large “star” in the sky. Even if you live in a major city, these planets are bright enough to be seen on a typical night, but when they appear to “merge” it will be even brighter and very easy to see.

What makes this one special is that the last time the planets appeared to be this close in the sky was in 1623 and it was dubbed “the Great Conjunction”  by Galileo Galilei who observed it. The last time that a conjunction between Jupiter and Saturn occurred at night was nearly 800 years ago in 1226!  The next one will occur in 2080. So be sure to get outside on the evening of December 21, if weather permits, and check out the “This Christmas Star”!

Sources

http://lasp.colorado.edu/outerplanets/giantplanets_whatandwhere.php

https://www.nasa.gov/feature/the-great-conjunction-of-jupiter-and-saturn

https://www.nationalgeographic.com/science/2020/12/see-rare-great-conjunction-of-jupiter-saturn-on-winter-solstice/