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About Fred Remer

Greetings! We are glad you stopped in to read our posts. This blog is sort of an experiment. I am an associate professor in the Department of Atmospheric Sciences at the Univeristy of North Dakota. I teach a class called AtSc 315 Broadcast Meteorology class. The purppose of the class is to provide students in our program some experience in media and broadcasting. I have challenged my students to post a blog daily on weather topics that interest them. I hope you find the topics interesting and insightful. This experiment will continue through the fall of 2012 until the class ends in December. I hopefully will continue the blog thereafter. Please provide us comments and feedback. It's part of the learning process!

An Introduction to Radars

You are at a ball game and you look out into center field and you notice the sky getting dark. First instinct is to take out your phone and check the weather radar.
Well that doesn't look good
After realizing that you aren’t in a good situation you come about thinking of how that information was even available and how does a radar get that information, well it is quite simple.

A radar sends out short horizontal pulses, which bounces off objects in its path and some of the energy comes back to the radar.
Radar Pulse
When it returns, the radar receives the energy, by then it now knows the direction of the objects and can find the distance by taking the amount of time that passed and multiplying it by the speed of light (the rate of speed of the pulses). Not only does it find the location, but with the amount of energy received by the pulse, the radar can then calculate its reflectivity, by which larger rain droplets and hail will give higher amounts of reflectivity then that off smaller objects such as snow and light rain. Reflectivity is what makes up all the pretty colors on your radar app when you check it. Red being higher, while blue and green being lower.

Now radar isn’t perfect and all things aren’t being accounted in this example. Things like birds, insects, bats, and other things that may fly in the air can also have a reflectivity. But next time you are checking the radar, just remember how the information got there in the first place.

-Tyler Reis

Understanding a Forecast

The other day, someone that I went to high school with posted on a social media site sharing a National Weather Service forecast for Macomb, IL, home of Western Illinois University. The forecast stated: “Occasional showers and possibly a thunderstorm before 2 pm, then a chance of showers and thunderstorms between 2 pm and 4 pm, then a chance of showers after 4 pm.” Her thought on this was that to sum it all up, they could have just said that it would rain all day.

Now I looked at this and thought about it longer than I care to admit. In fact I almost liked the post to agree with her. But then it hit me, While she isn’t wrong, the key word in that forecast is thunderstorm. This made me think that maybe people don’t always understand a weather forecast when they see one. Let’s break down this forecast. The first part tells us that it is possible for an occasional shower and a thunderstorm cannot be ruled out. The second part of the forecasts states that there is a chance for showers and thunderstorms. To me, this also tells me that this is probably the best chance for the two during this time of day. The last part is forecasting for rain only.

It is important to note that the NWS has to include thunderstorms in their forecast because of the threat of lightning. Folks that may have outdoor activities planned need to know the threat of thunderstorms. While a little rain never hurt anyone, a little lightning has. In fact, lightning is the second leading killer in weather-related deaths. So keep that in mind when you look at a forecast and think, well they could have just said it was going to rain today.

-Ben Lott

(Lightning fact courtesy of Walsh, K. M., M. J. Hanley, S. J. Graner, D. Beam, and J. Bazluki, 1997: A Survey of Lightning Policy in Selected Division I Colleges. J. Athl. Train., 32, 206–210.)

Trust your meteorlogist

Recently I was with a group of friends when one of my friends roommates sat with us at lunch. The roommate of the friend asked the group what our majors were. Naturally, being Atmospheric Sciences majors we are accustomed to explaining just what an Atmospheric Scientist is. As most of you can imagine the question, “Oh so you want to be a TV meteorologist?” is among the first to be asked after the explanation. Naturally though the second question is, “Oh so if you forecast will your forecasts be accurate?” TV weatherman become the butt of a lot of communities jokes. I myself will admit that I have and will Probably continue to make fun of my Local TV weatherman from where I grew up at. They’re the face that anyone with a TV is almost guaranteed to recognize. But how often are Weatherman wrong? Studies show that even if one TV station claims to be more accurate than the other, typically no TV station is more accurate than the other. A close friend of mine always likes to use the argument that Weatherman are literally attempting to predict the future.

With that said the hardest thing about forecasting the weather is that there is literally an overload on data while simultaneously being still somewhat in the dark. Weather forecasting is still a newer science. With Radar data and the computing power of old computers not even equally 1/100 of the cellphone you may be reading this blog on. Currently one can find over 6 different models with relative ease. Just by a simple Google search. Model runs vary with the addition of just 6 hours of data. The easiest thing to predict is whether or not it is going to rain that day. Predicting Highs and Low’s for the region is near impossible to get spot on across a large area because of all the small geographical differences. Then there are the opposite cases. Sometimes while forecasting weather I am positive is going to happen, it somehow manages to dissipate before it reaches the expected area. Overall Forecasting still has a lot of challenges in it. Slowly the science is beginning to catch up with it. But what would life be without the possibility of it raining on your parade every once in awhile? In final just give your weatherman a break. Trust me with the amount of Math and Science classes he has taken, he is definitely not a moron.

http://www.nytimes.com/2012/09/09/magazine/the-weatherman-is-not-a-moron.html?pagewanted=all&_r=1&

Surfing… on Lake Superior?!

If you live in the Northern Plains, chances are you’ve noticed a big cool down over the last few days. As mentioned in an earlier blog post, a strong cold front moved through on Monday, setting the stage for our much ballyhooed burst of cold air. But while we in the Northern Plains shiver, folks to our east have been dealing with the effects of a large low pressure system. This system, pictured below, has been producing very heavy rain and strong winds as it moves across the Upper Midwest. These strong winds were producing huge waves on Lake Superior, setting up the perfect conditions for surfing (assuming you don’t mind the 51 degree water!) (Think I’m kidding? WLUC TV6 News out of the Upper Peninsula wrote a short article about a group of surfers coming to Presque Isle to catch a few waves on Wednesday, which you can read here.)

Along with giving surfers a fun day, the storm system also caused some coastal flooding along the south shore, prompting the National Weather Service in Duluth to issue a lakeshore flood advisory. Here is a link to some Youtube footage of the flooding and waves in Ashland, Wisconsin posted to the NWS Duluth twitter by Cheryl of EXTREME PHOTOGRAPHY.
Ashland, Wisconsin Waves

So what caused the high winds and large waves? Well, if you take a look at the surface map shown below, you can see how the isobars (the black lines drawn on the map; isobars are lines of constant pressure) around the low pressure system are very close together. Often this is a good indication that there are very strong winds around the low. Since the winds around a low pressure system are counter clockwise, the strong winds were out of the northeast on the back side of the low, which funneled the wind over the open waters of Lake Superior and generated the large waves.

Here are a few other graphics to show you the wave heights and wind speeds from Wednesday afternoon.

So if you’re tired of the chilly weather and are looking to get away, I probably wouldn’t go surfing in Lake Superior. But you can take heart that it is only September after all, there’s likely still some time before winter truly arrives.

-Logan Lee

Ice Pellets of Doom.

We all have been there. During that scary moment when the car is parked outside and a severe thunderstorm warning pops up on the TV, you panic about the thought of hail damage to your precious car. Or worse, the effect it will have on your insurance. Instead of telling you the dangers of hail, which are apparent, I will illustrate the process in which it forms. Unfortunately, to some people, the dangers of hail were not glaringly obvious before they stepped outside. But I digress.

Iowa man caught in a 2010 hailstorm whilst running.


Hail is formed inside of the updraft of a thunderstorm. This cross-sectional view of a thunderstorm shows the updraft of a storm, and the hail core inside of it. Hail reflects very highly on the radar (seen in darker reds on this Figure).

From University of Alabama Huntsville


A hailstone is produced when a tiny ice particle, called an ice nucleus, comes into contact with a super-cooled liquid water droplet above the freezing line in the cloud. Super-cooled liquid water is water that exists at temperatures colder than 0 degrees Celsius and can exist up to -40 degrees Celsius! The newly formed hail droplet falls through the cloud and is reintroduced into the updraft at a lower part of the cloud. There is some debate between meteorologists on the exact path the hailstone takes as it grows, but one thing is known for sure. Two types of hail formation exist and can form two aesthetically different hailstones.

Wet hail formation occurs when an ice nucleus comes into contact with a super-cooled liquid water droplet. The water spreads slowly over the ice ball forming a smooth, clear surface. As the hailstone falls and rises above the freezing line again, it grows larger when the droplets slowly spreading and freezing onto the stone. It is eventually too heavy to be reintroduced into the updraft and falls out onto cars, roofs, and other valuable what-have-you’s. The resultant hailstone is smooth, fairly translucent, and dense.

Dry Hail formation occurs when an ice nucleus comes into contact with super-cooled liquid water and freezes immediately. The hailstone circulates in the same fashion, and falls out of the cloud when it becomes too heavy to travel back up through the updraft. The resultant hailstone is very different than its wet hail sibling. A dry hailsone is a bumpy, opaque ball. Tiny air bubbles trapped under the surface are the cause of the opacity of the hailstone.

Severe Thunderstorms are the most common factory of damaging hailstones. The criterion to warrant a severe thunderstorm warning includes one-inch diameter hail and/or 50 knot wind speeds. Note that hail can be produced at sizes smaller than one inch, and therefore is not always associated with a warning! Be sure to always to always heed weather warnings. The safest place during a thunderstorm is inside a sturdy building away from windows.

-Brianna Kump

Winter Already?

As you woke up this morning and looked out your window, I bet it looked like a pretty normal September day in North Dakota. Cloudy skies and wind blowing hard seems to be the norm. However, yesterday was 86 degrees and sunny. Not only that, but it was 13 degrees above the normal temperature for this month! What happened in between yesterday and today?!? Today’s high is forecasted to be 55 degrees. That is 18 degrees colder than the normal high! The low is supposed to get down to 42 degrees tonight.. That is about a 44 degree difference in just over 24 hours!

Let’s talk about what happened. At approximately 6:00 PM, a significant cold front came through the Grand Forks area that dropped temperature 20 degrees in about 3 hours. This front also switched the winds from SW at 10 knots to N at 20 knots, gusting to 29 knots, in just one hour. This front was caused by a frontogenesis event associated with a deformation zone.

Radar as the Cold Front was North of GF

Temperatures will continue to fall for the next couple of days, bottoming out in the upper 30s. A strong band of precipitation will occur south of our area. The years first chance of snow could occur with this event on Wednesday night into Thursday.

Hope you all enjoyed summer/fall!

-Joe Heiden, UND Meteorology

But I didn’t buy a ticket to Sacramento…

If San Francisco is known for one thing, it very well may be the bay fog. It is that smooth, almost cotton looking layer of moisture that rolls into the bay in the morning that when viewed from above, hides what is one of the great west coast cities from view.

And they built an airport right in the middle of it.


Why your flight was delayed.

It is far from uncommon that in morning when this fog rolls in, San Francisco airport comes to a grinding halt and most air carriers are either severely delayed due to approach availability or are forced to take the trek to their alternate airports, which often lie just a few miles inland where this fog loosens its grip on commerce. Sacramento is a frequent choice of alternate destination. The FAA decided that in an effort to improve safety, large air carriers running scheduled service that you can purchase tickets on need a certain amount of report visibility and cloud ceilings to even attempt an approach to landing.


“Captain, is that the runway or the bay bridge…? They look like brake lights…”

But why does this fog roll into the bay and put a hold on everyone’s arriving plans? Let’s imagine two parties. One of which is in a small studio apartment and the other is in large mansion. Each party is being attended by ten people. Someone brings a keg to both, but drunken coordination is never often hailed for its accuracy and as such events transpire and the keg explodes and sends beer flying everywhere. The same amount of beer is spilled in each party, but per unit area (let’s say a one square meter) you are much likely to find a person in the studio apartment. By extension, one could then state that the person to spilled beer ratio per unit area of the studio apartment is higher than that of the mansion. Imagine now an infinite keg of beer that just kept spilling and eventually fills up both the mansion and the apartment. Per unit area, the mansion can hold a lot more beer because one is likely to find fewer people in that square meter. The beer will run out of places to go per unit area quicker in the apartment than the mansion. Taking this analogy one step further, let’s replace the studio apartment with cold air and the mansion with warm air and the beer with water vapor. In the studio apartment/cold air the beer/water vapor will run out of places to go quicker. When moisture runs out of places to hang out in air, it changes forms and becomes visible moisture (fog/clouds). This happens in cold air quicker than warm air because, like the studio apartment, it is denser with molecules (although in this analogy, the apartment was denser with people).


The other reason your flight was delayed.

So the San Francisco bay can act like the venue for the party. The moist air that comes rolling in off the pacific ocean in the morning is like the spilled beer. The air over the land is colder, so it can’t hold that much beer. So, when that moist air rolls in to cold air, it doesn’t have a lot of places to hangout and thus must become visible moisture. This forms the fog, more specifically, advection fog, that caused your flight to end up in Sacramento.

-Brendan Farmer

Ready for a Change?

Aside

When the temperature drops, everyone wants to know how long it will last and when will warmer temperatures return. We are in the middle of a cold shot of air with wind chills expected to drop to dangerous levels. This may be the last shot of cold air we may experience for a while. The charts posted here show the 500 mb pattern, 850 mb temperatures and the precipitation forecast for today and seven days from now. Notice how the upper level winds are currently out of the northwest. Most of our current weather systems are originating in Canada and points north. In seven days our winds aloft switch to the southwest. The switch to southwesterly flow aloft will bring warmer temperature and more precipitation. While we may not expect temperatures in the 50s or 60s, we won’t see a extended cold snap below 0F for the short term. Hang in there … warmth is on the way!

Blizzard Aaron

Our first blizzard of the year has come and gone. The Grand Forks Herald named this one Aaron in honor of a UND basketball player. The storm did not produce high snowfall totals. It did produce blizzard like conditions with visibilities near zero and wind speed gusting over 35 mph. Here at the Grand Forks Airport the snowboard was bare but we estimated that 1.2″ of new snow fell. The NWS in town measured 2.4″ The visibility at the airport was 3/4 mile most of the night and early morning hours.

Powerful Winter Storm Bears Down on Red River Valley

A powerful winter storm is bearing down on the Red River Valley today. The storm is fueled by a strong temperature variation in temperature across North Dakota, Minnesota and Canada. Southerly winds ahead of the storm brought warm air into the valley with Grand Forks reaching a high temperature of 40 degrees Fahrenheit. Rain started as the sun set on Thursday afternoon but changed over to freezing rain as the temperatures cooled overnight. The cold air pushed through the northern part of the valley in the early morning hours and the winds switched from south to north at 4 am Friday morning. We are expecting 4 to 6 inches of snow this Friday afternoon into the evening as the main energy of the storm enters North Dakota from the southwest. A 150 knot jet stream is forecasted to intensify the surface low pressure system throughout the afternoon and evening. A strong pressure gradient across eastern North Dakota will cause surface winds to increase to between 30 and 40 mph causing near zero visibilities overnight and into Saturday morning.