Large Spring Storm Moves In
April 08, 2013 8:25 PM
I know the calendar says spring, with many of us are looking forward to warmer days, the pool, the shorts, and the sunscreen, but plenty of winter precipitation is in the forecast. So much in fact, some April snowfall records could fall across South Dakota as totals will likely top a foot in some areas. But before you dive off the deep end or book a very late and expensive trip to Florida, we need this moisture. Not all of us are farmers, but we all depend on precipitation for food and other resources, so this is actually good news. Now because the ground is still frozen in areas, not all of this water will make it into the ground, but at this point, couldn’t hurt. Here is a complete breakdown of the snow, ice, and rain that is expected and how the forecast can still change as this storm continues to develop.
The amount of moisture that this storm system is likely to have is pretty impressive for anytime of the year. Widespread liquid totals of 1 to 2 inches with locally more are possible. Here is the forecast for the next 3 days produced by the Hydrometeorological Prediction Center (HPC).
This shows the liquid equivalent of the precipitation that is expected to occur. So if you are going to get snow, if you were to take it and melt it down… this is how much you would get.
Speaking of snow…. We better touch on that subject. The forecast is far from concrete, but right now the forecasting computer models are coming together for a much better picture of what we can anticipate. But now that its April, the overall warming of the atmosphere and the ground can make it that much harder to forecast snowfall amounts. Remember that computer models DO NOT take this into account… this is where the meteorologists involvement comes in. Here is the snowfall expected from 2 different computer models.
That is a lot of snow!!! But notice the big difference…. The heaviest band of snow is in a little different place in these images. The top one shows a more northern and skinnier track to the heaviest snow band. But the second image shows a much broader heavy snow band encompassing much of our area with 6 to 12 plus inches of snow… which is definitely a possibility.
Here is another way to look at the snowfall potential across the area. The following images are also from the HPC showing the probability of a certain amount of snow. In this case, the 2 images below are the probability of receiving at least 2 inches and at least 12 inches of snow through Wednesday afternoon.
Impressive chances to get over a foot of snow in western SD and eastern WY with over a 90 percent chance in some spots. But if you have been watching the forecast, you know that snow may go into Thursday. So here is the probability of receiving at least 2 inches and at least 8 inches of snow from Tuesday afternoon through Thursday afternoon.
Notice now the east is involved in the snow card with much of the area expecting at least 2 inches of snow, but with parts of the east at over a 50 percent chance at 8 inches of snow.
But one of the big components of this storm, which could have a HUGE impact on precipitation type, will be cold air (or in some cases, lack there of). Temperatures will be falling, but may not be cold enough at all levels of the atmosphere to support snow in some areas. This brings a question of will the precipitation be rain or will it be freezing rain if temperatures are below that magical 32 degree mark. This is a real concern because if heavy and long lasting areas of freezing rain develops, power outages will be likely with conditions impossible for traveling. The greatest threat for freezing rain will be across the east where warmer air will be located. Here is a look at some of the ice potential.
This image shows a very uniform look to the icing, however, in reality it will likely be spotty where temperatures can stay below freezing the longest while raining. But these areas have the highest likelihood of experiencing the heavier freezing rain from Gregory and Platte, through Mitchell, Sioux Falls, Brookings, Pipestone, and Marshall.
Finally, the rainfall. Many areas of the southeast (especially northwest Iowa) will get plenty of much needed rain. Here is what futurecast shows for plain old rain across the area. This DOES NOT include the freezing rain, sleet, or snow that will fall…. Which will just add to the overall totals in these same areas.
So here is the KDLT Forecast for snowfall across our area through noon on Thursday…