Preparing For The Wind Tomorrow & Getting Ready For The Snow On Tuesday
by Angela Schilling, Meteorologist
February 26, 2012 8:58 PM
Just one day later and our upcoming storm is becoming more and more clear with heavy snow to the north and a mixed bag of winter weather in the southeast. The models are much slower than previous runs and show the activity sticking around through the first half of Wednesday and not really starting until Tuesday morning. The National Weather Service has issued a Blizzard Watch for our counties along and north of Highway 14 where we could see upwards of 12 inches once this system is said with and done. On top of the snow strong winds will also accompany the storm, therefore lowering visibilities significantly. To start things off, all of us will see snow Tuesday morning, with a change over to rain in the southeast as the day goes on. Areas south of the South Dakota state line will probably just see rain on Tuesday. In Sioux Falls, we’ll start things off with snow Tuesday morning, followed by a change over to sleet and freezing rain around lunch time, and then transitioning all over to rain by late Tuesday afternoon. Any left over showers throughout the region will fall as snow on Wednesday.
Tuesday Morning...widespread snow through 10am or so.
Precipiation type becomes more tricky by Tuesday afternoon with a changeover to rain & freezing rain in the southeast by around lunchtime.
By late Tuesday afternoon areas south of Highway 14 will transition over to rain, with rain totals around a half inch.
Snow totals will be the highest to the north, with lesser amounts south of Highway 14.
*************Make sure to read the rest of the blog below**********************************
High winds will be the main concern on Sunday with our next storm system approaching Monday night and lasting throughout the day on Tuesday. It’s been more active this past week, and this upcoming week doesn’t look to slow down. Beginning late Saturday night we’ll start seeing light snow develop north of highway 14 and clipping our far northeastern counties. Accumulations will be light, but blowing and drifting will still be a concern. Behind the front our winds will come out of the west, and will also usher in some colder air. The image below shows forecasted winds for Sunday afternoon. The second image is from the GFS model and shows mean sea level pressure for Sunday afternoon, with precipitation north of Highway 14 and tight isobars or lines of equal pressure (blue lines on the map below). Typically, the tighter the isobars, the stronger the wind will
GFS model, Sunday morning...snow stays north of Highway 14...1-2 inches with blowing/drifting
By Monday night our next storm will roll it’s way into our neck of the woods starting off with some light snow. The models are still in disagreement and ironing out the kinks, but the general consensus brings the majority of the activity to the I-29 corridor by Tuesday morning. With this particular storm some places will receive a lot of snow and others will receive a lot of rain, all depending on the location of the low. Moisture will not be an issue with this storm, as a matter of fact it looks like we’ll have plenty to go around, however, temperatures once again will be the deciding factor. Head south of I-90 and precipitation type becomes a little bit trickier. You can think of models as individual forecasters each with their own interpretation of what’s going to happen; now the trick for us as meteorologists is to know which one to go with. Each model has their own bias or habits, with the GFS typically too cold and too quick, which is ironic because this time around GFS is the warmest. The GFS is also the farthest north, which draws in warmer air from the south, while the NAM keeps the low farthest south while keeping the cold air in South Dakota.
GFS Model, Tuesday morning, widespread precipitation
GFS Model, Tuesday afternoon, low strengthens, bullseye directly north of low
Same timeframe as image above, focal point along wind shift from northeast/east...warmer temperatures found in the southeast and east of the James.
Nam for Tuesday afternoon...weaker low compared to GFS and much farther south
The European is in between the two, putting the low in northwest Iowa by Wednesday morning. The heaviest bands of precipitation are typically not found when the low is right overhead, which means things should start to wind down by Tuesday night. However, the Canadian model is much slower with lingering showers on Wednesday afternoon.
European model for Tuesday morning, with low in southeast Colorado (mean sea level pressure)
European for Tuesday night...low in northwest Iowa, with a lot of wind behind the low
So what makes sense?
You typically look to the north and west of the low to get the heaviest amount of snowfall. If you were to melt all of the snow and measure everything as pure liquid both the GFS and NAM would give Sioux Falls around a half-inch of precipitation, but different profiles produce different ratios of snowfall. For example 10:1 would mean a half inch of liquid would equal 5 inches of snow. Warmer profiles suggest lower ratios, like 10:1, while colder profiles suggest higher ratios, such 20:1. As a result, ratios will be much higher north of Highway 14, where the cold air is, which is also where were more likely to see snow. At this point in time it looks like we’ll see a mixed bag of winter weather in the southeast beginning Tuesday morning, with sleet, rain, and possibly freezing rain. As cold air continues to funnel in from the northeast any left over showers will fall as snow by late Tuesday night. Precipitation type will be easier to figure out to the north, with mainly snow.