From Snow To Fog, Pinpointing Your Super Bowl Weekend Forecast
February 03, 2012 8:28 PM
We’ve seen our fair share of winter weather in the Northern Plains over the years, but this year we continue to avoid the heavy snow, so it seems. Currently, a major winter storm is rolling through portions of Colorado and Nebraska, and will continue to trek northeast over the next couple of days. In our neck of the woods, low cloud cover and foggy conditions will prevail. The image to your left shows the current warnings and advisories across our region. The counties shaded in pink have Winter Storm Warnings and the ones in purple are advisories. By looking at the warnings alone you can tell where the snow will trek, to the east, and just south of highway 18. Denver, Colorado has picked up just over a foot of snow with around 2 feet already recorded in the foothills. The average Febraury snowfall in Denver is around 6 inches, and the record for highest 24 hour snowfall in Februray? 9.5 inches.
The models have not handled this particular storm all that well over the past week, and continued to flip flop from run to run. The current forecast brings the far outer edge of the snow band to Sioux City, where we could see around 1 to 3 inches. The majority of the activity will stay well to our south into Nebraska and Colorado. In Nebraska, snow fall rates have been around 2 inches an hour, and the snow looks to continue straight through Satuarday. Behind the low is where we’ll see the snow, and out ahead of it we’re actually seeing some severe storms. The image below shows current temperatures throughout the country, notice where the cold air is? Temperatures are below 40’s degrees just west of Kansas City and even in the 70’s in Texas. You typically get your heaviest snow fall to the north and west of the low, which is also where you can get warm air colliding with cold air thanks to a easterly wind wrapping around the storm. In simple terms, the warm air moves overtop of the cold air and the precipitation falls as snow. Warm air advection is also a way to get air to rise. Essentially warm air advection is warm air moving into a colder region.
The second image below is a satellite image from the upper levels of the atmosphere and shows the amount of water vapor in the atmosphere. This image gives you a good idea of where the low is…just east of Colorado and moving east. The brighter the color, the more moisture you have to work with. The line in front of the low represents a line of thunderstorms all out ahead of the cold front. Stronger storms are found a little bit farther south into eastern Texas, thanks to a Sub Tropical Jet moving in an east northeasterly fashion. Thunderstorms during the month of February seems rare, but it really isn’t for the south. College Station, Texas home of Texas A&M even saw 4 inches of rain over a time frame of just 3 hours.
Closer to home we’ll be dealing with fog instead of snow. High pressure will be our friend over the next couple of days shoving the low down to our south. However, we'll still be able to get some decent moisture out of the storm, which will keep us cloudy through Saturday. Depending on how far south the high moves will dictate how much snow we receive in Sioux City, it is a very close call, and the images below show just that.
12z run (GFS)
12z run (Nam)