Once again another system coming in from the south will likely cause problems for the central/northern Plains this weekend. An arctic air cold front should push over the area Thursday/Thursday night and begin to drop the temperatures through the weekend. The first shortwave expected with the cold front passage is likely to remain fairly dry, as without much moisture to work with and such cold air it will be hard to create any ice crystals and thus precipitation over the area. However, the next shortwave that comes through with a secondary low moving from TX to the midwest during the weekend will bring moisture to the area. This moisture will easily allow for precipitation across the state Saturday and Sunday, likely in the form of snow for most of the state. However, portions of southern Iowa and especially southeastern Iowa may see rain as the main form of precipitation. Also the potential for freezing rain is possible along the then stationary cold front that is likely to be draped over the area…
Amounts with this system are hard to point out at this time, with the exact track and strength of the system still a ways out from being in good forecast shape. However, with such cold air already in place as the moisture overrides the cold front and works its’ way into the area the snow amounts could easily pile up quickly. This will be due to the snow/water ratio being much higher than the typical 10:1, in this system the snow/water ratio could be 15:1 or even 20:1. Meaning that 1 inch of liquid rain would equal 20 inches of snow…
Currently, models are indicating that some fairly hefty precipitation amounts could be possible across NE/IA by the end of the weekend. Tonights’ model run of the GFS shows that in eastern NE and northern IA they could easily see snow amounts in the 6-10 inch range, this however is likely not getting the snow/water ratio correct at this time and many other factors could change the amounts. Got a complete look at tonights’ GFS indicating very heavy snowfall across Iowa/Nebraska, this agrees with the increased precipitation amounts also forecasted. Will have to watch this very closely, it will also be a great help once we get the NAM/WRF within range on this system as well. Just for humor, I will say that GFS snowfall forecast indicates 16-18 inches of snow for west-central Iowa (Remember this is definitely not a good forecast to make at this time, the 16-18 inches is currently in humor). I will likely issue my first forecast on potential snow amounts around Noon on Thursday (36 hours from now) with updates to follow approx. every 24 hours leading up to the event. For now, just keep an eye out on this system for snow amounts or what type of precipitation is expected depending on where you live. Once this system passes, be ready for the cold air of winter with highs not going above 20 and lows into the single digits easily…
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