A lot is going to be happening in weather in the next several hours, and none of it is good.
After a foggy start this morning, we’ve had partial sunshine today. There is a big difference in temperatures, from the warmest temperatures in SE KELOLAND thanks to a south breeze, to the 20s in Rapid City and the west, where there have already been wind gusts in excess of 70 mph!
Winds will continue to increase the rest of today as a very strong low pressure system moves out of Nebraska toward Sioux Falls this evening and then to Duluth overnight. High wind warnings are posted across most of KELOLAND, with eastern KELOLAND getting its strongest winds – gusts over 60 mph – this evening.
The fierce winds will be accompanied by raindrops in Sioux Falls, where ½” is possible, though forecast models suggest even Sioux Falls could get a little snow mixed in with the rain late tonight. North and west of Sioux Falls there will be some wind-driven snowflakes. We’re expecting accumulations under an inch, but the strong winds will magnify their impact, and there could be squalls with greatly diminished visibility this evening. Travel could be impacted. Advisories will be in effect this evening.
Then there is the severe weather threat. With a broad wall of wind coming toward Sioux Falls and SE KELOLAND late this afternoon, rare December thunderstorms will be possible. The main threat from any storms would be damaging wind, and the threat will be in Sioux Falls around the dinner hour. The expectation is that winds of 60-70 mph would be possible with strong storms. The Storm Prediction Center still rates Sioux Falls a marginal risk of severe storms, but the risk will be greater south and (especially) SE of the city, in NW Iowa. The strength of this system is such that we may even see tornadoes over snow-covered ground in Iowa as the center of the system swirls right over Sioux Falls around 6 pm.
The system will spin away overnight, though strong winds will be slow to decrease. Those west to northwest winds will draw in sharply colder air that may cause freezing or icing of any west spots on the roadways. Temperatures will fall to the teens overnight. Pay particular attention to road decks, which tend to become slippery in this type of situation.
Tomorrow will be partly to mostly sunny, but a lingering westerly breeze will keep things cool. Thursday highs will only be in the mid 20s to low 30s East River, and the mid to upper 30s West River.
Friday will be partly to mostly cloudy, and there could be some light snow showers north of I-90. Highs will be in the low 30s in Sioux Falls and SE KELOLAND, but only in the 20s in the north and west.
Saturday will be even colder. Morning lows will be in the single digits for many of us, and with mostly sunny skies we will only be in the teens to low 20s East River, and around 30 in the west.
Sunday will be partly cloudy and somewhat breezy. But it will also be warmer, topping out in the mid to upper 30s East River and the 40s to around 50 in Rapid City.
We’ve pulled the show showers from the forecast for Monday, which now looks like the start of a dry Christmas week.
Christmas is ten days away, and so far there no major systems showing up in the computer models through the holidays. The raw output of the models would give us highs in the upper 20s in SE KELOLAND for Christmas Eve and Christmas day – but as we always say this far out, stay tuned.