11/13 Forecast Discussion: Chinook me not

Dry, westerly winds pour across the Black Hills as snow looks likely for the weekend

GOES-16 Satellite, 11.13.2018 Black Hills

Tuesday evening: Temperatures will hold steady in the low to mid-30s tonight, as chinook winds take the edge off of cooler temps. As westerly winds descend from higher terrain, the air is compressed and heated with the increased weight of the atmosphere. Notice the clouds streaming in the above picture appear like ripples in a pond. The Black Hills are no different than a rock in a river when it comes to the atmosphere. Dry, warm air will continue to filter into the area into into tomorrow morning, with decreasing cloud cover.

Wednesday: Sunny conditions with highs in the low 60s can be expected by Wednesday afternoon. 10-15 mph westerly winds will continue to compress and heat the air around the Black Hills. A nice Wednesday on tap – great day to get yard work down or any other outdoor activity.

Chinook winds will keep us unseasonably warm before our high temperatures begin to plummet once again.

Wednesday night: Cloud cover will begin to increase slightly as the ridge of high pressure keeping us warm and dry begins to break down and retreat. Things will hold on long enough to give us mid- to high 30s for our low temperature on Wednesday evening, making for a cool, but at least relatively comfortable evening.

GFS Temperature Model – Thursday afternoon through Friday and Saturday morning

GFS Precipitation model – Thursday through Saturday morning

Thursday and Beyond: Looking ahead, cold air begins to fight back at the unseasonably warm conditions. Breezy to windy northwesterly winds will begin to bring cooler air, instead of warm, dry air. A cold front begins its descent into the Hills but holds off until Friday. Lows Thursday night look to remain in the 30s, as cloud cover continues to increase.

At this time, moisture and precipitation look likely early this weekend. Depending on how the moisture times up with the arrival of the cooler air mass, we could be talking either a mixture of rain and snow or just snow Friday afternoon going into Friday evening into Saturday morning. The cold front will be quick and efficient, plunging our high temperatures into the mid-40s and high 30s, dipping all the way to the mid to low teens by Friday night.

There is high confidence that by Friday evening going into Saturday morning, most if not all precipitation will be in the form of snow in the Black Hills. Where and how much exactly is not yet clear, but accumulations are looking likely. By Sunday and Monday, high pressure fights back and brings us warmer, drier conditions once again going into next week.

Snow Accumulations: As my forecasting professor once told me, “Anything past three days in forecasting is madness.” I would like to observe how models are handling the progression of our next system before trusting it on snow totals. If it’s moving it too fast or too slow, the timing could be off, and accumulation totals would thus be off as well. I’ll start posting more concrete snow totals Thursday morning in anticipation of a Friday snow event.

What is known: We have moisture, we have lift/energy and we have cold temperatures. Perhaps a movie night Friday evening could be considered at this point.

A Wyoming Sunset – Thanks Jame Grabrick!

Categories: Local News, Weather Daily, Weather Team