Friday, December 3, 2021


Current Conditions at Sanborn Field

Sunny. High: 67

Friday Night:
Scattered high clouds. Low: 40

Cooler with high clouds. High: 52

Saturday Night:
Clouds moving in. Low: 42

Overcast, then mostly cloudy. High: 68


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Unseasonably warm conditions will continue into this weekend with fairly quiet days ahead. Friday will see plenty of sunshine with southerly winds boosting high temperatures nearly 20 degrees above average. Overnight, a cold front will dip into the region from the north and bring a few clouds but the most noticeable change will be cooler conditions Saturday; temperatures will still be unusually warm for early December. This fair weather will be due to high pressure sliding by to our north, but as it traverses eastward, we will see a return of southerly winds and consequently higher temperatures on Sunday. Highs again reach upwards of 20 degrees above average on Sunday afternoon. Another more formidable cold front will push through the area near dinnertime on Sunday and may produce a few light showers but will certainly spell an end to the unseasonal warmth.

- Splater


Forecasters: Splater, Schneringer, Bongard

Date Issued: 12/3/21 10:00 AM CST

Technical discussion: 

A chance for light rain Sunday morning serves as the main focus for this forecast, with slight disagreement between the NAM and the GFS on precipitation placement serving as the crux of uncertainty. Due to the NAM's significantly colder handling of temperatures Thursday night into Friday morning, the GFS was consulted for this forecast, along with Skew-T's and cross-sections. 

A strong upper level jet streak is centered over northern Minnesota today as the polar front tracks roughly along the US-Canada border from coast to coast. A zonal flow regime is in place over the Great Plains at all of the upper levels. Moderate RH values at and around 250 mb serves as the only significant moisture present in the atmosphere over the forecast area today. A weak front pushes into the region from the north, bringing northerly flow and higher pressure behind it at the lower levels. Passage will occur around 21Z this afternoon, and will enforce a colder low temperature tonight.

Friday night into Saturday is much the same story aloft as the day before. Weak flow coupled with dry conditions will lead to calm weather. As a high pressure system progresses eastward across the Dakotas, winds will shift to the east at the surface throughout the day and into the evening. A progression towards southerly flow by 06Z will serve to stymie the low temperature Saturday night somewhat. Southerly flow aloft Saturday evening will also start advecting moisture into the forecast area in the lower levels.

Sunday sees the development of a trough at the upper levels to our northwest. Ahead of a strong, northwesterly jet blasting down through the Rockies, this pattern will begin to progress towards Missouri. The leeward side of the developing trough will push weak upper level divergence over the forecast region Sunday. Coupled with strong RH values at 850 mb, these features could lead to light precipitation values for the region. The uncertainty lies in the magnitude of forcing present over the region, with the GFS being slightly more reserved on precipitation amounts than the NAM. Either way, any showers that do occur will be very light. As the morning progresses, surface winds will shift to the southwest, and a cold front begins to approach the region Sunday evening.


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