Current Conditions at Sanborn Field

 

Wednesday Night - Overcast with flurries and light snow showers. Low: 10-14. 

Thursday - Overcast. Occasional snow flurries possible. High: 16-20.

Thursday Night - Overcast. A small chance for snow showers. Low: 4-8. 

Friday - Overcast. A slight chance of snow, especially late. High: 12-16. 

Saturday - Overcast. Snow possible early. Very cold. High: 6-10.

 

 

 

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Discussion: 

The broken record continues. We're looking at several more days of cold weather, with clouds and off/on snow chances into the weekend. Snow flurries and light snow showers are possible tonight as lows fall into the lower 10s. Any accumulations will be minor. For Thursday, another cold and cloudy day is on tap, although our chances for snow will be smaller (but still not zero). As we look towards Friday and Saturday, all attention turns to a reinforcing push of cold arctic air. Yes, we have not bottomed out yet in terms of temperatures. Snow is possible Friday night into Saturday as the colder air streams in, and temperatures this weekend will be dangerously cold. Lows Saturday night may drop well below zero, and plan on sub-zero wind chills throughout the weekend.

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Forecaster: Vanderpool

Issued: 5:00 PM CST 10 February 2021

 

Technical Discussion (The nerdy stuff we are discussing in class)

 

The pattern across the CONUS remains dominated by persistent blocking. This is causing the polar jet to plunge into the Midwest and allowing cold air and periodic snow chances to continue unabated.

Current WPC sfc analysis (18 UTC) shows a powerful arctic high over the upper Midwest. Well south of mid-MO, a warm/stationary front was observed through Louisiana, Mississippi, and Tennessee. A cross-section of theta, FGEN, and wind from Des Moines, IA to New Orleans, LA reveals that the layer of cold air stretching from the deep south and points northward is very shallow, and that there is significant positive FGEN at multiple points along the tight theta gradient. One such area of significant FGEN was just north of Columbia at approximately 750-mb, which corresponds to an ongoing region of light snow around and east of the city. A longwave trough in the upper levels was located over the southern Rockies, which is partially to blame for moisture advection ahead of it.

In the near term, the RAP/HRRR was used to provide sensible weather guidance. The RAP seems to handle current sfc temperatures very well (as of ~4:00 PM), whereas the GFS is several degrees higher and the SREF mean is nearly 10 degrees too warm. The SREF has had a significant warm bias over the past few days, so there will be little reliance upon it (temperature-wise) in this forecast. For the longer-range forecasting, a blend of the GFS/GEFS and NAM was used. 

 

This evening and overnight, ongoing light snow and/or flurries will continue to be supported by FGEN and decent moisture in the 925-700 mb layer. The RAP wants to produce an enhanced region of FGEN and omega near and southeast of Columbia between 04 UTC and 09 UTC, but the RAP QPF is low or nonexistent during this time. Nevertheless, we'll need to watch out for continued periods of flurries/light snow overnight, with the potential for mesoscale banding to slightly increase snow rates locally. Model soundings remain saturated through 800-mb, so any snow that forms should make it to ground level. In the spirit of persistence forecasting in a cold air regime, lows should reach the lower 10s or maybe the upper single digits.

Thursday, more clouds and cold weather are anticipated, with model soundings remaining saturated near 925-mb and the 12 UTC GEFS indicating a 100% probability of sky cover > 90%. A jet streak at 250-mb will be passing by to the northeast (indicating divergence aloft) but short-range models aren't too keen on producing snow, courtesy of a lack of lift in the column. Still, given plentiful moisture and the aforementioned longwave propagating eastward (but weakening before reaching the Midwest), snow flurries and showers cannot be ruled out for Thursday. The GEFS is the most bullish with this, with mean snow accumulations of ~0.5". Highs should reach the middle 10s.

 

For Friday and Saturday, the main concern shifts to a fresh plunge of Arctic air into the Midwest. Models are in agreement that the polar jet will dive south as surface high pressure moves in. As the transition to a colder airmass occurs, there may be some light snow Friday night into Saturday. The NAM, GEFS, and SREF all support this. QPF will be light with anything that falls, though the typical dusting to an inch cannot be ruled out. In terms of temperatures, negative single digits are likely Friday night and Saturday night, with the potential for even colder lows IF clouds can clear out. Right now, Saturday night would be the most likely time to see this, and chances of seeing clear sky even then are not great. Highs Friday will probably be in the lower 10s, with Saturday's highs in the upper single digits. Dangerous wind chills are likely, with wind chills as low as -25 not out of the question.