Current Conditions at Sanborn Field

 

Tuesday Night: Partly cloudy. Low: 16

 

Wednesday: Cloudy. High: 28 

Wednesday Night: Cloudy. Chance of flurries. Low: 22

 

Thursday: Cloudy. Snow likely. High:28

 

Thursday Night: Cloudy. Snow stopping early, becoming freezing rain/drizzle. Low: 17

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Discussion:

 

What a chilly "twos-day" this has been. Mid-Missouri has been steadily cooling off since a cold front passed last night, leaving us with northerly winds and a cooling trend that will continue through Tuesday night. The winds will keep flowing at about 15 mph from the northwest, forcing our temperatures into the mid-teens. Wednesday morning, the winds will slow to 5-10mph, and begin shifting to be northeasterly. The sky will become cloudier as the day progresses, capping our high temperature in the upper-20s. Sky conditions will become overcast overnight Wednesday, which will keep the low temperature in the lower-20s. Also, a low pressure over western Oklahoma will begin making its way eastward at this time. Due to the low pressure system, there is the opportunity to see some flurries after midnight, but we are not expecting much, if any, accumulation. Thursday will once again be interesting as snow, and possibly sleet, are expected to start falling around sunrise and continue throughout the day. Accumulation totals are expected to stay less than 2 inches. Thanks to the cloud cover, our high temperature will stay about 4 degrees below freezing. The winds will shift from the northeast to the northwest Thursday night as the low pressure moves into the southeast CONUS. The snow will transition to freezing rain/drizzle in the early evening and then stop around altogether midnight. Because of the winds shifting, we are expecting a cooler low (upper-teens) than the previous night.

-Alexander

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Forecasters: Alexander, Duff, Orr

Date Issued: 2/22/2022 5:00PM CST

Technical Discussion: 

    The GFS 12Z run was used in this forecast. Both the GFS and the NAM had a warm bias in forecasting surface temperatures, but the GFS matched up closely with upper level conditions. Soundings were used to diagnose precipitation type and timing of the event. The problem of the week and the focus of this forecast is similar to last week as an upper-level trough will bring snow and other associated wintry precipitation to the region late Wednesday and during the day on Thursday. 

    At 250-mb the flow of the atmosphere is very meridional, a positivity tilted trough sits over the Western CONUS and moves east during the forecast period. Winds at this level will increase as the jet stream rounds the base of the trough and a jet streak becomes centered over Missour. The streak intensifies around 21Z Wednesday, putting Columbia in the right entrance region indicating upper level divergence. A second jet streak approaches Mid-Missouri Thursday afternoon around 00Z Friday and strong divergence aloft is associated with the left exit region of the jet streak. 

    In the mid levels of the atmosphere, the trough is centered over the southwest and moves north east towards Missouri. At this level, circulations ahead of the trough begin 15Z Thursday, aiding in the development of precipitation. Vorticity intensifies around 03Z Friday, but due to lack of abundant moisture only supports cloud cover. Behind the passage of the trough the flow becomes more zonal and calmer conditions are expected. 

    Mid level relative humidity values begin to increase over central Missouri as moisture is advected from the south beginning 21Z Wednesday. A period of dry air at 700-mb and dry air at lower levels indicates that precipitation won't start until later Wednesday night, around 06Z Thursday, when moisture associated with the trough is advected into the area. Ample moisture until 06Z Fri will support cloud cover and precipitation. Clearing will begin after the precipitation ends early morning on Friday. 

At 850-mb a closed low pressure system moves off to the northeast overnight on Tuesday leaving behind colder air and a northwesterly wind. A col can be identified around 18z Wednesday. Winds die off as we are in the saddle point, but then switch to a southernly direction as a high pressure over Florida and a low pressure system to the southwest begin to dominate the flow at this level. The nose of the low level jet at 850-mb sits in southern Missouri but helps to saturate the region beginning 00Z Thursday. Winds will switch back to a northernly direction late Thursday.

    Sounding were helpful in the development of this forecast to diagnose precipitation type and timing of the event. A 03Z sounding from the GFS indicates ice from seeder clouds in the upper-levels of the atmosphere will help to saturate a dry layer in the mid-levels of the atmosphere. Moisture begins to increase at the surface level from 09Z- 12Z Thursday where periods of precipitation is possible. The likely precipitation at this time is freezing rain or drizzle, but will transition to snow after the atmosphere becomes fully saturated around 12Z Friday. Any precipitation will start to taper off around midnight Thursday. Early evening Thursday, snow will transition to freezing rain or drizzle, as the upper levels of the atmosphere dry out. The atmosphere will dry out from the top down leaving sufficient moisture in the lower levels for clouds and the potential for freezing rain or drizzle before the precipitation ends Thursday night. 

    Total precipitation accumulations are trace on Wednesday night and total snow accumulations are expected to be under 2 inches on Thursday. Potential impacts include hazardous road conditions. Future forecasters should pay attention to upcoming winter weather event. 

-Duff