Current Conditions at Sanborn Field 

 

Tuesday: Sunny. High: 47 

Tuesday Night: Clear. Low: 23

Wednesday: Mostly Sunny. High: 51

Wednesday Night: Partly Cloudy. Low:34

Thursday:  Sunny. High: 65

 

 

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Discussion: A very chilly beginning of the week will be compared to all time lows for the area, as temperatures are 10-15 degrees below average. A polar air mass looks to give mid-Missouri highs for Tuesday and Wednesday only reaching into the upper 40s, possibly the low 50s. Tonight, the low temperatures look to dip into the low 20s, and the cold air does not let up leaving us with mid 30s Wednesday night. Thursday will begin our warm up as a high pressure system looks to filter in warmer air from the south.

-Ritsema

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Forecasters: Ritsema, Clark, Baker

Date Issued: 10/17/2022 9:00 AM CDT

Technical Discussion:

 

A blend of GFS and NAM models were used in this forecast. The two models are in agreement for Tuesday and Wednesday with the location of the low pressure system over the Great Lakes and the intensity of the high pressure system over Arkansas and Texas.They begin to disagree on Thursday as surface winds on GFS shift to the southwest and NAM has a more delayed, lighter shift to the southwest of 5 to 10 knots. 

According to the 250mb maps, a low-pressure system is situated over the Great Lakes Region. This continues to bring in strong, northwesterly winds(80-100 knots) from the back end of the system, persisting through Wednesday. Thursday, winds shift from the northwest to the northeast at 18z. Further supporting the idea of cold-air advection at upper levels throughout the forecast period over Missouri. No divergence can be seen over Missouri between Tuesday and Thursday. 

At 500mb, High values of vorticity can be seen on Wednesday at 00z from the backside of the low pressure system. Wednesday night, though, a shortwave moves southeast close to Thursday 6z. This brings vorticity along with it. 

700mb winds are from the northwest and keep that flow throughout the forecasting period. Due to the shortwave moving through on Thursday at 6z, the NAM shows moisture moving over the area. This, paired with vorticity on the 500mb map, will lead to cloud cover Wednesday night, keeping the low temperatures higher than the night before.

Some moisture is seen Wednesday night on the 850mb along the shortwave, this will contribute to the cloud cover seen overnight Wednesday. Winds are weak(10 knots) from the North on Tuesday and shift the west northwest on Wednesday at 12z, this doesn't last long as the high pressure moving eastward into Arkansas begins to shift the winds to the southwest. This brings in warmer air to the region beginning Thursday afternoon. Direction of this warm-air advection is different between the NAM and the GFS as the GFS believes the shift will be more southerly. 

At the surface, winds follow about the same pattern as the 850mb maps show. On Tuesday, winds are from the north, Wednesday they shift to the west at 12z, and then Thursday is influenced by the high pressure system and the winds shift to the southwest bringing in warmer temperatures for the end of the week. 

-Ritsema