Current Conditions at Sanborn Field
Tuesday Night: Mostly Cloudy. Low: 59
Wednesday: Partly Cloudy. High: 77
Wednesday Night: Showers late. Low: 62
Thursday: Showers and storms. High: 70
Thursday Night: Mostly clear. Low: 45
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Discussion:
Another round of cold air is set to move through the area on Thursday. Coming with this cold air will be a line of showers and storms that will bring plenty of rain. Our highs before these storms will be in the mid to upper 70s while after the storms move through our highs will be in the mid 60s. Our lows will also cool off significantly with the low Thursday evening being 45 degrees.Forecasters: McCormack, Peine, Smith
Date Issued: 4/18/2022 5:00 PM CDT
The 12Z GFS was used for this forecast since the GFS accurately forecasted the observed high temperature for today due to its accurate placement of the surface warm front to our south. This warm front remained further south than the NAM forecasted, therefore, resulting in cooler observed temperatures.
Currently at 250mb, meridional flow is dominating the CONUS with an upper-level trough building into the Pacific Northwest with another, deeper trough over the Great Lakes region. In between these two troughs, there is a narrow upper-level ridge with the ridge axis currently over the Plains. This upper-level ridge will begin to weaken and broaden on Wednesday as it moves into the Midwest. Upstream of this ridge, at 500mb, a weak shortwave disturbance will traverse the southwest flow over northwestern Missouri midday on Wednesday. This shortwave will lead to the potential for isolated showers and storms, with the best chance for widespread storms staying over northwest Missouri. That is where the best forcing and atmospheric energy will be alongside the mid-level disturbance with over 2,000 J/kg of surface based CAPE in that area. With rising heights and southerly winds on Wednesday, temperatures will top out in the upper 70s, which is slightly above average (Avg High: 68).
By Thursday, the upper-level trough, that is currently to our west, will begin to dig into the Intermountain West with a coupled jet stream forming and leading to enhanced upper-level divergence over the central Plains. In response to this, a surface low will form over Kansas Wednesday night. Out ahead of the developing surface low, WAA and moisture advection will take place across the Mississippi River Valley as a low level jet ramps up advecting moisture from the Gulf of Mexico. This surface low will traverse northeast quickly and enter Wisconsin by Thursday afternoon. A trailing cold front attached to the surface low will move through central Missouri sometime during the afternoon on Thursday. Models are likely underestimating the highs for Thursday due to the prefrontal compressional warming that will occur as the cold front approaches Columbia. This additional warming would increase the instability available in the atmosphere and could potentially lead to thunderstorms out ahead and along the cold front on Thursday. However, the other possibility could be that convection and precipitation earlier in the morning on Thursday would lead to cooler temperatures that would take away atmospheric instability, leading to non-convective showers as the cold front moves through. Regardless, rain and thunderstorms are likely on Thursday along the cold front and potentially ahead of the cold front. Behind the cold frontal passage, CAA will knock down temperatures by about 15 degrees by Friday.
Future forecasting shifts should monitor the potential for much colder conditions this weekend due to a very deep trough that will dig into the Midwest and result in continued northwest flow.
- Peine
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