Tuesday, March 14, 2023

 Current Conditions at Sanborn Field



Tuesday Night:
Mostly Clear. Low: 29

Partly Cloudy. High: 61

Wednesday Night:
Increasing clouds overnight. Low: 48


Showers becoming more widespread in the afternoon. High: 56


Night: Rain ending before midnight. Snow may mix in. Low: 24



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Warmer conditions are expected on Wednesday and Thursday with high temperatures near 60! However, an umbrella will be needed for your Thursday commute as rain showers will be likely during the afternoon and evening hours. Rain may change to snow overnight on Thursday, but little to no snow accumulation is expected. Total rainfall amounts from Thursday morning to Thursday night will be around 0.5". Cooler air will move into the region behind the low pressure system as temperatures Friday morning will be in the mid-20s.

- McCormack

Forecasters: Peine, McCormack, Smith

Date Issued: 3/14/2023 5:00 PM CDT

Technical Discussion:

The 12Z GFS was utilized for this forecast due to its accurate depiction of current temperatures across the area and the placement of the surface high pressure currently over eastern Missouri. The problem for this forecast period was in regards to a low pressure system that will be impacting the area beginning during the day on Thursday until Friday morning. The timing of its associated cold front and the exit of precipitation will determine whether or not the rain briefly switches over to snow as the system departs Friday morning. This far out, confidence on snow occurring remains low, but it is something that needs to be monitored.

Current surface observations reveal a surface high pressure system that is located over eastern Missouri, which has resulted in a clear sky and very calm winds out of the southeast today. With no cloud cover and calm winds tonight, efficient radiative cooling will occur, resulting in temperatures that will drop into the upper 20s by tomorrow morning. This surface high will push east into the Ohio River valley on Wednesday leading to southerly winds across the region. At the same time an upper level ridge will be building into the Midwest resulting in rising heights aloft. This, along with a WAA regime in the lower levels and at the surface, will allow temperatures to rebound quickly tomorrow with highs topping out in the low 60s under a partly cloudy sky.

By Thursday morning, an upper level trough will begin to dig into the Intermountain West and push eastward into the Northern Plains on Friday. At the same time, a surface low will begin to form and deepen on the leeward side of the Rocky Mountains in response to a coupling jet stream that will be enhancing upper level divergence. With the surface low to the west of the region on Thursday, a low level jet will ramp up leading to moisture return that will result in precipitation chances beginning during the late morning on Thursday. Southerly winds will also result in continued WAA that will lead to seasonally average (Avg. High 56) high temperatures on Thursday despite thick cloud cover and intermittent showers. By Thursday night, the center of the surface low will slide across northern Missouri and into the Great lakes region on Friday. As this occurs, its associated cold front will pass through the region sometime Thursday night.

As mentioned earlier, the timing of the cold front and the exit of precipitation will determine if any snow will be possible as the system departs. At the moment, the GFS does have a brief period where snow is possible, around 06Z Thursday night, before the mid-upper levels of the atmosphere dry out and the precipitation comes to an end. Overall, a combined amount of around 0.5” of rain is expected during Thursday and Thursday night. Regardless of what precipitation type occurs on the back end of the system, temperatures are expected to plummet behind the cold front. Temperatures are expected to be in the low-mid 20s by Friday morning with strong winds out of the northwest resulting in a very cold morning.

Future forecasting shifts should monitor the potential for well-below average temperatures due to the continued northwesterly flow that will be in place into the weekend.

- Peine

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