Current Conditions at Sanborn Field         

 

             

Friday - Clear skies. High: 52-56

Friday Night - Clear skies. Low: 38-42

 

Saturday -Clear. High: 62-66

Saturday Night - Partly cloudy. Low: 34-38

Sunday - Clear, windy in the morning. High: 48-52

 

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Discussion: 

The region is in for a pleasant Halloween weekend as fair weather and sunny skies will the rule of the day through Sunday. Saturday will be breezy and slightly warmer than Friday with high temperatures warming into the low 60's. Trick-or-treat conditions will be favorable this year as the region will enjoy a cool, windy fall evening. A cold front will drop temperatures back into the 30's overnight Saturday into Sunday as we fall back with Daylight Savings Time as well. No precipitation is expected with this cold front but conditions Sunday will be windy and colder with sunny skies.

 

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Forecaster: McGuire, Bongard

Issued:  10 AM CDT 30 October 2020

 

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

 

Current conditions are cold and clear with high relative humidity. The NAM model and soundings were used for the duration of this forecast due to accuracy in 00Z and 06Z model output for the current conditions. GFS was promoting current conditions that were too warm for what was observed. SREF ensemble will also be used as supplemental information.

 

At the beginning of the forecast period looking at 250-mb model charts a broad ridge is located over the majority of the western CONUS with a trough axis located over the Ohio River Valley and jet streaks placed both upstream and downstream of this axis. The streak downstream being the stronger of the two having wind speeds of 195 kts above northern Maine. Mid-Missouri is located in the right exit region of the jet streak upstream of the trough axis. Friday afternoon will bring zonal flow at the 250-mb level as the ridge moves eastward, quickly transitioning across the CONUS exiting the Midwest by Sunday at 00z. Sunday at 06z Missouri will find itself within a trough axis with a jet streak core of 120+ kts over southern Missouri. Towards the end of this forecast the flow will look a lot like the current flow, that being, a ridge set up over the western CONUS and Missouri being in the right exit region of a jet streak.

The 500-mb height and vorticity compliments the 250-mb flow with the ridge/trough patterns with a lack of vorticity initially. A trough will build into the northern Plains Saturday and amplify. This will promote a short-wave and cold front development in the northern Plains that will advect vorticity into the region between 03z-06z as the front passes through. Behind the short-wave vorticity will advect out of the region by Sunday afternoon.

 

The lower levels in the atmosphere for the majority of the forecast period are dry except during fropa. Even then, this front will be moisture starved. Prior to fropa on Saturday, there will be WAA in the lower levels. The 850-mb wind speed chart provides that the Midwest is cutoff from Gulf moisture. Soundings along with prognostics of the low level maps indicate the lack of moisture, leading to fropa without precipitation likely.  

What this means for the region is that it will be a fairly pleasant forecast period with mostly clear conditions except with fropa, where clouds will be expected but due to lack of moisture for the area, precipitation is not anticipated. Temperatures will be seasonal Friday, becoming mild due to WAA on Saturday. Typical post frontal conditions for Sunday with NW winds and temperatures falling back to seasonal.