Current Conditions at Sanborn Field

Monday - Overcast. High: 44-48

 

Monday Night - Overcast. Low: 40-44

 

 

 

Tuesday - Cloudy with scattered thunderstorms developing during the 

                     afternoon. High: 54-58 

Tuesday Night - Cloudy with widespread showers and thunderstorms during the

                             evening, becoming less numerous after midnight. Low: 48-52

 

Wednesday - Overcast. High: 64-68

 

 

 

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Discussion: 

Conditions this morning are very December-like thanks to yesterday's cold frontal passage. We will remain dreary today with overcast skies and afternoon temperatures only reaching into the mid-40s. Skies remain cloudy overnight with temperatures dropping very little. Tuesday and Tuesday night will bring another dose of active weather, with a period of showers and thunderstorms expected due to the passage of a warm front. By Wednesday, the rain will have cleared out, but we will still be left with plenty of cloud cover. There will be a noticeable warming trend between today and Wednesday, with high temperatures Tuesday in the mid-50s and highs Wednesday in the mid- to upper-60s.

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Forecaster: Ethridge, Ritter

Issued:  10 AM CDT 19 October 2020

 

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

Firmly in the midst of perhaps the most active period of weather in some time, there is much to discuss regarding this forecast. The main issues with this forecast are the degree to which we warm during this warming trend and precipitation amounts Tuesday afternoon and evening. The GFS was used as primary guidance for this forecast, supplemented by GEFS and SREF plumes.

This morning, central Missouri was beneath the right-entrance region of a 250-hPa jet streak, creating enhanced divergence aloft. A secondary 250-hPa jet streak protruded into the Plains from British Columbia. Mid-Missouri was also sitting right at the base of a 500-hPa longwave trough centered over central Canada. Plenty of moisture was evident in the lower levels of the atmosphere, with weak southwesterly flow noted over Missouri. At the surface, temperatures have changed very little in the past twelve hours, and the clouds have yet to relent as well.

Looking ahead to the forecast period, the GFS suggests the 250-hPa jet will move up into the upper Midwest today and remain there through the period. A 500-hPa ridge will also begin to build in starting late Tuesday and continuing into Wednesday. Low-level moisture should be present throughout most, if not all, of the forecast period, but a 40-kt LLJ will push into the region Tuesday afternoon, helping to enhance moisture advection into the area Tuesday afternoon and evening. Skew-T's from the GFS suggest that the most likely time for Columbia to see rainfall will be between 21 UTC Tuesday and 06 UTC Wednesday, thanks mostly to the enhancement of the LLJ. With CAPE values exceeding 800 J/kg during this time and LI values <-3C, thunderstorms cwill be possible during this rainfall event, though none are expected to be severe. Additionally, with warm cloud depths near 4 km and PW values of 1.5-1.6 inches, heavy rainfall will be a possibility with any thunderstorms, although, considering dry antecedent conditions from 6 weeks of very little rainfall, flash flooding is not a concern at this time. By Wednesday, GFS Skew-T's show the mid-levels of the atmosphere drying out significantly Wednesday morning, so we will be left will a calm, cloudy day on Wednesday.

For temperatures, with that ridge gradually building in, GFS Skew-T's show veering winds with height both Tuesday and Wednesday; therefore, we should experience a warming trend throughout this period, although this will be tempered somewhat by the expected cloud cover. Nevertheless, today will be the coldest day of the period, with afternoon highs in the mid-40s. Temperatures hardly drop off tonight thanks to the ever-present cloud cover. Tomorrow will be noticeably warmer than today, with highs in the mid- to upper-50s. Lows again Tuesday night will only drop to near 50 thanks to cloud cover. By Wednesday, we should be back into the upper-60s.