Current Conditions at Sanborn Field
Tuesday: Becoming partly cloudy. High: 54
Tuesday Night: Partly cloudy. Low: 33
Wednesday: Partly cloudy. High: 47
Wednesday Night: Partly cloudy. Low: 29
Thursday: Sunny. High: 45
Discussion:
Much of the snow left on the ground will finally get the chance to melt as this week will be unseasonably warm. Tuesday will feel warmer than Monday, with few clouds and temperatures reaching up into the mid 50s. A weak cold front passes through Tuesday night which brings the low down to near freezing. This leaves Wednesday to be slightly cooler with temperatures in the upper 40s. Wednesday night will dip down into the 20s with some cloud cover. These low temperatures could allow for melted snow to refreeze on roads, so watch out for slick conditions. Thursday continues to cool down slightly into the mid 40s. No precipitation is expected through Thursday, leaving the perfect opportunity to get outside and enjoy the pleasant weather while its here!
- Cade
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Forecasters: Cade, Travis
Date Issued: 2/08/22 10:00 AM CST
Technical discussion:
Deceivingly quiet weather this week echoes true the saying "there's always something going on." Upper-level disturbances make there way southward from Canada, but a lack of moisture suggests mid-Missouri will stay dry. Thus, the main focus for this forecast is assessing how this, and remnant snow pack will affect temperatures going forward. Went with GFS guidance. Both the NAM and GFS were in good agreement with the upper-level setup and current conditions, but abnormally large spread in the SREF plumes for Tuesday afternoon high suggests the NAM is confused.
The La Nina wintertime ridge-trough pattern over the CONUS remains the story for the foreseeable future. Looking at 250- and 500-hPa output from the GFS shows that this setup will allow for clipper-like disturbances to fall out of Canada. A shortwave seen at 500-hPa over the Northern Plains will continue to propagate south and east as it rounds the base of the long wave trough parked over the eastern half of North America. This will be the theme until this pattern breaks down. PVA with this incoming shortwave will create forcing for ascent Tuesday night into Wednesday. As the first shortwave exits Wednesday night into Thursday, a second wave (and associated PVA) is quick to take its place, following the same general track. By the end of the forecast period, a third looks to be on the doorstep.
Looking only at 500 hPa, this period looks rather active. However, a lack of moisture seen in the 700-hPa RH field reveals a more detailed story. Neither of these disturbances have much moisture to do anything with, so precipitation is not expected. That being said, GFS soundings indicate a period of near-saturation in the upper levels coincident in time with forcing created by the PVA from the first wave. This would point to a cloudier sky Tuesday night into Wednesday morning. Even less moisture is available for the second wave as soundings depict a completely dry column. So, despite similar forcing Thursday morning/afternoon, much sunnier conditions are anticipated for Thursday.
Temperatures are the particularly tricky aspect of this forecast. There are two main factors that will play into the region's temperature trends: advection, and snow pack. GFS MOS indicates considerable warming compared to yesterday with a forecast high of 56. WAA advection is already at play with a 25-kt WSW wind at 850 hPa and broad solenoids seen between MSLP and 1000-500-hPa thickness. However, current thinking is that significant residual snow pack will result in diminished effects from WAA. As such went slightly cooler than model guidance for this afternoon's and tomorrow's highs. WAA will be short lived as a cold front seen at the surface will pass through the region Tuesday evening. This will help keep temperatures going forward in the 40s.
Future forecasters should pay close attention to overnight lows and daytime highs and how they are affected by the melting snow. The later shifts should also pay attention to what, if any, impacts the third incoming shortwave will have on Friday's forecast.
- Travis
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