Warm air moving into the region may produce a few slick spots Thursday morning, especially for points E and S of STL. This afternoon’s data is much less aggressive with the precipitation and hangs on to the dry air long enough to hold things at bay until temperatures warm above freezing. That dry air may briefly bring temps back below 32F as the rain begins, thanks to a process known as evaporative cooling, but that would be very brief. No issues are expected for areas west of STL to include KC.
The image below is a simulated radar graphic for 6AM Thursday morning and shows some light echoes from the MS river S & W and the 32F line still over SE MO.
Areas south of I-70/I-64 look to get some moderate rains through Sunday evening with the highest totals well SW of STL to SW MO where 1″+ may fall.
For the district, 3/4″ to 1″ looks possible over SEMO/SW IL with 0.30″ to 1/2″ for STL. Little, if any, significant rains are expected for KC to Topeka with amounts less than 0.10″, where a 6-week period has elapsed since the last date when rain fell greater than 1/2.”.
Other than this system, a generally quiet weather pattern is expected to continue for the next week or so as a very fast Pacific jet remains in place across the Pacific. The chart below, valid at noon Monday shows a fast cross-Pacific jet into western North America. There is currently no route for Arctic air crossing the pole from Siberia to get southward. Instead, it is being redirected toward Greenland and the North Atlantic.
This is nearly the same pattern as we had most of the winter of 2011-2012 and will result in a mild period of weather into the middle of December. We don’t expect this to be the persistent pattern this winter and there are indicators present which point toward a colder pattern toward the end of the month. For the time being though, winter is still on break.