Another shortwave system is now passing into Iowa early this morning, bringing clouds with it. With small rain/snow showers traveling across central Iowa in recent days, rising returns have been seen on the radar.
While temperatures are near or slightly above freezing, road surfaces are near or slightly below freezing, depending on how cold it is outside.
As a result, some slippery patches are anticipated to appear in certain regions this morning, particularly on less-trafficked roadways.
The shortwave travels fast eastward by mid-morning, bringing with it whatever precipitation that may have occurred, as well as some clearing behind the system.
Temperatures are expected to rise once again today, as they have in the previous couple of days, with readings once again substantially above average, particularly in the southwestern United States.
The emphasis then changes to a shortwave system that will descend southeast across Canada and approach the northern Plains on Friday.
As it advances near the Dakotas, this wave gains strength and then begins to narrow up as it dives virtually directly south over the Central Plains by Saturday morning.
Warm advection intensifies ahead of the storm tonight, with isentropic lift spreading from the northern Plains into Iowa overnight. This lift is widespread and will last for a significant amount of time on Friday into Friday evenings throughout the state.
This lift causes heavy saturation from the north to the south, with snow moving southward during the day as a result of the lift.
With the passage of the upper low on Friday night, kinematic forcing rises as well, which aids in the persistence of the precipitation throughout the evening and overnight.
As moisture levels drop, lower accumulation rates are forecast tonight, however, this will be largely compensated by higher snow ratios.
As previously stated, the length of snowfall is expected to be between 14 and 20 hours in most areas, allowing for widespread accumulations of more than 4 inches and accumulations of more than 8 inches in certain spots.
Also worth noting is that some of the greatest rates in central Iowa will occur in the late afternoon and early evening, coinciding with the Friday evening commute, which may cause travel issues for many people.
Something also worth noting is that several of the short-term CAMs, in particular the HRRR, are pushing the axis of higher snowfall farther east. As a result, the longer-term models and ensemble output tend to maintain the heavier axis across the northwest and into Central Iowa, making this an exception.
If there are no substantial changes to forecast guidance, the Winter Storm Watch will be extended, with an upgrade to warning expected for a large area of the region later today.
There hasn't been much of a shift from past discussions about the timeline after the storm.
Across the contiguous United States, a broad northwest flow persists, with shortwaves moving across the flow from time to time.
This will result in a roller-coaster of temperatures for the rest of the week, with just a small chance of precipitation.