Current Conditions at Sanborn Field
Friday Night: Mostly cloudy, rain. Low: 62
Saturday: Mostly cloudy with showers in the morning. High: 74
Saturday Night: Cloudy with a chance of light rain. Low: 50
Sunday: Partly cloudy. High: 68
Sunday Night: Clear. Low: 50
Discussion:
I would keep an umbrella handy with you this weekend as Missouri is going to have a cloudy/rainy forecast. Because of the low pressure system led by strong winds, Missouri will see precipiation that'll be followed up by some thunderstorms and moderate showers. The same thing is going to occur on Saturday but with lower temperatures dipping to the 50s due to a cold front passing through the Midwest. While most of this forecast will be gloomy and sticky, Sunday will be the day we can all look forward to because it's going to be less cloudy with pleasant temperatures.-Watts
Forecasters: Watts, McDonald, Travis
Date Issued: 04/29/2022 5:00PM CDT
The GFS was used for today’s forecast, as it’s initialization of
current features - such as low pressure over Southwest South Dakota - was much
more accurate in terms of both placement and intensity. Current temperatures
were also more accurate under the GFS, whereas the NAM had current conditions
too warm. The main forecasting issue of the weekend will be the movement of a
powerful low, of which the position will determine the potential for
rain.
Though negatively tilted, deep low pressure is visible at 250 and
300 mb, with the system expected to maintain its intensity through the weekend.
Currently positioned over southwestern South Dakota, the low pressure deepens
further as it slowly moves northeast, finally dissipating over Canada Sunday
night. With both the trough and jet stream tracking so far to the north,
Missouri will see little activity in the upper atmosphere.
While there is still some vorticity present through Saturday
morning, the 500 mb level stays quiet for the remainder of the weekend. Strong,
tight circulation is associated with the trough to the north, but it stays
north of Missouri in southern Iowa through Sunday. A slight southern deviation
in this circulation though, could change impacts at the surface.
Moisture content tells a similar story at 700 mb. There is plenty
of moisture and omega through Saturday morning, but the atmosphere quickly
dries up Saturday afternoon. An abundance of moisture is present throughout the
entire weekend in Iowa, though, making the difference between clear and cloudy
skies a sharp one.
While cooler air prevails for tonight, warm air begins to be
advected into mid-Missouri Saturday morning, as our winds shift from west to
South at 850 mb. The winds will shift back to the west Sunday morning, but with
wind speeds strengthening and cold air being contained to our north,
temperatures should remain warmer.
Surface analysis depicts WAA starting tonight and continuing
through Saturday night, raising surface temperatures by more than 10 degrees
for tomorrow’s high. Advection dissipates into Sunday, but the northerly trough
will likely not extend far enough to change the clam conditions.
GFS soundings show a solid chance of continued rain over the next
18 hours, but the window for strong thunderstorms has likely been shut. CAPE
below 1000 J/kg, a K-Index below 30, and CIN values increasing overnight will
certainly not produce the kind of severe weather expected over the Great
Plains. Weaker storms and continuous rain showers are the only likely precipitation
events to occur with these values. Soundings indicate increasingly dry
conditions after Saturday afternoon, with moisture not returning until late
Sunday night.
Future forecasters should closely monitor the Central Rockies, as
another deep low may begin to form there Monday morning.
- McDonald
