Thursday: Light Rain. High: 55
Thursday Night: Showers. Low: 41
Friday Night: Showers. Low: 40
Saturday: Scattered showers in the morning. High: 54
Our rain streak will continue until Saturday. Most of the rain will be limited to showers; however, on Friday we can expect moderate rainfall. Don't forget your raincoat or umbrella!
Forecasters: Hefner and Samson
Date Issued: 03/23/2023 10:00AM CDT
Rain will continue to be Columbia's biggest "issue" throughout this
period, as we will continue to see showers from today until Saturday.
For this forecasting shift, the 12Z run of the GFS model was used due to
a more accurate moisture profile correlating to real-time observations
compared to the moisture-rich NAM models.
at the 300mb-level, there is a trough, with no tilt, situated over the
southwest United States connected to a low-pressure system centered over
the northwest Four Corners region. The trough and associated low will
deepen and amplify as they move eastward. The trough will tilt
negatively at 21Z Thursday and begin to affect Columbia at 00Z Friday by
increased upper-level divergence from 00Z Friday until 12Z Saturday,
signifying low-level convergence. The trough's negative tilt indicates that the weather system is strengthening. This strengthening correlates with the amplification of the trough. There will be a powerful jet streak
near the right entrance region which will aid upper-level divergence.
Additionally, due to the jet streak being located on the right side of
the trough, both it and the associated low will begin to deamplify as it
passes through the mid-Mississippi Valley, eventually entering the
Great Lakes region, where it will eventually die, leaving Columbia in
the 500mb-level, spotty amounts of circulation occur over Columbia for
the forecasting shift; however, a vorticity maximum will go over
Columbia at 03Z Saturday, lasting until 21Z Saturday. This maximum is
associated with the low-pressure system noted in the 300mb-level
analysis, and the circulation will move out towards the Great Lakes
region with the low. The resolved circulation will aid in vertical forcing in the atmosphere, which can play a role in precipitation intensity.
humidity values at both the 700mb- and 850mb-level indicate a dry layer
starting at 12Z Thursday, and an increase in moisture will begin at 21Z
Thursday. However, a dry pocket of air remains over Columbia until 12Z
Friday, which can create a brief pause in precipitation. The high
moisture values (>65% relative humidity) will persist over Columbia,
eventually drying out at 21Z Saturday. If the
moisture at this level reaches saturation, thanks to high negative Omega
values, precipitation will occur, and the precipitation intensity will
depend on forcing at this level. For the 850mb-level, high
moisture values resolved except for one time period, 15Z Saturday, where
there will be a brief dry pocket before returning to moist air. So, cloud cover and precipitation support will be present at the 850mb-level for almost the entire period.
high negative Omega values correlate with high moisture values at the
700mb level at 18Z Friday until 03Z Saturday and again at 09Z Saturday
until 15Z Saturday. The negative Omega seen from 03Z Saturday to 09Z
Saturday is in conjunction with the vorticity max noted at the
500mb-level. This coupling of forcing mechanisms could lead to more
intense precipitation at that time period. However, the highest Omega
values are expected to occur on Friday at 18Z, and this lifting
mechanism will cause the highest intensity of our expected rain for this
at the surface level, cold FROPA occurred earlier than previous
forecasting shifts expected. FROPA resulted in a rapid decrease in
surface temperature which sparked our significant 10-degree change in
the forecasted high for today. Surface winds have a mostly northerly
component, combined with solenoids throughout the entire forecast
period, CAA is anticipated. As a result, the CAA will bring us temperatures down into the 40s. Additionally, a mid-latitude
cyclone will begin to affect the Columbia area around 00Z Saturday. The
most significant impact of this cyclone will be on wind direction for Columbia. Columbia's position relative to the front
will cause a westerly shift in winds. The cyclone, however, should not
cause Columbia to experience more precipitation. The reason for this conclusion, is that the cyclone will be too far east of Columbia for any precipitation associated with the cyclone to have an effect.
up this AFD with sounding analysis, GFS generated soundings resolved
the heaviest precipitation occurring at 18Z Friday. Negative Omega
values are the highest at this time period, and the atmosphere is
saturated (dewpoint temperature is equal to air temperature) up until
~680mb-level. The atmosphere is also close to saturation until around the
200mb-level, indicating the presence of moisture far into the upper atmosphere.
totals from now until Saturday are from 1.25" to 1.5". This was
determined using SREF plume guidance and sounding analysis.
-Hefner and Samson