Current Conditions at Sanborn Field
Thursday: Light rain with possible scattered thunderstorms. High: 77
Thursday Night: Mostly cloudy. Low: 46
Friday: Partly cloudy. High: 64
Saturday: Partly cloudy. High: 51
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Discussion:
Thunderstorm development with the threat of damaging winds and hail is expected to occur this afternoon. While unlikely, the possibility of a spin-up tornado can not be ruled out. Thankfully, rainfall totals will be on the lighter side as they are not expected to exceed 0.25". After the event weather today, temperatures will be in begin to drop causing a cooler weekend. =================================================================
Forecasters: Hefner, Samson, and Macko
Date Issued: 4/20/2022 10:00 AM CDT
The focus of this forecasting period is the incoming threat of severe thunderstorms with the potential of damaging winds and hail associated with it. A blend of models were used in the construction of this forecast. HRRR was primarily used to forecast the imminent weather due to its higher resolution. Additionally, sounding analyses of HRRR, RAP, GFS, and NAM were conducted to gain a better overall picture of different model outputs for potential severe weather threats.
Currently, Columbia is under a Hazardous Weather Outlook for today and tonight as, “thunderstorms are expected across much of the area.” Furthermore, the SPC has listed our region under a marginal risk for severe weather for today due to the potential of damaging winds and large hail. The catalyst for this evening’s events are a negatively tilted trough located over the Central Plains. Associated with this trough is a region of high divergence at the 250-mb level, intense vorticity, and a surface low-pressure system with an attendant cold front.
Thunderstorm development is likely to occur around 18Z today as surface CAPE values will exceed 3000 J/kg combined with weak to non-existent CINH. Additionally, the LI is expected to be less than -6 with Total Totals near 55. Both of these values are strong indicators of the possibility of severe thunderstorms.
The biggest threat associated with thunderstorm development is in the form of damaging winds and large hail. Damaging winds are a strong possibility as DCAPE values are expected to range from 800-1000 J/kg from 12Z to 20Z today, as well as multiple model soundings outputting high surface wind speeds. Sustained wind speeds of 20 knots with gusts over 40 knots are expected for today. In regards to hail, the high amount of instability present this afternoon will combine with strong negative Omega effectively lifting moisture aloft. This in combination with dry air aloft will allow for hail development given the presence of an updraft. Tornado development cannot be ruled out due to the high amount of instability present. However, low storm-relative helicity values, lack of directional wind shear, and unimpressive speed shear suggests the threat of tornadoes is low.
Storms will move out of the area along with the cold front at 22Z today. Precipitation will be light and should not exceed 0.25 inches. After frontal passage, surface temperatures will drop into the lower 60s with winds out of the northwest. Furthermore, the jet stream will transition to zonal flow due to a strong jet streak on the right side of the trough aiding deamplification.
-Hefner
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