Current Conditions at Sanborn Field
Thursday night - Increasing clouds. Low: 38 - 42.
Friday - Overcast with rain beginning around 4pm. High: 54 - 58.
Friday night - Rain throughout the night. Low: 42 - 46.
Sunday- Partly cloudy becoming sunny. High: 54-58
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For this forecast period, the NAM was mainly used due to its better handling of the low pressure system and accuracy with observed winds and temperatures. The focus of this forecast is the incoming low pressure system bringing precipitation over the weekend.
At the 250mb plot of heights, wind, and divergence, Columbia is under the influence of a shortwave ridge for the majority of Thursday going into Friday which will help our current pleasant weather stick around. On Friday morning, the overhead jet begins to push slightly south, leaving Columbia in the left exit region and therefore bringing much higher levels of divergence aloft, which will help fuel the precipitation we will see on Friday.
At the 500mb plot of heights and vorticity, the shortwave ridge is still visible in our area until Friday afternoon when a low pressure system begins to move into Columbia. The high levels of vorticity associated with the LPS will also be present in our area early Friday afternoon; the ideal time for widespread showers to begin. The LPS and the associated circulations will not move out of the area until Saturday evening, when we will briefly return to zonal flow with a positively tilted shortwave trough moving in behind it.
Moving down to the 700mb plot of heights and RH, Columbia experiences increasing moisture by the LPS, also mixed with moisture transport from the Gulf into Friday afternoon. Expect to see widespread rain and heavy cloud cover until Saturday evening as the heavy moisture sticks around. The atmosphere will start to dry out by Saturday night before returning back to mostly zonal flow on Sunday.
At the 850mb plot of heights, winds, and temperature, Missouri receives a weak to moderate northerly flow of winds on Thursday, helping to keep the chilly temperatures. The winds then shift southwesterly with the passage of the LPS on Friday, returning northerly on Saturday morning and will remain this way for the remainder of the forecast period.
On the MSLP and 1000-500mb thickness plot, the LPS is not as defined as in the upper levels. However, Friday evening a cold front associated with the system is suggested by the pressure contours helping to fuel the expected precipitation. By Saturday evening, the LPS moves northeast out of our area. The following solenoids suggest some weak CAA for the remainder of the forecast period.
Finally, according to soundings produced from the NAM, there is little saturation in the atmosphere until late Thursday night when we will see increasing cloud cover at the 850-mb level. The atmosphere continues to become saturated as we move into Friday. A small dry layer is depicted between the 850-700mb levels persists 21Z, which may help prohibit any heavy rainfall. By late Friday night, the atmosphere is almost completely saturated to about the 500mb level with some UVM being shown throughout almost all levels of the atmosphere. The atmosphere will again dry out by early Sunday morning to leave us with pleasant weather to end the forecast period.
The focus for the next forecast should be the positively tilted shortwave trough and its effects it will bring into the area.
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