Current Conditions at Sanborn Field
Thursday Night - Partly Cloudy. Low: 56-60
Friday - Sunny. High: 68-72
The 06Z NAM model run was used to create this forecast as it is handling the current system more accurately than the GFS has been. Current conditions at the time of forecast were best mirrored within the NAM guidance than within the GFS. Related skew-T outputs were used to determine the severity of storms throughout Wednesday. SREF plumes were also consulted in creating this forecast.
At the 250-mb level, a jet max is seen sitting over northern Missouri to kick off Wednesday morning. This jet max deepens over Iowa by 21Z Thursday afternoon. By 12Z Friday, there will be no significant jet streak over the forecast area.
500-mb outputs show significant vorticity at 15Z Wednesday until 18Z Thursday. Vorticity at this level suggests that active weather will be in the area, and this data is conducive with the idea of widespread rain and thunderstorms throughout this time frame. Vorticity exits the area almost completely by 09Z Friday.
The 700-mb guidance shows high relative humidity throughout the day and evening on Wednesday. Southwesterly flow is dragging in moisture from the Gulf of Mexico, and that moisture will help with mid-Missouri’s rain chances. At this level, the stalled out boundary that is stirring up these rain chances is very visible just to the south of the forecast area. RH values drop drastically by 21Z Thursday, suggesting that our rain event will end near or before that time.
At the 850-mb level, there is no defined LLJ over the forecast area, but the LLJ over Oklahoma is southerly which is helping drive the moisture and warm air from the Gulf of Mexico. CAA can be expected on the back end of this system by 12Z Thursday. At 18Z Friday, winds will shift to become more easterly, as a low pressure system slides into western Missouri. This low pressure system will continue pushing eastward through Missouri until the end of the forecast period.
Surface level guidance shows that winds will begin Wednesday coming from the southwest but will shift throughout the day to become northerly by 15Z Thursday. These northerly winds will bring cooler temperatures to mid-Missouri for Thursday. By 15Z on Friday, those winds will shift to become more easterly as a surface level low pushes into western Missouri. On the back end of this low, winds will shift to become more southerly as we head toward the weekend.
Skew-T outputs show a lack of low level shear which helps nullify our tornado threat for today. That being said, CAPE values between 500-1000 J/kg throughout the morning and afternoon Wednesday suggests that thunderstorms will be likely. Negative omega also indicates that hail could develop within these embedded thunderstorms. The main concern with this system will come from impressive rain accumulations over the next 36 hours. Southern portions of Missouri, where that boundary stalls out, could see 3”+ of accumulation. Luckily for us, our accumulations will likely be between 1-2” of rain. Flooding could be a problem, but we are not currently under any flooding advisories.
Future forecasters should monitor the intensity of storms for this afternoon plus the threat for flooding.
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