Monday, April 22, 2019

Tonight - Cloudy with a very small chance of isolated thunderstorms. Low: 48-52.

Tuesday Morning - Cloudy. High: 62-66.

Tuesday Night Cloudy. Low: 46-50.

 Wednesday - Partly cloudy. High: 68-72.

Thursday  - Partly cloudy. High: 72-76.

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The low temperature for Monday night will be between the low and upper 50s. An extremely small chance of isolated thunderstorms could occur tonight with precipitation of rain. By Tuesday morning, max temperature is expected to be in the upper 60s with cloudy skies. These clouds will persist into Tuesday night with low temperatures being below the 50s. As we head into Wednesday and Thursday, skies will be partly cloudy. The high for Wednesday will be around the 70s and the Thursday high will be in teh upper 70s.
Forecasters: Danaher and Hirsch

Issued: 5:00 p.m.; 22 April 2019

Technical Discussion (The nerdy stuff we are discussing in class!)

According to the WPC, the 12Z NAM/00Z UKMET are the recommended models to use because the 12Z GFS is faster with the surface low moving through the northern tier. However, the GFS will not be excluded in this forecast period for Monday night to Tuesday night because of skew-t differences and simularities as it will help determine if and when it will rain. So the chosen models will be a blend of the GFS and NAM for this forecast period.

The forecast for tonight has brought up a discussion on if the chances of isolated thunderstorm could happen over Columbia and the amount of rain. SREF plumes continue to show CAPE values above 1500 J/kg and decreasing as we transition through the night. GEFS plumes agree as they show CAPE values above 1000 J/kg with precipitable water over an inch throughout the rest of the night. From looking at the GFS skew-T a dry slot persists throughout the night at 700mb with moisture at 850mb. NAM agrees with the GFS as it also shows this low cloud layer persisting. The CAPE values for NAM and GFS continue to drop as we go through the night with CIN being reaching -374 J/kg at 3Z Tuesday while the GFS puts CIN at -161 J/kg that same time. CAPE at 3Z has significantly fallen along with precipitable water being lower than 1 inch. The CAP inversion for the GFS skew-T has stayed between 3C to 4C per 750mb. NAM skew-T has increased the CAP during the night from 3C to 5C per 750mb. So the possibility of any isolated thunderstorms or rain seems to be extremely small due to CAP being over 2C, CAPE significantly dropping overnight, and little to no negative omega.

Tuesday morning and night still show a fair amount of moisture among the lower layers continuing to make that low stratus layer. According to GFS skew-T, the model believes it will rain around 21Z Tuesday while the NAM skew-T suggests it will rain at 00Z Wednesday. Next, the NAM skew-T for 24Z Tuesday shows negative omega of about 10microb/s at 600mb to 400mb and positive omega of about 9microb/s from 925mb to 700mb. GFS skew-T on the other hand shows little to no positive or negative omega over the layers. So the potential for rain to happen according to the NAM shows it very unlikely throughout the morning into the afternoon while the GFS produces an output that will. However, from looking at the SREF plumes only 0.01" could reach the ground while GEFS plumes say 0.02" the NAM is the most reasonable model to use if rain will occur on Tuesday. Therefore, the chance of rain happening on Tuesday morning is less likely. If any precip would occur, it would most likely be a trace or drizzle.

On Wednesday and Thursday, the low stratus layer will ease a little according to the NAM skew-T around 15Z Wednesday. The GFS skew-T shows the clouds ease up by 00Z Thursday which is much later than the NAM. In a sense, the NAM seems to be more on track for now due to the GFS being slightly faster. The main focus for Wednesday and Thursday is that the clouds will not go away because of a no apparent Jet streak present helping the continuation of moisture across the midwest. For this reason, this is what is creating the continuous low-level to mid-level clouds across Columbia.

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