Wednesday, February 20, 2019

Wednesday Night - Partly cloudy.  Low:27-31

Thursday - Cloudy. High: 40-44

Thursday Night - Cloudy. Low: 28-32

Friday - Cloudy. Showers will develop in the evening High: 42-46

Saturday - Cloudy. Showers High: 52-56

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We will be in store for calmer weather for the next couple of days. We will remain cloudy throughout the forecast period with seasonal temperatures. The dry spell will not last as we will see precipitation starting Friday evening and remaining throughout the day Saturday as another system will make its way into the area. We will need to monitor Saturday's system closely as there is the potential for severe weather and possibly even more snow. That being said, it is still a ways out and conditions are subject to change.

Forecasters: Rojas, Sumrall and Hirsch
Issued: 4:00 p.m., February 20, 2019

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

The conditions on Thursday will keep dry due to the area of high pressure over Missouri ,  the attention for this forecast time will focus more on the system approaching to the area by Saturday night with possibilities of thunderstorm but will discuss that.

The cross section along Columbia for GFS shows an increasing of moisture at lower level starting on Friday at 15 Z, as the moisture colonize the column by 18 Z on Saturday the 100% values of relative humidity are combined with upward motion around -5 mb/s over Columbia and -8 mb/s east of us. Thus the rainy activity intensifies Saturday morning through early Sunday morning.

The cyclone system that will produce these conditions will originate at the west side of the CONUS at around 18Z on Thursday, the area of forecast will be below the downstream of the trough by Saturday at 18Z. As the actual westerly flow shift to easterly by Thursday afternoon and finally will became more southerly by Friday at 12Z. GFS soundings show veering at that time along with values of CAPE above 100 J/kg after 6Z on Saturday. GFS locates the higher values of accumulated precipitation southeast of Missouri. The moisture will be brought from the south (gulf of Mexico). The potential temperature profile indicates potential instability in the middle level of the atmosphere starting at 6Z until 21Z on Saturday. Definitely,the main aspect about this system will be the timing, it depends on how earlier the cold front would arrive to discuss the type of precipitation. These possible severe conditions suggested by the models need to be monitored in the following forecast periods. The type of precipitation that we need to concern about is more rain because of the freezing thickness line is north of us during this event.

GFS and NAM both show the maximum of precipitation over the southeast part of Missouri  and Illinois but there is still a disagreement in the maximum temperatures during the weekend.
Therefore, the rain will start Saturday morning and will last most of the day. Be ready for the fun.

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