Wednesday, April 15, 2020

Wednesday Night - Increasing clouds. Low: 34-38

Thursday - Cloudy, possible rain in the PM. High: 52-56

Thursday Night - Cloudy, with rain. Low: 34-38

Friday - Cloudy with rain in the AM. Clearing in PM. High: 44-48

Saturday - Mostly Sunny. High: 58-62

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Clear skies won’t be sticking around for long. There is a stationary front located in southern Missouri. That stationary boundary will push north, helping our temperatures increase into the mid-50s on Thursday. We will have a low-pressure system located to our west, this low-pressure system will help bring in cold air. But before that cooler air moves into the area, we are going to see a line of rain move into the area throughout Thursday evening. Rain will stick around into Friday morning. As this front starts to push east, winds will switch to the north. Temperatures will drop near freezing Thursday night into Friday morning. There is a slight concern for mixed precipitation, but for right now the freezing line is going to stick to the north of Missouri. Overall, we will mainly see rain associated with the low-pressure system. Going into Saturday, high pressure will move into the area giving us sunny skies and southwesterly winds. That will help boost our temperatures into the low-60s.

Forecasters: Pauley,Ritter
Issued:  5pm: April 15, 2020
Technical Discussion (The nerdy stuff we are discussing in class)

Model diagnostics from the WPC are suggesting a model blend, primarily 12z ECMWF/UKMET, both the GFS and NAM are running fast. The NAM was removed from the suggestion because of the stronger bias it was presenting. This forecast shift ended up going with the GFS because it matched up better with current conditions. 

Currently, the weather in central Missouri is pretty calm. Using top-down starting at 250-Mb height/winds there is a zonal flow over the state of Missouri. A subtropical jet streak is located over Texas stretching out into Maine and the Atlantic ocean. The jet max is present in Tennessee stretching out to West Virginia. At 500-Mb vorticity, there is a rather large long wave that is positively-tilted. Going down to 700-Mb vertical velocity the long wave is still present, but with a short wave starting to form off of it. Getting closer to the surface there is a lack of humidity, veering winds, and downward motion, which is all supporting the calm conditions that are present. 

Tonight, The zonal pattern remains at 250-Mb Height/winds. There is a slight ridging pattern that starts to form down at 500-Mb. The short wave starts making its way into Missouri. This short wave brings a ridging pattern at 700-Mb. This pattern will help switch the winds to the southwest. Throughout the overnight hours, there will be increasing clouds as humidity starts to build. Uplift starts to come in to Missouri, which could give us a slight possibility of rain. There is a stationary front located just to the north of Missouri. That stationary front will come into play on Thursday. 

Thursday, the stationary front will push to the north of Missouri, which will help temperatures warm up into the mid-50’s. That slight ridging pattern located at 500-Mb will become more zonal throughout the day. A line of rain will start to form a low-pressure system located just west of Missouri stretching down into northern Texas, moves to the southeast. The main bulk of rain that central Missouri will see will be into the late to overnight of Thursday. Thursday night, humidity will start to increase close to 100 percent between 03z and 06z Friday. A significant vertical lift will start to form west of Kansas City, Missouri around 00z Friday and make its way into central Missouri between 03z and 06z Friday. There are not significant CAPE values to indicate thunderstorms. The 540 thickness line is north of Missouri, the bulk of the precipitation will most likely take form as rain. 

Friday, we will start the day with unseasonably cold temperatures. Temperatures will be around 10 degrees below climatological averages for the month of April. The 540 thickness line needs to be constantly analyzed for these next few days ahead. There is a zonal pattern over central Missouri, but a shortwave passing north of the state. That shortwave then merges into the zonal pattern, bringing in cold air advection. There will be a line of rain that passes over the state in the morning hours. Just on the backside of this line of rain is the 540 thickness line. That brings concern for possible mixed precipitation. A GFS sounding on Friday at 12z indicates that there are vertical lift and saturation throughout the atmosphere, but temperatures are above freezing. This sounding helps analyze that this precipitation will be in the form of rain. Moving to 15z temperatures in the upper atmosphere are below freezing yet surface temperatures will still be in the mid-30’s. There is not a significant amount of vertical lift present in the 15z GFS sounding. Moisture will start to drop as a low-pressure system located to the southeast of Missouri continues to move out of the area. 

Saturday, we will be waking up to another unseasonably cold morning. Clouds moving out overnight on Friday into Saturday morning will help drop temperatures below the freezing mark. Other than cold temperatures for the morning, there will be a surface high-pressure system that will begin to push southeastern. There is a slight ridging pattern at 250-Mb, located over Missouri at 21z on Saturday. With a lack of moisture and winds coming from the southeast and sunny skies, this will support temperatures to warm up into the low-60’s.

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