Monday, April 15, 2019

Monday - Mostly sunny. High: 68-72

Monday Night - Becoming mostly cloudy. Low: 52-56.

Tuesday - Mostly cloudy. High: 78-82.

Tuesday Night - Cloudy. Low: 58-62.

Wednesday - Mostly cloudy. High: 74-78.  

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A rapid warm up is in store for mid-Missouri early this week. Mostly sunny skies can be expected today, with temperatures this afternoon 15-20 degrees warmer than yesterday afternoon. An appreciable increase in cloudiness can be expected tonight, with lows dropping into the mid-50s. These clouds will stick around through the remainder of the week. Tuesday will be the warmest day of the period, with afternoon highs approaching or perhaps exceeding 80 degrees. Tuesday night will be quite mild, with overnight lows around 60 degrees. Wednesday will be slightly cooler than Tuesday with afternoon highs in the mid- to upper-70s.
Forecasters: Ritter, Travis, and Hirsch
Issued: 10:00 a.m., 15 April 2019 

Technical Discussion (The nerdy stuff we are discussing in class!) 
After a weekend of below-average temperatures and even snow showers across mid-Missouri, we are in store for a quiet pattern before the approach of our next system by mid-week. The main focus of this forecast period is narrowing down sky conditions. This will affect our daytime highs and overnight lows. Went primarily with GFS guidance as WPC's recommendation and its coverage of the entire period. 

Sunday morning, parts of Missouri awoke to snow showers moving across the region. Radar reflectivity showed areas of heavy snow east of Columbia. CoCoRaHS reported 4.5 inches of snow in Ralls County, north and west of St. Louis. Down by the Ozarks, CoCoRaHS reported 1.5 inches out of Morgan County. At 850 hPa, RAP analysis loops showed Missouri well into the 0 Celsius-isotherm. Sanborn Field reported a low temperature, this morning, of 35 F. RAP analysis at 850 hPa shows the 0 Celsius-isotherm has shifted to our northeast and flow at that level has since shifted from the northwest to the southwest. This southwesterly winds will drive WAA potentially allowing our daytime high to reach the low 70s. 

Prognostically,  GFS 500-hPa hgts and absolute vorticity depict the exit of the cyclone that brought strong tornadic activity to the Lower-Mississippi Valley and the Southeast and snow in Missouri. As that system exits, zonal flow ensues over much of the central CONUS. GFS shows zonal flow persisting until quasi-meridional flow takes over out ahead of the system set to impact Missouri Wednesday afternoon. 

Monday, GFS Skew-Ts show minimal saturation throughout the column during the day and into the evening. High clouds build in Monday night at the layer from 400 hPa to 200 hPa saturates. These high clouds will efficiently trap any outgoing LW radiation and help keep our temperatures up overnight. GFS MSLP and 1000-hPa to 500-hPa thickness show a prominent solenoidal pattern shaping up over Missouri suggesting moderate WAA. This combined with the high clouds expected overnight will not allow overnight temperatures to dip into the mid-30s as we saw Sunday night into Monday morning. High clouds remain, and the saturated layer deepens to 450 hPa Tuesday as more clouds build in. Breaks between the temperature and dewpoint profiles in the Skew-Ts lead to belief that some sunlight may break through to the surface. Regardless, WAA will be strong enough to allow our daytime high to potentially reach 80 F. 

Tuesday Night, the entire layer from the tropopause at roughly 200 hPa, down to  550 hPa remains completely saturated from 03z Wednesday to 12z. Skew-Ts also indicate another saturated layer at 850 hPa. The result is completely overcast skies with a lower cloud deck and an upper cloud deck. These clouds will be better at trapping outgoing LW radiation and keep our temperatures from falling much below 60 F. 

Wednesday morning, Skew-T's hint at some partial clearing with persistent saturation at 850 hPa with periods of saturation between 300 and 500 hPa throughout the day. As the day progresses CAPE values increase, and dirunal heating allows the erosion of the cap. CIN values start off near 300 J/kg at 18z. This will help prevent the firing of early convection. As the day progresses, CIN values decrease to help set the stage for the potential of thunderstorms Wednesday night after 00z. Will defer to later shifts with respect to the threat of overnight convection Wednesday into Thursday. 

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