Monday, April 8, 2019

Monday - Skies clearing. High: 74-78

Monday Night - Skies becoming mostly clear. Low: 48-52

Tuesday - Clear skies. High: 68-72

Tuesday Night - Skies becoming cloudy. Low: 48-52

Wednesday - Cloudy Skies. Windy. High 70-74  

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Above average temperatures and clear skies will stick around for Columbia before the approach of the next system by midweek. A weak cold front passed yesterday that brought strong storms to much of mid-Missouri, but missing the Columbia area. Fortunately the front did not bring down our temperatures much at all overnight. Couds will clear out throughout the day Monday and sunny skies will hep our temperatures rebound back into the mid to upper 70s. We should see much of the same until Tuesday night when clouds approach out ahead of our the next big low pressure system. Wednesday into the latter half of the week will be windy as the system will be very strong coming off of the Rockies and into the Plain states.
Forecasters: Ritter, Travis, and Hirsch
Issued: 10:00 a.m., 8 April 2019 

Technical Discussion (The nerdy stuff we are discussing in class!) 
The main issues of this forecast period will be sky conditions and the resulting impacts on surface temperatures throughout the period as well as how an approaching system will impact us Tuesday Night into Wednesday. The WPC model diagnostic discussion suggests using a blend of the GFS and ECMWF, and with the GFS being readily available to us, we have decided to use it as our main guidance for the forecast period.
The pleasant weather mid-Missouri experienced most of this past weekend will continue into the next couple of days. Currently, the WPC's 12Z surface analysis shows a weak frontal boundary oriented roughly along the Interstate 44 corridor. Associated with this frontal boundary are the high clouds presently overhead. GOES-13 Infrared imagery shows these clouds moving quickly off to the east, and with no sizeable cloud cover to the west, skies should become completely clear by mid afternoon. Temperatures this afternoon will again be much warmer than average, although with the cloud cover around this morning and northerly surface winds due to the surface front to our south, they will be a few degrees cooler than the 80 degree high temperatures recorded at both Sanborn field and KCOU yesterday. For tonight, skies should remain mostly clear, although 06Z GFS Skew-T's show saturation between 250 and 300 hPa between 09Z and 15Z, which could signal some high-level cloudiness around sunrise Tuesday. Nevertheless, we do not believe these clouds will have much of an impact on tonight's overnight lows, which will be cooler than last night's due to overall lass cloud cover and northerly surface winds. After 15Z Tuesday, however, 06Z GFS Skew-T's show no saturation in the column throughout the remainder of the day Tuesday, leading to another mostly clear day. With northerly surface winds continuing through the day and the front pushing further to our south, high temperatures on Tuesday should be about 5 degrees cooler than Monday's, although they will remain well above avergae for this time of year.

Our next system will begin to impact us Tuesday night into Wednesday. The 06Z GFS shows a 130-kt jet core at 250 hPa moving out of the Desert Southwest and into the Texas and Oklahoma Panhandles by 00Z Thursday, putting mid-Missouri at the nose of the jet under an area of enhanced divergence aloft. A positively tilted 500 hPa shortwave trough and associated vort max will be moving off the Rockies Wednesday morning and will be located over Kansas by 00Z Thursday. The map of 700-hPa lift and moisture shows plenty of lift over Missouri by 21Z Wednesday, but it keeps moisture well to the north over the Upper Mississippi Valley. The 06Z GFS also generates a strong low level jet at 850 hPa on the order of 40+ kts. At the surface, a low pressure center will deepen rapidly as it moves off the Rockies and into southwest Kansas. This system will aslo become vertically stacked because the surface low and 500 hPa vort max will be colocated by 00Z Thursday. Dynamically speaking, this system has the perfect setup for thunderstorms Wednesday afternoon except for the fact that there is no moisture to speak of! 06Z GFS Skew-T's consistently show saturation between 200 hPa and 300 hPa, with the layer occasionally saturating down to 500 hPa, beginning at 03Z Wednesday and continuing throughout the end of the forecast period, suggesting this system will produce at least high level cloudiness Tuesday night into Wednesday, but with a deep dry layer below 500 hPa, that should be the furthest extent of this system's impact on sky conditions. However, with the deep low pressure over Kansas, there will be a tight pressure gradient setting up over the western half of Missouri by 18Z Wednesday. 06Z GFS Skew-T's suggest sustained southerly surface winds may exceed 30 knots.

Low temperatures Tuesday night will be very similar to those of Monday night due to cooler Tuesday afternoon highs, cloud cover overnight, and winds shifting to the south overnight. High temperatures Wednesday afternoon should be a couple degrees warmer than Tuesday even with cloud cover present all day due to strong southerly winds.

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