Friday, September 27, 2019

Current Conditions at Sanborn Field

Friday Night - Becoming Cloudy. Thunderstorms likely after sunset. Low: 69-73

Saturday - Cloudy skies. Scattered showers possible throughout the
day then, scattered thunderstorms possible in the evening. High: 80-84
Saturday Night - Cloudy. Rain continuing overnight. Low: 69-73

Sunday - Mostly cloudy. Showers ending in the morning. High: 82-86


Monday - Partly cloudy. High: 86-90

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We will get another cloudy weekend ahead of us with the possibility of scattered showers and thundershowers.  Friday and Saturday we expect thundershowers in the evening with cloudy skies and scattered showers throughout the day on Saturday.  The overcast skies will drive lower temperatures on Saturday as we expect a High of 80-84 degrees.  Our temperatures will increase on Sunday by approximately 10 degrees as we expect less widespread rain.  Cloudy skies persist into Monday and the maximum expected temperature for the start of the week is 90 degrees. 
Forecasters: Balkissoon, Taylor, Heaven, Travis, Hirsch
Issued:  5:00 p.m. ; September 27,  2019

Technical Discussion (The nerdy stuff we are discussing in class!)
Another active weekend has setup across mid-Missouri. Chances of rain will linger until until Saturday night into Sunday morning. With it will come the threat of strong to severe convection both Friday night and Saturday night.

RAP analysis of the last 24 hours keeps the upper level jet max well to our north at 250 hPa. A large longwave trough is currently parked over the Pacific northwest while a ridge remains off to the east according to analysis of RAP 500-hPa heights and vorticity. This puts Columbia southwesterly flow aloft and at the lower levels. The GFS has increased divergence aloft at 250 hPa following the general flow from the southwest. Stepping down to 500 hPa, the GFS shows a suspicious lack of any disturbance in the height field, and a lack of a distinct vorticity maximum. The atmosphere is thermodynamically prime for ensuing convection. GFS soundings for Friday afternoon into Friday evening show SBCAPE values approaching 3000 J/Kg, gradually decreasing as thunderstorms roll in around 03z. 0-6km shear is on the high side (19 m/s) according to GFS soundings. This will produce a more linear line of thunderstorms that progress through the region. Looking at CAMs, the 18z HRRR had the MCS moving north of I-70 and the 19z even further north. If current trend continues, Columbia itself may be clipped by rain while the bulk of the thunderstorm activity stays off to the north. While this system Friday night looks impressive thermodynamically speaking, it lacks impressive dynamic support. At 250 hPa, the GFS keeps the jet stream well off to the north in the Upper Midwest. Prognostics of 500-hPa height and vorticity does not show any distinct disturbance moving through the state. A small vorticity maximum does move through northern Missouri overnight probably indicative of present convection. At 850 hPa is where things look interesting. The LLJ is roaring from the southwest at 40-50 kts and has been for the past 12 hours according to RAP. This has been responsible for the rapid moisture and warm advection. This is about the extent of the dynamic support that this system has.

Into Saturday morning, both the HRRR and 3k NAM want lingering showers persisting into the daylight hours gradually tapering off as the day progresses. Interesting, the HRRR hints at mid-Missouri seeing some partial clearing into the afternoon. If Columbia does see sunlight, daytime highs may be able to creep higher than anticipated. The HRRR does want some discrete cells popping up out ahead of the line closer to Kansas City at 22z so not out of the question to see some afternoon storms fire.

By Saturday night GFS soundings indicate a saturated column throughout the night. Rain will likely continue into early Sunday morning, and taper off shortly after sunrise. Though the cold front should make it past, it will quickly lift back as a warm front as winds shift from the southwest once again. This will result in a gradual warming trend Sunday into Monday. The GFS 500 hPa does not favor much break down of the ridge to our east, or progression of the trough to our west. Highs will continue be unseasonably hot for late September and early October.

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