Current Conditions at Sanborn Field
Monday Night: Mostly clear. Low: 60-64.
A warm pattern will continue through Tuesday, with breezy conditions and highs in the low to middle 80s for Tuesday afternoon. Clouds will increase throughout the day ahead of the next storm system. The first round of rain and thunderstorms is likely to arrive Tuesday night into Wednesday morning, with locally heavy rain possible. Small hail and gusty winds can't be ruled out with these storms as well. The best chance of rain will come Wednesday afternoon and evening, with showers and storms developing ahead of a slow-moving cold front. Some of these storms may be strong to severe, though that will depend on if we can get any sunshine Wednesday afternoon to energize the atmosphere. Regardless of severe potential, heavy rain appears very possible Wednesday into Wednesday night, with anywhere from 0.5-2 inches likely in mid-MO. That will raise concerns for flash flooding and river flooding, since our ground is already waterlogged from recent rains. Rain looks to draw to an end Thursday morning, with sunshine possible again by Thursday afternoon.
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A warm, windy, and mainly sunny afternoon has developed across mid-MO. Current (20z) RAP analysis shows a strong pressure gradient at the surface, which has led to wind gusts as high as 40 kt in Sedalia, and as high as 30 kt at COU. The same RAP analysis indicates a thermal profile which is nearly dry adiabatic from the surface to 850-mb, which - in conjunction with the strong PGF - is responsible for our potent surface winds. With exceptional WAA and sunny skies, temperatures have pushed into the middle and upper 80s in mid-MO this afternoon.
Overnight, expect skies to remain mainly clear as the profile stays unsaturated. The GFS/NAM/RAP are all in agreement on an increasingly-strong LLJ at 850-mb overnight, with 850-mb winds upwards of 50-65 kt by 12z Tuesday. However, the LLJ will be largely oriented SW-NE; thus its moisture supply will be limited and no saturation is expected at any layer of the atmosphere. A nocturnal inversion will establish itself after sunset tonight and reduce wind speeds, but continued WAA will keep readings from falling any lower than the lower 60s.
For Tuesday, changes will start to occur as a positively-tilted upper-level longwave trof approaches the central CONUS. This approaching TROF will cause PVA to ramp up over the central and northern Plains, encouraging the formation of a weak circulation in the lower levels of the atmosphere in Nebraska and Iowa. That circulation will serve to create a surface boundary, which initially looks to take on the form of a stationary front. In mid-MO, increasing moisture throughout the column (particularly in the higher levels) will lead to increasing cloud cover throughout the day. Wind will be another factor, though conditions should be slightly less windy than they were today (gusts of 25-35 mph are still likely). Despite cloud cover, intense WAA will lift readings Tuesday afternoon back into the low to mid 80s, perhaps just a couple degrees shy of where they peaked this afternoon.
Late Tuesday afternoon into Tuesday evening, convective development appears possible southwest of mid-MO, primarily in Oklahoma and southern Kansas. The main round of convection will likely hold off until Tuesday night, however, and the majority of the stronger storms should remain well southwest of mid-MO. Nevertheless, it appears likely (given wind profiles) that some of this rain and thunderstorm activity will drift into mid-MO, especially in the 2nd half of the overnight hours Tuesday night. While the severe threat looks low, it is not nonexistent. Gusty winds and hail would be the main threats with any strong storms late Tuesday night/early Wednesday morning. Given PWATs near 1.5", heavy downpours and vivid lightning will also be possible.
Wednesday looks to be a messy day, and the evolution of Wednesday's precipitation entirely dependent upon what occurs Tuesday night. Right now, it appears that the aforementioned upper-level trof will continue to slowly progress east into the central CONUS, but this trof fails to mature and take on a negative tilt. Therefore, a true closed circulation is very unlikely with this system, and the rounds of precipitation will remain messy. It currently looks like the stationary surface boundary will slowly push southeast as a slow-moving cold front, eventually arriving at COU sometime late Wednesday evening or early in the night. This front will be one focus for shower and thunderstorm activity during the day Wednesday, though - as was said earlier - this will be dependent upon what happens early Wednesday morning. Models - especially CAMs - insist upon a large area of convection located in eastern OK, southern MO, and AR. This convection could effectively reduce moisture return and prevent areas north of it from destabilizing, owing to cloudiness from the thunderstorm anvils. So although it does appear that convection will eventually fire near the approaching front Wednesday afternoon and evening, this convection might not be strong to severe. Still, the SPC does have mid-MO in a marginal severe risk for Wednesday, so the possibility of damaging winds and hail is certainly not zero. The extended HRRR is something to watch here, as it has sunshine developing in mid-MO and temperatures in the upper 70s Wednesday afternoon, along with 1000-2000 j/kg of SBCAPE. If this setup occurs, then severe storms may be possible.
Wednesday night into Thursday morning, the cold front - and its attendant rain and thunderstorms - will push through Columbia. This is likely where mid-MO will pick up most of its rainfall. Lingering showers are possible into Thursday morning, though these should come to an end gradually by midday. Sunshine is even a possibility by the late afternoon. Although the front will have passed through by Thursday morning, the air behind it will not be very cold, and - if some sunshine does break out Thursday afternoon - mid-MO could easily see highs in the upper 60s and lower 70s. If clouds hang tough, readings could stay in the low to middle 60s. Models have been trending towards the first solution, and this forecast will reflect that trend.
After all is said and done, QPF is likely to vary widely across mid-MO. EPS means sit at over 1.6" for COU, while SREF means are only slightly lower at 1.5". The GEFS is the most conservative, preferring a southerly track to the heaviest rain and producing a mean of approximately 1.15". All of these ensembles also have incredible spread within their QPFs, indicating the disorganized and uncertain nature of this setup. With this in mind, a current QPF projection of 0.5-1.5", which isolated amounts greater than 2", seems reasonable. These are significant amounts, and - given recent rainfall and saturation - a flooding and flash flooding risk is present from Tuesday night through Thursday morning.
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