550 FXUS63 KEAX 181939 AFDEAXArea Forecast Discussion National Weather Service Kansas City/Pleasant Hill MO 239 PM CDT Thu Sep 18 2025
.KEY MESSAGES...
- Strong to severe storms this afternoon. Damaging winds will be the main hazard, but hail to quarter size is possible in the strongest storms.
- Dense fog possible early Friday morning.
- Multiple additional rain chances from this weekend into next week. The highest probability period is Late Saturday night through Sunday with an >85% chance of seeing at least 0.01" in the 24 hours ending 7 PM Sunday.
&&
.DISCUSSION... Issued at 231 PM CDT Thu Sep 18 2025
Water vapor imagery shows a strong shortwave trough, with at least a neutral tilt and potentially a slight negative tilt, over central KS currently. This shortwave will continue to push eastward through the afternoon and evening hours with models showing a tendency to negative tilting. At the surface, earlier convection, coupled with the ascent from the approaching shortwave, is keeping most of the area cloudy, limiting destabilization. However, dewpoints are in the low to mid 60s across the area and there is some clearing noted in our southern and eastern zones, which is allowing temperatures to climb into the 80s quickly. This combination of lower cloud cover, allowing for warmer temperatures, and the increased moisture will help southern and eastern portions of the forecast area build 1500-2000 J/kg of MLCAPE. Stronger flow moving around the base of the shortwave will also lead to modestly stronger shear with 25-30kt of deep-layer shear possible. All this points to a window when strong to severe storms would be possible in mainly our southern and eastern zones (roughly southeast of a line from Paola, KS to Kirksville) and in a time frame from about 20Z through 04Z. One other item to mention with this setup is that regional radar imagery shows what looks like an MCV moving into northeastern KS, with a line of storms developing along and southeast of the vortex. As this area moves into eastern KS and western MO, it looks to weaken as the instability isn`t as strong and better shear shifts to the south.
Showers and storms move east of the area tonight with skies potentially clearing out across northeastern KS and northern MO. While we won`t have high pressure centered right over the area, winds may become light enough overnight to limit boundary layer mixing and increase the potential for fog development. The latest HREF shows generally a 40-60% chance for visibility less than 1 mile late tonight into early morning. Have added fog, some of it dense, to the forecast for areas mainly north of the MO river.
There are multiple additional chances for precipitation from Saturday night through the remainder of the forecast. The greatest potential looks like Saturday night into Sunday. Models show a strong nocturnal low-level jet that noses into eastern KS and western MO. This LLJ will lead to strong moisture transport into the area and all ahead of a strong mid-level shortwave trough. Precipitable water values will be approaching 1.8" Sunday morning. Using the sounding climatology page via SPC, since the ensemble situational awareness table isn`t currently working, this puts eastern KS greater than the 90th percentile but less than the daily average max value. So this is an unseasonably moist airmass moving into the area and given the setup, there is potential for pockets of heavy rain. Ensemble guidance shows there is a small potential (5- 10%) for 24 hour precipitation to exceed 1.5" by 7 pm Sunday.
For the remainder of the extended, there are multiple periods with some probability of precipitation. Ensemble mean 500mb heights and clusters start early next work week with zonal to broad troughing noted. The upper pattern becomes more variable by Tuesday into Wednesday with nearly two-thirds of members showing varying strength of troughing over the middle of the country and a smaller percentage showing the area on the eastern edge of ridging. With the preference for troughing over the middle of the country, it`s not surprising there are small probabilities of precipitation throughout the extended with PoPs generally in the 20-40% range from Monday onward.
&&
.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1234 PM CDT Thu Sep 18 2025
Main change with this forecast was to adjust later the timing of another line of storms and refine the overall timing to 21Z-01Z for storms in the KC area terminals. Overall, it is looking like storms will initiate near or just east of the KS-MO state line near 21Z and then quickly track east through the late afternoon and evening hours. There is still some east-west variability in initiation so still have a three-hour period of time as the most likely to see storms. It is possible that storms initiate east of all the terminals. Overnight, focus shifts to the potential for fog, especially north of the Missouri River. Latest HREF showing a 40% to 60% probability of visibility less than 1 mile for most areas north of the river, and more spotty probabilities south. Have added some mention of fog in all forecasts and as confidence increases in dense fog, updates can be made.
&&
.EAX WATCHES/WARNINGS/ADVISORIES... MO...None. KS...None.
&&
$$
DISCUSSION...CDB AVIATION...CDB
NWS EAX Office Area Forecast Discussion