@ FXUS63 KLSX 192302 AFDLSX Area Forecast Discussion...Updated Aviation National Weather Service Saint Louis MO 602 PM CDT Tue May 19 2026 .KEY MESSAGES... - Today's cold front will bring in cooler and drier weather for the next few days. - Rain chances increase again late this week into this weekend. && .SHORT TERM... (Through Late Wednesday Night) Issued at 203 PM CDT Tue May 19 2026 A cold front is slowly pushing southeast through the region this afternoon. While a humid airmass still exists ahead of the front, extensive cloud cover and light rain streaming across the area as blow off from convection over Arkansas has really put a damper on solar heating, reducing the chances for additional thunderstorm development on the front as it moves through our area this afternoon. Most of us will just see clouds and light rain with perhaps a stray rumble of thunder through the evening. Better chances of thunderstorm development will be focused closer to the Ohio River Valley. As the front moves through, winds will shift to the northwest and our temperature and dewpoint drop into the 50s. This will be a noticeable change from our early season warm and humid air mass we've felt for the last few days. Extensive low level cloud cover behind the front lasts at least through the night tonight, ensuring we only bottom out in the 50s for most due to the cold advection and lack of additional radiational cooling. If thick clouds linger through the day tomorrow, then highs will struggle to make it out of the 50s, but if we get more sun we could make a run at 70. Current NBM forecast is on the higher end and represents expectations if clouds break up a bit more, while the MAV and MET both suggest more widespread upper 50s to low 60s, below the 10th percentile of NBM guidance. Kimble && .LONG TERM... (Thursday through Next Tuesday) Issued at 203 PM CDT Tue May 19 2026 The mid level flow pattern across the continent will increasingly feature some variation of troughing in the West and ridging over the Southeast US coast. This puts our area in southwesterly mid level flow steering subtle disturbances through the center of the country. At the surface, strong surface high pressure over the Great Lakes will maintain its influence locally, with easterly low level winds and warm sector heat and humidity staying largely south of our region. Thus while we see rain chances increasing late Thursday into Friday and continuing on and off through the weekend, this will by in large be showers and elevated thunderstorms with a minimal severe weather risk considering the lack of access locally to the richer low level moisture flowing off the Gulf. Greater confidence is with the Thursday-Friday time frame as an initial trough moves northeast through the flow. After that, guidance varies more considerably on how to handle the remaining trough with some maintaining a more robust cut off low over the Southern Plains which keeps us in the line of fire for additional disturbances through the weekend while others transition towards northwest flow. Latest NBM continues rain chances through this weekend which is warranted, but our confidence is lower on the timing and location of these rounds of rain. Regarding temperatures, NBM continues to occupy the top spot among all of guidance for maximum temperatures this weekend. Its spring bias correction is dominating the physical forecast. For high temperatures, modeled temperatures aloft are a first stop for any forecast. This weekend among the long range ensemble guidance there's fairly good agreement that 925MB temperatures will be in the 16-18C Friday through Sunday with an IQR of only 2 to 3C. Assuming strong mixing to the surface, which can be expected on a sunny May day, high temperatures would top out in the low to mid 70s. But strong mixing isn't a given. As noted in the prior paragraph, subtle disturbances in the southwesterly flow may bring additional rounds of clouds and showers this weekend, and if that occurs we would not expect full mixing. So while the official forecast has temperatures drifting well into the 80s for the holiday weekend, we have low confidence in this and strong reason to suspect below normal temperatures continuing. Kimble && .AVIATION... (For the 00z TAFs through 00z Wednesday Evening) Issued at 551 PM CDT Tue May 19 2026 A cold front has finally pushed through all terminals with northwesterly surface winds drawing drier air into the region. Aside from KUIN, where improvement continues in the first couple hours of the TAF period, the remainder of the terminals will dip into a long period of MVFR with brief bouts of IFR. Precipitation chances continue to decrease with an isolate shower possible. Chances are <20% and only continue to decrease in time. Improvement will be gradual Wednesday with VFR favored to expand from north to south from late-morning through afternoon. Maples && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX