268 FXUS63 KLSX 040246 AFDLSX Area Forecast Discussion...Updated National Weather Service Saint Louis MO 946 PM CDT Tue Sep 3 2019 .UPDATE... Issued at 936 PM CDT Tue Sep 3 2019 The cold front was located near a Chicago to Quincy to Kansas City line at 02z. Warm air aloft was resulting in signficant capping and the only convection was located just ahead of the front across NE IL where CIN was much less. The cold front will continue to move southward through the remainder of the CWA tonight. The chances of surface-based storms appears pretty remote given the current CIN and forecast CIN. I can't completely rule out the possibility of an isolated and short-lived elevated shower or storm forming associated with increasing clouds/moisture in the 850-700 layer spanning the frontal zone, but even that chance seems rather low at this point. Glass && .SHORT TERM... (Through Late Wednesday Night) Issued at 335 PM CDT Tue Sep 3 2019 Latest surface analysis indicates that the front extends from eastern Iowa into far northwest Missouri. Satellite trends continue to show extensive mid clouds along the front, but a limited cumulus along the front with the only thunderstorms over northeast Illinois and Indiana. Convective development farther westward as been hindered by stout cap shown well by the RAP soundings today, and this trend is expected to continue into this evening. CAMS have kept shower/thunderstorm development over Illinois tonight, so will do the same. Have only isolated showers and thunderstorms over west/south central Illinois during the evening hours. If updrafts are stout enough to develop and remain upright, then there will be sufficient CAPE/shear parameters for a few severe storms, particularly over Illinois. These storms will be capable of producing large hail and damaging winds. The cold front will push south of the CWA late tonight. Then dry weather is expected Wednesday and Wednesday night as a surface ridge moves in from the upper Midwest and the atmosphere becomes dry through a deep layer. Highs on Wednesday will be cooler behind front with cold air advection. Britt .LONG TERM... (Thursday through Next Tuesday) Issued at 335 PM CDT Tue Sep 3 2019 Expect mainly dry weather from Thursday into Saturday as a large surface high moves across Missouri and Illinois under generally dry northwesterly upper flow aloft. This will change by Saturday night into early next week as the deterministic global models and GEFS mean show a pair of shortwave troughs dropping southward out of the Northern Plains. These troughs will combine with a stalled front over southern Missouri and Illinois to bring a chance a showers and thunderstorms late in the period. Temperatures will be close to normal on Thursday, but will then warm up above normal on Friday ahead of a cold front with 850mb temperatures close to 20C. Temperatures behind the front will likely be at or below normal behind the cold front with a chance rain, but the spread on the GEFS ensemble temperatures is showing an increasing spread which lowers the confidence in the overall forecast in early next week. Overall trend in guidance is showing temperatures going back above normal by next Tuesday. Britt && .AVIATION... (For the 00z TAFs through 00z Wednesday Evening) Issued at 659 PM CDT Tue Sep 3 2019 A cold front currently stretches from northwest IL across southeast IA into northwest MO early this evening. This front will move southward tonight and will be accompanied by a increasing swath of VFR clouds with bases from 4,000 to 5,000 feet. Precipitation chances with the front look iffy and if a shower or thunderstorm does develop this evening, then the coverage should be rather isolated. The TAFs reflect the wind shift with the cold front and clouds, and are void of any precipitation given the aforementioned low probability. SPECIFICS FOR KSTL: A cold front currently stretches from northwest IL across southeast IA into northwest MO early this evening. This front will move southward tonight and should move through the terminal around 05-06z. The front will be accompanied by VFR clouds with bases from 4,000 to 5,000 feet. Precipitation chances with the front look iffy and if a shower or thunderstorm does develop this evening, then the coverage should be rather isolated. The TAF reflects the wind shift with the cold front and clouds, and are void of any precipitation given the aforementioned low probability. Glass && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX