224 FXUS63 KLSX 231158 AFDLSX Area Forecast Discussion...Updated Aviation National Weather Service Saint Louis MO 558 AM CST Sat Nov 23 2019 .SHORT TERM... (Through Late Tonight) Issued at 347 AM CST Sat Nov 23 2019 A closed 500mb low over eastern Kansas will move east across Missouri and Illinois today. Areas of light precipitation will continue this morning ahead of the system, especially ahead of the 850mb reflection of the upper low. Have had a few reports of frozen/freezing precip north of the I-70 corridor this morning, but surface temperatures are marginal...hovering near or just above freezing...and the precipitation is generally pretty light. Therefore any accumulations are expected to be minimal and primarily on grassy areas. Precipitation intensity and coverage should diminish after 12-14Z as the 850mb low moves east of the area into eastern Illinois, but there will likely be some lingering light precip along and east of the Mississippi River into early afternoon ahead of the primary upper level low. There will likely be at least partial clearing late this afternoon from west to east, with the sky finally clearing out across the entire area by early to mid evening. Highs today will be very dependent on how long precip/clouds hang on, but should generally be in the upper 30s to low low 40s. It looks like a quiet and cool night tonight in the wake of the storm system with a mostly clear sky and lows in the upper 20s to low 30s. Carney .LONG TERM... (Sunday through Friday) Issued at 347 AM CST Sat Nov 23 2019 Sunday will be the final day of our current NW flow pattern. An upper level disturbance will drop down through this flow but the track of this feature will be too far north--keeping the main area of lift there. Also, the system will be too progressive in what will be too dry of a column to have any real impact on cloud cover over our region. Thanks to SW flow and deeper mixing, temps should rise into the 50s across the forecast area, making a run on 60 degrees for portions of central and southeast Missouri and the STL metro area. Monday will be a day of transition as the main flow pattern begins to change across the central CONUS as the beginnings of a TROF take shape in the western CONUS. Locally, another dry day looks on tap with a surface cold front approaching from the northwest late in the day, but SW flow persisting until then. This should result in another mild day with max temps a few degrees above persistence, from upper 50s to mid 60s areawide. The beginnings of a new, more active, SW flow pattern will take hold on Tuesday and prevail through the rest of next week. There are potentially three systems to watch during this stretch, but with strong cold air intrusions essentially locked up north, none of the potential storm systems appear strong enough to induce enough cold air to result in an impactful wintry precipitation event. The first storm system is set for Monday night-Tuesday-Tuesday night and there has been reasonable agreement on what looks to be a strong negatively tilted shortwave driving through the area later on Tuesday. Mild air and higher than normal moisture will be in place, with good support for what should be showers and possibly thunderstorms. CIPS analogs even shows a conditional severe storm probability, but considerable cloud cover and what could be a lot of precipitation in place will hinder thunderstorm development along with an uncertain timing of the main shortwave system. High PoPs look justified with this type of system regardless. There is potential also for max temps to be higher than what is advertised currently, but again cloud cover looks to limit rises at this time and stuck close to a largely persistence max temp forecast on Tuesday. Some colder air works its way in for Wednesday and Thanksgiving Day but again, the main core remains well to the north, with the main result being a cooling back to normal temps from temps about 10 degrees above normal earlier in the week. There has been better agreement on another system for Thanksgiving Day. Cold air will be limited and the opportunity for any snow will encompass a pretty tight window in time. Rain appears to again be the dominant precipitation type with GEFS members reasonably clustered at or above 40 degrees for much of this time period. If there is any opportunity for snow, it appears to be limited to the early morning hours only. The pattern doesn't support it and the system is not strong enough. Finally, as the longwave upper TROF becomes well established and deepens over the western CONUS by late next week, upper ridging will be the result over our way, with a third system looking set for the weekend with mild temps in place. Once again, looks to be showery with temps too high for any snow potential. Other than Wednesday and Thursday where a minor cooldown to near normal takes place, temps will be above normal for much of this period as the cold air takes a hiatus. TES && .AVIATION... (For the 12z TAFs through 12z Sunday Morning) Issued at 543 AM CST Sat Nov 23 2019 A broad area of IFR conditions generally along and south of I-70 in Missouri and I-64 in Illinois will continue to prevail through much of the morning. Within that area of IFR areas of light rain and drizzle will also move through the region, with some snow occasionally mixing in, mainly in central and northeast Missouri into west central Illinois. Precipitation is expected to end from west to east through mid to late morning. Some lingering rain is possible during the early afternoon across parts of south central Illinois. Flight conditions will gradually improve into MVFR and then VFR through late morning/early afternoon, with ceilings clearing from wet to east from late afternoon through early evening. VFR flight conditions are expected to prevail thereafter. SPECIFICS FOR KSTL: IFR flight conditions with occasional light rain or drizzle is likely to prevail at Lambert through the morning. There's some uncertainty as to exactly when the ceiling will lift to MVFR range, but most guidance is pointing to between 17-19Z. Expect ceilings to continue to rise gradually through the afternoon, and then clear out by early evening. VFR conditions are expected to prevail thereafter. Carney && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX