083 FXUS63 KLSX 071922 AFDLSX Area Forecast Discussion National Weather Service Saint Louis MO 222 PM CDT Wed Jun 7 2023 .SHORT TERM... (Through Late Thursday Night) Issued at 147 PM CDT Wed Jun 7 2023 The cold front has slowly pushed westward across the region this afternoon. A pocket of low level moisture immediately behind the front and convergence along the front aloft (bent back behind the surface front) has led to a rather persistent area of rain and a few embedded thunderstorms. This has finally begun to dissipate as the frontal zone continues to push west and south. Plenty of cloud cover has also kept temperatures cooler and made it more difficult to achieve the kind of surface based instability that would be needed for more rigorous convection. The best chance of this is ahead of the surface front in central Missouri. Cooler and drier air will push in from the northeast tonight and tomorrow. This air mass has origins in the Arctic but will continue to be modified by each day of sunshine. We'll likely top out in the upper 70s to low 80s tomorrow in strong sunshine. Dewpoints remain low, though, in rather extreme territory for this time of year. While this makes for a very pleasant June day, it does not help ongoing drought. Fire weather concerns remain limited by spring green up, but the drought has certainly left fuels more stressed than normal this time of year. High pressure begins to move into the area from the north Thursday night allowing winds to diminish under a clear sky. This will set up the coolest night of the forecast where valley locations will drop into the 40s while even urban areas will fall into the mid 50s. This is about 10 degrees below normal for this time of year. Kimble .LONG TERM... (Friday through Next Wednesday) Issued at 147 PM CDT Wed Jun 7 2023 The high pressure center of this modified Arctic air mass continues to push south and then east Friday and Saturday. The air mass continues to modify in place, with each day several degrees warmer than the day before. By Saturday afternoon temperatures will close in on 90 degrees especially now that rain chances look to hold off until later in the day or Saturday night. On the topic of rain chances, we do have some good news. A trough dropping south through the Great Lakes will shove a cold front southward along with it. A wave of low pressure tracks along the front this weekend helping to pull in some Gulf of Mexico moisture into the frontal zone setting up the best chance for widespread rainfall that we've seen in quite a while. The details are still a little fuzzy at this time range, but the general idea is that an area of showers and thunderstorms will occur as this wave moves through. The timing and track of this wave will determine who gets how much, but there's a pretty strong chance that we'll all get something and some of us could get a good amount. Ensemble probabilities of at least 0.1 inch are in the 70 to 80 percent range while probabilities of at least 0.5 inch are up to 30 to 40 percent. We're still a bit cautious on advertising a soaking rainfall in the middle of a drought especially when so much is based on the fickle nature of convection, but there is at least a chance of a noticeable and beneficial rainfall. Latest guidance is shifting the most likely time frame more towards Sunday for our area. The cold front ushers in another very dry, modified Arctic air mass behind it. So we'll cool off several degrees before warming back up again toward the middle of next week. By then, there's some signs that the overall blocking pattern begins to break down a bit as the western trough actually makes progress eastward across the southern half of the country. This will bring another chance of rain around the middle of the week and may even get the upper air pattern moving again rather than staying stuck in the stagnant blocky flow. Kimble && .AVIATION... (For the 18z TAFs through 18z Thursday Afternoon) Issued at 1214 PM CDT Wed Jun 7 2023 Persistent area of showers along the Mississippi River has shown signs of weakening, so we expect impacts to improve shortly. Mid and higher level cloud cover should limit the potential for additional thunderstorm development this afternoon, but if it occurs it is most likely in central MO. Cold front continues to ooze southwest with a northeast flow behind it. Generally VFR is expected behind it, though some patchy IFR has been noted in areas within the persistent rain band. Kimble && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX