791 FXUS63 KLSX 152339 AFDLSX Area Forecast Discussion...Updated Aviation National Weather Service Saint Louis MO 639 PM CDT Mon Jul 15 2019 .SHORT TERM... (Through Late Tuesday Night) Issued at 335 PM CDT Mon Jul 15 2019 First wave of rain moving through east central MO and southwest IL this afternoon associated with the remnant low of Barry which is currently over northwestern AR. Barry will move northeastward into south central MO late tonight and through east central MO Tuesday morning. The precipitation should become more scattered this evening, but then ramp up again late Tuesday morning and afternoon as Barry moves through our forecast area along with some destabilization of the atmosphere due to surface heating which should result in at least isolated storms. The best coverage of rain will be across southeast MO and southwest IL. There will still be the potential for heavy rain across parts of southeast MO tonight and Tuesday so will continue the Flash Flood Watch for a small portion of southeast MO. Will have lingering showers and a few storms across southeast MO and southwest IL Tuesday evening, but the precipitation should finally shift southeast of our forecast area by late Tuesday night as weakening Barry moves east of our area. High temperatures Tuesday should be relatively cool again for mid July across southeast MO and southwest IL due to the cloud cover and precipitation. GKS .LONG TERM... (Wednesday through Next Monday) Issued at 335 PM CDT Mon Jul 15 2019 Much warmer temperatures can be expected on Wednesday as upper level heights rise and a weak warm front moves northeastward through our area. Could not rule out an isolated storm along this warm front as the atmosphere becomes quite unstable Wednesday afternoon with plenty of daytime heating and humidity. A typical hot and humid summertime weather pattern is expected for the rest of the work week and into the weekend as an upper level ridge builds over our area along with persistent south-southwesterly surface/low level winds. There will be plenty of diurnal solar insolation due to the lack of cloud cover as well as little if any convection as frontal boundaries remain north of our area and the atmosphere becomes capped to convection with rising mid level temperatures. A prolonged period of dangerously high afternoon heat indices of around 105 is forecast from Wednesday through at least Saturday so will issue an Excessive Heat Watch for this time period for most of the forecast area. May see at least a slight cool down by Monday as both the operational GFS and the ECMWF models try to bring a cold front southeastward into our area as an upper level trough moves eastward through the northern Plains and Great Lakes region suppressing the upper level ridge further southward, and bringing our surface winds around to the northwest after passage of the cold front. There may also be convection along and just ahead of this front as well on Monday. GKS && .AVIATION... (For the 00z TAFs through 00z Tuesday Evening) Issued at 628 PM CDT Mon Jul 15 2019 Confidence is high that flight conditions will be poor through the morning, but questions remain regarding just how bad the conditions will get. Upstream cigs are generally slightly higher than 1000 ft, but with nightfall coming, it stands to reason that cigs may fall a bit in the next few hours. Additionally, many of the high resolution models at our disposal are pointing to IFR cigs into the morning, so went ahead and dropped all TAFs save UIN to IFR. All that said, cigs may fluctuate around 1000 ft, especially early this evening. Showers should remain isolated to widely scattered through the night and the thunder potential seems quite low. Given the very high humidity and weakening winds as the center of Barry approaches the area, we may also see some fog develop between the showers overnight. Again, not very confident on just how poor the vis will get, but at least patchy fog is possible, especially toward central MO. Finally, showers are expected to persist through tomorrow afternoon, with storms coming back into the picture by the afternoon. Again, at this point it looks like showers and storms will be scattered for much of the period, so just went with vicinity mentions for now. As guidance comes into better agreement on shower and storm timing, we may be able to introduce prevailing or tempo groups with more specific precip timing. BSH && .PRELIMINARY POINT TEMPS/POPS... Saint Louis 72 83 74 93 / 50 60 30 5 Quincy 70 84 72 93 / 20 20 5 5 Columbia 69 85 71 93 / 30 30 5 5 Jefferson City 69 85 70 95 / 30 30 5 5 Salem 72 81 72 90 / 60 70 50 20 Farmington 69 80 69 91 / 70 70 40 20 && .LSX WATCHES/WARNINGS/ADVISORIES... MO...Flash Flood Watch through Tuesday evening for Iron MO-Madison MO- Reynolds MO. Excessive Heat Watch from Wednesday afternoon through Saturday evening for Audrain MO-Boone MO-Callaway MO-Cole MO- Franklin MO-Gasconade MO-Jefferson MO-Knox MO-Lewis MO- Lincoln MO-Marion MO-Moniteau MO-Monroe MO-Montgomery MO- Osage MO-Pike MO-Ralls MO-Saint Charles MO-Saint Louis City MO-Saint Louis MO-Shelby MO-Warren MO. IL...Excessive Heat Watch from Wednesday afternoon through Saturday evening for Adams IL-Bond IL-Brown IL-Calhoun IL-Clinton IL- Fayette IL-Greene IL-Jersey IL-Macoupin IL-Madison IL- Marion IL-Monroe IL-Montgomery IL-Pike IL-Saint Clair IL- Washington IL. && $$ WFO LSX