231 FXUS63 KEAX 301629 AFDEAX AREA FORECAST DISCUSSION National Weather Service Kansas City/Pleasant Hill MO 1129 AM CDT Tue Apr 30 2019 .Update... Issued at 1129 AM CDT TUE APR 30 2019 The combination of the MCS that moved through the area this morning, the warm front just to our south, and renewed shower/storm development in south central KS and southwest KS, will help to keep the area clouded over. This will really limit surface based instability. Forecast soundings for later this afternoon and this evening do show some elevated instability developing. Latest convection allowing models are doing a decent job handling the multiple areas of showers/storms. But they are all in agreement in moving in a line of storms late this afternoon through early this evening, approximately 23Z-03Z. With the instability the models are showing, this time frame may be the best chance for anything severe, with some hail and strong winds possible. && .Discussion... Issued at 417 AM CDT TUE APR 30 2019 Today will be an active day with multiple rounds of different threats to the area as a shortwave trough ejects out into the southern plains. Currently the LLJ is helping to create isentropic accent along an elevated warm frontal boundary from central OK up into NW MO. A MUCAPE axis of 750-1000 J/kg will allow elevated convection to occur along this boundary as it progresses to the NE. Effective bulk shear of 35-40kts along this boundary may allow some of these storms to intensify to severe levels, as we had one cell already show that potential near KMCI this morning. While isolated large hail is possible the main impact from this line of storms will be heavy downpours with PWAT values near 1.5" and rain rates of up to 1" per hour. This developing MCS will push through eastern KS and western MO around sunrise and may cause some impacts to any morning commutes. 1 hr flash flood guidance over this area is around 1.75" with 3 hour leaning towards 2.25". These values do have the possibility of being exceeded so flash flooding will need to be monitored with this first passing MCS, especially over the KC Metro area. This MCS looks to push east by the late morning and the timing of this exit will have an effect on how the rest of the day plays out. As the upper level shortwave trough exits into the southern plains the surface warm front over OK will begin to undergo frontogenesis and lift to the north towards our area. Almost all of our uncertainty with the severe weather potential this afternoon will lie on how far north this boundary will get by sunrise. Model guidance does not have a consensus with the CAMs indicating it will reach just south of HWY50, while the GFS and ECMWF push it up into the Missouri River. We are leaning on the southern solution being more accurate as a large cold pool is likely to form due to the morning MCS and cloud coverage all day is going to make it difficult for us to destabilize throughout the day and possibly stall that northern movement of the warm front. While there is uncertainty on the placement of the front, the type and intensity of the severe weather in regards to this boundary will be similar, so monitoring the frontal evolution in the early afternoon will set up the threats we may have to deal with. On the cold side of the warm front elevated supercells may be possible with MUCAPE ~1500 J/kg and 0-6km bulk shear of 40-50kts. The main threat in this region will be large hail and heavy rainfall. In the warm sector of this system the main threat will be discrete supercells with ~1500-2000 J/kg of MLCAPE (depending on how much heating we get) and 0-6km bulk shear of 40-45kts. Outside of the large hail threat there will be a low chance for some damaging winds in wet microbursts, but there will also be a threat for tornadoes. Hodographs on modeled soundings indicate nice anticyclonic curvature with 0-1km SRH 200-300, 0-1km bulk shear of 25-30kts, and LCL heights 50-100m. If a supercell can get going in this environment conditions will be primed for rain- wrapped tornadoes that would develop quickly. This threat looks to be very short-lived as the window for any destabilization in the warm sector before sunset is narrow and would likely be after 3pm until sunset. Going through current guidance this threat looks to stay south of the KC Metro and more from Butler to Sedalia, unless this boundary can push further north than expected. As this threat diminishes the next threat will start to develop over eastern Kansas as a line of storms and possible QLCS in the last afternoon. This feature looks to quickly push through our area with the main threat being damaging winds and maybe isolated large hail. Fortunately for our area the 0-3km bulk shear vectors are more SW-NE oriented which should decrease the wind and tornado threat. The most likely area to see higher winds will be once again south of the KC Metro in that same corridor of Butler to Sedalia and into the Lake of the Ozarks. Flash flooding will need to be monitored very closely in the late afternoon as saturated soils will lead to quick runoff and potential life threatening conditions depending on how much training of storms an area gets. This QLCS looks to quickly push to the east after sunset and may even be out of our area by midnight. The cold front associated with this system looks to stall down through central MO on Wednesday. A series of upper level shortwaves may help develop another round of possible severe weather, mainly over southern MO but could reach into our southern counties from Butler to Sedalia once again. The main threat with these storms looks to be large hail and damaging winds with DCAPE value near 1200 J/kg, fortunately the effective bulk shear will be more like 20- 25kts decreasing the chance for supercell formation and more likely to see multicell development along that boundary. With how much rainfall this area is likely to get in the next 24 hours flash flooding will once again need to be monitored going into Thursday. North of this boundary elevated storms may bring some lighter QPF into the area, but any severe threat or flash flooding look low going into Thursday morning. High pressure finally builds into the area Friday into Saturday drying out the area and allowing us to get into the 70s on Saturday. A cold front moving through the northern plains may result in us getting some remnant showers Sunday morning form an MCS over Nebraska. This boundary may linger into the beginning of the work week and provide spotting rain chances through Tuesday. && .Aviation...(For the 18Z TAFS through 18Z Wednesday Afternoon) Issued at 1129 AM CDT TUE APR 30 2019 IFR ceilings are expected to persist throughout the forecast. Models suggest the next round of storms may be in the 23Z-03Z time frame late this afternoon/early this evening. Confidence was high enough to include a TSRA tempo group during this time frame. Winds will eventually shift to the north late this evening and to the northwest early tomorrow morning. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...Flash Flood Watch through Thursday morning for KSZ025-057-060- 103>105. MO...Flash Flood Watch through Thursday morning for MOZ008-013>017- 020>025-028>033-037>040-043>046-053-054. && $$ Update...CDB Discussion...Barham Aviation...CDB