742 FXUS63 KEAX 171736 AFDEAX AREA FORECAST DISCUSSION National Weather Service Kansas City/Pleasant Hill MO 1236 PM CDT Fri May 17 2019 .Discussion... Issued at 401 AM CDT FRI MAY 17 2019 An expansive area of showers and thunderstorms were located this morning across Nebraska and Iowa in proximity to a quasi-stationary front. While outflow cold pools and subsequent redevelopment has nudged new convection closer to the forecast area, the southern extent should generally be limited to the Iowa/Missouri border. Otherwise, the weather should be relatively quiet for the daylight hours today. Backing winds in the lowest 5kft in response to pressure falls with the approach and emergence of the upper trough into the western Plains will realign the H85 thermal axis westward, resulting in slightly cooler afternoon temperatures compared to yesterday, with readings in the middle to upper 80s. A strengthening low-level jet overnight will continue to transport deep moisture into the area, with the potential for elevated convection to develop late evening into the early morning hours as ascent overspreads the region. A few strong storms producing hail cannot be ruled out between midnight and sunrise Saturday. The forecast for the remainder of Saturday remains complex and highly dependent on each potential phase of convection and the degree of disruption/recovery of the environment in its wake. With the approach of a strong shortwave trough overspreading deep ascent, widespread convection is expected to develop both along a cold front and within the warm sector by noon or early afternoon. The early morning precipitation coverage and remaining cloud debris will have a role in determining the degree of instability ahead of these storms, but current indications suggest sufficient instability and deep layer shear will support storm organization and some maintenance for a hail and wind threat. Models also hint at another organized cluster of storms that evolve during the late-afternoon immediately ahead of the upper trough over southern Kansas and northern Oklahoma. High uncertainty exists with respect to the eventual track of this cluster as atmosphere/residual outflow from earlier convection may tend to keep most robust convection trending to the south. However, any stronger atmospheric recovery than expected could allow for a second round of severe weather during the evening hours across the forecast area. If this occurs, all severe weather modes would be possible. To reiterate, the forecast remains highly complex with several mesoscale variables unresolvable at this juncture, but some severe weather threat will exist on Saturday into Saturday night. In addition, several rounds of heavy rain will be possible on Saturday, with 1-2 inches of rainfall possible by Sunday morning. Depending on where the heaviest/repeated corridors of heavy rainfall occur, localized flash flooding cannot be ruled out. Shortwave ridging and cold air advection will allow for a tranquil and cool Sunday, with precipitation shifting east of the area by late morning and highs in the middle 60s to lower 70s. This quiet weather is short-lived as an active weather pattern continues across the central CONUS with another strong upper trough emerging into the Plains on Monday. Once again, deep-layer shear and instability appears to be supportive of a severe weather threat Monday night and potentially into Tuesday. Another heavy rain event may also materialize with repeated convection, with 2-3 inches possible. Models currently have strong QPF convective feedback, but locally higher rainfall amounts will be possible. As with any convective event 4 days out, details are nearly impossible to pin down, including specific rainfall amounts and their respective heavy swaths, but the potential is certainly there for another round of severe weather and heavy rainfall. && .Aviation...(For the 18Z TAFS through 18Z Saturday Afternoon) Issued at 1232 PM CDT FRI MAY 17 2019 VFR conditions will prevail for the majority of the period with a strong southerly wind of 15kts gusting to 20-25kts. A strong area of winds aloft will move into the region around 08z creating possible LLWS over western Missouri that will last through sunrise. A frontal system will begin to move into the area around sunrise causing possible MVFR ceilings and scattered rain showers. By the end of the period a complex of thunderstorms is expected to move into the region, but there is still uncertainty in the timing so VCTS was utilized for now. This timing will likely be resolved and upgraded to on station thunderstorms in subsequent forecasts. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ Discussion...Blair Aviation...Barham