113 FXUS63 KTOP 191104 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 604 AM CDT Sun May 19 2019 ...AVIATION UPDATE... .SHORT TERM...(Today and tonight) Issued at 417 AM CDT Sun May 19 2019 08Z water vapor imagery and profiler data showed the upper trough axis/MCV over northeast KS. This could be seen in the radar data as well with the cyclonic circulation in the rain. Further west an upper low was moving towards the coast of northern CA with shortwave ridging over the central Rockies. At the surface, an area of low pressure was centered over IA with a cold front stretching through southeast NEB and into west central KS. The rain showers are expected to exit to the east of the area by mid morning as the upper low continues to move east and north. Then dry weather should prevail through tonight as the shortwave ridging over the Rockies propagates east over the plains. With the models showing general subsidence this afternoon, skies are expected to become partly sunny. Although highs are not expected to be significantly warmer as weak high pressure builds into the central plains. This is forecast to maintain some weak low level cold air advection keeping highs in the mid and upper 60s. Lows tonight should fall into the mid 40s as dry air works its way south. .LONG TERM...(Monday through Saturday) Issued at 417 AM CDT Sun May 19 2019 Transitioning into the extended period the primary concern continues to reside with additional heavy rainfall which will likely lead to flooding. In addition, severe thunderstorms are possible Monday into Monday night and again Tuesday afternoon. By Monday morning a midlevel shortwave ridge axis will be positioned across the forecast area with an attendant surface ridge draped across the MO River Valley. The main midlevel trough will remain well-west of the Plains across portions of southern CA. With cyclonic flow overspreading the High Plains through the morning, the lee low across southeastern CO will rapidly deepen, resulting in a low level mass response across the Southern Plains. This will lift a warm front to near the KS/OK border by midday. A batch of WAA showers/storms are possible by late morning/early afternoon, primarily across north central KS. Modest lapse rates combined with impressive wind fields could foster a large hail threat with this round of elevated convection. Continued WAA near 850 mb through the day will likely allow for scattered shower/storm activity through the day. As the main midlevel trough ejects into the Plains, generally afternoon 03-06Z, storm coverage is progged to rapidly increase across western OK, spreading northeast across the forecast area through the night. As the trough rotates northeast through the night into Tuesday several rounds of thunderstorms appear likely, unfortunately. Very rich Gulf moisture, characterized by PWAT values exceeding 1.5" (nearing the daily record at TOP) will result in very heavy rainfall. Radar estimations suggest most of the area received 1-3 inches of rain late Friday night through Saturday. Deterministic and ensemble guidance remains consistent with additional rainfall amounts of 2-5" area-wide Monday into Tuesday, with locally higher amounts likely. Consequently, flooding and flash- flooding appear likely. As a result, a Flash-Flood Watch has been issued for the entire forecast area from 1 PM Monday through 7 PM Tuesday. Moreover, the heaviest rain is likely to fall during the overnight hours Monday night/Tuesday morning, further increasing the flood danger. The infrequent combination of very wet antecedent conditions across the area -- including fully saturated soils and swollen lakes and rivers -- and additional very heavy rainfall may result in significant flooding. As far as the severe weather potential goes for Monday night, the strongest storms look to be capable of large hail and damaging winds. Additional severe storms are possible midday Tuesday through the afternoon, mainly across far eastern KS, as the surface low and Pacific front traverse the area. At this point, all modes of severe weather appear possible, including large hail, damaging winds, and tornadoes. The active weather pattern looks to continue with broad troughing remaining across the western US. A stationary front looks to set up across the central US by weeks-end into next weekend. Unfortunately, additional rounds of heavy rain are possible. Temperatures look to moderate by midweek with afternoon highs into the 70s to near 80. && .AVIATION...(For the 12Z TAFS through 12Z Monday morning) Issued at 604 AM CDT Sun May 19 2019 Models continue to over do the low stratus. So have scattered out the low clouds a little quicker than prev forecasts. There is some lower clouds moving southeast across central NEB that could keep some MVFR CIGS across northern KS into the afternoon. For the terminals, think these clouds may be more scattered at or above 3 KFT. Eventually dry air advection and subsidence should take over with VFR conditions prevailing. && .TOP WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from Monday afternoon through Tuesday evening for KSZ008>012-020>024-026-034>040-054>056-058-059. && $$ SHORT TERM...Wolters LONG TERM...Baerg AVIATION...Wolters