149 FXUS63 KTOP 172039 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 339 PM CDT Sat Aug 17 2019 .SHORT TERM...(This evening through Sunday night) Issued at 338 PM CDT Sat Aug 17 2019 This afternoon the region was wedged between surface low pressure along the east side of the Rockies and high pressure over the eastern U.S. As a result, prevailing southerly flow continued to support warm, moist-air advection with afternoon highs reaching into the upper 80s to around 90 degrees for much of the CWA, with the exception of far east central KS where lingering cloud cover from nearby showers has helped to hold temperatures in the low/mid 80s. With dewpoints reaching into at least the low 70s, decent destabilization has been occurring this afternoon. While the cap will continue to weaken into late this afternoon, latest short-range model soundings suggest we may not be able to completely eliminate the cap. As a result, the scattered showers and isolated storms over southeastern KS are looking to stay predominantly in that region and may potentially skim across east central KS into early evening. Bigger concern for thunderstorms will be late this evening through the overnight hours as another complex of storms looks to develop as a result of a mid-level embedded shortwave over southwest NE/northwest KS. As this complex of storms progresses eastward toward the CWA, the 35-45+kt LLJ should help to amplify storms late this evening and overnight. Model soundings show steep mid-level lapse rates with sufficient effective shear and instability to support strong to severe thunderstorms with the primary hazards being damaging winds, some large hail, and heavy rainfall. In fact, several runs of the HRRR have consistently been developing a bowing segment across the CWA, so damaging wind gusts of 60-70 mph certainly will be possible. While these storms may be more progressive compared to storms from the previous couple of nights, latest short-range model runs suggest that back-building storms will be possible as the mid-level shortwave continues to progress across the area with a strong LLJ still in place. As a result, expect some areas of heavy rainfall with widespread 1-2 inches and locally higher amounts of 2-3 inches possible. Considering how saturated soils are from thunderstorms over the last two nights, resulting in lowered flash flood guidance values, went ahead and issued a Flash Flood Watch for much of northeastern KS into portions of east central KS. Models show surface low pressure advancing eastward into the area, with an associated cold front extending into north central KS by Sunday morning. Some scattered showers and storms may continue to develop across portions of northeast and east central KS through the day as the front slowly progresses southeastward across the area. Depending upon how quickly it can exit the area, cannot rule out that enough destabilization can occur through the day to support a few strong to marginally severe storms late afternoon into the early evening, but otherwise expect conditions to gradually dry out Sunday night as the front shifts east of the area. Even with this passing system, dewpoints in the low/mid 70s will still remain with highs reaching into the mid 80s in north central KS to the low 90s over east central KS. As a result, afternoon heat index values in the 100- 105 degree range will be possible in east central KS. .LONG TERM...(Monday through Saturday) Issued at 338 PM CDT Sat Aug 17 2019 The overall weather pattern by Monday should feature a building upper ridge into the central Plains which will set the stage for heat indices easily reach or exceeding 100 degrees Monday through Tuesday. By Tuesday night a deep upper trough will slide into the Great Lakes pushing a cold front south into the state which will likely get hung up across the state. NW flow aloft along with the front and LLJ appear to set the stage for another overnight complex of storms Tues night into Weds and perhaps again Weds night into Thurs as nightly low level forcing of WAA and convergence from LLJ will continue to plague us. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 1239 PM CDT Sat Aug 17 2019 For the 18z TAFs, best chances for scattered storms to impact the TAF sites look to be late this evening and overnight as another complex of storms will track eastward over area. However, there is still some uncertainty in the exact tracking of these storms. Any storms that impact the TAF sites may produce some strong to severe wind gusts, so will continue to monitor this potential. && .TOP WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from 10 PM CDT this evening through Sunday morning for KSZ009>012-021>024-026-036-038>040-055-056-059. && $$ SHORT TERM...Hennecke LONG TERM...Omitt AVIATION...Hennecke