525 FXUS63 KTOP 302259 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 559 PM CDT Mon Sep 30 2019 ...AVIATION UPDATE... .DISCUSSION... Issued at 325 PM CDT Mon Sep 30 2019 Main concern for this forecast issuance remains the potential for heavy rain beginning by tomorrow morning and extending through Wednesday night. LPW imagery shows a strong plume of deep moisture tied to T.S. Narda extending directly into the forecast area, providing PWAT anomalies greater than 1 inch throughout much of central and northeastern KS. However, as high pressure expands and retrogrades slightly across the southeastern CONUS, this moisture fetch will drift northward tonight and position across far north central KS into eastern Nebraska. The deep trough over the Rockies will elongate before truly making any eastward push on Wednesday, providing the long-duration ingredient to the heavy rainfall setup along a very slow moving cold front currently stretching across Nebraska from North Platte to Sioux Falls. The bulk of the precipitation will develop along and remain tied to the surface and elevated cold front, keeping much of the heavy rainfall confined to far northwestern portions of the forecast area on Tuesday. The shortwave trough will finally begin to eject eastward and give the cold front a southeastward shove by early Wednesday, spreading precipitation chances through the remainder of the forecast area. High PWATs and the potential for multiple rounds of showers and storms remain indicative of locally heavy rain and areas of flooding, but the worst coincidence of extreme rainfall parameters currently appears to to be setting up just north of the area. Will keep the flash flood watch as-is for now, due to uncertainty with the speed of the front and coverage of storms once it separates from the parent trough, but the overall favorable atmospheric ingredients for heavy rain. Regarding severe weather potential; instability and lapse rates will certainty be questionable throughout the duration of the event, and while deep layer shear will be high, organized severe weather does not look likely without robust, long-lived updrafts. If anything, a few storms may produce briefly strong winds, but the primary hazard will be flash flooding. Additional showers and storms continue to look possible for the weekend, and should be followed by significantly cooler temperatures for early next week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday) Issued at 559 PM CDT Mon Sep 30 2019 Models show strong southerly flow remaining over the terminals into Tuseday afternoon with the frontal boundary remaining to the northwest. As a result, CIGS are expected to remain above 3 KFT and the potential for LLWS increases as the low level jet strengthens. The probability for TSRA moving into MHK looks to increase towards 00Z Wednesday. && .TOP WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from Tuesday morning through Wednesday morning for KSZ008-009-020-021-034. Flash Flood Watch from Tuesday evening through Wednesday morning for KSZ010>012-022>024-026-035>039. && $$ DISCUSSION...Laflin AVIATION...Wolters