Area Forecast Discussion
Issued by NWS Topeka, KS

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152 FXUS63 KTOP 182341 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 641 PM CDT Sun Apr 18 2021 ...Update to aviation forecast discussion... .DISCUSSION... Issued at 314 PM CDT Sun Apr 18 2021 As of 20Z Sunday afternoon a midlevel shortwave trough was advancing eastward across central MO. Steep low-level lapse rates combined with modest ascent from the trough was yielding sprinkles and isolated rain showers. As the trough progresses east, all precip should move into MO. Afternoon temperatures have warmed into the low 60s. Drastic changes in the forecast arrive Monday into Tuesday. A strengthening midlevel trough was diving southward from British Columbia and Alberta with a sharpening surface trough extending across SD and MN. Forecast guidance remains in good agreement with the evolution of each feature into Monday and Tuesday. The surface trough is progged to move across the northern counties early Monday morning and the southern areas by early afternoon. Temperatures will quickly tumble into the 30s and 40s by afternoon. As the main midlevel trough ejects into the Central Plains Monday night, an expansive precip shield is expected to develop -- overspreading north-central KS between 00-03Z and the rest of the area after 03Z. Rain will quickly transition to snowfall, continuing through the mid- morning hours Tuesday. Model guidance continues to suggest the potential for a narrow zone of strong midlevel frontogenesis Tuesday morning from central KS into northeast KS. This combined with a deepening dendritic growth zone could yield a brief window (06-12Z) for snow-to-liquid ratios to increase to near 10-12:1 (5-8:1 otherwise) which would certainly increase snow totals. At this point, expect widespread snow totals of 1-3" with higher amounts possible within the aforementioned enhanced frontogenesis band. Travel impacts are probable especially for the morning commute Tuesday. As temperatures warm into the 40s by late morning/early afternoon, travel should greatly improve. For simplicity purposes, have replaced the Freeze Watch with a Winter Weather Advisory from 03-15Z Tuesday. There is the potential that snow cover could insulate sensitive vegetation and limit damage even with temperatures in the upper 20s/low 30s. A surface high is progged to move into the area Tuesday night/Wednesday morning, setting the stage for clear skies, light winds, and cold temperatures. Overnight lows are forecast to reach the mid to upper 20s with temperatures remaining below 32 for 5-7 hours. As a result, will continue with the Freeze Watch from Tuesday night/Wednesday morning. Temperatures will slowly moderate for the remainder of the week as zonal midlevel flow overspreads the Plains. Unfortunately, another sub-freezing night is expected, with lows reaching the upper 20s/low 30s Thursday morning. Precipitation chances will make a return by weeks-end as a western trough ejects into the Plains. Highs may return to the 60s and 70s by next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 638 PM CDT Sun Apr 18 2021 Expect VFR conditions through the morning hours of Monday. A strong cold front will move southeast across the terminals during the afternoon hours. Behind the front winds will switch to the north at 15 KTS with gusts of around 25 KTS. Also, a stratus OVC with ceilings of 2500-3000 feet will move in behind the surface front during the late afternoon hours of Monday. && .CLIMATE... Issued at 326 AM CDT Sun Apr 18 2021 Record Cool Maximum for April 20th Topeka 34 set in 1918 Concordia 41 set in 1966 Record Low for April 21st Topeka 24 set in 1966 Concordia 24 set in 1966 Record Low for April 22nd Topeka 25 set in 1986 Concordia 30 set in 1992 && .TOP WATCHES/WARNINGS/ADVISORIES... Freeze Watch from Tuesday evening through Wednesday morning for KSZ008>012-020>024-026-034>040-054>056-058-059. Winter Weather Advisory from 10 PM Monday to 10 AM CDT Tuesday for KSZ008>012-020>024-026-034>040-054>056-058-059. && $$ DISCUSSION...Baerg AVIATION...Gargan CLIMATE...Wolters is the U.S. government's official web portal to all federal, state and local government web resources and services.