340 FXUS63 KTOP 260541 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 1141 PM CST Fri Jan 25 2019 ...Update to aviation forecast discussion... .SHORT TERM...(This evening through Saturday) Issued at 236 PM CST Fri Jan 25 2019 Active northwest flow aloft continues to impact much of the central plains in the form of frigid temperatures and several weak systems traversing the area through next week. The first embedded 500 mb wave was noted on water vapor imagery passing through central KS this afternoon. There was enough isentropic lift around 5 kft to result in scattered snow showers through early afternoon towards far east central Kansas. Accumulations are not expected and should come to an end by late afternoon. Westerly winds are expected to weaken this evening as the sfc trough exits. A second elongated wave may impact far northeast Kansas by Saturday morning in the form of light snow, otherwise the CWA remains dry through the weekend. The latest runs of the NAM and GFS MOS guidance are stronger with the westerly downslope flow across the state Saturday afternoon, resulting in highs being raised Saturday a few degrees to the upper 30s and lower 40s. With the exception of far northern Kansas, skies start out mostly cloudy before drier air lifts northward during the afternoon, with mostly sunny skies returning to northeast Kansas. .LONG TERM...(Saturday night through Friday) Issued at 236 PM CST Fri Jan 25 2019 Sunday morning is trending towards clearer skies and warmer lows in the 20s, helping to lift highs back into the lower 40s on Sunday afternoon. A much stronger shortwave trough is expected to organize and quickly migrate southeastward Sunday night and Monday, increasing chances in our area for rain and snow. The bulk of the lift and available moisture is consistent between guidance of remaining north and east of the area, with less than a tenth of inch of qpf at best through Monday afternoon. Precip type is once again tricky as strong southerly, warm advection ahead of the wave brings temps into the upper 30s by Monday morning before gradually falling through the day Monday. Initial precip type looks to be rain through sunrise before changing over to light snow or wintry mix mid morning onward for areas generally along and southeast of the Kansas turnpike. Little to no accumulations are anticipated. What may be more impactful are the strong winds to follow Monday afternoon behind the deepening low as sfc speeds could come close to advisory criteria ranging from 25 to 30 mph sustained. Winds will gradually wane by the evening hours as high pressure begins to build into the region. The biggest hazard in the extended period is the extreme cold temperatures beginning Tuesday morning with wind chills between zero and 10 degrees below zero. These numbers are likely to fall even lower Wednesday and Thursday mornings as a poignant sfc high invades the central plains. The latest GFS is as much as 25 degrees colder compared to the ECMWF solution so there are uncertainties to the depth of the cold air and location of the trough axis. Current forecast is the compromise of both solutions with temps in the signal digits with wind chill readings between 10 and 17 degrees below zero on both mornings. High temperatures during this time may only reach the teens to low 20s. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1139 PM CST Fri Jan 25 2019 Breaks in the high and mid clouds will allow some patchy freezing ground fog to develop at the terminals. Visibilities at KTOP may drop down to 0.5 to 1 sm at times. Visibilities at KFOE and KMHK may drop to 3 to 4 sm. Later this morning we may see more mid level clouds which may limit the ground fog potential. Otherwise, expect VFR conditions through the remainder of the TAF period. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Prieto LONG TERM...Prieto AVIATION...Gargan