403 FXUS63 KTOP 222341 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 541 PM CST Fri Nov 22 2019 ...Update to aviation forecast discussion... .SHORT TERM...(This evening through Saturday) Issued at 312 PM CST Fri Nov 22 2019 A complicated upper air pattern remains in place at this hour across the CONUS. A trough with associated frontal system at the surface continues to move through the New England region. The central Plains is dealing with an upper low that had deepened earlier in the day as it continues to translate east out of the central Rockies -- more about this to follow. The western CONUS has a few upper level minor circulations along the coastal areas. Sub-tropical jet stream is is making its presence on WV imagery along the Gulf coastal region with the modified southern branch of the polar jet and associated cyclonic flow over the southern Plains region. Near the surface over the local area, a band of heavy to moderate snow as been continuing to erode as it lifts north over the area. The band of now light to moderate snow remains over the hwy 36 corridor. Have canceled the previously issued winter weather advisory for portions of north central Kansas. This area generally saw 1-2 inches of snowfall with a few higher amounts locally as some convective elements were maintained for a period of time within the band early on with some pockets of negative EPV and more intense ageostrophic circulations within the overall 700-600mb mid level frontogenetical band. Much drier air has been maintained to the north of the area, so the rest of the snow band should continue to erode much more quickly into the latter portions of the afternoon as it moves into Nebraska. Only expecting some areas of light snow over northern zones to flurries points further south to the I-70 corridor for the next few hours. Expecting low stratus to be maintained for much of the evening and overnight hours with enough wrap around moisture continuing to impact the area as the upper low slowly lifts to the east and northeast of the area by early Saturday morning. Saturday and the rest of the short-term forecast period look to remain dry. Thinking cloud cover clears the area too late tonight for efficient enough radiational cooling to take place. Therefore, have not gone with an fog mention at this time. Perhaps if clearing can take place and winds calm enough with any localized decoupling then fog may set up over primarily western areas that have seen snowfall. Have maintained highs only in the 40s for Saturday as weak ridging aloft works over the area and mostly a northwest flow component is in place. With snow still on the ground over northwestern areas of the forecast area, then could see some cooler air advected back over the area. This would likely counter any insolation with the lower overall solar angle anyway. Saturday night also remain very chilly with light west to northwest breeze behind a weak surface trough moving through late Saturday -- looking for lows to fall into the upper 20s. .LONG TERM...(Saturday night through Friday) Issued at 312 PM CST Fri Nov 22 2019 Conditions will remain quiet heading into Sunday as flow turns westerly, which will result in WAA bringing temperatures to the mid to upper 50s under mainly sunny skies. Above average temps will continue through the overnight hours with lows in the 30s area-wide by Monday morning. A shortwave trough will develop in the western US on Monday with surface low pressure ahead of this feature in the southern Rockies. There are hints in the models for winds to shift northwest during the afternoon with a weak frontal boundary, but this appears to have little or no effect as temperatures still reach the mid to upper 50s and dry weather is expected. The main front associated with this system should arrive Tuesday as the trough passes through the Central Plains. Plenty of details with this system are still in question as the ECMWF deepens the trough more than the GFS, and the GFS has shifted the track of the low further northwest again compared to yesterday's runs, while the ECMWF tracks it slightly further west than the GFS. This has resulted in the better precip chances shifting back toward northern KS into NE, where lift is maximized in the base of the trough. Rain looks most likely for a majority of the CWA during the day Tuesday with temps ranging in the 40s and 50s, but some rain/snow could mix in early in the morning for places closer to the NE border, especially given the proximity of the 540 thickness line for 1000-500mb. That being said, however, the timing of the cold front as well as the system track will both likely have a considerable impact on temperatures and ultimately p- type in all locations. The ECMWF solution drags the system behind a bit longer into the evening, so any lingering rain could transition back to snow as well. Given the uncertainty in play for the Tuesday system, confidence is even lower in the forecast beyond that as that pattern will have a lasting impact on what comes after. For now, we do look to dry out for Wednesday as weak ridging comes in place, but only briefly. Weaker waves ahead of a large trough off the CA coast combined with return flow could result in small precip chances on Thursday and Friday. But again, many variables such as temperature and p-type will be dependent on the synoptic pattern and overall environment left behind after Tuesday. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 541 PM CST Fri Nov 22 2019 VFR and MVFR cigs will be prevalent through 12Z, but low mvfr to ifr cigs are possible in the MHK terminal through 14Z. Forecast sounding show cigs improving to vfr in the 15Z to 18Z time period at all locations. Winds light north becoming variable then light west under 10 kts after 14Z. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Drake LONG TERM...Picha AVIATION...53