986 FXUS63 KEAX 240820 AFDEAX AREA FORECAST DISCUSSION National Weather Service Kansas City/Pleasant Hill MO 220 AM CST Thu Dec 24 2020 .Discussion... Issued at 220 AM CST THU DEC 24 2020 Christmas Eve and Christmas this year will not be white, but it will be cold. The arctic airmass behind the strong cold front yesterday has already started to build into the region with the arctic front currently over northern Missouri. Winds will continue to remain relatively high for as the tighter pressure gradient will remain in place until tomorrow night, when high pressure slides into eastern KS. This will cause wind gusts of 20-30kts to be fairly consistent over the area today and into tomorrow evening. Those winds combined with the cooler temperatures will lead to the lowest wind chills of the season. Single digit wind chills will be in place all night, with negative values north of HWY 36. Temperatures will rise slightly today into the mid 20s, so wind chills will climb into the teens for the afternoon before dropping again overnight. The arctic airmass will be firmly in place over our area Christmas morning, leading to lows in the single digits to lower teens. Winds will be lighter though, which will decrease the wind chill threat compared to this morning. The pattern will shift quickly on Christmas afternoon as ridging and southerly flow return to the region. This will create a sharp temperature gradient of 40s along the KS/Mo border with 20s over NE Missouri. This warming trend will continue into Saturday as a warm front develops over our area with highs in the 50s. This low pressure system will slowly shift east with the cold front coming through Sunday afternoon. Currently this system looks relatively dry with no real PoPs expected. Once winds shift to the NW the cooler airmass will build into the area, dropping lows into the teens to 20s Monday morning. Wind chills will also be an issue with 10kts of wind or so in the morning, bringing values down to the single digits to teens. This cooler airmass will stay in place through Tuesday. How far south this cooler airmass goes will become a major factor in how a possible winter storm Tuesday will play out. Current ensembles and our NBM model have the freezing line right down by Springfield Tuesday morning and plenty of cold air in place as the warm front of the system would push into the area. The current NBM has the 50th percentile for snowfall around 3-4" north of the Missouri River and 1-2" to the south. We'd have to tap into the 75-90th percentiles to get to winter storm criteria for snow. The deterministic models are depicting a synoptic setup with warmer air aloft getting into our area, increasing the possibility of freezing rain or sleet being an issue. The 50th percentile for total ice is around 0.01-0.05", but the 90th percentiles jump up to more like 0.1 over the area. It is still way to far out to clamp on to any real numbers, but the signal for a nice winter storm system moving through from I-44 to I-90 is looking more likely and worth watching trends as we get closer. && .Aviation...(For the 06Z TAFS through 06Z Thursday Night) Issued at 1111 PM CST WED DEC 23 2020 A small wave quickly moved through the region bringing brief periods of snow flurries along with MVFR ceilings. CIGs have improved over the past couple of hours as clouds swiftly move toward the southeast. Gusty winds continue for the next few hours before a brief break as slightly calmer air from central KS/NE moves in overnight. STJ, MKC, and MCI look to have a few hours of refuge from gusty winds just before sunrise; however, IXD will only see a brief break from gusts just before sunrise. Diurnal heating Thursday morning mixes down the LLJ and gusty winds return. Widespread gusty NW winds (sustained: 12-15kts; gusts: 25-30kt) prevail until after sunset when winds calm down with only some brief gusts overnight Thursday into Friday. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ Discussion...Barham Aviation...Pesel