045 FXUS63 KIND 261044 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 544 AM EST Sat Dec 26 2020 .UPDATE... The AVIATION section has been updated below. && .SYNOPSIS... Issued at 310 AM EST Sat Dec 26 2020 Dry weather is expected to continue through much of the weekend as southwesterly winds bring back warmer than normal temperatures to the area. A quick moving system will bring light rain to the area Sunday night before quickly moving out by Monday. A stronger system arrives Wednesday with widespread rain followed by a brief shot for some light accumulating snow Wednesday night into Thursday. && .NEAR TERM /Today/... Issued at 310 AM EST Sat Dec 26 2020 Upper level northwesterly flow will be coming to an end today as weak surface high pressure builds and southwesterly surface winds advect in more seasonable air to the area. Dry weather is expected through the day with cloud cover gradually decreasing through the day as dry air gradually works its way in. With the southerly flow returning, temperatures should warm to around 20 degrees higher than yesterday with highs ranging from the the mid 30s across the north to the low 40s in the south. && .SHORT TERM /Tonight through Monday night/... Issued at 310 AM EST Sat Dec 26 2020 Dry weather will continue into the overnight hours as the weak surface high pressure that was in place begins to break down. By late Saturday night into Sunday, an upper level trough and associated surface low pressure will begin to strengthen in the lee of the Rockies before moving into the Upper Midwest. There looks to be a brief period of time Sunday night where some light rain looks likely across the area. Even with the southerly flow in place Saturday into Sunday, overall the moisture profile doesn't look very conducive for any significant rainfall, but a quick shot of around a tenth of an inch seems reasonable considering how quickly the system enters and exits the region. Highest confidence in rain is across the northern counties which is where the strongest upper level forcing looks to be. Current expectations are that this shot of precipitation is going to be all rain, but there could be a few lingering flurries/snow showers as the system exits and much colder air works its way in. Cold air advection in the aftermath of the system should keep skies mostly cloudy to cloudy for much of the day Monday, so will decrease high temps by a degree or two across the board. Skies should then clear by Monday night which will allow for more efficient radiational cooling and colder than normal temperatures. Highs will climb into the mid to upper 40s on Sunday, followed by the low to mid 30s on Monday. Lows will fall into mid to upper 20s tonight and Sunday night and then down into the mid to upper teens on Monday night. && .LONG TERM /Tuesday through Friday/... Issued at 252 AM EST Sat Dec 26 2020 The long term will start off quite as high pressure drifts east across the lower Great Lakes and Ohio Valley. Very dry column and subsidence support plenty of sunshine, although could see some late day increase in cirrus ahead of the next big system. Despite sunshine, neutral advection suggests temperatures will not quite make it to normal with afternoon highs in the 30s. As the high moves to the Appalachians Tuesday night, a southern Plains system will get going. Warm and moist advection ahead of this one will result in temperatures not dropping much Tuesday night. Blend brought in low PoPs overnight over west central sections. Confidence is low the showers will make it in that quick, but left them in for now and in the form of snow per BUFKIT soundings. Things should really get going late Wednesday and Wednesday night as 70 plus knot low level jet noses in from the south and a 150 know upper jet streak moves into Illinois. This feature will place central Indiana in the right rear quadrant, which is favorable for enhanced vertical motion and precipitation. Soundings and strong warm advection suggest rain and snow mix will become all rain Wednesday afternoon as the precip becomes widespread. With such strong warm advection, the well above normal temperatures look good for Friday with highs in the 50s possible south of Indianapolis. Models are slowing down with the cold front. The 00z Canadian and Euro are not bringing it across until after 12z Thursday now and even the faster GFS is still slowing down. So, after consulting with adjacent offices, raised overnight lows several degrees Wednesday night. This should delay lingering rain showers from mixing with or changing to snow until mainly after 12z Thursday. Even then, things should be winding down, so do not expect more than a minor snow accumulation Thursday and Thursday night. Model soundings showing very dry column and subsidence by Friday. However, much cold air in the wake of the system will result in below normal temperatures in the 30s to ring in the New Year. && .AVIATION (Discussion for the 261200Z TAF Issuance)... Issued at 544 AM EST Sat Dec 26 2020 IMPACTS: VFR conditions through the TAF period. Winds 200-230 degrees at 10 knots or less through 04z or so, Then, winds will back slightly to 160 degrees to 190 degrees less than 10 knots. DISCUSSION: Should only see some cirrus from time to time under the influence of surface high pressure. CONFIDENCE: High confidence in VFR through the TAF period. High confidence in wind trends. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...White NEAR TERM...White SHORT TERM...White LONG TERM....MK AVIATION...MK