381 FXUS63 KABR 100247 AAB AFDABR Area Forecast Discussion...UPDATED National Weather Service Aberdeen SD 947 PM CDT Tue Oct 9 2018 .UPDATE... Issued at 947 PM CDT Tue Oct 9 2018 The 00Z ABR RAOB indicates snow lives appx 2500ft agl, and is melting into rain (or mostly rain) as it falls through that roughly 2000-2500ft agl "warm layer" to the ground. Temps holding in the 39 to 42 degree range across the eastern half of the cwa (Brown/Spink Counties eastward), while temps have fallen into more of a 34 to 39 degree range west of those counties. A couple area webcams across central South Dakota even hinting that p-type has begun mixing with/changing over to snow already this evening. So, the forecast is on track at the moment. Basing a few minor adjustments to qpf/snow accums off the latest available RAP13/ECAM/NBM/NAM qpf progs. RAP13 cross sections depict the ever familiar maxed out forcing/lift couplet (in the deformation zone) existing tonight (mainly between appx 04Z and 10Z) and settling down basically along and up to 30 miles either side of a line from Kennebec, SD up to Ashley, ND. This area will need to be monitored closely overnight for the need to upgrade from an advisory (2-5 inches of snow) to a winter storm warning (4 to 8 inches of snow). Updates are out. UPDATE Issued at 627 PM CDT Tue Oct 9 2018 See below for an aviation forecast discussion for the 00Z TAFs. && .SHORT TERM...(This Evening through Wednesday Afternoon) Issued at 345 PM CDT Tue Oct 9 2018 A strong upper level low pressure trough and its associated surface low pressure area to our south late this afternoon will be making their way northeast through the night and Wednesday. Intense deep layer lift with this system will result in rain overspreading the entire cwa through the evening. The issue will be with the temperature profiles along with the location of the dry slot surging north into the eastern part of the region tonight. As a result, the models vary on the change over to snowfall tonight into Wednesday. The GFS was the warmest with the NAM the coolest with the thermal profile through Wednesday. The EC and Canadian were in between these two models. Believe the cooler models and the change over to snow should occur by midnight west of the James Valley and to the east of the James Valley after midnight into Wednesday morning. The dry slot will lift into our far east and will affect snowfall amounts. Otherwise, there are good indications of a good deformation zone setting up northwest of the upper low along with some mid level frontogenesis combined with some negative epv. Therefore, there could be some banded snowfall with heavier amounts. The trowal feature will be also be wrapping around the upper low pressure area. Snowfall should be heavy enough during the nighttime to be able to accumulate decently on the grassy surfaces. Roads will also see slushy accumulations. At this time, 2 to 5 inches look good with lesser amounts in the far east and southeast in the Wheaton/Watertown areas. The winds will also be strong in the 20 to 35 mph range with blowing snow not expected to be an issue. Lowered highs on Wednesday with the expected caa and snowfall occurring. Expanded Winter Weather Advisory east from the James Valley to the Sisseton Hills earlier today. .LONG TERM...(Wednesday Evening through Tuesday) Issued at 345 PM CDT Tue Oct 9 2018 Gusty winds and snow will continue into Wednesday evening across the northeastern half of the forecast area. While the main 500mb low exits our northeastern counties Wednesday night, the large trough remains in place across the Northern Plains through Friday morning. The sun looks to return Thursday, at least glimpses of it as high pressure moves in at the surface. Looking back at the MODIS imagery, this may be the first time of significant sunshine since September 28th. It will still be cool through, with temperatures topping out in the 30s and 40s. Even with the warmup later Friday and Saturday (40s and 50s), temperatures will remain well below normal. While a brief 500mb ridge slides overhead Friday, it will quickly be replaced by zonal flow on Saturday as the next 500mb low (and surface low) shifts across south central Canada. Gusty winds look to return for Friday night (not quick mixing to the 35kt wind around 900mb) and Saturday where 15-20kt winds should be common over the western half of the forecast area. Light snow may clip the ND/SD border Sunday morning. Reinforcing cold air will move in for Sunday, with highs in the mid 30s to near 40 degrees. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening) Issued at 627 PM CDT Tue Oct 9 2018 The flying weather conditions are forecast to remain below VFR over the next 24 hours due to a combination of stratus clouds and reduced visibility in drizzle, rain, snow and fog. Rain is moving north and west across the forecast area (already occurring at KATY). Eventually, the precipitation will reach KABR, KPIR and KMBG between 00Z and 06Z tonight, and most likely in the form of rain. However, overnight the p-type will transition to snow at KABR, KPIR and KMBG. Eventually, KATY will see the p-type change too, but probably not until late morning/early afternoon on Wednesday. Mainly between 09Z and 15Z Wednesday, the rain fall at KATY may slacken to periods of drizzle. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...Winter Weather Advisory until 1 PM CDT /noon MDT/ Wednesday for SDZ003>005-009-010-015>017-033>037-045-048-051. Winter Weather Advisory until 7 PM CDT Wednesday for SDZ006>008- 011-018-021. MN...None. && $$ UPDATE...Dorn SHORT TERM...Mohr LONG TERM...KF AVIATION...Dorn