Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000 FXUS63 KABR 171640 AFDABR Area Forecast Discussion National Weather Service Aberdeen SD 1040 AM CST Fri Jan 17 2020 .UPDATE... Issued at 1040 AM CST Fri Jan 17 2020 Slowed down the exit of snow by 3-6 hours, and increased precipitation/snow amounts for late this evening on as another push of snow moves into the area. CAM solutions have been hinting as the slower exit this morning, and it looks reasonable. The main result is slightly higher snow amounts of around 1 to near 2in for areas east of the Missouri River, as well as Lyman County. Headlines still look good for now. Will need to monitor precipitation amounts for our southwestern counties, to see if anything but High Wind Warnings will be needed. If significant snow falls, they will need to be included in a Winter Weather Advisory this evening, or Blizzard Warning overnight. && .SHORT TERM...(Today through Saturday Afternoon) Issued at 356 AM CST Fri Jan 17 2020 A complex storm system will impact the region over the next 36 hours. Strong south to southeasterly winds this morning is producing areas of blowing and drifting snow with visibility at KABR down to one mile at times. Visibility at other observation points are between 3 to 6SM. Various webcams also show blowing snow, but not whiteout conditions, even with sustained winds above 30 mph. Winds are expected to slowly weaken today in the eastern CWA as accumulating snow moves in. With the strong warm air advection, along with LLM, there could be a brief period of freezing drizzle and sleet before transitioning over to all snow. Hi-res models show a very small window of mixed pcpn. Ensemble viewer from WPC also indicates very little to no ice today. Winter weather headlines for the today period is very problematic in the eastern CWA. The southeasterly winds, along with falling snow could cause near whiteout conditions. Will maintain the current winter storm warning for now and allow the day shift to upgrade as needed. Snowfall amounts, if one is able to measure with the winds, should range from 1 to 3 inches in the James Valley, to four inches or more east of I-29. Of note, models have shifted slightly westward with light, accumulating snowfall. Headlines tonight through Saturday are slightly less problematic. The combination of strong cold air advection and 6-hour pressure rises of 10 to 15 mb will bring powerful winds to the CWA tonight through Saturday. Will issue a high wind warning for tonight for counties west of the Missouri River, and a few counties to the east where little snowfall is expected today. If more snow falls in the Pierre area tonight, then a blizzard warning will be needed. Elsewhere, fresh snowfall of an inch to 4 inches, along with wind gusts of 50 mph will cause blizzard conditions. The SREF probability of blizzard conditions met still highlights a portion of eastern South Dakota late tonight into the morning hours on Saturday. .LONG TERM...(Saturday Evening through Thursday) Issued at 356 AM CST Fri Jan 17 2020 Overall, the long term looks relatively tranquil, until perhaps toward the end of the period. A somewhat progressive mid-level flow pattern continues across the CONUS, but does slow up to some degree. A ridge aloft builds into the region for Sunday through about Tuesday, with generally dry conditions expected during that period. The ridge pushes off to the east by Thursday and Friday as a trof aloft advects into the middle of the CONUS. There are some differences in the speed/orientation/latitude of this system, and thus forecaster confidence in the details is somewhat low at this time. In house model blend will do fine for now. That said the deterministic GFS/CMC are fairly aggressive with a storm across the Central and perhaps even Northern Plains Thursday and Friday. The ECMWF is somewhat muted in comparison. Need more time to nail down the details with this potential storm. Temperatures will start the period cold, but then should trend toward or even above normal as the ridge builds over the region for the middle of next week. && .AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon) Issued at 1040 AM CST Fri Jan 17 2020 Winds continue to gusts 30 to 40kts, with winds at MBG/PIR diminishing after 20Z as the surface low nears from western SD. This brief period of lighter winds moving west to east across the TAF sites will quickly increase again behind the front and become out of the northwest with gusts nearing 40-50kts at MBG/PIR by 03Z, ABR by 06Z, and ATY by around 08Z Saturday. Light snow and freezing drizzle have been reported across the area, at the onset of the precipitation. Expect snow to become the dominant weather type during the afternoon hours. MVFR to IFR ceilings/vis will dominate, with lower conditions in moderate snow and strong winds/blowing snow. As a system moves closer to the region, IFR cigs are expected to advect across the area this morning. Vsbys will also lower to MVFR/IFR over the eastern part of South Dakota as the snow moves into the region this morning. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...Winter Weather Advisory until 9 PM CST this evening for SDZ004>006-009-010-017-018-036-037-051. Blizzard Warning from 9 PM this evening to 3 PM CST Saturday for SDZ004-005-009-010-017-036-037-051. Winter Storm Warning until midnight CST tonight for SDZ007-008- 011-019>023. Blizzard Warning from midnight tonight to 6 PM CST Saturday for SDZ007-008-011-019>023. High Wind Warning from 6 PM CST /5 PM MST/ this evening to 6 AM CST /5 AM MST/ Saturday for SDZ003-015-016-033>035-045-048. Blizzard Warning from 9 PM this evening to 6 PM CST Saturday for SDZ006-018. Winter Weather Advisory until 6 PM CST this evening for SDZ048. MN...Winter Storm Warning until 3 AM CST Saturday for MNZ039-046. Blizzard Warning from 3 AM to 6 PM CST Saturday for MNZ039-046. && $$ UPDATE...KF SHORT TERM...SD LONG TERM...TDK AVIATION...KF is the U.S. government's official web portal to all federal, state and local government web resources and services.