textproduct: Aberdeen

KEY MESSAGES

- Sisseton hills downslope winds should take a break tonight before ramping back up again on Wednesday as part of a larger Prairie Coteau Wind Advisory.

- Temperatures will again top out 15 to 25 degrees above normal Wednesday. Rain Wednesday afternoon and evening potentially leaving wet roads when temperatures plummet below freezing late Wednesday night.

- Another arctic blast has the potential to generate 55 to 65 mph wind gusts late Wednesday night into Thursday. A thin ribbon of banded snow is expected to accompany this arctic cold frontal passage, before more widespread light snow potential descends upon northeast South Dakota and west central Minnesota Thursday morning. Will continue to monitor for snow squall potential with any of this banded snow early Thursday morning.

- Over northeast South Dakota and west central Minnesota, strong northwest winds in excess of 30 mph with gusts gusts in excess of 55 mph and light falling snow could cause periodic significant reductions in visibility Thursday morning.

UPDATE

Issued at 521 PM CST Tue Dec 16 2025

Forecast remains on track this evening. No major changes are planned.

SHORT TERM /THIS EVENING THROUGH WEDNESDAY NIGHT/

Issued at 258 PM CST Tue Dec 16 2025

At 2 PM CST, skies are mostly cloudy and a cold frontal passage is in progress. Over the past couple of hours, there has been a sprinkling of observation sites gusting between 45 and 50 mph (lower bound wind advisory gusts) with the commencing of the cold front's passage. There have been gusts up to nearly 55 mph within the Lee-of-the-Prairie-Coteau downslope wind event's corridor that is ongoing this afternoon, too. Suspect there will probably continue to be a few stations buffeting the lower bound of advisory criteria between now and 6 PM CST. Overall, winds are from the west or west-northwest around 15 to 30 mph with gusts generally between 35 and 45 mph. Temperatures have warmed into the 40s and 50s throughout the CWA today as well.

Surface high pressure will be quickly transitioning across the region tonight into Wednesday morning. By mid-morning on Wednesday, low level WAA and a rather pronounced low level jet (in December) out ahead of the approaching super-clipper will run sustained winds up/or close to wind advisory criteria up on the Coteau Wednesday afternoon. A Wind Advisory has been issued for that, plus these south-southwest winds of 50 to 60 knots will create yet another downslope wind event for Wednesday afternoon (covered in the Wind Advisory). Low temperatures tonight into Wednesday will continue to run 10 to 20+ degrees above normal for this time in December.

Models/ensembles continue to paint some light (rain) precipitation across the CWA Wednesday afternoon through early Wednesday night mainly east of the U.S. Highway 83 corridor. Generally up to a tenth of an inch of precipitation expected with this rainfall. After a preliminary cold frontal passage with modest low level CAA Wednesday evening, a much more potent arctic cold frontal boundary attached to this clipper system will sweep southeast through the CWA between 06Z and 18Z Thursday. Strongest half kilometer winds showing up across the Missouri River valley region and points west, but the 20- 25+hpa/6-hourly pressure rises should help push high wind potential conditions over into northeast South Dakota after 12Z Thursday. A High Wind Watch has been issued for this concern. Along with the arctic cold frontal passage comes the concern that temperatures will quickly plummet below the freezing mark, leaving any wet roads/bridges/sidewalks potentially frozen (flash freeze) round about the time any potential snow squalling could happen across the CWA from northwest to southeast between 06Z and 12Z Thursday. Snow squall parameters still lighting up (over 8 now in the latest RAP13 data), so still messaging snow squall potential late Wednesday night/early Thursday morning.

Lastly, as the signal for TROWAL-forced snow in the wrap-around moisture of this clipper continues to slowly increase for the northeast third of forecast zones in the CWA Thursday morning, the less than a tenth of an inch of guidance-given qpf is translating into around 1-1.5in of accumulating snowfall on the western half of the Prairie Coteau Thursday morning. Blowing snow model (starting off with no blowable snow on the ground) is generating "advisory" level blowing snow over the Prairie Coteau counties of Marshall, Day, Clark, Roberts and over into Traverse county MN. So, for now, have collaborated a Winter Storm Watch "for possible blizzard conditions" for said counties for 12Z Thursday to 00Z Friday. Not overly confident in this unfolding, but if the TROWAL snow signature gets stronger (ie. greater snowfall potential), or temperatures are colder, or winds are stronger than currently forecast, this current watch headline could end up evolving into some sort of advisory or warning headline.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 258 PM CST Tue Dec 16 2025

Thursday evening into Friday, the upper-levels have northwest flow over SD. Under this, the low levels push some warm air into the state causing temperatures to warm slightly during the day Friday from the cold temperatures Thursday. Around normal temperatures look to occur over northeastern SD (in the mid 20s to mid 30s) while temperatures will be 10-20 degrees warmer over central SD (in the mid 30s to mid 50s). A surface high pressure moves to the east early Friday morning and a surface low pressure strengthens in Alberta causing a tight pressure gradient between them. This tight pressure gradient will cause winds to increase during the morning, though they will be weaker than what will occur Thursday. There is a 30-60% chance for winds to be 30 mph or greater by noon Friday and less than a 20% chance for gusts of 40 mph or more, with the highest chances over the Prairie Coteau.

During the day Friday into Saturday, a small shortwave over Canada moves from Alberta to the east over Manitoba. Under this shortwave, a surface low pressure follows the same path, with a frontal boundary that stretches down to the south moving over SD. This frontal boundary pushes cold air back into the state, cooling temperatures slightly to have around normal highs for December. Some models show precipitation moving into central and northeastern SD along this front while others keep it out of the area, reducing confidence. The NBM has lower chances for precipitation to occur, and keeps it mostly over the north of SD, though there are lower chances over the Prairie Coteau Friday night. The variability in the models also applies to the timing, type, and amount of precipitation that could happen. This will need to be watched to see if upcoming model runs start to come to more of an agreement on this precipitation.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 521 PM CST Tue Dec 16 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are expected to prevail through Wednesday afternoon. Gusty northwest winds this evening will shift to the south Wed morning and increase again with gusts of 30 to 40 knots. Southerly winds then shift to the west in the afternoon ahead of a stronger cold front expected Wednesday night.

ABR WATCHES/WARNINGS/ADVISORIES

SD...Winter Storm Watch from Thursday morning through Thursday afternoon for SDZ007-008-011-019.

High Wind Watch from Thursday morning through Thursday evening for SDZ020>023.

High Wind Watch from Wednesday evening through Thursday morning for SDZ003-004-009-015-016-033>035-045.

High Wind Watch from late Wednesday night through Thursday afternoon for SDZ005-010-017-036-037-048-051.

High Wind Watch from late Wednesday night through Thursday afternoon for SDZ006-018.

Wind Advisory from noon to 9 PM CST Wednesday for SDZ007-008-011- 019>023.

MN...Winter Storm Watch from Thursday morning through Thursday afternoon for MNZ039.

High Wind Watch from Thursday morning through Thursday evening for MNZ046.