textproduct: Aberdeen

KEY MESSAGES

- Winds gusts of 30 to 40 mph, with locally higher gusts, will be possible again late tonight over the eastern slopes of the Sisseton Hills.

- Temperatures will rise to near and above normal today through Wednesday, with highs mainly in the 40s Tuesday and Wednesday with 50s possible over south central SD.

- Another Arctic blast has the potential to generate 40 to 60+ mph wind gusts late Wednesday night into Thursday. Snow showers that accompany the front will greatly reduce visibility.

UPDATE

Issued at 510 AM CST Mon Dec 15 2025

Updated discussion for the 12Z TAFs below.

SHORT TERM /TODAY THROUGH TUESDAY AFTERNOON/

Issued at 228 AM CST Mon Dec 15 2025

High clouds continue to track southeast as the CWA remains on the downstream side of a ridge that is currently over the northern Rockies into Canada. Temperatures are much warmer than last night ranging in the teens to lower 20s, with temps in the upper 20s along the eastern slopes of the Coteau due to the warmer winds. Speaking of, the highest wind gusts recorded with this downslope event have been 54 mph at Altamont and 64 mph at Peever just before midnight per SDDOT.

A weak surface trough over the area will continue to track eastward into MN today as the region lies between this exiting wave and stronger trough, with the axis setting up over the western Dakotas and northwestward this evening, south of a low/clipper over Alberta. Models have a good handle that through the overnight hours, this clipper will deepen as it tracks eastward across Canada with the surface trough tracking eastward over the Dakotas. By 12Z, the clipper will further intensify (984mb!) as it is forecast to be over Manitoba at this time, with the axis of the surface trough extending through the eastern Dakotas and southward through the central Plains. Its fropa will track northwest to southeast over the CWA through the day on Tuesday and exiting the southeastern CWA by Tuesday afternoon/evening as northwest flow will be dominant. Some of the CAMs (HRRR/RAP/NamNest) do try to show a little bit of precip with the fropa as it tracks southeast over the CWA Tuesday morning, however, timing and placement do vary between these models with others not indicating much in the form of precip, so low confidence exists as of now. Latest NBM has pops 5% or less.

With winds out the south/southwest tonight, and you know this means, another round of gusty downsloping winds off the Coteau between ~06- 12Z. NAM sounding at Peever indicates 850/925mb winds between 20- 30kts at 06z, increasing to 35-45kts through 12Z. Both HREF/NBM indicates downsloping wind gusts of 30 to potentially 40 mph with prob of gusts>45 both at 0%. With ongoing steep pressure gradients and gustier winds aloft associated with this low, winds will increase widespread by late Tuesday morning through the afternoon with HREF indicating gusts of 35-45mph over the CWA with the possibility of 50mph gusts over the Leola Hills/Coteau as 850mb winds will range between 50-60kts at this time! However, deterministic NBM is about 5-10kts less than HREF with gusts of 30- 40mph. To get the gusts of HREF, it is more of NBM75th and 90th. However, NBM potential "MAX" wind gusts both NBM4.3/5 are pretty close (difference of 0 to 3kts at any one location) does indicate gusts of 45-55kts over north central, Leola Hills, and Coteau. Will let the day shift take a closer look with the next model run and determine if they need to be increased a bit, so stuck with the deterministic NBM in the grids for now.

Warmer air at 925mb is expected today giving us a nice warmup from the arctic blast we dealt with. Highs for day will range in the 30s to the mid 40s with overnight lows in the teens and 20s. Highs for Tuesday is forecast to top out in the 40s to even 50 over south central SD!

LONG TERM /TUESDAY EVENING THROUGH SUNDAY/

Issued at 228 AM CST Mon Dec 15 2025

Focus is on winds Thursday. A strong shortwave zips across the Dakotas, with a surface low that is tracking across North Dakota. Between the suite of deterministic guidance there is a note slight shift south from previous runs. This has 1) increased the chances for moisture across the area and 2) nudged up wind potential.

With the system, temperatures in the warm sector at 850mb Wednesday afternoon run form +6 to +12C, or a standard deviation above climo. There is a pre-frontal trough passage initially, shunting the modified Pacific airmass southeast, during the evening, followed by the Arctic front about 6 hours later. Strong cold advection follows with 850mb temperatures dropping to as low as -22C (EC/Canadian models) with a slightly less intensely cold airmass in the GFS/NAM. In BUFKIT this translates into an almost 10C drop in surface temperatures.

GFS 1/2km winds in the warm sector are 30 to 50kts with a signal for Sisseton downslope winds Wednesday to start it all off. They remain around that range in the post frontal environment. GFS pressure rises in the post frontal airmass are also running close to 20mb per 6 hours. The gradient across the state peaks at about 24mb. The pressure rises and gradient are a tad stronger than the last clipper where we featured strong winds, though 1/2km winds are a little lower. GFS BUFKIT mixed tool gets us again close to 50-60kts. EFI/shift of tails is also higher in comparison to the last event, highlighting the entire CWA.

As NAM/GFS BUFKIT profiles cool, there is a jump in CAPE (a peak of about 20-30j/kg) with the top of the mixed layer touching the dendritic growth zone. Both models show an area that cycles through the CWA with a snow squall parameter of 1 to 6. Still 4 days away so the focus area/timing is expected to shift, and the current timing is the overnight, but will need to start messaging the potential.

This Arctic blast is short lived, with warm advection starting Friday and another mild shot of air ahead of the next clipper/cold front around the Saturday timeframe.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 510 AM CST Mon Dec 15 2025

Terminals KABR,KATY,KPIR,KMBG

VFR cigs are forecast through the TAF period. Gusty downslope winds along the eastern slopes of the Coteau is possible once again late tonight with KATY gusts of 20kts or so.

ABR WATCHES/WARNINGS/ADVISORIES

SD...None. MN...None.