textproduct: Aberdeen

KEY MESSAGES

- Mostly dry through late Thursday.

- Temperatures 15 to 25 degrees above normal Thursday (Highs: low 70s to low 80s) and low humidity. This and south winds 25 to 30 mph results in High/Very High Grassland Fire Danger.

- Colder Friday/Saturday. Saturday high temperatures 10 to 20 degrees below normal (Highs in the 40s).

DISCUSSION

Issued at 1217 AM CDT Tue Apr 14 2026

Surface high to the north continues to feed cool stable air into the region around midnight. As such, upslope favored areas with this wind trajectory will again see fog/stratus expand over the next few hours. Towards morning, the pressure gradient is much weaker, winds gradually organizing around to westerly as a surface low lifts northeast across North Dakota. 850mb temperatures are coolest today, ranging between +3 to +9C from northeast to southwest respectively. Will give temperatures a slight bump above deterministic NBM which falls about 3-4 degrees below the NBM mean given the favorable mixing direction, with the expectation that shallow low clouds/fog also mix out with these light west winds. We fall under the influence of a very weak surface high tonight, and on the backside, winds shift back to southerly for Wednesday. We start to see milder air moving in late Wednesday, with the core of the warmest air overhead for Thursday, though with a front positioned just to our northwest.

Its another interesting temperature forecast for Thursday with the deterministic NBM again falling close to the 10th percentile for high temperatures, about a difference of 8 degrees between that and the mean. Deterministic model 850mb temperatures run from +16 to +19C with the Canadian being a distinct cool anomaly. The surface flow is around a low that develops over Wyoming with an inverted trough/warm front extending up northeast across South Dakota. This provides for a favorable mixing environment with southwest winds south of the boundary. The big question here is where does this surface feature set up with the main deterministic models having a pretty tight thermal gradient across northwest South Dakota to south central North Dakota and any wobble in the next several runs could translate this gradient elsewhere, and as such could result in a forecast or forecast adjustment bust. Will leave NBM temperatures alone Thursday for now.

A side note in regards to these conditions, it is interesting how deep mixing is depicted in NAM BUFKIT profiles, up to approximately 12kft out by Pierre, 10kft for KMBG and 8kft for KABR! Shallow high/surface based altocumulus may result but there is limited CAPE above the deep surface boundary layer, and a substantial dry layer. All this above the 0C layer as well. So maybe add the option for some additional gustiness with dry/snow microburst.

That surface low translates southwards, bringing much colder air back into the region for Thursday night/Friday. We go from 850mb temperatures a standard deviation above climo, to a standard deviation below climo for Saturday. Forecast temperatures reflect this with about a 35F drop between Thursday and Friday/Saturday.

Precipitation will be pretty meager for the next few days. A mid level deck is depicted in the NAM across south central and far eastern South Dakota today with a deep dry layer.

We also see precipitation chances in the NBM increase Friday, as a trough deepens to our west. Most of the model QPF appears to come on the backside of the system as the surface low has moved off well to the east. GFS BUFKIT profiles hint that a deep stratus layer accompanies the change in airmasses, though if this is the case then we'd be looking at more drizzle/sprinkles type precipitation. And while NBM POPs are quite high, overall the QPF is from a few hundreds to maybe 2/10ths. GEFS is in line with this thinking with just a few members showing moisture greater than a tenth of an inch. NBM probability of 0.25 inches or greater is only about 40% across the northern tier of the state, to around 20% from Pierre to Watertown.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 618 AM CDT Tue Apr 14 2026

Terminals KABR,KATY,KPIR,KMBG

Morning fog has fallen to around 1SM at ABR, but improved to 5SM or higher at other sites at least temporarily. IFR ceilings at ABR/ATY will improve to MVFR to VFR by 15Z as the lower ceilings. 10kt or less winds will continue through the period.

ABR WATCHES/WARNINGS/ADVISORIES

SD...Dense Fog Advisory until 8 AM CDT this morning for SDZ004-005- 007>011-016-017-019-020-034-036-037. MN...None.