textproduct: Aberdeen

KEY MESSAGES

- Rain showers (embedded thundershowers) into the evening hours. Most areas less than a half inch. No severe storms expected.

- Frost possible (33 to 36 degrees) across portions of central SD early Tuesday morning. Much better potential for widespread frost/freeze conditions Wednesday morning. Temperatures forecast around 29-33 degrees.

UPDATE

Issued at 625 PM CDT Mon May 18 2026

Due to the cloud cover, temperatures should remain fairly steady overnight. Increased lows a few degrees across the board, leaning toward the HRRR and ConsShort. That leaves lows on the cusp of frost advisory under the current headlines. Will leave headlines as-is for now, but confidence is low in temperatures below 37 degrees except in valleys.

DISCUSSION

Issued at 237 PM CDT Mon May 18 2026

Starting to see an uptick in areal coverage of showers (embedded thundershowers) as activity continues moving north-northeast across the region. Instability is lacking today, so don't expect anything in the way of severe storms. Did some massaging of PoPs through late afternoon into early evening to account for radar trends and expectations. Total rainfall amounts forecast to remain less than a half inch for most areas.

Later tonight into early Tuesday morning, surface high pressure settles in across the western Dakotas. Chilly temperatures in the 30s are forecast across the CWA tonight, and there are some concerns about frost potential with temps dropping to between 33 and 36 degrees. Clouds are expected much of the night, along with a northwest breeze, so certainly not ideal radiational cooling conditions. In fact, inherited NBM lows seemed a tad too cool, so blended in some warmer (ConsMOS) readings to bring readings up a couple degrees in spots. All said and done, forecast lows across central SD are generally between 33 and 36 degrees, so have therefore issued a Frost Advisory for the western CWA. Much better potential for more widespread frost/freeze conditions late Tuesday night into Wednesday morning as the surface high is more overhead. Winds are expected to be lighter, with mostly clear skies (especially for eastern areas) leading to better radiational cooling conditions. Current forecast lows are closer to 30-32 degrees for many areas. Highly likely more headlines are in store.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 625 PM CDT Mon May 18 2026

Terminals KABR,KATY,KPIR,KMBG

A mix of MVFR/IFR conditions will persist into Tuesday morning with the continuing rain and cloud cover. As high pressure moves in Tuesday, cigs should improve.

ABR WATCHES/WARNINGS/ADVISORIES

SD...Frost Advisory from 4 AM CDT /3 AM MDT/ to 9 AM CDT /8 AM MDT/ Tuesday for SDZ003>005-009-010-015-016-033>035-045. MN...None.