textproduct: Aberdeen

KEY MESSAGES

- Chances for light rain are possible over the next few days mainly over far south central South Dakota through this evening (30-50%) and more widely scattered (20-40%) for Wednesday and Thursday. Thunderstorms are possible Wednesday afternoon and evening, no severe weather is anticipated.

- High temperatures 5 to 15 degrees below normal expected through the work week. Highs will be in the 50s through that period. Weekend highs will increase slightly into the 60s.

DISCUSSION

Issued at 143 PM CDT Tue Apr 28 2026

A broad troughing pattern continues over the Central and Northern Plains, on the southern side of a broad low spinning over Canada. Models indicate a weak embedded shortwave, with its axis over WY, tracking eastward and over SD/NE through late this afternoon and evening, with the CWA on the backside of it by early Wednesday morning. Another embedded and stronger shortwave has been the main focus for rain showers further south in Nebraska. Shortwave pulses on the PVA side of this northern wave is producing the bulk of the rain showers over southwestern SD with the northern edge of this rain currently over south central SD, mainly Jones and Lyman Counties per radar. This will be the main focus for ongoing chances of rain where we have better better 1000-500mb. NBM is a little bit more aggressive on the northern extend of this rain (and pop chances) than CAMS, which continue to keep the bulk of it south of the CWA through this evening.

Late this evening through early Wed morning, another weak embedded shortwave over MT/WY will bring more chances of light rain with CAMs indicating spotty convective showers moving in from western SD and tracking southeast. However, CAMs show these either weakening or dissipating as they move in over the western CWA. Additional development of spotty showers (HRRR) are possible over portions of south central and east central SD however hi res models are not too thrilled and very spotty and NBM does not have anything. These will be moisture starved so most likely sprinkles at most or virga. Ran with ECAM between 00-12Z with pops up to 15% at most. So low confidence on if they will even form and where they will initiate if they do. HREF Probability of 0.01" through 12Z Wednesday is 30 to 50% over portions of south central SD with the highest prob over Stanley and Jones with most of this QPF through this evening NBM runs 40-70% for this same area so NBM running a bit more hot with pop chances and QPF. The 10-25% chance will be pretty splotchy over the rest of the CWA (with the exception of far northeastern SD/western MN) per these convective shower possibilities.

This broad trough overhead for Wednesday plus additional shortwave energy/pulses and daytime heating, CAMs indicate the development of very spotty elevated convective showers/thunderstorms tracking northwest to southeast between 18-03Z across the CWA as HREF composite reflecting>40 dbz paintballs as well. Instability will be weak with MUCAPE of 500j/kg or less and mid level lapse rates less then 7C. However bulk shear will be around 30kts out of the northwest. So thunderstorms could be possible with no severe weather anticipated. Any stronger rain shower or thunderstorm could produce sub severe winds given an inverted V sounding. Another embedded positive tilted shortwave moving in out of Canada and tracking over the CWA will bring isolated spotty convective showers once again Thursday. However forcing and instability is really not there, so if showers do form they will be weak with pops of 15-20%.

Finally, for the end of the week as this upper low/trough pushes more eastward and over the eastern CONUS, models indicate split flow over the western CONUS with a ridge over the Pacific Northwest and trough over southern CA/Mexico. The Northern Plains will continue in overall northwesterly flow aloft between the ridge to our west and trough to our east. This should overall produce dry weather Friday and Saturday with more shortwaves moving across the region early next bringing slight chances of pops (15-20%).

With this overall broad troughing pattern, 850mb temps continue to be below average through the end of the week, hovering a bit above or below 0C, with values as low as the 10-20th percentile. Highs for Wednesday through Friday will range overall in the 50s with temps warming into the 60s for the weekend. Climate Predication Center 6- 10 day outlook (5/3-5/7) indicates below average in precip and temp.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1220 PM CDT Tue Apr 28 2026

Terminals KABR,KATY,KPIR,KMBG

VFR cigs are forecast through the end of the TAF period. A weak shortwave aloft this afternoon may produce weak rain showers over far south central SD. Confidence is low on if this light rain could surge further northward affecting KPIR through the evening. So left these rain chances out of the TAF for now. Through the overnight, isolated convective rain showers are possible once again for portions of central and east central SD, however, forcing and moisture is limited. With low confidence on if these form, left them out of the TAFs. If they do form, could affect KPIR/KATY through early Wednesday morning. Additional showers and weak thunderstorms are possible across the region Wednesday afternoon and evening.

ABR WATCHES/WARNINGS/ADVISORIES

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