textproduct: Aberdeen

KEY MESSAGES

- A Heat Advisory remains in effect through this evening for central and portions of northeastern SD and west central MN with heat indices as high as 103 degrees.

- Western wildfire smoke may impact visibility at times across the region through Thursday morning. Smoke may drop air quality to the point of impacting those sensitive to smoke.

- A Marginal Risk (level 1 of 5) for severe weather is in place over the western portions of Dewey and Corson Counties this evening through late tonight. Wind gusts of 60 miles per hour will be the main severe threat.

- A Slight Risk (level 2 out of 5) for severe weather is in place over portions of south central SD Thursday. A Marginal Risk (level 1 of 5) for severe weather is in place for the rest of the forecast area. The main hazard will be wind gusts of 60 to potentially 70 mph and hail of one inch in diameter. Heavy rain that could lead to localized flash flooding is also possible with any stronger storm.

DISCUSSION

Issued at 226 PM CDT Wed Jul 29 2026

Main concern in the forecast is the ongoing smoke, both at the surface and aloft, and the return of shower and thunderstorms (potentially severe) with beneficial rain in the forecast across the region late tonight through Thursday night. As of 2pm, temperatures are in the upper 80s to around 100 with dewpoints in the upper 60s to the upper 70s, highest James River and eastward thanks in part to peak evapotranspiration and south to southeast winds. Heat indices range in the 90s to the lower 100s. Went ahead and expanded the Heat Advisory to cover the remaining forecast area with the exception of Codington and Hamlin. Besides fair weather cumulus over central SD and portions of NESD skies remain free of clouds with ongoing smoke and hazy skies. Smoke from the wildfires out west will continue to affect the region with lighter concentrations of near surface smoke continuing through the rest of the evening and tonight before lifting northward Thursday morning for a few hours before moving back in mainly east of the Mo River late Thursday night/Friday morning. This may continue to bring a reduction in visibility and affect people who are sensitive to smoke. Periods of smoke aloft/haze will continue through at least the end of the week.

The Northern Plains continues to be under the upper level ridge with its mid level high over the southern CONUS and winds across the CWA slightly west to to northwest flow. A shortwave (which originated over Arizona) will continue to track northeastward and over Wyoming by 00Z Thursday with a lee north to south oriented surface trough along the western Dakotas and eastern WY/MT. The CWA will be within the warm sector (between this and a high over MN) with ongoing south to southeasterly winds at the surface to 850mb and ongoing moist air. By 06Z, there really only seems to be a slight shift eastward in the surface trough which is connecting to a low over the Northern Rockies. By this time, the majority of the CAMs keep any convection just to the west of the CWA. Between 12-18Z the center of the low on this surface trough really only shifts a bit east and over south central SD. Widely scattered showers and thunderstorms will mainly continue along and west of the Missouri River. However, NBM is a bit more bullish and has pops extending to the James River. Through the afternoon and evening the surface trough will orient itself more northeast to southwest over the eastern half of SD/NE with the convection continuing to track eastward with additional development of shower and thunderstorms across the entire CWA. CAMS do vary quite a bit on timing and the location of development/storm track through the midday Thursday. So low confidence remains, however, NBM does a good job keeping the pops widespread due to this. Later on in the afternoon a few of a models do show the potential of storms clustering and eventually growing upscale/cold pool development and forming into a line of storms extending from Nebraska through central and northeastern SD into MN where it will track east/southeast and hopefully out of the eastern CWA by late Thursday night. HRRR indicates the potential for a bowing segments, however, as of now this looks to be south and east of our CWA.

Looking at the mesoscale parameters, the low level moisture will be abundant, as mentioned, as dewpoints will overall be in be in the the upper 60s to the upper 70s through Friday evening. SB/MUCape will generally be around 1000j/kg or less this evening and overnight with values increasing by midday Thursday, ranging from 1000-2500 j/kg highest over northeastern SD. However, 21Z and after values decrease to around 1000-1500 j/kg and diminishing even more after sunset. However, RAP is much higher with CAPE values of 2000 to 3000 j/kg with some areas indicating 4K! This looks to be a high CAPE low shear setup as bulk shear looks to remain below 30kts and no real LLJ. RAP soundings indicate low level lapse rates will be steeper whereas mid level lapse rates are not as steep with DCAPE values above 1000 j/kg early Thursday morning but does decrease below 1000j/kg by the afternoon. So the main threat with the storms will be damaging wind gusts of 60 to potentially 70 mph with a few storms possibly producing quarter size hail. If the line of storms does form/grow upscale and/or potentially bow over any part of the CWA then wind gusts could potentially be higher. Main caveat will be the cloud cover which could keep instability on the lower side for Thursday as well as a cap over much of the region setting up late tonight through the morning before breaking Thursday afternoon. A Marginal Risk (1/5) continues over north central SD for the convection overnight/early Thursday. A Slight Risk (2/5) for portions of south central SD with a Marginal Risk covering the rest of the CWA for Thursday with the main threat being damaging wind gusts.

PWAT values will range from 1.3 to 2" with the highest amounts James Valley and eastward. Therefore, any rain that falls could be heavy, especially with any stronger storms or training storms, leading to flooding. There is a slight risk of excessive rainfall for Thursday James Valley and eastward due to the high PW's meaning a 15% chance of rainfall exceeding flash flood guidance within 25 miles of a point in the slight risk. The probability of rainfall of 0.5" or more is 50 to 90% across the entire CWA with the probability of 1" ranging from 40 to 75%, mainly along and east of the Mo River with the highest chances over northeastern SD, mainly Spink County and eastward. Prob of 2" is 30-50% James Valley and eastward. Again this will be convective so exact amounts at any one location is hard to predict, but any rain will be beneficial to the area. NBM 25-75th spread for the 48 hour period, ending Friday evening is quite high ranging from 0.6 to 2 inches, highest James Valley and eastward. This leads to low confidence in exact amounts.

Behind this shortwave, the ridge amplifies with the axis more along the intermountain West with its mid level high encompassing much of the southwestern US Friday through early Saturday. A large mid level low, over the Gulf of Alaska, will track eastward across Canada and breaking down the ridge, with the southern portion of the shortwave possible clipping the Northern Plains early next week bringing a chance of showers and thunderstorms associated with a fropa through the middle of next week, however, confidence remains low at this time as this is several days out. Temps will be cooler for the end of the week with highs overall in the 80s for Thursday and even upper 70s to upper 80s/90 Friday, warmest along and west of the Mo RIver. As the ridge becomes more positive tilted for the weekend over the CWA, warmer air moves back in with highs in the 80s to the upper 90s/100, again warmest along and west of the Mo River.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1223 PM CDT Wed Jul 29 2026

Terminals KABR,KATY,KPIR,KMBG

VFR cigs continue through the TAF period. Both smoke at the surface and aloft will continue in waves over the region as well through the TAF period. This may bring slight reduction to visibility at times, especially during the late evening and again in the morning. Widespread showers and thunderstorms will track west to east across the region late tonight through Thursday afternoon. A few of these storms could become severe with the main threat being damaging wind gusts of 60 to potentially 70 mph.

ABR WATCHES/WARNINGS/ADVISORIES

SD...Heat Advisory until 9 PM CDT /8 PM MDT/ this evening for SDZ003>011-015>019-021-023-033>037-045-048-051. MN...Heat Advisory until 9 PM CDT this evening for MNZ039-046.