FXUS63 KABR 020813 AFDABR Area Forecast Discussion National Weather Service Aberdeen SD 313 AM CDT Wed Jul 2 2025 .KEY MESSAGES... - Scattered showers and thunderstorms (30-60% chance) continue to move southeast across the state this am. Storms have been sub- severe for the most part. - Heat and humidity are the main story today through Friday, with highs in the upper 80s to near 100, and dewpoints in the 60s to low 70s. Heat indices may top 100 degrees in a few spots Thursday. - A system late Friday/early Saturday will bring relief from the heat and humidity in the form of storms (60-80% chance eastern SD/western MN). Main concern is the potential for heavy rainfall. && .DISCUSSION... Issued at 310 AM CDT Wed Jul 2 2025 Cluster of sub-severe storms overhead early this morning with a wave embedded within northwest flow. This activity will continue southeast through the morning, with CAMS suggesting a departure time around 11-13Z. Through the day today, profiles destabilize in far eastern SD/western MN. CAM coverage is essentially negligible, and we are seeing increasing heights and 700mb warm advection. There is still a weak mid-level trough in the area so cant rule out an isolated weak storm. Warm air continues to migrate into the area tonight/Thursday. NBM 25th/75th box and whiskers range for high temperatures tomorrow is closer to about 5F now, though we are still falling at or below the 50th percentile for deterministic NBM highs Thursday. We still maintain a bit of a south southeast wind component, and the other wrinkle is that the NAM has some mid-level moisture across the northern portion of the state which could impact daytime heating. NBM heat index values are close to +100 in a few spots but not widespread enough for headlines at this point. This is generally in line with the deterministic HREF values of upper 90 heat index values. Probabilistically however, the HREF still gives us a 40-70 percent chance of exceeding 100F heat index values mainly up through the James valley. Friday, temperatures are again into the 90s, and we still remain at the 50th percentile or less for highs. Surface winds are more south southwesterly ahead of a surface front, meaning we will probably overachieve for highs, though it would be a wash in regards to heat index values with that wind trajectories greater mixing potential. With that mixing, despite warm temperatures aloft, NAM suggests that the CAP isn't going to be so strong that the front will go through dry. As for thunderstorm activity, 0-6km shear is relatively weak peaking at less than 30kts. PWATS remain 2 standard deviations above climo, above 1.75". And yes, while 700mb temperatures are a standard deviation above climo, 500mb temperatures are closer to 2 standard deviations, resulting in weak mid-level lapse rates which will further limit severe weather potential. With weak flow and a rich airmass expect the main threat will be heavy rain. The rest of the long term remains active with seasonal temperatures thanks to a constant parade of waves embedded within wobbly zonal flow. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1221 AM CDT Wed Jul 2 2025 Terminals KABR,KATY,KPIR,KMBG Generally VFR conditions. We have PROB 30 for PIR/MBG for storms, but the more likely location is ABR then into ATY in about an hour for this morning. Additionally KPIR/KATY will have a few hours of LLWS with a low level jet briefly overhead. Winds are primarily south southeast. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ DISCUSSION...07 AVIATION...07