FXUS63 KABR 151051 AFDABR Area Forecast Discussion National Weather Service Aberdeen SD 551 AM CDT Wed Apr 15 2026 .KEY MESSAGES... - Warming trend continues. Temperatures today top out in the 70s (15 to 20 degrees above normal) and Thursday into the upper 70s to mid 80s (15 to 30 degrees above normal). - The combination of warm temperatures and southerly winds of 25 to 30 miles per hour result in High to Very High Grassland Fire Danger Thursday. A Fire Weather Watch is also in effect for late Thursday morning into the late afternoon. - A cold front will move through the area Thursday night, leading to below normal temperatures (highs in the 40s) and precipitation Friday and Saturday. Precipitation starts out as rain Friday afternoon before transitioning to snow as colder air moves in. Overall not a lot of moisture with this system. && .DISCUSSION... Issued at 1242 AM CDT Wed Apr 15 2026 Isolated elevated shower activity early this morning, with BUFKIT profiles and regional observations indicating ceilings up around 8-10kft or higher. NAM BUFKIT profiles also indicate a fairly dry layer of air below, so that will really limit what reaches the surface. Added sprinkles through the overnight. CAMS are also highlighting the northeast for another round of fog formation, and we've already seen Wheaton down to 1/4 mile. For Today, the weak wave responsible for the ongoing activity has shifted into western Minnesota, with a second wave over central Nebraska, both heading northeast with the influence now east of the CWA. We end up in broadly diffluent flow aloft as a stronger wave comes into the Pacific northwest. Good mixing conditions for the day with a light southwest component to the winds. HREF probability of exceeding 20 mph only tops out at 20-40% for a few hours in the morning when we first mix out, then drops to zero. NBM deterministic highs are about 1 to 4F below the 50th percentile, and with ample sun and mixing winds, bumped temperatures up. Afternoon humidity across much of the area will be from 20 to 30%, and the HREF probability of falling below 20% is actually from 40 to 60% across our west river counties. But again, winds are going to fall well below criteria for Red Flag. Across the east, mainly the far northeast, NAM BUFKIT profiles also indicate some weak/shallow convective instability. Profiles suggest convection limited to between 5 and 10kft which may be enough to generate moisture. CAMS only have a few blips. Have added a 20% chance up across the northeast. Wednesday night, flow aloft continues to be diffluent, resulting in a lee low forming over eastern WY/MT and the western Dakotas. This increased the gradient, though only about 10mb across the state. Increased flow is southerly, with 1/2km winds of 25 to 40kts. There will also be warm advection through the overnight hours, though no elevated instability is indicated in the NAM. As we continue into Thursday, flow aloft is southwesterly, with southwesterly low level flow, though the lee low weakens into more of an inverted trough stretching northeast to southwest across the state. Inverted V style profiles are depicted by the NAM, with a few j/kg CAPE above the 0C level, up around 12kft. No POPs with this profile, but along with the system derived winds being strong, this may add additional gustiness as a fire weather wrinkle. As for temperatures Thursday, again, NBM falls around the 10th percentile, with a 5 to 8 degree cool bias vs the NBM 50th percentile. This again is likely due to a significant thermal gradient across northwest South Dakota and south central North Dakota and the array of possible ensemble placements. Winds for most of the area during the day are also in a warm advection regime, meaning the NBM should provide the cap for highest wind gusts (outside of the aforementioned convection) so this will give us a good idea of whether we'll meet Red Flag. NBM gives us 50 to 70% probability to exceed 25 mph and a 30 to 50% probability for winds in excess of 30 mph. That means the potential for a fairly widespread Red Flag wind wise. For afternoon humidity, the deterministic NBM is around 20 to 25% with the far northwest and northeast up over 30%. Cold front moves through during the overnight hours, with a wind shift and increase. Strongest pressure rises are out in western South Dakota, but the gradient from southeast to northwest is about 16 to 20 mb. NAM/GFS BUFKIT profiles indicate status follows, with mixed winds in the 25 to 35kt range. Concern is that any ongoing fires will experience a sudden shift in trajectory. The gradient persists through Friday, at about 20mb across the state, keeping winds up. We still go from a standard deviation above climo for 850mb temperatures Thursday to a standard deviation below climo by Saturday, with a 30-40 degree temperature difference between highs Thursday in comparison to Friday/Saturday. Trends for moisture: NBM POPs have dropped, and shifted the total moisture west. Still only averaging a tenth of an inch or less. GEFS is likewise a tenth or two, with a few blip up around a half inch. NBM probability of a 1/4 inch are also down, up north of Mobridge its only about 30-40% with lower elsewhere. Profiles still suggest a transition to snow as well, but with ground/air temps wouldn't expect it to last. && .AVIATION /12Z TAFS THROUGH 12Z THURSDAY/... Issued at 551 AM CDT Wed Apr 15 2026 Terminals KABR,KATY,KPIR,KMBG Outside of morning LIFR to IFR fog at ATY, VFR conditions and winds around 12kts or less will continue over the next 24 hours. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...Dense Fog Advisory until 9 AM CDT this morning for SDZ007-008- 011-020>023. Fire Weather Watch from Thursday morning through Thursday evening for SDZ005>008-010-011-016>023-033>037-045-048- 051. MN...Dense Fog Advisory until 9 AM CDT this morning for MNZ039-046. && $$ DISCUSSION...07 AVIATION...06