####018006076#### FXUS63 KBIS 200617 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 117 AM CDT Mon Jul 20 2026 .KEY MESSAGES... - Windy on Monday, with near-critical to possibly critical fire weather conditions in the southwest and south central North Dakota. - Cooler on Tuesday, then becoming hot once again by the end of the week. && .UPDATE... Issued at 115 AM CDT Mon Jul 20 2026 A few stray showers and thunderstorms continue to roam through the southern James River Valley at this late hour. Severe weather is no longer anticipated, but some smaller hail cannot be ruled out with the strongest storms. Lingering showers and storms should exit our forecast area well before sunrise. UPDATE Issued at 929 PM CDT Sun Jul 19 2026 A cluster of thunderstorms is present over parts of south central North Dakota, including the southern James River Valley. These storms will become strong to severe at times, though should move out of the forecast area, potentially weakening as well, over the next couple hours. Strong winds and large hail are the primary threats with any severe storms that develop. && .DISCUSSION... Issued at 235 PM CDT Sun Jul 19 2026 Currently there is near zonal flow over the Northern Plains as the large ridge that is mostly over the CONUS has a flat top now. An upper level low near Vancouver is creating a slight southwest tilt in the flow over the northern Rockies and North Dakota. This, along with some speed shear at the mid levels is creating our severe storm risk today. At the surface there is weak low pressure influence in the state, and a surface trough/front that has moved east into western North Dakota. Little to no clouds are currently floating around, except some cumulus forming on the boundary in the southwest. As the afternoon progresses, strong diurnal surface heating and mixing will bring temperatures near 100 degrees across the west and south. There is generally a large cap across most of the severe risk area, however the forecast high temperatures are near or above the convective temp to start surface based storms. Otherwise storms may stay elevated like previously forecasted. Model soundings across the area continue to show a strong dry level near the surface shown by large invert V soundings. Looking at DCAPE across the west and central, values are well over 1000 J/kg. This lower dry air is a big limiting factor for surface based storms to form, leading to the idea that these will likely be elevated. MUCAPE is currently elevated and is 1000-2000 J/kg. The forecast CAPE axis by 00z is north to south in the James River Valley with values up to 3000 J/kg. The shear vector is currently straight off the boundary leading to isolated (possibly supercells) forming, however with the straighter hodographs splitting storms will be a very real thing. Eventually the CAMs have these storms forming into a line as the boundary becomes more parallel with the shear vectors. This will be when 70 to 80 mph winds are possible as the dry air surges the wind towards the surface. Timing looks to be around 22/23z somewhere west of Highway 83. When these isolated cells then hit the bigger CAPE to the east, and the boundary is less straight on with the shear vectors is when it would go linear around 8pm (somewhere east of Highway 83). With the high CAPE and shear values around 45kts, we are still advertising 2 inch hail, which would happen when storms are isolated still. Since storms could be splitting and possibly reforming on outflow boundaries, there is a low brief tornado risk when these storms interact with these boundaries. Based on the CAMs these storms should be in the Red River Valley by midnight. Behind all these storms is a surface cold front that will move into the northwest corner of the state by midnight. Unfortunately this will carry near surface smoke with it. Expected a hazy and smokey day Monday whether the smoke stays elevated or mixes down. The thickest surface smoke is forecast to move through the southwest half of the state overnight, but may linger in the post frontal air through the day. Temperatures from the cold front will generally only be cooler in the far north around 80 degrees with the rest of the area still in the 90s. As with most cold fronts, northwest winds will gust 20 to 40 mph, especially in the central and James River Valley. There are some fire weather concerns in the southwest and south central but the wildland grasses just aren't dry enough to be concerned with the large uncontrollable fires that the Red Flag Warning is intended for. We opted to just stick with the near to possibly critical wording without any products. There is also a low chance of isolated rain showers in the north Monday. The rest of the week will restart the extreme warming trend as another large ridge builds back in. By next weekend temperatures will be back into the 100s, with likely heat headlines. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 115 AM CDT Mon Jul 20 2026 VFR conditions are expected to prevail through the forecast period. A few stray showers or thunderstorms remain possible over south central North Dakota overnight. Scattered showers and isolated thunderstorms could then enter northern North Dakota late Monday afternoon and evening. There is a low probability of a shower or storm reaching KMOT, but not high enough to mention in the TAF at this time. It will become windy on Monday, with northwest winds around 20-25 kts and gusts around 30-35 kts. Smoke from distant wildfires could become thicker aloft on Monday, but visibility restrictions at the surface are unlikely. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Hollan DISCUSSION...Smith AVIATION...Hollan ####018005267#### FXUS62 KCAE 200617 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 217 AM EDT Mon Jul 20 2026 .WHAT HAS CHANGED... Confidence in a fairly active pattern during the mid to late week continues to increase. Aviation discussion updated for 06z TAFs. && .KEY MESSAGES... - 1. Isolated to widely scattered convection possible today and Tuesday with hot/humid conditions continuing. - 2. A more active pattern is expected during the mid to late week with slightly cooler temperatures and chances for stronger thunderstorms Wednesday. && .DISCUSSION... Key Message 1: Isolated to widely scattered convection possible today and Tuesday with hot/humid conditions continuing. TD Two is expected to begin slowly drifting NNW across the Gulf through the day today as low level flow over the FA becomes increasingly southerly. The plume of deepest moisture associated with this system is expected to remain confined toward the Gulf Coast, but PWAT's between 1.85-2" are expected to remain over the region. Surface troughing is expected to gradually weaken through the day, but pieces of shortwave energy from the troughing pattern over the eastern CONUS are expected to pass near the Pee Dee this afternoon/evening. Surface dewpoints are expected to remain in the upper 60s to low 70s with mean HREF MUCAPE values nearing 2000 J/kg through the day with lingering cloud layer shear values near 20-30 kts. With the subtle nature of forcing, expect convective coverage this afternoon/evening to be fairly isolated with the best chances along and east of the I-26 corridor. Generous mixing should once again yield DCAPE values that could close in on 1000 J/kg so a stronger storm cannot be ruled out with this activity. Tuesday likely acts as a transition day where surface troughing and any upper support exit the CWA, but hot/humid conditions should still yield seasonable instability and isolated diurnal shower/storm chances. Temperatures today and Tuesday are expected to once again push the mid to upper 90s with heat indices up to 100-106F expected, remaining just under Heat Advisory criteria. Key Message 2: A more active pattern is expected during the mid to late week with slightly cooler temperatures and chances for stronger thunderstorms Wednesday. The upper pattern is expected to amplify a bit through the day Wednesday and into the late week as both the EC Ensemble and GEFS mean solutions show a strong trough (500mb heights 2-2.5 standard deviations below normal) extending from the eastern Great Lakes down into the Mid-Atlantic. This trough is expected to push a cold front down into the region which could near the FA by late Wednesday where IVT ahead of the front could reach the NAEFS 90th to 99th percentile and PWAT's exceed 2". LREF cluster analysis shows uncertainty in the depth of the upper trough exists, but even weaker solutions show decent PVA and kinematics reaching the FA with deep layer shear nearing 20-30 kts and a 20-25 kt LLJ in place. With seasonable to moderate instability likely in place, this trough and front could bring a chance for more widespread shower/storm chances by the evening where strong to severe storms could be possible. Global models depict the frontal boundary stalling near/within the FA on Thursday as another shortwave likely moves in. With anomalous IVT continuing, scattered to widespread rain chances could continue where heavy rainfall will be possible as EC Ensemble and NBM probabilities for greater than 1" of QPF near 50-60%. With the region remaining in northwest flow into the weekend, a series of shortwaves are expected to continue pushing through, bringing more rain chances. Due to upper troughing and increased rain chances, Temperatures that start near normal Wednesday are expected to cool to slightly below normal during the late week. Fairly large 6-8 degree IQR ranges remain during this time period, but even the blends 75th percentile brings temperatures right around normal. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... VFR Conditions Expected to Continue. VFR conditions over the area with few to scattered clouds around 5kft but relatively high confidence in VFR conditions continuing through the TAF period. Winds will generally be out of the SSW, increasing during the afternoon with gusts generally in the mid to upper teens. While guidance generally indicates a bit of a deep layer moisture increase associated with a tropical depression along the Gulf Coast, convection coverage will likely be somewhat limited again today. Confidence remains low in thunderstorms impacting the terminals so have left out the mention of tsra but will need to monitor trends in high resolution guidance with subsequent updates. EXTENDED AVIATION OUTLOOK...Potential for restrictions from showers and thunderstorms continues with the threat increasing later in the week. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$ DISCUSSION...DH AVIATION...96