Area Forecast Discussion

KEY MESSAGES

- Dry conditions are expected into the first half of this week with temperatures warming back above normal into Wednesday.

- There is a 30 to 50 percent chance of the region west of a line from Watertown to Ortonville picking up a quarter inch or more of rainfall Wednesday night into Thursday.

- Elevated fire weather conditions will return Monday with gusty winds and low relative humidity values expected across far eastern South Dakota over into Minnesota. Additional concerning fire weather conditions are being monitored for Wednesday afternoon.

- Strong sustained west-northwest winds 25 to 40 mph with gusts up to 50 mph are expected on Thursday.

DISCUSSION

Issued at 139 PM CDT Sun Apr 19 2026

At 1 PM CDT, skies are sunny/mostly sunny and temperatures are warming through the 30s and 40s. Surface high pressure is centered north of the CWA, with north winds around 5 to 15 mph with some occasionally higher gusts.

Northwest flow aloft holds the line until a vigorous/energetic upper level longwave trof pushes the western CONUS upper level ridge eastward over the region around mid-week. Given the synoptic-scale set-up rolling into Wednesday night when the upper level low begins to move out onto the central/northern plains states, could be seeing the first taste of strong convection over this CWA for this convective season. A lot will depend on from where the moisture for thunderstorms will be coming. From Thursday through the start of next week, the pattern aloft becomes quite blocky/stagnant, with a blocking upper low off the CONUS east coast, essentially causing the upper low/trof to stall out across southern Canada. The upper low's strong subsidence region is expected to glance this CWA heading into Thursday. At this point, model progs and guidance suggest that a wind advisory for westerly/northwesterly component winds is a slam dunk for Thursday into Thursday night. The question is will there be any counties in the CWA that experience High Wind Warning conditions. The blustery winds look to persist into Friday as well.

Ensemble PoPs indicate that there is a 35 to 75 percent chance of showers (thunderstorms is included here) Wednesday night into Thursday. GFS soundings in BUFKIT indicate more than enough instability at/above 2km for thunderstorms. Not much shear, though. Presently, the probability of 0.25in or greater of precipitation Wednesday night/Thursday is 30-50 percent west of a line from Watertown to Ortonville. Eventually, additional shortwave energy is expected to swing around the base of this upper trof and sweep through the region, bringing some shorter-lived/lower-qpf potential precipitation chances over the weekend into early next week.

The warm-up that begins on Monday is expected to continue into Wednesday, when temperatures could be exceeding 90 degrees over a good portion of the forecast area throughout and west of the James River valley. The cold front that sweeps through the region Wednesday night will signal a sharp drop in temperatures back down into the 50s for daytime highs for most areas Thursday through Saturday.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1208 PM CDT Sun Apr 19 2026

Terminals KABR,KATY,KPIR,KMBG

There could be a few hours of low level wind shear potential overnight at KPIR/KMBG. Otherwise, VFR conditions are forecast through the period.

FIRE WEATHER

Issued at 139 PM CDT Sun Apr 19 2026

Lots of dry air is expected to be around on Monday when low level return flow southerlies get going. As temperatures warm into the 60s and 70s on Monday, afternoon rh's fall below 20 percent over much of the western half of the CWA. However, the winds are forecast to be relaxing over that area, at least, enough that Red Flag conditions are not anticipated for 3 or more hours. However, on and east of the Prairie Coteau, there are areas where rh's are expected to be below 25 percent and wind gusts of 25 mph or more should last long enough to satisfy Red Flag criteria.

A cold front is expected to switch winds around to the northwest Monday night before they switch around to the southeast around 5 to 15 mph on Tuesday. Tuesday should also be about 5 to 10 degrees cooler than Monday with higher afternoon relative humidity everywhere across the region but south central South Dakota, where afternoon humidity may fall to between 15 to 20 percent. Afternoon southeast wind gusts could get up between 20 and 25 mph as well, so south central South Dakota could be into some elevated fire weather conditions.

Also, will be keeping a watchful eye on whether or not Gulf moisture can make it this far north by Wednesday/can make a meaningful enough dent on rh's to preclude fire weather headlines that afternoon. Right now temperatures warming into, at least, the 80s with dewpoints up into the 30s and 40s won't do it. Afternoon minimum rh's are progged to fall well below 20-25 percent CWA-wide on strong southerly winds well beyond gusts of 25 mph. Wednesday could be another fire weather headline day.

ABR WATCHES / WARNINGS / ADVISORIES

SD...Fire Weather Watch from Monday morning through Monday evening for SDZ008-021-023. MN...Fire Weather Watch from Monday morning through Monday evening for MNZ039-046.