Area Forecast Discussion

KEY MESSAGES

- Warm temperatures return next week, bringing near critical or critical fire weather conditions Monday thorugh Wednesday.

- An unsettled pattern bringing rain and Thunderstorm chances to the region Thursday, and rain and snow chances Friday into next weekend.

UPDATE

Issued at 619 AM CDT Sun Apr 19 2026

Snow showers and even most of the clouds have moved out of the CWA. Some lower clouds still hanging around the SD border, but will clear out in the next few hours and leave our area quiet and cold for the rest of the day. Adjusted sky grids a bit for current trends, but no other changes to what we have going.

DISCUSSION

Issued at 253 PM CDT Sat Apr 18 2026

..Synopsis

Large scale pattern still features troughing across the Great Lakes/Upper Midwest, with north-northwest flow over the Northern Plains. Several embedded waves within this flow are moving into the region and may bring shower chances late afternoon through the evening/early overnight period. Mid/upper level ridging already building over the western US is expected to move east into the Central and Northern Plains and drier/warmer conditions are favored through Wednesday. All ensemble systems show deep longwave troughing developing across the western US, with southwest flow across the plains late next week. This trough eventually moves across the Central and Northern Plains. This pattern shift will resulting increasing precipitation chances late in the week into the weekend, with cooler/below average temperatures returning once again.

..Snow showers this afternoon and tonight

The mid level waves moving through the region arrive as steep low and mid level lapse rates will remain in place, with a layer of elevated instability through the evening even as low levels decouple (MU CAPE 50-100 J/KG). This on the surface isn't impressive, but may enough for some of the showers to support brief/higher rates and localized visibility reductions (under 1 mile). There will be substantial dry air in the low and mid levels that could limit coverage and any potential for accumulations, though where rates are high enough a dusting of snow accumulation on grassy/elevated surfaces may occur.

..Fire weather monitoring early next week

The pattern shift towards more dominant ridging/rising heights supports above average temperatures Monday through Wednesday, with increased mixing and generally sunny conditions. The flattening of the ridge and slight shift towards west-southwest flow Wednesday does tend to support stronger lee troughing to the west and increasing southerly low level flow. The pattern aloft tends to support at least periods of increasing upper level clouds, but also even warmer temperatures and deeper mixing. While both Monday and Tuesday may see near critical fire weather conditions over parts of the region, Wednesday is the main day of concern for potential fire weather impacts an increased chance for critical fire weather conditions/Red Flag Warning conditions. HDWI probabilities are maxed out for exceeding the 75th percentile are very high (actually maxed out in our south) with increased chances to (40% or greater) to exceed the 95th percentile. Adjusting for better mixing heights Tds may fall more in line with NBM 10th percentile with many locations near or lower than 25% for RH values in our south. Mixed layer winds would support gusts exceeding 30 mph as well, with some gusts higher if vertical mixing is maximized.

..Unsettled pattern late next week into the weekend

As southwest flow develops deeper moisture advection builds into the Northern Plains with NAEFS highlighting anomalous PWATs (exceeding 1") Thursday into Thursday night. EFI highlights that period for anomalous instability (values exceeding 0.8) though climatologically that isn't as hard to accomplish with even modest instability present. Depending on the evolution of the upstream low pressure building out of Colorado within this flow we may see organized periods of rain and embedded/elevated thunderstorms Thursday into Thursday night, and this will be a period to monitor. Depending on mesoscale details (clearing/frontal positions) strong effective shear could coincide with enough elevated instability for a few strong or even marginally severe thunderstorms.

As frost depth has reached zero based on observations in our CWA as of the last warm-up we are not approaching this rain event with hydrophobic tendencies as we normally would in early spring. Thus, it will take heavier rain totals in shorter periods to cause excessive runoff impacts as there could be at least some storage in soil. There is a signal in NBM for 1"+ rain totals (10-20% chance), however the signal for greater than 2" of rainfall is currently zero and those types of totals would likely be needed for at leas some flood impacts.

Ensemble spread increases regarding the evolution of the pattern, lowering confidence in precipitation coverage and measurable precipitation timing/coverage/amounts. The colder air settling into the region does raise the potential for wintry precipitation dependent on evolution/timing. There are some ensemble members that show accumulating snow potential and WPC pWSSI shows a 10-20% probability for advisory/minor winter weather impacts from snowfall. Higher snow rates would be required to overcome warmer ground temperatures and increase impacts and all details are very uncertain at this time and range.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1208 PM CDT Sun Apr 19 2026

Cumulus clouds are developing this afternoon with cloud bases around 2500-3500 feet. MVFR conditions may arise briefly at any TAF site if coverage is high enough, so expect at least some potential for shifts in from VFR to MVFR this afternoon. This will diminish after sunset as mixing ceases. Winds will diminish through the day today as a surface high moves overhead. As the high pushes off to the east, southerly winds will increase. Gusts should start to arise after 12z tomorrow beneath VFR conditions, with gusts between 25-35 mph expected through the morning.

FGF WATCHES / WARNINGS / ADVISORIES

ND...None. MN...None.