textproduct: Twin Cities

KEY MESSAGES

- Elevated to near critical fire weather conditions develop Wednesday.

- Showers and thunderstorms return to the forecast Thursday. A few storms may be strong to severe.

- Warm next few days, followed by a drop in temperatures for the upcoming weekend.

DISCUSSION

Issued at 310 AM CDT Tue Apr 21 2026

Clear and quiet start to Tuesday across the Upper Midwest, with light southerly flow supporting 24-hr temperature changes on the order of 20+ degrees. Surface analysis captures a cold front advancing south through ND/northern MN. High pressure will expand over the region in the wake up the front, resulting in light northerly winds and sunny skies overhead. It will not be nearly as breezy as the past couple of days thanks to the influence of the incoming surface high, which will help to limit fire weather concerns this afternoon. Efficient boundary layer mixing will yield another day of critical RH's (20-25 percent) across central and southwestern MN, so we would likely be talking about a fire weather headline if the winds were any stronger. It's worth mentioning that we did blend in some of the hi-res guidance into the dew point grids to try and better capture the minimum RH's this afternoon. Otherwise, it will be a beautiful day with highs ranging from the upper 60s (north of I-94) to the mid 70s (along I-90).

An upper-low spinning off the coast of California is forecast to breakdown and advance across the Rockies before taking on a negative tilt and phasing with a trailing wave over NW Canada Thursday into Friday. A surface cyclone will develop across the northern Plains in response to the upper-level evolution and will the main forecast feature of interest over the next few days. The first "sign" of the incoming weather maker will be the passage of a warm front Wednesday. Large scale warm advection will increase ahead of the developing storm system and is reflected by 925mb T's of 20-25C expanding across the southern half of MN. Another day of efficient mixing will produce surface highs in the 80s for most of our MN counties and the upper 70s/near 80 across western WI. The warmest locations will be across western MN, where 90 is not out of the question. (Looking at you Madison!). While there will be an increase in atmospheric moisture within the region of warm advection, the combination of warmer temperatures and dew points in the 40s to lower 50s will still yield an afternoon of RH's dropping to near-critical fire weather values. Even if the RH's remain slightly more marginal (say more like 30 percent), the return of stronger southerly winds may be problematic particularly across western MN where the recent stretch of weather has been fairly dry. The potential need for a fire weather headline on Wednesday will be discussed by today's dayshift.

Focus will shift from fire weather to convective chances as the surface system takes shape across the northern Plains Wednesday night into Thursday. Guidance depicts a negatively tilted shortwave trough pivoting over the Dakotas with an associated ~980s mb surface low set to track north/northeast from ND into Manitoba as the upper features undergo the phase. As the low lifts northeast, a cold front will translate eastward across the Upper Midwest. This front will be the driver of convection on Thursday. A few notes about the setup: 1) Due to the expected model spread in phasing scenarios, there are still some questions on how far east the systems dry slot will expand. This will be important to watch as solutions that show a more westerly track/wedge of dry air also depict convection developing farther to the west. 2) Should a more easterly solution come to fruition, we'll have to watch western MN for a potential sneaky fire weather day.

An EML, characterized by a plume of 8.5deg/km lapse rates, is forecast to expand over central MN Wednesday night into Thursday morning. Early morning convection will be possible on the nose of the LLJ/ahead of the EML, which is forecast to extend into northern MN. Would suspect skies are quiet across the MPX forecast area until midday, when the consensus solution illustrates the cold front advancing eastward into western MN. Convection that develops ahead of the front will have the potential to become severe per environmental forecast soundings that highlight ~1000 J/kg of CAPE, steep mid-level lapse rates, and unidirectional shear through the column. SPC's new Day 3 outlook features a Slight Risk (Level 2/5) across southwestern MN and a larger Marginal Risk (Level 1/5) for the remainder of the WFO MPX forecast area. We'll be able to better refine timing and specifics, but we can say it looks like damaging winds will be the primary hazard associated with these showers/thunderstorms. As referenced in the previous discussion, rainfall totals should generally remain below a half inch, but it's also likely that there will be a few winners of heavier amounts tied to the stronger convective cells.

Temperatures will cooldown behind the frontal passage as weather across the northern CONUS will be under the influence of a an upper low/troughing over south central Canada. Look for highs in the upper 50s/near 60 and lows in the 30s to lower 40s through the weekend. Most of the weekend aims to run dry, though we do start to see the return of PoPs heading into early next week as a shortwave moves across the central CONUS. NBM's PoPs of 30-40 percent on Monday are reasonable.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 621 AM CDT Tue Apr 21 2026

Solid VFR conditions expected throughout this duration. Clear skies expected, although some high passing cirrus may occur from time to time. Light/variable winds this morning will turn N during the day today then more easterly tonight into Wednesday morning, all with speeds under 10kts.

KMSP...No additional concerns.

/OUTLOOK FOR KMSP/ THU...MVFR/-RA likely, mainly PM. Wind S 10-15G25-30 kts. FRI...VFR. Wind. W 10-15G25kts. SAT...VFR. Wind NW 10G20kts.

MPX WATCHES/WARNINGS/ADVISORIES

MN...None. WI...None.