textproduct: Twin Cities

KEY MESSAGES

- Another round of showers and weak storms will affect primarily southern MN this morning. Isolated showers with some rumbles of thunder remain possible during the day.

- Another chance for rain arrives Thursday into Friday, with a few strong storms possible.

- Quiet weather returns after Friday, with seasonal temperatures and only hit or miss chances for rain.

DISCUSSION

Issued at 301 AM CDT Tue Aug 18 2026

The initial round of showers and storms that was expected as this mid level shortwave coupled with a surface front push through the area, and round two is the cluster of showers and storms over eastern South Dakota. This second round is expected to move across southern Minnesota this morning, arriving in our coverage area closer to 5-6am and affecting the area along and south of the Minnesota River, with the best chance for more than showers being on the southern edge of the line that is more likely to be in Iowa. All this to say, we do not expect to see significant or widespread impacts from the second round, primarily some showers and maybe rumbles of thunder that exits the area later this morning. The CAMs all have some form of cold air northwest flow isolated showers lingering throughout the day, and with a bit of mixed layer CAPE we could see a few rumbles of thunder from any activity as well, although with unidirectional northwest flow, it is unlikely that anything more than a rumble or two results from it. The front will fully pass through during the day and leave us with weak high pressure by this time tomorrow morning, resulting in quiet weather through Thursday when our next chance for showers and storms arrives. Temperatures today and tomorrow will be in the 70s thanks to the weak subsidence from the weak high pressure as well as the meager CAA from the northwest flow, returning to the 80s on Thursday as our next system arrives.

Speaking of, our next chance for rain will arrive on Thursday as a broad area of weak forcing stretches south of a weak surface low in central Canada, with northwesterly flow aloft continuing. The surface low looks to move southeast towards the northern tip of Lake Superior by 12z Friday, and as it does our area finds itself between the weak leading warm front and sagging cold front, resulting in chance for scattered showers and storms starting late Thursday morning and continuing until the cold front moves through by midday Friday. The setup is rather interesting with a narrow upper level jet streak left exit region arriving Friday morning coupled with a low level jet, with the low level jet also within northwest flow which is a rather unique setup as typical nocturnal low level jet features tend to favor southerly flow. One would think we will struggle with moisture with this kind of setup, which is certainly a consideration, however most of the guidance shows dew points in the low to mid 60s with the ECMWF even suggesting upper 60s by Thursday evening. As long as our low level advection does not contain significant dry air, we should have enough moisture to force showers and storms. I would expect the forecast trend as we approach to gradually favor increasing PoPs and QPF, with ensemble probabilities showing above 80% likelihood for at least a tenth of an inch across most of the MPX coverage area by 7am Friday. The percentages get lower than 30% for a half inch or more, which seems realistic given the pattern. As the cold front arrives on Friday, one last push of precipitation will make way for more seasonal temperatures and weak high pressure to round out the 7 day period into early next week. The longer range pattern continues to favor northwest flow aloft as the ridge slides westwards, giving us potential for shortwaves to produce precipitation, however also favoring a relatively low confidence forecast at this time scale.

AVIATION /18Z TAFS THROUGH 00Z THURSDAY/

Issued at 1144 AM CDT Tue Aug 18 2026

Lingering rain and cloud cover is clearing out from this morning's showers, resulting in widespread VFR conditions to start the afternoon. Isolated storms are expected to development along a southward moving front this afternoon. This leaves KMKT and KEAU in the areas with the best chance of seeing any impacts. Winds remain primarily out of the W/NW today, and become light and variable overnight.

KMSP...There is a low end chance that a stray storm develops north of the front this afternoon, but otherwise anything tied to the front will remain south of the terminal with it just now moving through already.

/OUTLOOK FOR KMSP/ THU...VFR, chc PM MVFR/-TSRA. Wind SW 10-15 kts. FRI...VFR. Wind W 10-15 kts. SAT...VFR. Wind NW 10-15 kts.

MPX WATCHES/WARNINGS/ADVISORIES

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