480 FXUS63 KMPX 081835 AFDMPXArea Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 135 PM CDT Mon Sep 8 2025
.KEY MESSAGES...
- After a cool start to the month, normal temperatures with highs in the 70s this week.
- Multiple chances for showers and thunderstorms, with the best chances tonight into tomorrow.
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.DISCUSSION... Issued at 259 AM CDT Mon Sep 8 2025
Today and Tomorrow... After a prolonged period of cold air advection to start the month we have now moved into a warm air advection regime. This will help to limit the cooling this morning, with temperatures not as frosty as they were yesterday morning. Despite this, with clear to mostly clear skies we are still radiating out amd have temperature falling into the 40s. This could cause some of the more frequent fog spots (like valley and near bodies of water) to have fog this morning as they reach saturation. Once the sun comes out temperatures will warm into the 70s today, with a chance to break 80 in western Minnesota. As this is largely advecting in aloft around 850 mb, a substantial warm nose is expected to develop today. This will largely inhibit convective chances for much of the day. Even when convection might form later today into tonight an elevated storm is more likely than a surface based storm. Precipitation timing will favor late as the LLJ will provide the best support tonight. The areas with the best chance for storms will be along the nose of this LLJ. Current high resolution guidance has this favoring to our north more into the arrowhead of Minnesota. There will however be a trailing boundary to the southwest of this area where lapse rates are expected to be better. The overall PoP is lower here, but if an updraft can come together there is a better chance for severe weather in this area of central Minnesota where SPC has placed a marginal risk. Overall this marginal risk area is very conditional and more likely than not will not occur, but if deep convection can initiate the conditions would allow for it to become severe with the forecast shear profile. This setup will continue into tomorrow morning until the warm front lifts through the region or the LLJ dissipates.
Another boundary is expected to pass through in the afternoon/evening tomorrow. Along this weaker, more cold frontal boundary another round of storms are possible. Once again elevated storms would be favored based on forecast soundings which favor high LCLs. There is more uncertainty when it comes to tomorrow afternoon and evening. More instability could come together, but getting an overlap with the better shear is what may not occur. Overall uncertainty in how all the pieces line up has kept us in just general thunder for day 2.
Wednesday through the Weekend... Looking ahead to the rest of the week we are still expected a ridge to build in for the middle of the week. This will provide for a period of drier weather in the middle of the week. Later in the week a trough looks likely to build in the western CONUS in global guidance. What has more spread though is out to the east over the eastern Canada/Great Lakes region. The different global models take the upper low on different paths. How this side of the larger scale pattern evolves will be one the keys in how active the weather is later in the week into the weekend. If it sets up more as a blocking pattern the warmer and dry weather will continue. For this reason NBM PoPs in the late week remain in the slight chance category due to the spread in global ensemble systems.
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.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 122 PM CDT Mon Sep 8 2025
Shower and thunderstorm chances are decreasing for the rest of the afternoon & this evening, but are still expected across much of the area early tomorrow morning into at least late morning. The coverage of these showers & thunderstorms is expected to remain fairly scattered, so will keep the PROB30 mention going for now until we can narrow down the most likely window of precipitation impacts to a two to four hour period. MVFR conditions would be likely with any showers but visibility could drop to VFR with heavier downpours during thunderstorms. Clouds will build this evening & become BKN/OVC overnight, with ceilings gradually lowering into the morning. The most likely window for precipitation tomorrow looks to be between 4-10 AM, with MVFR ceilings likely developing after this round of precipitation moves through. Southerly winds gusts up to 25-30 kts this afternoon, the gusts diminish after sunset but southerly winds will still be around 10 kts.
KMSP...A few rounds of showers are possible through the period, with the most likely window for precipitation between 5-10 AM. A rumble of thunder or two can not be ruled out, but the thunder chances may end up being higher for any isolated showers that may develop during the afternoon.
/OUTLOOK FOR KMSP/ WED...VFR. Wind E 5-10 kts. THU...VFR. Wind SE 5-15 kts. FRI...VFR. Wind SE 10-15 kts.
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.MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None.
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DISCUSSION...NDC AVIATION...ETA
NWS MPX Office Area Forecast Discussion