539 FXUS63 KMPX 091054 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 554 AM CDT Wed Jul 9 2025 .KEY MESSAGES... - Dry and warm today, with the chance of showers and thunderstorms across southwestern Minnesota overnight. - Marginal Risk (1/5) for strong to severe thunderstorms Thursday afternoon into early Friday. - Widespread soaking rain and storms continue Friday. && .DISCUSSION... Issued at 320 AM CDT Wed Jul 9 2025 Today and Tonight...Our Wednesday begins quiet and comfortable, with temperatures in the low to mid 60s. We have not seen much in the way of fog up until this point, however as temperatures cool under clear skies it remains plausible that patchy ground fog develops here and there through daybreak. It`ll be warm (mid 80s) and sunny for most locations today as the Upper Midwest remains under the influence of Great Lakes high pressure, which will also work to keep humidity levels in check. The exception will be across southwestern MN, where heat (upper 80s) combines with increasing humidity (dew points in the upper 60s). It`s these locations that will be the first to potentially see the return of active weather in the shape of showers and thunderstorms late tonight. Early morning upper air analysis reveals a dominate ~594dm ridge over the SW CONUS with troughing over the Great Lakes. Water vapor captures ongoing convection across the north central Plains, which appears to be tied to the low-level jet. This jet will push a warm front east across the Dakotas, which will serve as a focus point for new convection as a mid-level impulse pushes east across the flow today. It will take some time before any convection approaches western MN and it should be mentioned that CAM solutions offer a rather murky view into how things may unfold. In general, any convection that develops should strengthen into the evening in response to the nocturnal low-level jet, which will be positioned farther east tonight. A smoothed solution from the HREF displays a narrow axis of strong instability across the eastern Dakotas/into southwest MN. Would tend to think of the eastern axis of instability as the "tracks" for one or two clusters of storms to traverse into early Thursday morning. Additionally, HREF does keep ~1500 J/kg of MUCAPE in place across western MN well into the night. With this in mind, we have collaborated with neighboring offices to raise PoPs above the NBM to ~30-40% along and west of a line from Pope to Freeborn counties. The potential for these storms to be severe is low given a very weak shear. Wet Weather to End the Work Week...The main drivers of the forecast through the end of the week will be a shortwave trough moving across the Great Plains today into tonight, a stronger vort max moving across southern Canada, and the eventual phasing of these two features Friday into Saturday. Despite the complexity of the forecast, confidence is high in the return of widespread precipitation chances Thursday night through Friday. The evolution of tonight`s convective episode will have impacts on boundary/frontal placement heading into Thursday. However, the atmosphere should recover and allow for some airmass thunderstorms Thursday afternoon. A better chance for showers and storms will arrive later Thursday night as the shortwave trough advances east and ascent increases. Given strong instability, isolated instances of damaging wind and hail will be possible across western MN through the early morning hours of Friday -- though from a severe weather perspective, locations to the west across the Dakotas will have a higher threat with over these next few days. The nocturnal timing and weakly sheared environment will limit a greater risk. Phasing of the initial shortwave trough into the the northern vort max will be the driver of more widespread rain and thunderstorm chances on Friday. Guidance displays an atmosphere conducive for heavy rain, with PWATs nearing the 90th percentile of sounding climatology (>1.5"). Consensus blend shows the potential for 1-1.5" across eastern MN/western WI by the time all is said and done, however there are still some heavier solutions on the table tied to more convectively driven rainfall rates. We will likely have numerous clusters of rain and storms ongoing Friday, along with the potential for an MCV to develop and spin through the region (further enhancing the heavy rain potential). We`ll lean on upcoming CAM guidance to try and tighten the forecast up. Weekend and Beyond...Dry weather will return for much of the weekend following the passage of a cold front Saturday morning. Temperatures are forecast to be in the upper 70s to lower 80s Saturday and then climb into the mid 80s Sunday and Monday. The warming trend is tied to increasing warm advection ahead of the next storm system that aims to send a cold front/precipitation chances through the Upper Midwest on Tuesday/Wednesday. && .AVIATION /12Z TAFS THROUGH 12Z THURSDAY/... Issued at 550 AM CDT Wed Jul 9 2025 GOES-East satellite and surface obs indicate that patchy ground fog has developed across portions of the area. The fog/mist behavior is somewhat transient, so have opted to only include a TEMPO for visibility reductions at AXN where degraded obs have been the most persistent. Short term AMD`s may be needed if fog develops at any other terminal. Patchy fog will erode early in the 12z TAF period. Winds between 5-10 kts through the afternoon, with diurnal Cu around ~5kt feet. It`s possible the western MN will need -SHRA/TS mention late tonight in association with storms that are forecast to develop over the Plains. Confidence in impacts is currently too low to include in the 12z TAFs. KMSP...No additional concerns at this time. /OUTLOOK FOR KMSP/ THU...VFR. SHRA/TSRA likely late night. Wind S 10-15kts. FRI...SHRA/TSRA likely. Wind SW 5-10kts bcmg WNW 10-15kts. SAT...VFR. Wind NW 10-15 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ DISCUSSION...Strus AVIATION...Strus