188 FXUS63 KMPX 090745 AFDMPXArea Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 245 AM CDT Tue Sep 9 2025
.KEY MESSAGES...
- Scattered showers and a few thunderstorms are possible today. The highest chances (30-50%) reside across eastern MN/western WI.
- Temperatures continue to warm through the week. Weekend highs climb back into the mid to upper 80s across southern MN.
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.DISCUSSION... Issued at 245 AM CDT Tue Sep 9 2025
Early morning infrared satellite displays convection ongoing across the Arrowhead. This shower/storm activity has developed on the nose of a ~40kt low-level jet, which is oriented back to the southwest across much of MN into northern IA. To the west,satellite imagery captures isolated showers and perhaps a storm or two across SD, which are tied to a weak ~1010 mb surface low near Pierre. Our forecast area remains quiet and dry at this hour, though it is noticeably warmer as compared to recent mornings. Continued southerly flow will limit temperatures from falling out of the lower 60s through daybreak (Those were our high temperatures just a few days back!).
Today`s precipitation forecast features both complexity and a degree of uncertainty. Aloft, a weak wave within the upper-flow is progged to slide southeast over the region, which will place the best source of synoptic lift over eastern MN/western WI. In addition, the warm front that is located across northern MN (associated with the ongoing warm advective precipitation) is forecast to become diffuse later today and will gradually drift southeast. This feature will likely not be a major forcing mechanism for convection, however there may very well be enough convergence along the boundary to produce isolated to scattered showers and a few storms across western/central MN. Overall, the forcing for today`s precipitation chances is on the weaker side and that is likely why we`ve can see a variety of solutions displayed across the CAM suite. We leaned heavily on the RRFS-A/HRRR/REFS handling of the short term forecast in our grids, due to their better handling of the ongoing regional convection at initialization. In doing this, the latest forecast features roughly three PoP sub-groups. The first is from daybreak through midday, where slight chance PoPs are in place across the entire forecast area, largely tied to the position of the low-level jet axis overhead. In essence, we`re saying there is a chance for a few showers anywhere this morning, however coverage will likely be low. The second "sub-group" appears across eastern MN/western WI from midday through the afternoon, where ~30-50% PoPs exist. The passage of the weak shortwave aloft is the focus for these PoPs and is the driving factor behind the higher confidence. We are not expecting these storms to pose a severe weather threat given limited instability and weak shear. Finally, the third "sub-group" is also the lowest confidence portion of today`s forecast. We have opted to maintain slight- chance PoPs through the afternoon and into the evening across south central MN, tied to the approach of the aforementioned diffuse boundary that will act as a wind shift/focus for surface convergence. Guidance varies greatly in the what the environment may look like across western/southern MN during this time period, however the general consensus is an atmosphere characterized by slightly higher dew points and as a result greater instability. Perhaps this scenario will allow for some airmass type showers/storms (though this is poorly represented across most of the hi-res guidance suite).
To sum it all up, it`s likely that there will be plenty of dry time today. However, various weak forcing mechanisms will support isolated to scattered convection throughout the day. Despite the low confidence in specific`s regarding point-based timing, there is fairly high confidence that any convection that develops will remain sub-severe due to limited instability and weak shear. Rainfall amounts are generally expected to remain below a quarter of an inch.
Large scale ridging will build east over the Upper Midwest for the remainder of the work week. The large scale subsidence will yield dry weather and warming temperatures. Afternoon highs are forecast to top out in the mid 70s Wednesday, the upper 70s/low 80s Thursday, and continue to warm into the low to mid 80s for Friday. It`s doesn`t look like the warming trend stops for the first half of the weekend, as the ridge axis remains positioned directly over the region. NBM`s latest run advertises highs in the mid to upper 80s, perhaps near 90 degrees across southern MN on Saturday. The NBM takes a step back into the low 80s Sunday and then into the upper 70s early next week. At this time, I`d say confidence in surface temperatures drops quite a bit from Sunday onward given diverging solutions in the global guidance with respect to the strength/duration/and position of the large scale ridging. Global guidance illustrates an omega block setting up on Sunday, however the degree of "blocking" vs. a more progressive transition of the upper features is a question at this distance. Should the Upper Midwest remain beneath the ridge axis, temperatures may remain well above normal into next week. Conversely, a more active upper pattern and quicker breakdown of the ridge should promote cool, but still mild temperatures and the return of precipitation chances.
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.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1240 AM CDT Tue Sep 9 2025
Regional radar displays showers and thunderstorms ongoing across northeast MN, along with a few showers moving through SD. Hi-res guidance continues to struggle with the evolution of shower and thunderstorm chances through the 6z TAF period. Opted to lean on the drier side for the western/central MN terminals, where weaker forcing has resulted in less of a precipitation footprint in the latest guidance. Have included PROB30s at MKT/MSP/RNH/EAU where the better chances for isolated to scattered convection will be later today. Can`t rule out some showers in the morning, however the main focus for the PROB30s is tied to afternoon thunderstorm activity. Cigs should continue to trend VFR through the night, then are forecast to lower in association with any precipitation that develops.
KMSP...LLWS setup remains marginal and will improve early in the 6z TAF period. The overall theme should be continued dry weather through the night and into the first half of the day. We cannot rule out a few showers in the morning, however confidence was too low to include in the TAF. Instead, the greater focus is from 18-24z, when isolated thunderstorms are forecast to develop over eastern MN/western WI. Continued to maintain a PROB30 for the potential convection.
/OUTLOOK FOR KMSP/ THU...VFR. Wind SE 5-15 kts. FRI...VFR. Wind SE 10-15 kts. SAT...VFR. Wind SE 5-10 kts.
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.MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None.
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DISCUSSION...Strus AVIATION...Strus
NWS MPX Office Area Forecast Discussion