


Area Forecast Discussion
Issued by NWS Twin Cities, MN
Issued by NWS Twin Cities, MN
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031 FXUS63 KMPX 151824 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 124 PM CDT Tue Jul 15 2025 .KEY MESSAGES... - Hot & humid today with heat index values approaching 100 degrees. - Numerous rounds of showers & thunderstorms this afternoon into Wednesday. Locally heavy rainfall in excess of 3-4" is likely, along with a few severe storms this evening. - Well-below normal temperatures Wednesday, with below normal temperatures into the weekend. && .DISCUSSION... Issued at 245 AM CDT Tue Jul 15 2025 It`s a very warm night with sustained southerly flow & warming temperatures aloft keeping temperatures from cooling off much overnight, highlighted by MSP still maintaining 80 degrees at 3 AM. Some robust thunderstorms have taken advantage of the 3000+ J/kg of CAPE overnight across South Dakota, & the question for the rest of the night becomes how long could convection continue across central Minnesota? There`s little deep shear to work with & 700 mb temperatures will continue to warm above 10 C through the early morning, so it`s unlikely that the ongoing severe cell over the SD/ND/MN border would continue for much longer - but, the lack of shear hasn`t kept it from maintaining it`s intensity for several hours now. A thunderstorm threat looks plausible for Morris, Alexandria, & far-west central Minnesota over the next hour or two, but the storm should dissipate beyond that given it`s entering a more capped environment. With that uncertainty stated, we get into the thunderstorm chances for today. Strong capping is expected to persist into much of the afternoon across central & southern Minnesota, however a few high- resolution models attempt to initiate a round of scattered thunderstorms as early as late morning over central Minnesota. This is a result of strengthening ascent in the right entrance region of a strengthening jet over northern Minnesota, which could weaken the capping enough for storms to initiate given the very unstable atmosphere already in place. Think these morning solutions are a bit too early & strong with the strengthening of the jet, but we should see thunderstorm chances increase through the afternoon across central Minnesota, and by the evening across southern Minnesota & west-central Wisconsin. Assuming we don`t get the earlier round of precipitation, & we clear out the cloud debris from overnight, temperatures should be able to warm into the low to mid 90s ahead of the slowly advancing cold front, with head index values approaching 100 degrees this afternoon. A threat for severe storms exists with the initial rounds of thunderstorms to develop this afternoon & evening, owing to surface- based CAPE values of 2500-3000 J/kg & deep shear values increasing to around 30 kts with the strengthening jet aloft. The severe threat looks to mainly be from damaging wind gusts & large hail from a few clusters of storms, primarily across central Minnesota & northwest Wisconsin where the shear values will be greatest & storms will initiate during the most unstable part of the day. The severe threat will wane through Tuesday night, but multiple rounds of thunderstorms are expected to continue developing through the night & overnight hours as the forcing aloft continues along the slowly moving cold front. Locally heavy rainfall becomes the main threat Tuesday night into Wednesday morning as storms will be efficient rainfall makers with precipitable water values approaching 2" along the front along with slow storm motions. Several high-resolution models depict localized amounts in excess of 3-4", generally somewhere across east-central Minnesota & northwest Wisconsin.The good news is that these heavy rainfall amounts come mainly from multiple waves of thunderstorms through Wednesday morning, as opposed to thunderstorms training over the same location, which should mitigate the flash flooding potential as water from each wave should have some time to soak into the ground. Outside of these locally excessive amounts, generally expect widespread rainfall totals of 1-2" across central Minnesota & western Wisconsin, tapering down to 0.5-1" across southern Minnesota. Precipitation will likely linger into Wednesday afternoon, but generally as light rain showers as we`ll be in the much cooler air on the back side of the cold front & surface low. This will create a nice reprieve from today`s heat in areas where it rains & stays cloudy for most of the day, with afternoon highs remaining in the 60s. Temperatures will still warm well into the 70s across southeast Minnesota & western Wisconsin where the front won`t pass until the afternoon. Temperatures remain cool Thursday & Friday as well as Canadian high pressure slides over the region, but we`ll have to see how much smoke accompanies the high before calling them a few top 10 weather days. More seasonable weather returns over the weekend & into next week, along with a few chances for rain as a number of shortwaves pass over the Upper Midwest. Models vary with the timing of these waves, but Friday night-Saturday morning & Monday into Tuesday looks to be the main timing windows. the active pattern continues through next week, as very strong ridge develops over the central plains & mid-Mississippi valley, placing our area under a classic "Ring of Fire" pattern on the northern periphery of the ridge. A few severe thunderstorm complexes look possible somewhere across the Upper Midwest late next week, along with very warm & muggy conditions. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1251 PM CDT Tue Jul 15 2025 Some scattered development of storms and showers is occurring along the cold front in west/central MN and near the Twin Ports associated with the warm front. Models continue to show a messy storm mode along the front as it sags southward this evening. As the boundary stalls, storms could train over parts of east- central MN and western WI. Mostly SHRA is expected, but with plenty of instability present, periods of TSRA will remain a possibility. There is just limited wind shear, so storm organization will be lacking making it more of a pulse-y environment. Cigs will gradually lower through the night, with all sites reaching low MVFR, and many dipping into IFR for a period tomorrow morning. KMSP...Confidence is high for a 2-4 hour period of storms this evening, but the exact timing is uncertain. Recent model trends indicate a later start time, closer to 02z, however the early development out west warrants keeping 01z as the start time for the TEMPO this evening. The boundary stalls overnight, and scattered showers and storms will move from west to east. There is a chance (30-50%) that this cluster of rain stays north of KMSP, allowing a 6-8 hour window of dry conditions before more consistent yet less intense rain tomorrow morning. We could see BR/DZ continue after 18z tomorrow, especially if the low cigs hand around longer than expected. /OUTLOOK FOR KMSP/ THU...VFR. Wind NE 5-10 kts. FRI...VFR. Chc -TSRA after dark. Wind SE 5-10 kts. SAT...VFR. Chc -TSRA early morning. Wind SE bcming N 5-10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...Heat Advisory until 8 PM CDT this evening for Anoka-Carver- Dakota-Hennepin-Ramsey-Scott-Washington. WI...None. && $$ DISCUSSION...ETA AVIATION...BED