Area Forecast Discussion
Issued by NWS Twin Cities, MN
Issued by NWS Twin Cities, MN
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855 FXUS63 KMPX 280907 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 407 AM CDT Fri Jun 28 2024 .KEY MESSAGES... - Showers & thunderstorms move across Minnesota & Wisconsin this morning. Rainfall amounts around 0.5" are expected, with amounts closer to 1" across central Minnesota. - Dry this weekend, with the next round of widespread rain coming Monday. Heavy rain & severe thunderstorms are possible. && .DISCUSSION... Issued at 323 AM CDT Fri Jun 28 2024 Warm-air advection driven showers and thunderstorms continue overnight across the eastern half of Minnesota & western Wisconsin, while a decaying MCS also enters western Minnesota & move eastwards through the morning. MLCAPE values fall off greatly along the MN/SD so we`re not expecting anything strong or severe out of the MCS, but MUCAPE values near 1000 J/kg extending all the way to the MN/WI border mean the complex should hold together through the morning. The MCS will take over as the primary driver of precipitation this morning as it overruns the WAA-driven precip, with the rain coming to an end by 8-9 AM across eastern Minnesota & by late morning across western Wisconsin. Widespread rainfall amounts around 0.5" are generally expected, but amounts closer to 1" are likely across central Minnesota where the WAA-driven precip overnight has been more widespread. While the rain comes to and relatively early in the day, forecast soundings show plenty of boundary-layer moisture which will result in low cloud cover sticking around through much of the afternoon. This will limit instability for a potential second wave of thunderstorms as the surface cold front moves through the area during the afternoon. The widespread cloud cover in addition to a weakening surface low means the threat for severe thunderstorms, let alone any thunderstorm development, continues to trend lower with the SPC downgrading our area to a Marginal Risk. A few CAMs still initiate cluster of thunderstorms across far-southern Minnesota so the threat can`t be totally ruled out, but most locations can probably bet on staying dry this afternoon once the morning precipitation ends. Shower and thunderstorm chances look a little more likely late tonight across central Minnesota as a compact shortwave pivots through the region. Most CAMS are in agreement with initiates isolated to scattered thunderstorms with this feature, mainly north of I-94. Shear values will be quite high overnight so a few organized cells can`t be ruled out with a threat for isolated hail. Dry & pleasant weather is expected this weekend as high pressure builds over the region behind today`s system. Temperatures will be on the cooler end for late June with daytime highs only expected to be in the low 70s. Sunday morning looks to be seasonably chilly as well with lows dropping well into the 40s, & a non-zero chance at very patchy frost wherever the core of the high sets up across northern MN/northern WI. The dry break will be short-lived however, as the upper-air pattern becomes more active & a surface low out of the central plains brings another round of widespread soaking rainfall Monday through Tuesday. Ensemble mean Precipitable water values approach 2" across southern Minnesota & NBM/ensemble guidance show probabilities over 50% for rainfall amounts exceeding 1". Exact rainfall amounts still depend on the track & timing of the system, & whether any boundaries can develop for storms to train along, but the rainfall amounts will have to be watched Monday for additional flooding impacts. An environment supportive of strong or severe thunderstorms is also likely wherever the surface low ends up during the afternoon & early evening, although confidence in the timing of the system remains low at the moment. The pattern has the potential to remain active through the rest of the week, although models diverge on when & where any shortwaves develop & generate additional precipitation tracks. Midweek generally favors drier conditions but precipitation chances ramp up again later in the week. Temperatures will generally be close to normal with highs in the upper 70s to low 80s along with muggy dew points. && .AVIATION /06Z TAFS THROUGH 06Z SATURDAY/... Issued at 1130 PM CDT Thu Jun 27 2024 A broad area of light rain extended from far western WI across much of MN, though there were some breaks, primarily in portions of central and southwest MN. More showers, however, continue developing in western MN. There have also been some thunderstorms northwest of Alexandria and in the southwest near Worthington. As the low level jet strengthens, most areas will be susceptible to thunder for two or three hours early Friday morning. The other concern is MVFR/IFR ceilings. As of 03Z, MVFR is spotty across the region, but models remain consistent with developing widespread MVFR after 10Z Friday. Given the low level moisture in the wake of the rain, MVFR makes sense and it is certainly plausible for IFR to occur. KMSP...the two main concerns are the potential for south winds to gust above 30 knots Friday morning during the time when MVFR ceilings are likely and IFR ceilings are possible. As for a thunderstorm chance Friday afternoon, it appears that low clouds lingering well into the afternoon will reduce that threat, though it will not be impossible for storms Friday afternoon. /OUTLOOK FOR KMSP/ SAT...VFR. Wind NW 10-15G25 kts. SUN...VFR. Wind N bcmg E 5-10 kts. MON...VFR/MVFR, chc -TSRA. Wind SE 10-15G25 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ DISCUSSION...ETA AVIATION...TDK