Area Forecast Discussion
Issued by NWS Twin Cities, MN
Issued by NWS Twin Cities, MN
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847 FXUS63 KMPX 222356 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 656 PM CDT Sat Jun 22 2024 .KEY MESSAGES... - Rain showers and embedded thunderstorms are expected this s afternoon. The threat for severe weather is low. - There`s a Slight Risk (level 2 of 5) of severe storms Monday evening. - Active pattern continues with another round of precipitation expected Thursday afternoon through Friday night. && .DISCUSSION... Issued at 329 PM CDT Sat Jun 22 2024 An area of showers and embedded thunderstorms across west central Minnesota will continue to trek just north of due east this afternoon. The severe threat is low, not non-zero, but the main concern is the additional rainfall on already saturated soils and rising area rivers/tributaries. Additional rainfall amounts of 0.25" to 0.5" are likely, with locally up to 1 inch where embedded thunderstorms track. We are closely watching rain rates and amounts as this area tracks through given the potential impact to the ongoing flooding across southern Minnesota. After this exits east we`ll dry out for the remainder of this weekend. Temperatures will stick in the low to mid 70s this afternoon and lows in the upper 50s and low 60s tonight. Sunday looks to finally be a drier day for a change and presents us an opportunity to tackle any yard work that`s piled up over the past week or two. The next wave arrives in northwest flow from Canada late tonight and will move across northern Minnesota into northern lower MI on Sunday. There is a threat for some isolated afternoon showers & storms northeast of I- 94 but instability will be minimal, around 500 j/kg, so the severe risk Sunday is low and most of us should remain dry! Our attention turns to Monday and the potential severe weather threat, especially Monday evening and Monday night. SPC`s severe weather outlook highlights much of Minnesota and NW Wisconsin under a Slight risk (2 out of 5) for severe thunderstorms. Monday and Tuesday will be the warmest days of the week with highs in the mid to upper 80s and given the recent rainfall dewpoint temps will be in the upper 60s and 70s across the region. Warm air advection ramps up in response to a shortwave in Canada. This should lead to an impressive build up of instability in the warm sector. How favorable will the thermodynamic environment get? A mean of various guidance would build in 3000 to 4000 j/kg MLCAPE values beneath steep mid level lapse rates Monday afternoon. Forecast soundings do have favorable curved hodographs with good low level shear and SRH that would be capable of supporting tornadoes, damaging winds, and large hail. Monday afternoon and evening`s severe potential is evident but there are a few questions that we`ll need to answer first. Surface to 3km lapse rates are forecast to range between 5.5 to 6.0 deg/km under an appreciable cap. 700 hPa temperatures will range from 12 to 16C and likely require additional forcing mechanism for initiation in the warm sector Monday PM. Looking aloft, the upper level support isn`t great as the best forcing remains off to the north across northern Minnesota and Canada. The most likely scenario is that convection fires Monday evening over NW MN where a weaker cap is overcome by either the sfc cold front and/or the strengthening LLJ before growing upscale into an MCS and tracking across central MN into NW WI. This would still pose a severe threat across our area, but the warm sector likely remains storm free throughout Monday afternoon. Our environment will be capable of supporting severe thunderstorm threat if we`re able to get thunderstorms to initiate. There is plenty of uncertainty with what scenario will play out. Any convection that develops will pose a heavy rain threat with ample moisture to work with. This will support impressive rain rates where storms track, although the isolated to scattered coverage should help limit any additional flash flood concerns for now. Tuesday and Wednesday appear to offer a much needed stretch of dry weather. High pressure will bring drier air as it settles in through mid-week. The end of the week looks active as another system impacts the Upper Midwest. For Thursday through Friday night, a shortwave will trek along the international border to Lake Superior. Guidance supports the development of a LLJ across the Dakotas and western Minnesota Thursday night. This would support the potential for two rounds of thunderstorms, one Thursday night with the LLJ and one Friday afternoon and evening with the cold front passage. Given the recent wet pattern, this system will support both potential severe weather and excessive rainfall. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 656 PM CDT Sat Jun 22 2024 Scattered showers are lingering across eastern MN and WI early this evening. Otherwise, MVFR/IFR cigs will prevail this evening, then should rise to VFR overnight outside of any foggy areas. Northwest winds will continue, with some gusts of 20 kts Sunday afternoon. KMSP...Cigs around 1kft and northwest winds 5-10 kts expected this evening. Improvement is expected overnight as drier low level air arrives. /OUTLOOK FOR KMSP/ MON...VFR. Chc -TSRA/MVFR late. Wind SSE 10-15 kts. TUE...VFR. Wind NW 10-20 kts. WED...VFR. Wind NW 5-10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ DISCUSSION...BPH AVIATION...Borghoff