Area Forecast Discussion
Issued by NWS Twin Cities, MN
Issued by NWS Twin Cities, MN
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191 FXUS63 KMPX 280554 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 1254 AM CDT Sun Apr 28 2024 .KEY MESSAGES... - A cool & rainy day is on tap for Sunday. - Another round of showers & thunderstorms likely on Tuesday, with a few stronger storms possible across S MN. - Rest of next week looks dry with seasonable temperatures. && .DISCUSSION... Issued at 248 PM CDT Sat Apr 27 2024 Satellite imagery highlights a potent mid-level trough over the western CONUS with a more vigorous shortwave evident over the Four Corners region. Our sfc low is moving over Lake Superior leaving the Upper Mississippi valley in the wake with northwest or westerly winds and seasonable temperatures. Speaking of temperatures, Looking back toward the southern Plains, another developing sfc low is ejecting out of the Four Corners and will trek into the Plains later today. Current obs reveal temperatures in the mid to upper 50s with 10-15mph W/NW winds. Dry conditions last into the overnight period ahead of the next system that`ll bring another round of rain & wind on Sunday. For Sunday, We`ve seen things continue to slow down vs previous guidance runs. PoPs really ramp up after 12z Sunday morning so tonight should remain dry for most of us. Our sfc low looks to remain to our south on Sunday and this will keep us on the cooler side. High temperatures will be rather brisk, struggling to hit 50 outside of the I-90 corridor, with a steady rain expected as well. As for the severe risk, SPC day 2 places I-90 and S MN into the Marginal risk category but guidance doesn`t seem all to excited with storms in S MN. The better environment stays off to our south and east in Iowa & Wisconsin as the warm front really doesn`t clear our counties. An isolated storm or two will be possible in S MN, particularly late afternoon into Sunday evening, with a non-zero chance of becoming strong or severe. Looking at the week ahead, we`ll dry out and remain cooler to start the week with high temps in the low to mid 50s on Monday. The cooldown doesn`t last long as a warm front moves through Monday night into Tuesday, with temperatures forecast into the low to mid 70s Tuesday afternoon. Along with the warmer temperatures comes another, arguably better set up for thunderstorms Tuesday afternoon. Guidance tracks a healthy shortwave through the Dakotas on Tuesday. NBM ramps up the PoPs Tuesday afternoon. This system tracks the cold front through southern & central MN Tuesday afternoon & evening. This lines up nicely with diurnal heating maxima and should mean we`re dealing with convection vs stratiform rain. There will be a severe risk with a low CAPE/higher shear set up looking to play out. Forecast soundings highlight a few 100 J/Kg of surface- based instability and 35+ kts of effective shear & curved hodographs. Our limiting factor will be the lack of sufficient lapse rates and that should keep the severe threat to an isolated strong storm or two vs many. Still, this looks to be an environment that could support a few marginally severe storms. Afterward Tuesday, we`ll return to cooler seasonable temperatures (50s/60s) and a break from precipitation until next weekend. So why does the forecast have a slight chance for showers Thursday and Friday if guidance is mostly dry? The NBM`s make up contains a lot of ensemble members that likely feature timing differences or features that likely won`t impact us. This time of year going forward 30 to 40 PoPs are pretty standard despite no driving system in the deterministic models. So, the NBM is actually favoring drier conditions which DOES line up with the bulk of the ensemble guidance. In reality, seasonable temperatures and a stretch of dry weather will wrap up the week before next weekend. Guidance is beginning to hint at another low pressure tracking into the Upper Midwest that would give us yet another damp/cool weekend. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 1237 AM CDT Sun Apr 28 2024 Mixed bag of low VFR/high MVFR ceilings over the terminals early this morning. General trend was to keep cig heights around 3k feet over the next few hours. MVFR ceilings will win out from daybreak onward, with further lowering expected as an incoming storm system moves in from the south. Initial band of rain will likely battle some low-level dry air, so opted to bring -SHRA in at each terminal mid to late morning. More widespread, sustained rainfall will arrive heading into the afternoon and will be accompanied by IFR ceilings and visibility. Chances for thunder look very low, so have continued the trend of excluding any mention from the TAF set. Winds increase out of the ENE through the afternoon, with gusts up to 30 knots. KMSP...Dry weather expected at the terminal until mid-morning at the earliest. Few hours of -SHRA will precede higher rainfall rates and expected IFR conditions during the afternoon & evening. Gusty northeast winds will create crosswind scenario on the parallels later today. /OUTLOOK FOR KMSP/ MON...MVFR/-SHRA early, then VFR. Wind E bcmg WSW 15-20G35 kts. TUE...VFR in the morning, MVFR/-TSRA likely in the afternoon/evening. Wind SW 10-15G30 kts. WED...VFR, chc MVFR/-SHRA. W 10-15 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ DISCUSSION...BPH AVIATION...Strus