Area Forecast Discussion
Issued by NWS Twin Cities, MN
Issued by NWS Twin Cities, MN
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611 FXUS63 KMPX 301948 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 248 PM CDT Thu May 30 2024 .KEY MESSAGES... - Showers and weak thunderstorms move from west to east the rest of today through tomorrow morning. Lingering showers and storms possible tomorrow. No severe storms currently expected. - Best chance for widespread showers and storms arrives Sunday into Monday, with a continued on and off diurnal pattern through next week. Alongside Sunday into Monday, Tuesday/Tuesday night appears to have a better chance for a few stronger storms. && .DISCUSSION... Issued at 248 PM CDT Thu May 30 2024 There are a few strikes of lightning within what has otherwise remained a cluster of unorganized showers in western Minnesota this afternoon, with the complex moving from south-southwest to north- northeast amidst southerly steering winds at the surface. Satellite shows the limited extent to this grouping as more organized convection has begun to fire in east-central South Dakota, with this line of convection producing our only concern-worthy storms for later this evening as they move into southwestern Minnesota. Elsewhere, we have upper level clouds stemming from the weak convection and some fair weather cumulus over portions of western WI. Showers and weak convection will gradually move eastwards this afternoon and evening before stalling around sunrise tomorrow morning with a weak boundary draped over east-central to southern Minnesota. The question is how long showers linger and if we see any organized storm activity within, and CAM response has remained relatively muted today with limited thunderstorm activity due to a lack of significant instability. The nocturnal showers are propped up by a present but weak low level jet which looks to dissipate after sunrise tomorrow morning. Scattered showers overnight could produce over a quarter inch of rainfall in some locations, however there will be gaps so not everyone will see appreciable rainfall from this system as it pushes out of the area tomorrow. Further chances for isolated to scattered showers and weak thunderstorms will arrive on Saturday driven by diurnal processes in an area of weak AVA as a trough swings through central Canada. Saturday has the best chance to stay mostly dry for the next few days as the forcing is weak and cloud cover looks to hamper any kind of significant instability from developing. This changes by Sunday as flow aloft remains zonal but a strong 850mb jet begins to advect moisture northwards originating from the Gulf, with instability growing later on Sunday as the jet strengthens over Minnesota. Upper level support is weak but present in the form of zonal flow and a bit of shortwave energy pushing through the region, however the main player will continue to be a surface low forming at the nose of the LLJ in northern Minnesota, with WAA and the LLJ helping to produce more widespread rainfall and the potential for a few stronger storms late Sunday into early Monday. We have yet to get CAMs involved, however synoptic scale ensembles and deterministic solutions show a complex of showers and thunderstorms present over much of the state by early Monday morning, and there should be enough instability present to maintain thunderstorms with the main question being the strength of any storms. For now, expect some widespread moderate to strong rain showers and the potential for a few storms with a chance to see a stronger complex of storms or MCS depending on what CAMs look like as we get a bit closer. As showers and storms dissipate during the day Monday, we see around a 24 hour break before yet another system looms on the horizon, this time in the form of an occluded upper level low producing widespread synoptic lift and spinning up a surface low by late Tuesday to early Wednesday. Uncertainty remains fairly high due to differences in timing and the stacking of upper level and surface features, however the dynamics to produce more widespread rainfall and stronger storms does appear present within current guidance. The system continues to be the primary player in the region through much of next week as it occludes and spins over the Great Lakes, with decent consistency over the last few days of this feature persisting through much of next week. This remains a `wait and see` type of forecast as we need to get through our first system Sunday into Monday before we can have greater confidence as it pertains to next week, just keep in mind that a continued unsettled pattern looks to persist into the first week of June. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1225 PM CDT Thu May 30 2024 A difficult TAF period ahead with increasing clouds and shower chances increasing after 00z as they spread eastwards overnight. AXN/RWF are already seeing -SHRA/-TSRA approaching the sites by 20-21z, with increasing chances by 00z. As we get past 02-03z, -TSRA should transition to mostly -SHRA as the line pushes towards the rest of the sites. Winds initially at 150-180 at 10-15kts gust up to 25kts through this afternoon before decreasing as the -SHRA arrives. Chances for -TS once again pick up towards the end of the period roughly 18-21z tomorrow. KMSP...The main consideration within the TAF is whether or not to include TS mention overnight, which has been omitted in favor of -SHRA for now. There is still a roughly 10-20 percent chance for lightning from 06z to 13z which is the primary time frame for -SHRA, however the confidence is still fairly low as the environment remains unfavorable until tomorrow afternoon. /OUTLOOK FOR KMSP/ SAT...VFR/MVFR, chc -TSRA. Wind SW 10-15kts. SUN...VFR, likely MVFR/-TSRA late. Wind S 10-15kts. MON...MVFR/-TSRA early, then VFR. Wind W to NW 10kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ DISCUSSION...TDH AVIATION...TDH