Sunrise 5:27 AM   Sunset 8:54 PM Moonrise 1:44 AM   Moonset 2:21 PM

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FXUS63 KMPX 010528 AFDMPX

Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 1228 AM CDT Sat Jun 1 2024

KEY MESSAGES

- Showers & thunderstorms become more widespread this evening.
Localized heavy rainfall possible from south-central Minnesota through western Wisconsin.

- Severe thunderstorms & localized heavy rain possible Sunday evening, especially across western and southern Minnesota.

- Another chance for widespread rain likely Tuesday night.

UPDATE
Issued at 848 PM CDT Fri May 31 2024

Recent rain rates have been low enough that the flash flooding threat is decreasing. This is due to lower instability values as daytime heating has come to an end. Rain will continue along the largely stationary boundary tonight, but thunderstorm coverage will continue to decrease as we head into the overnight hours.

DISCUSSION
Issued at 240 PM CDT Fri May 31 2024

TONIGHT/SATURDAY MORNING...Showers and thunderstorms are becoming more widespread across southern Minnesota this afternoon, as frontogenesis & moisture convergence increase along a slow moving front. This activity will continue to spread north and east along the front this evening, with showers and thunderstorms continuing into tomorrow morning as the front slowly exits the area to the east. Storm motion & low-level moisture return vectors are oriented parallel to the slow moving front, meaning showers & thunderstorms are likely to train over the same areas tonight. Precipitable water values in the 90th percentile are high, but not extreme, so while localized heavy rain & flash flooding fare a potential concern - it does not appear to be a widespread threat. High resolution ensemble guidance continues to highlight a swath of 1-2" of rain from south-central Minnesota, through the southern reaches of the Twin Cities metro, & into west-central Wisconsin. Individual high-res models depict localized pockets of 3-4" where training of the heaviest thunderstorms occur, so while we can't say exactly where these heaviest amounts may occur, our confidence is fairly high that we will see some localized heavy rain impacts tonight through tomorrow morning. CAPE & shear values are fairly paltry for a severe weather threat, but can't rule out isolated small hail and/or gusty winds from a few storms this afternoon & evening.

SATURDAY-SUNDAY MORNING...The rain will be out of eastern Minnesota by mid-morning & western Wisconsin by early afternoon, with dry weather then expected into Sunday afternoon.
Guidance continues to indicate an environment favorable for severe weather developing across western Minnesota by late Sunday afternoon, ahead of a cold front/surface low approaching out of the eastern Dakotas. MLCAPE values around 2000 J/kg & effective bulk shear of 30-40 kts will support all modes of severe weather, although the threat for large hail/tornadoes looks to mainly be limited to discrete supercells early in the event across eastern SD/far-southwest MN. Early long-range CAM guidance suggests that these initial discrete storms will merge into a MCS by the evening, which will move into western & southern Minnesota through the evening. Instability values are forecast to drop off across central Minnesota, so the severe threat is not really anticipated to continue into eastern Minnesota & western Wisconsin Sunday night, but we'll have to see if this trend continues. Heavy rain could also be a concern given PW values forecast to be above the 90th percentile, but the progressive nature of the MCS & its expected weakening through the night should act to limit rainfall amounts to the 1-2" range. While the severe threat may diminish across central & eastern Minnesota, the thunderstorm complex is still expected to persist as it heads east, with stormy weather continuing into Monday morning across western Wisconsin.

MONDAY THROUGH FRIDAY...Monday will be dry in the wake of the departing storm system, however this will be short-lived as another system approaches the area Tuesday. The surface low with this system is actually forecast to be stronger than the one Sunday night, but displaced more to the north over southern Canada. Widespread convection is again expected along the cold front draped to its south, which will bring good chances for another 1" of rain (at least) through Tuesday night. Confidence is still fairly low on the potential for severe weather and heavy rain/flooding concerns, given differences in the timing of the front & uncertainty on the quality of deep shear this far south along the front. Beyond Wednesday, cooler northwest flow develops aloft as a broad & persistent trough lingers over the Great Lakes & eastern CONUS through next weekend. Temperatures will be cooler, with periodic shower chances but lesser chances for organized thunderstorms/heavy rain.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
Issued at 1221 AM CDT Sat Jun 1 2024

The area of showers that's been with us through much of the past day is slowly shrinking in coverage and intensity early this morning. A few more hours of -SHRA are expected from KMKT/KMSP/KRNH with some lower cigs moving in for all except KAXN which has found the edge of the cloud shield. Some fog/mist may accompany these lower cigs through mid morning before things clear out from west to east, leaving VFR conditions for all through the end of the period. Winds will be westerly to southerly at generally 5kts or less.

KMSP...Went a bit more on the pessimistic side with the cigs/vis through this morning and may need to adjust with the 09z AMD.
VFR conditions return by early afternoon.

/OUTLOOK FOR KMSP/ SUN...VFR, MVFR/-RA likely late chc TS. Wind S 10-20 kts.
MON...MVFR/-RA early chc TS, then VFR. Wind SW to NW 10-15 kts.
TUE...VFR early, then MVFR/SHRA/-TSRA. Wind S 10-20 kts.

MPX WATCHES/WARNINGS/ADVISORIES
MN...None.
WI...None.

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