Sunrise 6:03 AM   Sunset 8:16 PM Moonrise 12:42 AM   Moonset 8:48 AM

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FXUS63 KMPX 291158 AFDMPX

Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 658 AM CDT Mon Apr 29 2024

KEY MESSAGES

- Slight Risk (level 2 of 5) of severe weather for south central Minnesota Tuesday with what will be our next round of widespread showers and thunderstorms.

- Pattern to remain active with rain chances every 24 to 48 hours, with another widespread soaking rain looking likely Thursday and more showers possible Saturday and again early next week.

DISCUSSION
Issued at 356 AM CDT Mon Apr 29 2024

At 3am, the surface low was near Redwood Falls. It will move through the Twin Cities metro this morning, on its way to the western U.P.
of Michigan this afternoon. With this low is the primary shortwave aloft and it's the PV feature with this shortwave that is driving this last batch of rain and a few thunderstorms moving north across southern MN overnight. This area of showers will slowly clear out of central MN through the morning and linger over northwest WI into the afternoon. For most of us, today will be another cool and cloudy Spring day with temperatures not moving much today, with highs in the mid 40s (central MN) to mid 50s (west central WI).

Tonight, we'll slowly clear the low level clouds out, but mid level clouds will be increasing as we see WAA develop ahead of the shortwave coming Tuesday. This continues to look like an impressive wave, with a strong PV anomaly, a negatively tilt, and highly diffluent mid/upper level flow. The biggest question when it comes to our severe weather threat is what will the quality of the moisture return be ahead of the cold front that will sweep across our area. Right now, the HRRR indicates 500-1000 j/kg of CAPE will be possible into south central MN. Wind shear will not be an issue, with a conducive wind field for organized severe weather with curved and long hodographs in place ahead of the cold front. It's just a question of can we get enough instability to create severe convection with those hodographs. Given the diffluence aloft, upscale growth into a line of showers and storms is expected, with the greatest risk for severe weather being south of Mankato where instability has the greatest likelihood of exceeding 500 j/kg and the SPC has a Slight Risk in the Day 2 severe weather outlook.

Outside of the severe weather, given the forcing, another widespread round of showers and storms is expected Tuesday into Tuesday night.
This band of showers and storms will be fairly progressive, so we're only looking at rainfall amounts around 0.5", but LPMM QPF from the HRRR does highlight some potential for amounts closer to 1.5" near the Iowa border where stronger convection is expected.

The next wave in the train shows up on Thursday and this will be yet another shortwave taking on a negative tilt as it rotates around the main upper low centered back near the ND/Manitoba/Alberta border.
This wave looks to go a bit farther south than Tuesdays, which puts us in line for seeing more of the deformation rainfall on the cool side of the surface low. This could be another shot for a pretty large footprint of 1"-1.5" of QPF from south central MN into east central MN and western WI.

Looking beyond, the ECMWF shows addition chances for rain Saturday, Sunday night into Monday, and Tuesday into Tuesday night of next week. Although there's low confidence on how strong any one of these waves will be, where they will track, or if they will even come to fruition, what it does show is that this very active pattern is going nowhere anytime soon.

AVIATION /12Z TAFS THROUGH 18Z TUESDAY/
Issued at 648 AM CDT Mon Apr 29 2024

Surface low is starting out this period near New Ulm (KULM) and will be tracking across the Twin Cities through the morning.
The worst conditions are expected in and near the surface low, where DZ will at times bump vis down to IFR levels and CIGS LIFR. It will be a slow improvement to the IFR cigs through the day, but by the end of the day, most terminals should be MVFR.
Clearing will be slow to occur Monday night, though RAP soundings do show low clouds starting to clear toward sunrise Tuesday for MN terminals west of MSP.

KMSP...Occasional vis down to 1sm in DZ will be possible through the morning as we work the surface low over the field. 9z RAP forecast soundings show stratus finally clearing MSP between 12z and 15z Tuesday with the next round of shra/tsra not impacting MSP until closer to 00z Wed (7pm CST Tue).

/OUTLOOK FOR KMSP/ TUE...VFR. MVFR/TSRA 23-03z. Wind SE 10-15 kts.
WED...VFR. Wind W 5-10 kts.
THU...MVFR/-SHRA likely. Wind E 10-15 kts.

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

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