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FXUS63 KMPX 290902 AFDMPX

Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 402 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 /00Z TAFS THROUGH 00Z TUESDAY/
Issued at 1103 PM CDT Sun Apr 28 2024

Large rain shield continues to push off to the northeast, bringing in a fairly broad dry slot across the area to start so have initialized all sites as precip-free. From this point on, chances for additional precipitation through this TAF duration drop off with potentially only a few weak showers the rest of the overnight hours through late Monday morning. Ceilings will drop back to IFR for all sites by the early morning hours and remain there through most of the day Monday then slowly rise.
Winds will be a bit tricky to time, especially directions, as the low pressure circulation crosses southern MN, although speeds will be 10kts or less during these wind shifts.
Eventually, by late Monday afternoon, winds will become westerly with speeds upwards of 15G20kts.

KMSP...Ceilings to bounce between low-MVFR and IFR for the first few hours before settling on IFR shortly before daybreak. IFR ceilings expected to hold most of the day and into Monday evening before conditions improve Monday evening through Tuesday morning. Winds to undergo frequent shifts from E to S to W during the day Monday then become a bit breezy Monday evening.

/OUTLOOK FOR KMSP/ TUE...VFR through mid afternoon. MVFR or IFR with TSRA late aftn/evng. Wind SE 10-15G30 kts.
WED...VFR. Wind light/variable.
THU...MVFR/-SHRA likely. Wind ENE 10-15G25kts.

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

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