Area Forecast Discussion
Issued by NWS Twin Cities, MN

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745 FXUS63 KMPX 212003 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 303 PM CDT Fri Jun 21 2024 .KEY MESSAGES...
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- A flood watch remains in effect across southern Minnesota into western Wisconsin into Saturday due to additional rainfall across saturated soils. - After the rain ends on Saturday we should see a break Sunday into Monday. - River flood concerns will extend into next week, with several local sites forecast to reach major flood stage.
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&& .DISCUSSION...
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Issued at 303 PM CDT Fri Jun 21 2024 Rest of Today... Rainfall overnight trended farther to the south the originally expected. This trend was noticed in this last discussion with the decaying MCS following the better moisture across far southern Minnesota. Heavy rainfall occurred with this system with 2 to 5 inches measured. Additional showers and periodic thunderstorms occurred across parts of this same area later in the morning causing flash flooding, areal flooding, and river flooding across southern Minnesota. Thankfully recent model trends have continued a southern trend with the heaviest rainfall. This is due to the expected location of the warm front. The I-90 corridor south into Iowa now looks like best location for thunderstorms and heavy rainfall due to this frontal placement. There remain some model spread that keeps this farther north, such that the watch remains in effect to the north. This is also largely due to saturated soils such that there would not need to be much rain for flooding too occur. This saturation is shown by current FFG values. However this threat remains more likely to the south as outlined in the SPC Mesoscale Discussion and southward shift of the WPC moderate ERO. Saturday... The flood watch continues into Saturday as rain is expected to continue Saturday morning into afternoon (mainly WI for afternoon). This will be tied to the slow moving synoptic forcing with the surface low shifting into Wisconsin on Saturday. Rain chances should go down quickly on the western side of the low. Light rain and drizzle could persist on the western side of the low, but little additional rainfall is expected. Sunday through Thursday... Sunday into Monday is when we finally get a dry period. This should allow some time for water to start to receded along the smaller streams and overland. Larger, especially mainstem rivers, will continue rises for a while as water flows into them. There are two times that could see another round of rain next week: a frontal passage Monday night into Tuesday and again near the end of the week. The first event Monday night into Tuesday should move through faster and should not be as long of a duration event as we have recently seen. Of course any thunderstorms could still have high rain rates and soils would still be more sensitive than normal. Looking ahead to the end of the were there is still to much of a spread in the ensembles to have much confidence past saying that the Upper Midwest will see more rain.
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&& .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1233 PM CDT Fri Jun 21 2024 This remains a low confidence TAF set as the models have continued to struggle with handling this convective environment. I was able to reduce the hours of prevailing TS mention and drop TS from some terminals entirely. The warm front is just north of I-90 with widespread showers along and to the south of it. Immediate impacts will be to MKT/EAU with fringe impacts to RWF/MSP. Our current thoughts are that greatest chance for TS development this afternoon will be along and south of that boundary. This highlights MKT being most at risk for see TS development. Tonight, precip coverage will expand as the LLJ intensifies in response to a shortwave moving across Neb. Guidance has the heaviest rainfall occurring along and south of the I-90 corridor in southern Minnesota and northern Iowa. Given the southern MN focus for forcing, did keep AXN/STC dry during this TAF period. With this warm front just making it past I-90, the MPX terminals (with the possible exception of MKT) will remain north of the warm front this period, which means persistent MVFR/IFR cigs can be expected. KMSP... Higher confidence on warm front placement has allowed us to drop TS mentions this evening/tonight. -SHRA is still forecast overnight into Saturday AM. /OUTLOOK FOR KMSP/ SUN...VFR. Wind NW 10-15 kts. MON...VFR. Chc-TSRA/MVFR late. Wind SE 10-15 kts. TUE...VFR. Wind NW 5-10 kts. && .HYDROLOGY...
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Issued at 303 PM CDT Fri Jun 21 2024 Despite a lack of confidence in the location of highest QPF for tonight, we`ll see enough rain in areas already having issues from last night`s and this morning`s rain to warrant an areal flood warning in south central MN. This warning will need to be watched for extension to the south depending on how the precip sets up along I-90, could also go through the night. River forecasts are mainly on track this afternoon, paying particular attention to the Cannon where training has occurred today, along with the mid/lower Minnesota where lots of inflow coming from the tribs south of Mankato.
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&& .MPX WATCHES/WARNINGS/ADVISORIES...
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MN...Flood Watch through Saturday afternoon for Anoka-Blue Earth- Carver-Dakota-Faribault-Freeborn-Goodhue-Hennepin-Le Sueur-McLeod-Nicollet-Ramsey-Rice-Scott-Sibley-Steele- Waseca-Washington-Wright. Flood Watch through Saturday morning for Brown-Martin-Redwood- Renville-Watonwan-Yellow Medicine. WI...Flood Watch through Saturday afternoon for Dunn-Eau Claire- Pepin-Pierce-St. Croix.
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&& $$ DISCUSSION...NDC AVIATION...BPH HYDROLOGY...CCS