451 FXUS63 KMPX 041800 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 100 PM CDT Sun Apr 4 2021 .SHORT TERM...(Today through Monday) Issued at 351 AM CDT Sun Apr 4 2021 The key messages of the forecast are very low humidity today. There is a chance of thunderstorms Monday evening/overnight, with a marginal risk of large hail. Looking ahead, there will be a prolonged period of rainfall next week with cooler temperatures and cloudy skies. Areas in the southern half of Minnesota could easily see an inch or two of rainfall next week. Today - The dry air mass remains in place across the region. Yesterday had humidity fall into the single digits across western Minnesota and teens elsewhere. Today should be no different, as the HREF ensemble min RH which has been performing the best the last few days has widespread very low humidity across the region. Fortunately winds should be light, but there could be some gusts near 20 mph across southeast Minnesota and western Wisconsin. Aside from the dry conditions, expect a warm day with highs in the 70s. Tonight and Monday - A small tongue of theta_e advection will lift up toward I-90 in southern Minnesota and western Wisconsin tonight into Monday morning. Forecast soundings show around 1000 J/kg of instability, and the HiRes models try to speckle some precipitation as well. The forcing is weak, but do envision some widely scattered showers/thunderstorms late tonight into Monday morning across far southeast Minnesota and western Wisconsin. The rest of the region should stay dry. On Monday higher dewpoints spread across the region beneath an impressive elevated mixed layer. This yields around 2000 J/kg of MUCAPE by late afternoon, and there should be enough convergence to lift a few air parcels to their LFC and produce some thunderstorms. Overall not expecting much in the way of severe weather, but some of the stronger updrafts could lead to a few severe hail reports, and the mid level dry air could support a few sporadic gusty surface winds with some of the storms. The Storm Prediction Center continues the marginal risk of severe weather for Monday evening into Monday night. .LONG TERM...(Tuesday through Saturday) Issued at 351 AM CDT Sun Apr 4 2021 No impactful weather concerns in the extended forecast, but there is high confidence in a multi-day long duration rainfall event during the middle of the week. This will be a significant change in the weather compared to the dry and sunny conditions. Tuesday through Friday - A upper level PV anomaly will develop as it crosses the Tetons, and this will lead to lee-side cyclogenesis across the central US. This system will slow down and become cut off across the Midwest as the overall weather patterns undergoes stagnation due to the downstream ridge off the southern tip of Greenland. The end result is several days of PV advection and with multiple band of precipitation expected to rotate across the region from late Tuesday through perhaps as long as Friday. There is still uncertainty with the timing of these bands of precipitation, but confidence is very high that most locations will see accumulating rain during this time period. A cluster analysis of the 90 member GEM/GFS/ECMWF ensemble shows differences in the placement of the heaviest axis of QPF, but overall indicates measurable precipitation across the forecast area. For that reason did raise pops above the blended guidance, as these values are lower due to the 6hr window. In other words, the chances of seeing precipitation during any given 6hr block of time is around 60 percent, but the chance of seeing rain during this multi-day event is closer to 100 percent. As for amounts, areas across the southern half of Minnesota should pick up at least an inch, with two inches possible. At this time not expecting any flooding concerns given the dry conditions and overall stratiform nature of the rain. Saturday and Sunday - continued with blended guidance, but there is low confidence in the forecast for next weekend due to the uncertainty of when the mid-week system will exit the region. && .AVIATION...(For the 18Z TAFS through 18Z Monday afternoon) Issued at 100 PM CDT Sun Apr 4 2021 Only issue this period is wind shifts with the front moving across the area this afternoon that will wash out. This will result in winds shifting toward the north behind the front this afternoon, only to quickly swing back over to the southeast overnight as low pressure moves into the Dakotas. Lower atmo is incredibly dry, with nothing more than high clouds expected. Chances for precip don't really show up until late Monday afternoon as the next cold front moves into western MN. KMSP...High confidence in the TAF this period. We'll quickly loose the gusty winds this afternoon as the frontal boundary moves into the Twin Cities. Does look like there will be TS potential, but not until Monday evening (2z-6z Tue). /OUTLOOK FOR KMSP/ Mon evening...Chc MVFR/-TSRA. Wind S bcmg N 5-10kts. Tue...VFR. MVFR/-SHRA likely late. Wind NE 10-15kts. Wed...MVFR/IFR with -SHRA likely. Wind E 10-15kts. Thu...MVFR. Chc IFR/-SHRA. Wind N 5-10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ SHORT TERM...JRB LONG TERM...JRB AVIATION...MPG