664 FXUS63 KMPX 062357 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 657 PM CDT Wed Oct 6 2021 .SHORT TERM...(This evening through Thursday night) Issued at 252 PM CDT Wed Oct 6 2021 The stratus deck that moved up from the southeast this morning is narrowing and where the sun has been able to come out CU fields have developed. The NBM was pretty aggressive in reducing cloud cover overnight, so in coordination with neighboring offices we bumped up the cloud coverage overnight. An upper low will move north out of the Arkansas/Missouri area, more or less tracking along the Mississippi River, and advect deeper moisture into our forecast area. This will bring the chance for isolated to scattered showers tomorrow. Reduced the PoPs a bit for tomorrow as the NBM PoPs looked overdone. Rainfall totals look to be quite light with only a few hundredths, to perhaps a tenth of an inch. The best chance for any showers will be in eastern Minnesota and west central Wisconsin. There is some CAPE in the forecast, so some thunder is possible, particularly in southern Minnesota. Clouds overnight should keep the threat of fog pretty minimal. The chance for showers will continue into Thursday evening before winding down overnight as the upper low gets caught up in the southwest flow aloft and begins tracking more to the northeast. Not much change in temperatures through the short term. Highs tomorrow will be mainly in the low to mid 70s with the warmest temperatures in western Minnesota. Lows tonight will fall into the 50s, to around 60 in the Metro area, with clouds increasing. Low temperatures tomorrow night will be similar, perhaps a degree or two .LONG TERM...(Friday through Wednesday) Issued at 252 PM CDT Wed Oct 6 2021 The already above normal temperatures are forecast to climb even more Friday into Saturday as a thermal ridge builds into the Central Plains from the southwest. Highs Friday and Saturday are forecast in the mid to upper 70s, with a chance of isolated 80s. In fact, the deterministic ECWMF and GFS show MSP reaching 80 at least one day to end the week. Lows Friday and Saturday night will be in the mid to upper 50s, with the Twin Cities heat island remaining slightly warmer. Showers are possible across our eastern CWA Friday afternoon as a weak, cutoff low over the Mississippi River Valley slowly meanders northward. This disturbance will eventually make its way into the Great Lakes before getting caught up in the upper-level flow and traveling east. Meanwhile, our next good chance of precip looks to be Saturday into Sunday as a vorticity maximum associated with a positively tilted trough over CA/NV breaks off and travels northeast into the Northern Plains. A strong, 140 knot southwesterly jetstreak ahead of the vorticity max should allow for a deepening surface low, moving from the Dakotas across northern MN into Sunday night. Guidance favors the heaviest area of precip along the northern periphery of the low near the warm front and deformation zone. To the south, the moisture profile in the low to mid-levels is drier causing models to be more stingy with rain. As such, NBM has likely to definite PoPs across northern MN, decreasing to chance then slight chance PoPs as one goes south to southern MN. QPF amounts follow the same regime with perhaps our northern MN counties nearing an inch total for the weekend. Guidance does hint multiple inches across northwest MN; an area that desperately needs rain. Heading into early next week, models amplify a vast upper-level ridge across eastern North America in response to strong low-level WAA. The placement and strength of this ridge should act to steer any future systems northward as they enter the central CONUS. Indeed, another chance of rain is possible across the Upper Midwest Monday into Monday night as the remainder of the aforementioned CA/NV trough finally ejects east of the Rockies. Following this system is when things could get really interesting. A strong upper- level jetstreak is forecast to dive south along the west coast Monday, highly amplifying a trough over the western CONUS by Monday night. Long range models show this trough crossing the Rockies and ejecting northeast into the Northern Plains by mid-next week. While timing and placement uncertainty exists, ensembles and deterministic guidance seem to agree that there will be a strong low and surface cyclone affecting some part of the north-central CONUS Wednesday into Thursday. Thus, our first strong low pressure system for the Fall season could be on the horizon. Temperatures for next week are forecast to cool but still remain slightly above normal for early to mid October (normal highs are in the lower 60s while lows are in the lower 40s.) && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 657 PM CDT Wed Oct 6 2021 The biggest issue this period surrounds around MVFR stratus timing/extent on Thursday. Trends for precip are on a downward direction for the day on Thursday, but increasing Thursday evening (after this period for all but MSP). For the stratus, favored the more conservative GFS for bringing it in and how far northwest to take it. This did delay when MN terminals see the stratus and we introduced it into WI as well. RAP/HRRR are a bit more aggressive with the stratus for both bringing it in earlier and spreading it across all MPX terminals, so continued modifications to the cig forecast are likely. KMSP...RAP shows stratus moving into MSP as early as 11z and quite a bit lower (IFR) than the GFS. However, with the sub-VFR stratus currently just a narrow east-west band of MVFR cigs from the Quad Cities to Chicago, not confident enough in the RAP to go that aggressive yet. /OUTLOOK FOR KMSP/ Fri...VFR. Wind S 5-10 kts. Sat...VFR. Chc MVFR/-SHRA. Wind SE 15G25 kts. Sun...VFR. Chc MVFR/-SHRA. Wind W 10-15 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ SHORT TERM...CEO LONG TERM...CTG AVIATION...MPG