443 FXUS63 KMPX 191139 AAA AFDMPX Area Forecast Discussion...UPDATED National Weather Service Twin Cities/Chanhassen MN 639 AM CDT Sat Sep 19 2020 .SHORT TERM...(Today through Sunday) Issued at 336 AM CDT Sat Sep 19 2020 Another north-south elongated mid level stratus deck has formed over western MN overnight and is moving little. RAP forecast soundings aren't too promising in scattering it out until later in the day. The last visible satellite images from yesterday showed thick, elevated smoke moving back eastward across the Dakotas. HRRR-Smoke model continues to have a good handle on it, and the 06Z run builds it eastward through the day, reaching WI this afternoon. Kept sky cover around 50 percent for the smoke, but most locations aside from western MN shouldn't see many clouds. Upper level trough extending westward to the Great Lakes will push off to the east as a ridge and another trough following the ridge both track east across the northwest and north central CONUS. Temperatures will warm from the upper 60s to mid 70s today, to the low 70s to low 80s Sunday. As the trough approaches Sunday, increasing pressure gradient with the stationary surface high over New England will result in gusty southerly flow. Forecast soundings show potential for wind gusts of 30-40 kts across the entire region. This should fall short of wind advisory criteria of 30 mph sustained winds or 45 mph gusts, but depending on mixing depth there could be a few rogue gusts around that threshold mid afternoon. A dry forecast continues through Sunday, although by late afternoon there could be a few sprinkles or light showers developing along the cold front, per a few model solutions. Thinking the atmosphere will be too dry to support activity until Sunday night. .LONG TERM...(Sunday night through Friday) Issued at 336 AM CDT Sat Sep 19 2020 At the start of the period, a weak, negatively tilted upper-level trough will be centered over central Saskatchewan with the trough axis passing southeast through ND into western MN. This trough is forecast to pivot northeast and be replaced by overall zonal flow Monday morning. In fact, until late next week, the entire CONUS will experience zonal flow. A transition back to a more "summer-like" pattern looks probable for the central and western US to end September. Indeed, the Climate Prediction Center's extended outlooks have temperatures trending above normal for the next few weeks in these regions. The only thing that will not be "summer- like" is the lack of moist/humid air. This, combined with the lack of large-scale lift from amplified troughs (due to more zonal flow), means we could be hard pressed to see any accumulating rainfall during the next week. Returning to Sunday night, with the main vorticity maximum displaced to the northwest, the MPX CWA will experience only meager lift from upper-level diffluence. When combined with the relatively dry forecast vertical profiles, forecast models struggle to produce anything more than showers across MN and WI (evidenced by 30% PoPs at most in our CWA). Perhaps a 0.1 to 0.2" of QPF is possible from eastern MN to western WI, though it likely won't be continuous nor widespread. Afterwards, Monday and Tuesday both look dry with few clouds and highs ranging from the mid-70s to low-80s. Our next, albeit not great, chance for precipitation arrives on Wednesday as a shortwave quickly translates eastward along the US/Canadian border downstream of a strong, landfalling jetstreak on the Northwest coast. Again, greatest PoPs are displaced north of our region owing to the increased dynamical lift closer to the shortwave. However, currently can't rule out a chance of showers and thunderstorms Wednesday. Temperatures will also be more of the same Wednesday afternoon but a cold frontal passage Wednesday night slightly cools us off. Wednesday night's lows and Thursday's highs will be in the low to mid 50s and upper 60s to low 70s, respectively. Towards the end of next week, the arrival of the aforementioned strong jetstreak from the Pacific will allow for cyclonic wavebreaking; significantly amplifying the upper-flow. However, forecast models differ in both the timing and location of the wave breaks. The 00z GFS is about one-half wavelength out of phase compared to the 12z ECMWF. If the GFS is correct, strong northwest flow would dominate the end of next week. However, if the ECMWF is to be believed, strong ridging occurs instead. (Meanwhile, the 00z GEM is a mellower version of the ECMWF.) Additional model runs are needed to get a handle on the evolving pattern. Regardless, differences between solutions seem to result in only short-term trends for temperature. As stated above, our region will trend to above normal temperatures to end September. The long-term also looks drier as strong moisture advection from the Gulf of Mexico does not appear likely. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) Issued at 639 AM CDT Sat Sep 19 2020 Mid level stratus deck over western and central MN is slowly drifting east early this morning, but the eastern edge is also eroding. Thus, not expecting it to reach eastern MN and it should continue slowly dissipating through the morning. Otherwise, elevated smoke returns today and southerly winds will gust to around 20 kts. KMSP...No concerns through the day, but some modest wind shear is possible tonight as warmer air aloft works in and increases a low level inversion. /OUTLOOK FOR KMSP/ Sun...VFR. Chc -SHRA late. Wind S 15-20G35 kts. Mon...VFR. Slight Chc mrng -SHRA. Wind SSW 10-15 kts. Tue...VFR. Wind SSW 10-15 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ SHORT TERM...Borghoff LONG TERM...CTG AVIATION...Borghoff