351 FXUS63 KMPX 201729 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 1229 PM CDT Sun Oct 20 2019 .UPDATE... Updated to include 18z aviation discussion below. && .SHORT TERM...(Today through Monday) Issued at 433 AM CDT Sun Oct 20 2019 Surface analysis shows weak north-south oriented high pressure aligned over the Mississippi River with a departing cold front over the central Great Lakes into the Ohio Valley. A more potent low pressure system continues to deepen over WY/CO with a trailing cold front extending southwest into the Four Corners region. Aloft, generally zonal flow sits atop MN/WI into the Dakotas while a trough axis continues to dig southward over the Rockies. The high pressure area will push off to the east today, allowing clouds in advance of the western trough to gradually fill in over the region as the day progresses. The low pressure system to the west will shift into central SD by late this afternoon with the cold front nudging into eastern SD/NE. A few bands of showers will likely move into far western MN by this evening. The upper trough is expected to pivot through the Northern Plains late this afternoon into this evening, aiding in further strengthening the surface low. With plenty of Pacific moisture already wrapped into this system along with tapping some Gulf of Mexico moisture, this system is expected to produce fairly widespread rain tonight through Monday. Though there are multiple model projections of some dry-slotting during the day Monday, the timing/duration of such is highly variable and difficult to determine at this point. Even so, with the movement of the system northeast into the Great Lakes Monday afternoon and evening, precipitation likely will return in earnest again Monday night. While MUCAPE is rather unimpressive (less than 500 J/kg throughout the duration at any point), enough upper level support with strong jetting and divergence aloft may be enough to produce a few isolated thunderstorms tonight through Monday. There will be two other noticeable features with this system: strong winds and decreased temperatures. In advance of this system, highs today will still reach the upper 50s to lower 60s due to the aforementioned zonal flow preventing any appreciable warm or cold air advection behind the departing cold front. However, the cloud/rain complications expected for Monday combined with the start of cold air advection (which will continue through midweek) will bump highs down to the upper 40s to mid 50s. As for winds, the tightly wound structure of this system will effectively produce a strong pressure gradient on its western periphery. As the system moves into Wisconsin by late afternoon Monday, this gradient will produce strong northwesterly winds in the 20-30mph range with gusts upwards of 45mph for western and southwestern MN. These strong winds are then expected to continue and expand across much of the WFO MPX coverage area Monday night. .LONG TERM...(Monday night through Saturday) Issued at 433 AM CDT Sun Oct 20 2019 Active to start out the long term period, along with well-below normal temperatures through next weekend. After a possible lull in precipitation Monday afternoon/evening, we'll see rain continue across the area Monday night through Tuesday as the wrap-around region of the surface low passes overhead. This rainfall will be lighter and more scattered compared to Monday's, so only expect to add another tenth to quarter of an inch by the time precipitation wraps up from west to east through the day on Tuesday. Could possibly see a rain/snow mix or flurries Tuesday morning across western and central Minnesota as colder air filters in to the region, but no impacts are anticipated. While the precipitation will be light Monday night into tuesday, the main impact will come from increasing west/northwest winds on the back side of the system. The pressure gradient will tighten over the region Monday night as the low continues to deepen as it tracks off to the northeast, and cold advection/steepening low-level lapse rates will allow for some gusts over 40 mph to mix down to the surface. Current timing still looks to bring the strongest gusts in overnight Monday into Tuesday, but Tuesday is still looking like a raw and blustery day with highs in the 40s and wind gusts of 30-40 mph continuing through sunset. As the low departs to the northeast, another shot at precipitation comes Wednesday as a shortwave pivots around the larger trough centered over the Great Lakes. Guidance continues to trend farther south with the best forcing from this shortwave so precipitation looks to remain light or even stay south of the CWA entirely. Will hold on to 20-30% PoPs for now but could very well see a dry forecast if this southerly trend continues. Should precipitation fall this north, temperatures look cool enough Wednesday morning to support a light rain/snow mix across northern portions of the CWA. High pressure then builds into the region Thursday and should keep the forecast dry through at least the first half of the weekend. Temperatures will remain around 10 degrees below normal through Friday with highs in the 40s and lows well into the 30s. && .AVIATION...(For the 18Z TAFS through 18Z Monday afternoon) Issued at 1230 PM CDT Sun Oct 20 2019 KEAU finally broke free of the LIFR FOG and stratus around 1530z. They should be VFR until late tonight. Mid/high level clouds moving into the area this afternoon. Lowering cigs to MVFR as the bands of -ra moves from west to east through 12z Monday. As developing surface low moves into southern MN late tonight, will likely see return of more widespread IFR cigs. THis may improve to the south Monday afternoon before wraparound clouds/showers move back into late Monday/Monday night. Surface winds SE-E ahead of the developing low. May become gusty into the evening over much of the areas as the low begins to deepen. Expect a wind shift to NE-N and eventually NW as the low travels east Monday afternoon, with winds increasing and gusty over the western area by 00z Tue. KMSP...VFR trend until beginning of rain, sometime around 08z. Then MVFR lowering to IFR cigs by 13z. Expect improving to MVFR again through about 18z Mon. May see a break in the more widespread rain or taper to periodic drizzle into the late morning/early afternoon before more wraparound rain moves in during the afternoon. /OUTLOOK FOR KMSP/ Mon night...IFR/-SHRA. Bcmg MVFR. Wind SW 5-10 kts bcmg NW 20G30 kts. Tue...MVFR chc IFR. -SHRA likely. Wind NW at 25G35 kts. Wed...Chc MVFR/-SHRA. Wind NW at 15G25 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. && $$ SHORT TERM...JPC LONG TERM...ETA AVIATION...DWE