412 FXUS63 KMQT 241033 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 633 AM EDT Sun Oct 24 2021 .SHORT TERM...(Today and tonight) Issued at 322 AM EDT SUN OCT 24 2021 Upper air pattern consists of a 500 mb closed low in central Ontario this morning which is embedded in a trough in the ern U.S. and a trough in the western U.S. There is also a shortwave in the central Rockies this morning. The upper low will slowly head into western Quebec by 12z Mon while the shortwave in the central Rockies heads towards the lower Missouri River Valley. Will still be cold enough for lake effect pcpn through tonight with enough lake-850 mb delta-t of 15C with the lake sfc temperature of 11C and 850 mb temperatures of -4C. The wind will also veer to the northeast and will keep some pcpn chances going into tonight in north to northeast lake effect wind belts. Otherwise, did not make too many changes to the going forecast. .LONG TERM...(Monday through Saturday) Issued at 400 AM EDT SUN OCT 24 2021 An amplified and rather blocked up large scale pattern will persist through much if not all of the long term period. A rex block consisting of a very anomalously strong ridge over Hudson Bay and a closed upper low over the Midwest will persist Monday before shifting eastward into Quebec and New England for Tuesday and Wednesday. At the same time, an amplifying ridge over the Northeast Pacific will push onshore into the West Coast driving downstream amplification of a short wave over the Southern Plains. By the end of the week, that wave will be cut off from the flow somewhere over the eastern half of the CONUS. However, ensemble clustering analysis shows there is still considerable uncertainty in the strength and placement of the low, with cluster mean centers ranging from near Toledo to near Nashville on Friday. The cutoff low is expected to drift eastward into the Mid Atlantic by next weekend. On Monday, NE flow between the low to the south and ridge to the north will keep cool air locked in place. 850 mb temps around -2 to - 3 C will still be sufficiently cool for continued lake effect cloud cover. Inversion heights will be dropping gradually through the day, and the PBL drying out. However, several CAMs show enough low-level saturation for light precip in the NE wind lake effect belts, especially over the higher terrain of the north-central U.P. Given the shallow precipitating layer and cloud top temps almost certainly warmer than -6 C, this precip would be drizzle. Thankfully it looks warm enough that there will not be any freezing drizzle concerns. Highs should be in the 40s for most. The low levels will continue to dry out Monday night, bringing any drizzle to an end, but lake effect clouds will likely persist into Tuesday morning before gradually diminishing Tuesday afternoon. Look for lows in the 30s most areas Monday night (some upper 20s possible far west) and then highs again in the 40s to around 50 on Tuesday. The next chance of rain will be late Wednesday night into Thursday and Friday. A negative tilt trough (the precursor to the aforementioned cutoff low that will develop in the Ohio Valley) will approach the Upper Great Lakes. However, with the pattern being rather blocked up, it will be slow to arrive. Have trimmed back POPs for Wednesday night and Thursday to confine them to the west half of the U.P. until Thursday afternoon in accordance with a persistent signal in the GEFS and EPS for precip to not arrive until Thursday. Precip may struggle to even reach the east half as the northern stream forcing will be lifting off to the northeast at the same time that the low over the Ohio Valley will be cutting off from the flow and drifting south away from the Upper Great Lakes. Have maintained chance POPs for Thursday night and Friday for now given the previously mentioned uncertainty for the end of the week. The general trend in temps will be for an increase to back above normal for the last few days of the month. && .AVIATION...(For the 12Z TAFS through 12Z Monday morning) Issued at 633 AM EDT SUN OCT 24 2021 With NW winds veering to the NE today and with a cool air mass remaining over the area, lake effect stratocu will continue to stream off Lake Superior. Expect cigs for much of this fcst period to vary btwn high MVFR and VFR at IWD/CMX/SAW. With a more direct upslope nne wind developing off Lake Superior at SAW today, MVFR cigs should be most persistent at that terminal. && .MARINE...(For the 4 AM Lake Superior forecast issuance) Issued at 322 AM EDT SUN OCT 24 2021 The wind will increase to 20 to 30 knots this afternoon and veer to the northeast with the pressure gradient increasing as a low pressure system develops in the Plains and moves through the Ohio River Valley tonight into Monday. Winds will then diminish to under 20kt Monday night into Wed as a high pressure ridge moves across Lake Superior before increasing to 20 to 25 knots Wed night and Thu. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...07 LONG TERM...RJC AVIATION...07 MARINE...07