822 FXUS63 KMQT 301915 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 315 PM EDT Thu Sep 30 2021 .SHORT TERM...(Today and tonight) Issued at 427 AM EDT THU SEP 30 2021 Water vapor imagery and RAP analysis show an amplified pattern over N America, featuring a sharp mid-level ridge extending n across the western Great Lakes to Hudson Bay with trofs over the Rockies and eastern Canada/ne U.S. The mid-level ridge is supporting a sfc high pres ridge extending from Hudson Bay to the Upper Ohio Valley early this morning. With the ridge nearby and only a weak upstream sfc trof over the Red River Valley of the North, it's been another quiet night across the fcst area. Only some sct-bkn thin ci is spreading over western Upper MI with clear skies to the e. Some patchy fog/shallow stratus has formed over s central Upper MI. Temps are in 40s, except for the w into the n central closer to Lake Superior where readings are in the 50s. Similar to yesterday at this time, IWD and Copper Harbor are around 60F. A few of the traditional cold spots over the interior e have slipped into the upper 30s. Until sunrise, patchy fog/shallow stratus will probably expand across the s central and into the eastern fcst area under quiet/calm conditions. The fog may be locally dense. This fog and shallow stratus will mix out within a few hrs after sunrise. Otherwise, expect nothing more than some mainly thin high cloudiness at times across the area today. With little change in 850mb temps from yesterday, today will be another unseasonably warm day with high temps very similar to yesterday. Highs should generally range from the lwr 70s F e to the upper 70s w. Some locations over the w will likely reach 80F again. Easterly component to the wind near Lake Superior will be weaker today than yesterday, so areas near the lake that were cooler yesterday should see max temps a few degrees higher today. Tonight, the mid-level ridge over the area will deamplify. One shortwave will be drifting nne across MN while a more notable shortwave trof shifts e into northern Ontario. In response to the wave over MN, a modest 20-25kt low-level jet lifting across eastern MN will likely support some sct shra/tsra. With the nose of the low- level jet w of Upper MI thru the night, don't expect any pcpn to reach the western counties before 12z Fri. Some fog/stratus may develop again overnight across the s central and eastern fcst area. With a little more wind up Lake MI tonight, there will probably be a better potential of a more widespread stratus development across the eastern fcst area tonight. Low temps tonight will be a little higher than recent nights, ranging from the upper 40s/lwr 50s s central and e to the mid/upper 50s F w into the n central closer to Lake Superior. .LONG TERM...(Friday night through Thursday) Issued at 315 PM EDT THU SEP 30 2021 The overarching theme of the long range forecast is warmer and drier than normal weather prevails through most of next week. A messy upper level pattern characterized by at least three weak shortwave troughs results in isolated showers from late Friday into Sunday. Surface ridging builds into the area Sunday night and Monday and lingers through the end of the long term period. This should result in a pattern with large diurnal temperature ranges, mostly clear skies, and nocturnal fog development. The forecast period starts out rather tricky with lots of run-to-run variability in model guidance. Models appear to be struggling with interactions among the various shortwaves. The first wave tracks southeast across Ontario Friday night draping a frontal boundary across our CWA. The second wave appears to track east along the remnant boundary on Saturday. The third and strongest shortwave appears more likely to track south of our CWA on Sunday. WPC Cluster analysis showed about 85% of available ensemble members favor a farther south track for Sunday's system resulting in a mostly dry forecast for our CWA on Sunday. With all that said, the operational 12z GFS has a radically different solution and was therefore treated as an outlier for this forecast package. The highest precipitation chances appear to be Friday night through Saturday. Generic elevated thunderstorms can't be ruled out Friday night with more mixed layer t-storm potential across the south- central on Saturday afternoon. Friday night's activity should be tied to a modest 25-30 knot low level jet transporting a weakly unstable airmass into the area. 12z HREF guidance indicates around 500-750 MUCAPE with the highest precipitation chances across eastern Lake Superior late Friday night. Precip chances decrease Saturday morning, but diurnal destabilization may allow for some afternoon redevelopment south of the cool front. By Saturday evening precipitation chances should be ending as cool/dry air advection continues behind the cool front. Sunday should be mostly cloudy with cool northerly flow off Lake Superior. Skies should begin clearing Sunday night so that mostly sunny skies are expected for Monday. Surface ridging stays in place through at least the middle of next week, which should lead to sunny skies with warm days and cool nights. Well above normal lake temperatures suggest the primary weather hazard may be nocturnal fog, especially for areas of onshore flow. && .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) Issued at 134 PM EDT THU SEP 30 2021 Prevailing conditions of VFR for all terminals is expected through the period. Wind gusts will remain below 10 kts today, and become VRB to calm overnight. Low confidence in the possibility for patcy, ground fog stretching north overnight from Lake Michigan and reaching KSAW, but the possibility does exist between 9Z and 12Z Friday morning. && .MARINE...(For the 4 AM Lake Superior forecast issuance) Issued at 427 AM EDT THU SEP 30 2021 A high pres ridge will linger from Hudson Bay to the Lwr Great Lakes thru tonight. Meanwhile, a weak low pres trof over the Red River Valley of the North will drift e, reaching the Upper Mississippi Valley and northern Ontario on Fri. This trof will slowly drift se across Lake Superior late Fri night/Sat and settle toward the Lwr Great Lakes on Sun. A high pres ridge will then approach Lake Superior on Mon. Throughout this time, the pres gradient will remain relatively weak across Lake Superior. Thus, winds are likely to remain mostly under 20kt thru early next week. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...EK AVIATION...BW MARINE...Rolfson