675 FXUS63 KMQT 230809 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 409 AM EDT Fri Aug 23 2019 .SHORT TERM...(Today and tonight) Issued at 409 AM EDT FRI AUG 23 2019 Much of Upper Michigan saw cloud-free conditions during the overnight hours, allowing temperatures to tank into the upper 30s and low to mid 40s early this morning. Temperatures are expected to further cool a few more degrees until sunrise, so maintain mentions of frost across the interior west, and continued the inherited SPS to highlight the potential through early this morning. Near the Great Lakes, land-breezes and maritime influences helped keep temperatures in the 50s and 60s. Nighttime Microphysics satellite data does show some hints of patchy fog inland from the Great Lakes as well. Today, high pressure centered just north of Lake Superior will gradually drop south through this afternoon. Mid-level clouds southeast east of surface ridging have already started to work southeast over the tip of the Keweenaw and northeast parts of Upper Michigan. This cloud cover is expected to continue its southeastward progression throughout the day, with additional widespread diurnally driven cloud development as cold air aloft lingers over the area. There is a slight chance again for a few light rain showers, especially across the north central this morning, and then out east this afternoon. Temperatures will be trick today. Onshore flow along the Lake Superior shoreline will become reinforced this afternoon with an enhanced pressure gradient coming onshore with high pressure moving over Lake Superior. Lingering cold air advection aloft will also impact the east half of Upper Michigan during peak diurnal heating. Therefore, expect the north central and east parts of Upper Michigan near Lake Superior to be the cool spots today, with low to mid 60s. Across the south central and east near Lake Michigan, downsloping northerly winds will aid in boosting temperatures into the upper 60s to perhaps around 70 degrees. Out west, warm air advection will start to move in, which should help keep cloud cover more scattered and aid in afternoon highs climbing to near 70. As for winds today, the above mentioned enhanced pressure gradient this afternoon will allow for a window of breezy northeast to north winds across the central and east, respectively. Vertical shear profiles do not show much in the way of momentum to tap into with diurnal heating/mixing, so think wind gust will be more on the sporadic side opposed to frequent. Tonight high pressure will continue to exit Lake Superior and move eastward into Ontario. This will push any lingering mid-level moisture east of the region and allow for diurnal clouds to dissipate after sunset. This surface pattern will favor easterly, downsloping wind across eastern Upper Michigan, light and variable winds across the central, and southerly winds out west. Winds remaining light, skies clearing, and a strong subsidence inversion remaining in place we make for another cold night inland from the Great Lakes. The coldest spots look to be across the interior west, central, and far eastern Upper Michigan, where pre-dawn temperatures will range from the mid 30s to near 40 degrees. Not out of the question that we could see more patchy frost, especially closer to the surface ridge axis. With overnight lows expected to drop below the crossover temperature in spots, it is not out of the question that we could see patchy fog develop across the interior. .LONG TERM...(Friday night through Thursday) Issued at 301 PM EDT THU AUG 22 2019 Upper air pattern consists of a 500 mb trough in the northern and central Rockies, a ridge over the plains into the upper Great Lakes and a trough in the lower Great Lakes region and New England 00z Sat. The ridge remains in the upper Great Lakes Fri night into Sat as the trough moves eastward to the northern plains. The trough then moves into the upper Great Lakes on Sun. Looks quiet and dry for this forecast with cooler than normal temperatures. Could even be some patchy frost Fri night in interior sections. In the extended, the GFS and ECMWF show a 500 mb ridge across the southern half of the U.S. extending up into the ern U.S. with a trough in the northern and central plains 12z Mon. This trough has a cold front in MN 12z Mon. The trough moves into the Great Lakes region 12z Tue and a sfc cold front moves through the area then. More troughing then comes into the area on Wed into Thu. Another cold front moves through the area Wed night into Thu. && .AVIATION...(For the 06Z TAFS through 06Z Friday night) Issued at 119 AM EDT FRI AUG 23 2019 Some patchy fog is expected at KIWD overnight and possibly at KSAW as well with occasional MVFR conditions. Diurnal cloud development will return tomorrow morning at KSAW under conditions similar to Thursday, but shallow cloud depth should prohibit any showers. At this time, it appears ceiling heights would remain VFR but could briefly approach MVFR thresholds. && .MARINE...(For the 4 AM Lake Superior forecast issuance) Issued at 409 AM EDT FRI AUG 23 2019 Northerly winds generally less than 15 knots are expected today as high pressure sinks south across the lake. Locally higher winds, up to 20 knots are expected to funnel into Whitefish Bay and the Duluth Harbor later this afternoon and evening. Otherwise, high pressure will keep winds to speeds below 15 knots through Saturday. Saturday night, high pressure continues to move east of the region and southerly flow starts to increase to between 15 to 20 knots. Sunday through Monday, the surface pressure gradient between the departing high and an advance cold front from the west will keep southerly flow between 15 and 25 knots over the lake. As the front starts to push east across the lake late Monday into Tuesday, across far eastern parts of the lake southerly flow may increase to 30 knots. As the front clears the lake Tuesday, the main area of low pressure will remain north of the lake keeping an enhanced pressure gradient across the lake through at least Wednesday. West-southwest to westerly winds between 20 and 30 knots will persist during this time period. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Ritzman LONG TERM...07 AVIATION...Voss MARINE...Ritzman