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Displaying AFOS PIL: AFDMQT Received: 2022-12-22 19:21 UTC
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850 FXUS63 KMQT 221921 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 221 PM EST Thu Dec 22 2022 .SHORT TERM...(Through Tonight) Issued at 220 PM EST THU DEC 22 2022 Key Messages: -Lake-enhanced system snow bringing 2-5 inches of snow through tonight -Road conditions are slick, but still driveable if absolutely necessary Winter Weather Advisory-level snow continues for the Upper Peninsula as a weak, broad surface low passes through the region ahead of a deepening, negatively tilting 500mb trough. 850 mb warm advection will decrease through the day as the low passes and winds aloft begin turning to be out of the north. Snow today is mostly system snow however it is lake enhanced from Lake Michigan with southerlies ahead of the low and Lake Superior with northerlies behind the low. The 850mb temperatures ahead of the low are in the -8 to -10 C range while behind the low the temps aloft are easily into the negative teens and 20s C. As far as the snow:liquid forecast, a fairly deep dendritic growth zone will support higher ratios but those will be kept in check by strong winds and wind shear tearing apart some flakes, so mostly forecasting around 15:1, though 10:1 was been observed at the office in Negaunee Township this morning and that has increased throughout the day. With those snow ratios in mind, most of the UP will see an additional 3 inches (give or take an inch or 2) leading up to the warnings late tonight. With multiple observations and reports of slick roads thus far, travel is not necessarily advised, but it is still possible for now. .LONG TERM...(Tonight through Wednesday) Issued at 414 AM EST THU DEC 22 2022 Strong storm occurring with a closed 500 mb low in central Minnesota 00z Fri. This low heads southeast to northeast Indiana 12z Fri and causes the 500 mb trough to become negatively tilted Thu night over the Great Lakes region. The 500 mb low then heads northeast to north of Lake Ontario 00z Sat and then to near James Bay by 00z Sun. This will keep the area under upper level troughing through this forecast period. Part one of the storm is ongoing and will continue until 06z tonight. Extended advisories until 06z and chose that end time to when the wind picks up. After 06z tonight to 00z Sunday with the strongest winds, blizzard conditions will occur went with blizzard warnings near Lake Superior and winter storm warnings elsewhere. Tied the winter storm warnings to where lesser amounts of snow will be seen, but the snow that does fall and has fallen with event one will cause blizzard conditions anyway, just might not have the amounts, but the visibilities will still be very low. With Southern Schoolcraft County, the strong wind will push the lake enhanced snow further inland than usual and this will make it all the way down to U.S. Highway 2, so thought blizzard warning appropriate there. These are the changes made to the going forecast. In the extended, GFS and ECMWF show a 500 mb ridge in the western U.S. and a trough in the eastern half of the U.S. in a highly amplified pattern 12z Sun. The ridge moves into the Rockies 12z Mon. Pattern starts to de-amplify 12z Tue with the ridge beginning to be flattened over the Rockies as a shortwave moves into the northern Rockies. Pattern becomes a mess 12z Wed with weak upper troughing remaining over the upper Great Lakes and a ridge in the southern Plains. Troughing moves into the northern plains 12z Thu. Temperatures start out below normal and then a warming trend takes place with temperatures near normal on Tue going above normal for Wed and Thu. && .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) Issued at 104 PM EST THU DEC 22 2022 IFR conditions will be the dominant category at all TAF sites for this TAF period minus IWD, which has been VFR in a dry slot all morning and will start the TAF period MVFR. Eventually, lake effect snow, gusty NW winds, and blowing snow will drive the aviation impacts in the forecast at all sites. With all 3 TAF sites within a Blizzard Warning after 06Z tonight, occasional whiteout conditions are possible, though exact periods of airport minimums will be difficult to pinpoint until it happens in real time. Some wind shear is also present in the SAW TAF as rapidly changing wind speeds with height in the vicinity of the TAF do reach LLWS criteria. && .MARINE...(For the 4 AM Lake Superior forecast issuance) Issued at 414 AM EST THU DEC 22 2022 Major storm force wind event will continue on Lake Superior for this forecast. Winds increase tonight quickly and kept the storm warning time the same. The wind does get up earlier in the far west to gale, but with storm warning out, a gale warning before that would be implied. To remove confusion, kept the start time the same but went storm when gales would start. The wind stays at 15 to 30 knots today before increasing to north gales tonight to 45 knots and then storm force winds to 60 knots through Saturday. The strong gale to 45 knots drops off then by Sunday night. In addition to the winds, strong northerly winds will usher in cold air and a heavy freezing spray hazard and wind-driven waves in the eastern half could exceed 25 feet Saturday. Marine interests with passage plans through Lake Superior tonight through Monday should make the appropriate plans now to avoid these conditions. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Weather Advisory until 1 AM EST Friday for MIZ001>007- 009>014-084-085. Blizzard Warning from 1 AM Friday to 7 PM EST Saturday for MIZ001>003-005>007-009-014-085. Winter Storm Warning from 1 AM Friday to 7 PM EST Saturday for MIZ004-010>013-084. Lake Superior... Storm Warning from 1 AM Friday to 1 AM EST Sunday for LSZ162- 240>251-263>267. Heavy Freezing Spray Warning from 1 AM Friday to 1 AM EST Sunday for LSZ162-240>251-263>267. Lake Michigan... Storm Warning from 1 AM to 7 PM EST Friday for LMZ221-248-250. Heavy Freezing Spray Warning from 1 AM Friday to 7 AM EST Saturday for LMZ221-248-250. && $$ SHORT TERM...GS LONG TERM...07 AVIATION...GS MARINE...07