Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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741 FXUS63 KMQT 241129 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 729 AM EDT Fri May 24 2024 .KEY MESSAGES... - An approaching low pressure system will bring a round of showers and a slight chance (around 20% chance) for some thunder to Upper MI this afternoon into early Saturday. - There will be more opportunities for rain next week although model uncertainty leads to low forecast confidence on timing/extent. && .SHORT TERM /THROUGH THIS AFTERNOON/... Issued at 536 AM EDT Fri May 24 2024 Current GOES-16 Nighttime Microphysics RGB imagery shows mostly clear skies with a small band of low to mid level clouds streaming southeast across the Keweenaw toward Alger County. Clear skies continue as a 1012 mb ridge builds slowly east, allowing nighttime temperatures to decrease to the mid-40`s across the UP. Closer to the Lake Superior shoreline, onshore flow has encouraged nighttime lows in the high 30`s and low 40`s. A 996 mb low, currently centered on eastern North Dakota, will move northeast throughout the day; ensemble analysis estimates the low will deepen slightly to 994 mb by the time it reaches the Canada-US border around 00Z Saturday. As this mid-level trough progresses, cloud cover will move in mid-afternoon, and gales will begin to build into far western Lake Superior. Expect winds on Lake Superior to peak around 20Z, reaching around 35kt sustained and gusting to 40kt, then to diminish to 20kt sustained gusting to 30kt over the next 6 hours. Modeled radar reflectivity suggests rain showers moving into the western UP by 20Z tonight and persisting through early Saturday morning. Six-hour QPF`s are between 0.07 and 0.54 in through Saturday 12Z, with most precipitation being concentrated in Menominee and Dickinson Counties. As vorticity streamers from the low trough pass east through the UP, models show successive bands of rain, with the bulk of precip arriving in the early Saturday morning hours. Successive model runs have brought this system into the CWA more and more slowly; so we may expect to be slowed even further as this mid- level trough lifts into Canada. Regarding thunderstorm potential, the 00Z HREF differs somewhat on available instability, with the mean MUCAPE remaining below 500 J/kg until 00Z Saturday. However, with the maximum SBCAPE values around 500 J/kg by 00Z Saturday in the west, a few rumbles of thunder are expected, but severe weather can be ruled out. && .LONG TERM /TONIGHT THROUGH THURSDAY/... Issued at 333 AM EDT Fri May 24 2024 Upper air pattern consists of a deep 500 mb trough on the west coast, a negatively tilted shortwave and closed 500 mb low in the upper Mississippi Valley 00z Sat. This shortwave heads northeast into the upper Great Lakes 12z Sat and across Ontario on Sat night. Upper troughing then remains over the area into 12z Mon as more energy comes out of the west coast trough and keeps troughing over the area. A wave of pcpn will come in tonight and move out late tonight into Sat morning with dry weather moving in for most of Saturday before the next system moves in for Sun. There are some pops that could make it into the far west by Sat evening and have slights in there to cover it. Otherwise, did not make too many changes to the going forecast. In the extended, the GFS and ECMWF and Canadian all show a 500 mb trough in the Great Lakes region 12z Mon which moves to the lower Great Lakes region 12z Tue. Ridging then moves into the northern plains 12z Wed and into Thu. Upper troughing then moves into the northern plains 12z Fri. Temperatures look to be near normal for this forecast period. Only prolonged dry period looks to be Wed for now. With troughing, does look unsettled. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 728 AM EDT Fri May 24 2024 VFR conditions prevail at all TAF sites this morning under weak high pressure. Showers associated with a low pressure over the Dakotas will approach the region this afternoon and evening, resulting in deteriorating ceilings and -SHRA. Chances of TS are around 15-35%, so VCTS has been introduced to the TAF. With the -SHRA, IWD is expected to fall to MVFR with a 25% chance of IFR while SAW and CMX are expected to fall to IFR with 20-25% chances of LIFR. Current model guidance does not suggest LLWS at any of the TAF sites, but some LLWS may be more prevalent over Lake Superior where the LLJ may be stronger tonight. Once showers pass tonight, expect improvements to MVFR and eventually VFR near the end of the TAF period. && .MARINE... Issued at 333 AM EDT Fri May 24 2024 East winds will begin to ramp up to 20 to 30 knots today in advance of another low pressure lifting from the Northern Plains towards Lake Winnipeg. Northeast gales to 35 knots will continue across the far western part of the lake today. Winds over the west half becoming southwest behind the low and the passage of its cold front late tonight into Saturday and generally stay in the 15 to 25 knot range. Winds decrease late Saturday behind the exiting system, then expect light winds of 20 knots or less across Lake Superior for the rest of this weekend as a high pressure ridge builds over the area. Looking ahead to early next week, another system moving out of the Plains will head towards the Great Lakes. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Warning from 11 AM EDT /10 AM CDT/ this morning to 8 PM EDT /7 PM CDT/ this evening for LSZ162. Lake Michigan... None. && $$ SHORT TERM...RE/GS LONG TERM...07 AVIATION...GS MARINE...07