Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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961 FXUS63 KMQT 241848 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 248 PM EDT Fri May 24 2024 .KEY MESSAGES... - Another shortwave and low pressure system will bring a round of showers and some thunder tonight into Saturday morning. - There will be more opportunities for rain next week although model uncertainty leads to low forecast confidence on timing/extent. && .SHORT TERM /THROUGH SATURDAY NIGHT/... Issued at 247 PM EDT Fri May 24 2024 Water vapor imagery and afternoon RAP analyses show a negatively tilting midlevel trough over the Northern Plains, and an associated 994mb surface low centered over the western MN border. A pronounced dry slot is curling into central MN. Robust warm air advection and isentropic ascent into the Great Lakes out ahead of the system has touched off convection across WI, but so far, though high cloud cover is overspreading the Upper Peninsula, bands of showers/storms haven`t survived the trek through northern WI given a very dry airmass (see early afternoon NUCAPS profiles, latest model soundings, and surface dewpoint depressions on the order of 20 degrees). Weak radar returns moving over the UP so far are not producing much by any way of accumulations, but have allowed for some isolated shower activity in the forecast across the western half of the UP the rest of the afternoon. Some rumbles of thunder will also be possible over the far west with a few flashes over Superior already. Meanwhile, in spite of increasing cloud cover, temperatures have been able to rise quite nicely across the area with most of the UP climbing well into the 60s already. Many spots should peak in the lower 70s today. The exception remains areas along hte lakeshores, where onshore flow is keeping temperatures from climbing out of the 50s along Superior, and suppressing them into the lower 60s along Lake Michigan. Winds are turning gusty, particularly across the far western UP so far where SE gusts up to 20-30mph are becoming more common. Winds should pick up across the central and possibly eastern UP into the early evening with a tightening pressure gradient and increasing winds aloft. As the increasingly vertically stacked system off to our northwest moves northward over the Ontario/Manitoba border region, the base of the midlevel trough swings through the area, eventually dragging a cold front through the area late tonight. An associated swath of convection currently over central and southern WI reaches the southern UP by the early evening, and sweeps through from west to east overnight before exiting eastward during the pre-dawn hours. So far, under a capped atmosphere, CAPE remains quite limited, and this should not improve much heading into the evening hours. Still, a couple hundred j/kg of elevated CAPE is present off the soundings this evening, so will not totally rule out some thunder. As far as rain totals go, guidance continues to favor a widespread 0.20- 0.50in, and some higher embedded totals near (and perhaps in excess) of 0.75in mainly along the WI border. Rain ends from west to east the second half of the night as the dry slot moves in, with clearing skies. Otherwise, look for breezy conditions to continue into the night, with SE winds continuing to gust to around 20 mph ahead of the approaching boundary. Winds turn calmer behind this while shifting more to the WSW. Temperatures, meanwhile, fall back into the lower 40s in the western UP (behind the boundary) and in the upper 40s to lower 50s in the east (ahead of the boundary). && .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 /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 127 PM EDT Fri May 24 2024 VFR conditions prevail at all TAF sites so far, but rain showers working into the area beginning at IWD early this evening will result in deteriorating ceilings and -SHRA. -SHRA arrive at CMX by 00Z, and at SAW by 03Z. There is around a 25-35% chance for TSRA as well, so VCTS remains in the forecast at all terminals. 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. A quick improvement to MVFR and then VFR is expected from west to east as showers move out after 06Z. Otherwise, expect gusty winds mainly out of the south at IWD and CMX this afternoon and evening. Winds turn calmer behind the passing wave tonight, shifting over to the SW. && .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 until 8 PM EDT /7 PM CDT/ this evening for LSZ162. Lake Michigan... None. && $$ SHORT TERM...LC LONG TERM...07 AVIATION...LC MARINE...07