Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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943 FXUS63 KMQT 081130 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 730 AM EDT Mon Jul 8 2024 .KEY MESSAGES... - Scattered showers and thunderstorms this afternoon. In addition to heavy downpours, brief gusty winds and/or small hail are possible, but severe storms are not expected. - At least through Tuesday, daily chances of showers and thunderstorms, highest chances in the afternoons. - Drier weather expected for the last half of this week, though ~25% chance Beryl`s remnants complicate the forecast. - Hot weather possible into the weekend, with ~35% chance of isolated high temperatures in the 90s over the weekend. && .SHORT TERM /THROUGH THIS AFTERNOON/... Issued at 345 AM EDT Mon Jul 8 2024 Water vapor imagery and RAP analysis show mid-level troffing extending from Hudson Bay thru the central U.S. One shortwave is over far ne MN/adjacent Ontario. A more notable wave is over IA, and it has a cluster of shra/tsra associated with it. At the sfc, the pattern is ill-defined with really no discernible boundaries noted, just simply broad troffing extending from northern Ontario into the Upper Mississippi Valley. Last of the shra/tsra that were lingering over portions of western Upper MI last evening have recently dissipated. Otherwise, it`s been a quiet overnight. There is little to no wind, and temps currently range from the upper 50s to mid 60s F. Shortwave currently supporting the convection across eastern IA may further support isold shra/tsra development downstream to the ne into s central and eastern Upper MI over the next few hrs. Otherwise, attention is on the mid-level trof axis to the w that will reach western Upper MI this aftn, providing a favorable setup for convection to develop. Perusal of 00z models suggests about 500- 1200j/kg of MLCAPE will build today. As was the case yesterday, the HRRR is around or blo the low end of that range, and the NAM is mostly above that range, as high as 2000-2500j/kg. Deep layer shear should be on the order of 20-30kt with the greater shear over roughly the e half of Upper MI. Some storm organization is possible where storms develop in the higher shear environment, but at this point, don`t anticipate any svr storms today given the currently expected parameters. Brief gusty winds and/or small hail are a possibility in addition to the brief hvy downpours that will accompany some of the storms. Expect shra/tsra to begin developing btwn 16-18z. There should be a focusing of convection vcnty of lake breeze pushing inland over western and northern Upper MI during the aftn. For the most part, high temps will be in the upper 70s/lwr 80s F. && .LONG TERM /TONIGHT THROUGH SUNDAY/... Issued at 329 AM EDT Mon Jul 8 2024 Overall, expect the middle of the extended period to be fairly dry with a slight warming trend to finish off the end of this work-week into this weekend. However, we could see some showers and thunderstorms through some shortwave low action tonight through Tuesday and again this weekend into early next week. In addition, while the chance remains low (~25%), we could have the remnants of Beryl bring rain showers over the south central and east Wednesday. A more detailed discussion of the weather for the rest of this week into early next week follows below. Rain showers and thunderstorms dwindle from west to east this evening and tonight as the shortwave low lifting through today continues northeastwards out of our area and the setting sun cuts- off diurnally induced CAPE. While wind shear is not strong enough to support severe storms this evening, we could see some gusty winds, small hail, frequent lightning, and heavy downpours in the strongest storms right before to an hour or so after sunset across the U.P., mainly in the central and east where the convection will be focused early tonight. By late tonight, expect the rain chances to drop to 0%. However, like the past few nights, we could still see some patchy fog develop across the region, mainly in the east, north central, and near the Keweenaw. Like the past few nights and days, the patchy fog looks to burn off by the mid morning hours. Expect Tuesday to be a bit drier as yet another weak shortwave moves through the region. With the forcing being so weak, convection will be relegated to the afternoon hours. While we could see sfc-based CAPE get up to 1 to maybe even 2 kJ/kg, with model guidance showing bulk shear values below 30 knots, only garden-variety showers and storms are expected. The convection will die-off in the evening as the sun sets. Wednesday is when we begin to see differences between the different model suites as the remnants of Beryl and a high pressure ridge over northern Ontario come into play. As the high pressure block over the western U.S. slowly waddles eastward this week, a high pressure ridge moves through the Canadian Prairie provinces and into northern Ontario by Wednesday. Simultaneously, the remnants of Hurricane Beryl look to undergo cyclogenesis as it moves from the Ohio Valley towards Detroit. While the model and ensemble consensus seems to be pretty set in stone about the track of Beryl`s remnants, whether we get some light diurnally-induced convection from it is still up in the air as it will depend on the strength and placement of the high pressure ridge over northern Ontario. Currently, the track of the high remains just to the south of Hudson Bay. Therefore, with weak ridging looking to be over our area, it is plausible, but not likely (around a 20 to 30% chance) that we could see some light rain showers and maybe a stray thunderstorm or two over generally the south central/interior west and east on Wednesday. Afterwards, a localized high pressure ridge builds to 1017-1020mb over Lake Superior Thursday, causing us to remain dry from then until this weekend. As we head into this weekend from the middle of this week, expect to see a slow increase in temperatures across Upper Michigan as warmer air trains in from the west due to the high pressure block moving eastwards into the central and eastern U.S.. By the time we reach our warmest temperatures come Friday through Sunday, we have a 15- 25% chance of seeing high temperatures at least reach 90F across many of the interior areas, with some isolated spots getting up to a 30 to 40% chance; currently, the days that are most likely to get that hot are Friday and Sunday. However, don`t expect the heat to stick around for too long, as model guidance suggests that a Clipper low will bring rain showers and thunderstorms back across our area as soon as Saturday and some cooler temperatures by early next week. && .AVIATION /12Z TAFS THROUGH 12Z TUESDAY/... Issued at 729 AM EDT Mon Jul 8 2024 While VFR is likely to prevail at IWD/CMX/SAW during this fcst period, there are some exceptions. Sct shra/tsra are anticipated across much of Upper MI this aftn. Developing stabilizing flow off of Lake Superior should result in less potential of shra/tsra at IWD/CMX, especially CMX. Fcst includes a VCTS mention at IWD and only VCSH mention at CMX. At SAW, there is the potential of a few rounds of shra/tsra during the aftn and early evening. While fcst has MVFR mention with the tsra, brief IFR certainly possible if any hvy rainfall occurs. Late tonight, there is some potential for fog to develop, bringing the prospect of MVFR or IFR. && .MARINE... Issued at 329 AM EDT Mon Jul 8 2024 Light winds of 20 knots or less continue through the rest of this week into early next week as a high pressure block over the western U.S. slowly trudges eastwards with time throughout the next several days. That being said, we could see some isolated thunderstorms over the eastern lake this morning and then along the nearshores today into this evening. In addition, some patchy fog could be seen over the lake today. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...TAP AVIATION...Rolfson MARINE...TAP