Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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291 FXUS63 KMQT 170524 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 124 AM EDT Mon Jun 17 2024 .KEY MESSAGES... - Possible strong to severe thunderstorms this evening and tonight. Large hail, damaging winds, frequent lightning, and heavy downpours will be possible. - Possible strong to severe thunderstorms Monday and possibly Tuesday night/Wednesday. - Very warm early next week, with frequent chances for showers and thunderstorms throughout. && .SHORT TERM /THROUGH TONIGHT/... Issued at 142 PM EDT Sun Jun 16 2024 Rain showers continue to lift through the forecast area atop a very moist surface layer. As of publishing this AFD, rain showers were spread across the eastern and central UP with dewpoints in the mid 50s to low 60s across the region. Destabilization ahead of mid-level ridging building into the west may support additional shower development, or some thunderstorms in this afternoon across the east half before they exit into Ontario. Severe weather is not expected in this wave. The atmosphere will further destabilize ahead of a cold front/low pressing eastward through Minnesota this afternoon. Guidance continues to suggest this will result in shower and thunderstorm development with quick upscale growth into an MCS, which will progress east-southeast into Wisconsin and Upper Michigan this evening. The strong destabilization in the pre-frontal space stretching from Wisconsin into the U.P. is characterized by 2000- 3000 j/kg of elevated CAPE. While the region where this will develop is expecting much stronger deep layer shear, guidance over Lake Superior generally suggests around 30-40kts of 0-6km bulk shear oriented off the boundary, suggesting the linear complex may survive the transit and move into Upper Michigan. With DCAPE 500-1000j/kg and increasing mid-level lapse rates to around 8C/km, strong to severe thunderstorms will be possible if so. Main hazards will be large hail up to 1 inch in diameter, strong or damaging winds upwards of 60mph, frequent lightning, and heavy rain upwards of 1+ inches this evening. Primary risk areas will be across the west/central, but some guidance packages, namely the RAP, ARW and FV3, suggests the thunderstorms could hold together as they move into the east half around midnight. A warm and muggy night is projected after the convection ends. As temps begin to cool, patchy dense fog may develop overnight. Overnight lows and dewpoints are likely to remain in low to mid 60s for most of the forecast area. && .LONG TERM /MONDAY THROUGH SUNDAY/... Issued at 332 PM EDT Sun Jun 16 2024 The active weather pattern doesn`t look like it will relent over the rest of this week as troughing deepens over the western U.S. and ridging amplifies over the Eastern Seaboard early this week. This keeps us on tap for very warm and moist conditions Monday through Tuesday, before the troughing pattern moves east and brings cooler temperatures across our area Wednesday into Thursday; be careful if working outside Tuesday, as the hot and humid weather could cause heat exhaustion and heat stroke! Meanwhile, expect showers and thunderstorms chances to continue across Upper Michigan throughout the rest of this week into next weekend, with a few strong to severe storms being possible Monday and Tuesday night/Wednesday. The severe weather threat, should any occur, would be hail, winds, and repeated heavy rainfall causing ponding. Additional details follow below. Monday starts out with a band of showers and thunderstorms making there way from west to east across the U.P. during the morning to early afternoon hours due to a cool front kicking-off the convection. While most of the CAMs show the convection weakening with time, the most recent extended HRRR shows the convection becoming quite vigorous in a couple of the cells. With 0-6 km bulk shear being around 30 knots and MUCAPEs around 250-1000 J/kg across the area, we could see a few strong to marginally severe thunderstorms in this band of convection Monday morning through early afternoon, with the primary threat being hail and the secondary threat being winds. However, with cloud cover remaining over the area throughout the day, the severe weather potential is limited. Another band of showers and thunderstorms could move into the western U.P. late in the afternoon Monday. With MUCAPE values and shear being higher, the severe weather threat is likewise higher with this round of showers and storms, with hail and winds being an equal threat. In addition, these storms could train over the same area that received the rainfall from the previous round during the morning hours. With PWATs being about 1.50 inches (near the 90th percentile of modeled climatology), heavy rainfall is possible. When combined with the training aspect of these storms, we could see some isolated ponding in the poor drainage areas. What may prevent the severe weather, though, is if the better convection ends up further south in Wisconsin. However, it appears that most of the CAMs bring some strong to severe convection over us now during the late afternoon hours over the west and central. Moving into the early night hours Monday, the convection could keep going into the eastern U.P. and Lake Superior (such as seen in the NAMNest). However, with the loss of the daytime heating and weakening of the bulk shear, its more likely that we will see the showers and storms weaken as they move into the eastern U.P./Lake Superior Monday evening. As we continue past midnight, expect the shower and thunderstorm chances dwindle and move northwards as warm frontogenesis forces the convection towards northern Ontario, bringing drier weather across our area by Tuesday morning. Expect sunny skies, muggy conditions, and probably the warmest weather of the summer yet come Tuesday as we sit directly underneath the warm sector of a low lifting through the Lake Winnipeg area. Tuesday could also be fairly breezy, with the ECMWF EFI highlighting unusually high southerly winds throughout the day. However, with a low-level cap in place, it may be difficult to get the winds to gust much more than 30 mph, save for the downslope areas near Lake Superior where mixing could be locally enhanced. Expect temperatures to get into the high 80s to low 90s during the afternoon hours, with dewpoints reaching up into the low 70s. This will cause the heat index to get into the 90s across much of the area, with a spot or two possibly flirting with 100! Therefore, be sure to take lots of water breaks if you are outside Tuesday, as heat exhaustion and heat stroke are much quicker and easier to occur than normal; hopefully the breezy southerly winds will provide a little relief from the stifling hot and humid weather. Moving into Tuesday night, showers and thunderstorms slowly move back over us as the troughing pattern over the western U.S. slowly trudges eastwards into the Plain states and weakens. We could see some strong to severe thunderstorms yet again along the frontal boundary as MUCAPEs could exceed 1000 J/kg and 0-6 km bulk shears approach 40 to 50 knots. In addition, expect heavy rainfall, with ensembles showing PWATs near the max of climatology/around 2 inches! With storms possibly training ahead of the frontal boundary, some ponding of water in poor drainage areas is certainly possible; while the chance is low (<5%), we could also see other flash flooding concerns such as ponding in better drainage areas and swollen creek beds. As shortwaves continue along the frontal boundary during the middle of this week, expect rain shower and thunderstorm chances to continue. Weak high pressure looks to move into the Northern Plains and northern Ontario along Lake Superior near the back-end of this week, forcing most of the rain chances more so to the southern parts of our area. Going into next weekend, a low pressure lifting off of the Colorado Rockies and an upper level Clipper low look to phase with each other over the Upper Midwest. This will bring additional showers and thunderstorms across our area via warm frontogenesis through at least the first half of next weekend. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 122 AM EDT Mon Jun 17 2024 Expect maybe some isolated showers across the area tonight with showers affecting mainly IWD and CMX. The moist conditions could still lead to MVFR conditions overnight in patchy fog or stratus. Around round of convection is expected to move in from the west after sunrise as ceilings will likely go to MVFR during the day on Monday. Showers will be most prevalent at IWD and SAW with SAW having the best chance of getting a thunderstorm. A break in the showers in the afternoon could be followed by more scattered showers Monday evening. Look for MVFR ceilings to lower to IFR Mon evening and fog formation possible again. && .MARINE... Issued at 332 PM EDT Sun Jun 16 2024 Southerly winds of 20 to 25 knots over the eastern lake this afternoon decrease to 20 knots or less by this evening as a shortwave lifts from Lake Superior into northern Ontario. The light winds continue through Monday before increasing from the south to 20 to 25 knots over the eastern half of the lake Tuesday. In addition, expect some downsloping winds near the southern shoreline to gust up to 20 to 30 knots, with a few gale force gusts up to 35 knots being possible, particularly in the nearshores from Marquette to just west of Whitefish Point. The winds weaken back down to 20 knots or less again by Tuesday night/Wednesday morning as the frontal boundary just west of the area finally begins moving across the lake. The light winds look to continue through the rest of the week as weak high pressure ridging settles over northern Ontario. Showers and storms are expected across the lake from this afternoon through Wednesday. Some strong to severe storms are possible during this time, with hail and wind being the main threats. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JTP LONG TERM...TAP AVIATION...Voss MARINE...TAP