Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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464 FXUS63 KMQT 140910 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 510 AM EDT Sun Jul 14 2024 .KEY MESSAGES... - Seasonably warm again this afternoon with a 20-30% chance of showers/thunderstorms in lake-breeze convergence zones. - Marginal risk (category 1 out of 5) of severe thunderstorms on Monday, main threat is damaging winds. - Cooling and drying trend into the midweek portion of next week with the arrival of high pressure. && .SHORT TERM /THROUGH THIS AFTERNOON/... Issued at 509 AM EDT Sun Jul 14 2024 Radar mosaic is quiet early this morning across Upper Michigan with all reflectivity returns concentrated over Wisconsin and far eastern Upper Michigan. And, will continue with this trend through Sun 12Z under a rather stable environment. At that point, have ~20% chance Pop mention over the eastern portions of the forecast area through the morning, but this is low confidence as CAMs continue to struggle with consistency in the short term. As a result, highly likely that even those Pops will be removed with future updates. For now, highest confidence for any convective development is within the lake- breeze convergence zones later this afternoon, which would have just enough instability to initiate some pop-up thunderstorm activity in the hot and muggy environment. With daytime highs progged to top off in the mid to upper 80s once again and widespread dew points in the 60s, SBCAPE values will climb into the 1000-2000 J/kg range. So, any weak perturbations/lake-breezes that do form will have a chance at convective development. && .LONG TERM /TONIGHT THROUGH SATURDAY/... Issued at 456 AM EDT Sun Jul 14 2024 Starting tonight, lingering showers and storms over the east from the lake breeze will drift southeast over Lake Michigan leaving dry weather for the UP through Monday morning behind a cold front. Lows fall into the upper 50s to mid 60s with light winds and mostly clear skies. Moving onto Monday, our next shortwave trough over MN and Manitoba swings through the region. A sfc low develops off the Rockies into the northern Plains Sunday night. This low moves east toward Upper MI and Lake Superior for late in the day monday, continuing into Quebec by Tuesday afternoon. This brings another round of showers and storms across the UP ahead of a cold front. Bulk shear significantly increases to 40-45 kts (7/14 0Z LREF mean) with the passing shortwave supporting organized convection. Monday will be another warm day as well with highs in the upper 70s to mid 80s and ample moisture as dew points hang around the mid 60s and PWATs increase to around 1.5"(~90th percentile of the GRB sounding climatology). This should allow for some instability, yielding weakly capped SBCAPE ~500-1000 J/kg; mid level lapse rates struggle to reach 6C/km. Although the instability is not impressive, the forcing is good, so thunderstorms are expected with a few being potentially strong to severe, consistent with the SPC Marginal Risk (category 1 of 5). Given the orientation of the shear with the cold front, a more linear mode is expected leaving the main threat with any severe storms to be damaging winds. A drier airmass moves in Monday night into Tuesday behind the cold front, diminishing precip and cloud cover. Lows are expected in the mid 50s to low 60s. Tuesday and Wednesday, the positively tilted mid level trough over northern Ontario becomes more vertically oriented as it pivots over the UP before swinging east toward Quebec and New England for late next week. This should support some light northwest winds gusting up to 20 mph, increased cloud cover accompanied by some light showers and maybe a rumble of thunder on Wednesday, and cooler temps. Highs on Tuesday stay in the 70s while Wednesday cools off even more with highs only in the mid 60s to low 70s. Lows Tuesday and Wednesday night dip into the 40s in the interior with 50s near the lakeshores. High pressure then builds in from the west Wednesday, continuing to shift over the Great Lakes through the rest of the week and next weekend. This results in a gradual warming pattern late next week into the weekend with dry weather. Model guidance begins to diverge next weekend, specifically regarding when precip returns. Likely, any precip will be supported by a shortwave dropping southeast through the region. However, deterministic solutions of the Canadian/ECMWF/GFS all show additional high pressures shifting back into the region again next week with mid level ridging finally moving east toward the midwest. So, the dry pattern may only be briefly interrupted as it continues into the following week. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 124 AM EDT Sun Jul 14 2024 Upstream convection has been observed in Minnesota and Ontario on DLH radar. As of this writing, convection has mostly been scattered in nature and continues to grow upscale into a line as it presses southeast across Lake Superior and northern Wisconsin. Terminals that are most likely to see showers and maybe a thunderstorm are KIWD and KCMX. At KSAW, early period vicinity showers will continue, but thunderstorms aren`t expected. As the upstream wave moves through Upper Michigan, its unclear if it will hold together enough to impact KSAW. If it does, timing currently looks like early-mid morning. Outside of convection, VFR conditions are expected in this TAF period. && .MARINE... Issued at 456 AM EDT Sun Jul 14 2024 Very light southerly winds below 15 kts this morning become west to southwest by the afternoon as a cold front progresses across the lake. Winds are generally expected to remain below 20 kts during this period, however the strongest winds up to 20 kts are expected between Isle Royale and the Keweenaw. Winds turn very light again tonight through Monday morning. A round of storms is expected Monday into Monday night as a low pressure system moves through the area. Patchy dense fog is a possibility in the wake of any precipitation. Following the low pressure system`s cold front, northwest to west winds increase to around 15-20 kts across much of the lake Monday night and Tuesday. After another period of 15-20 kt northwest winds on Wednesday, high pressure begins to build in from the west resulting in winds to remain below 20 kts through the remainder of the forecast period. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ UPDATE... SHORT TERM...TDUD LONG TERM...Jablonski AVIATION...JTP MARINE...Jablonski