Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000 FXUS63 KGRR 180916 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 516 AM EDT Fri Jun 18 2021 LATEST UPDATE... Mesoscale Discussion .MESOSCALE DISCUSSION...
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Issued at 515 AM EDT Fri Jun 18 2021 Wake low related winds have developed north of the convection in the Ludington area, with gusts over 50 mph recently reported at the Ludington buoy and Big Sable Point. Using HRRR sfc pressure analysis for short term/nowcast guidance it appears these stronger wind gusts will eventually spread south/southeast with time, and could impact the MKG/GRR areas by 7 am (in addition to the convection coming onshore). Gusts to 55 mph and power outages may occur during the morning commute time.
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&& .SYNOPSIS... Issued at 330 AM EDT Fri Jun 18 2021 -Thunderstorms, with a risk of gusty winds early this morning -Occasional rounds of convection Saturday through early Monday -Warm through the weekend; sharp cool down early next week && .DISCUSSION...(Today through next Thursday) Issued at 330 AM EDT Fri Jun 18 2021 -Thunderstorms, with a risk of gusty winds early this morning We`ll be watching the line segments moving east from southern Wisconsin early this morning. The first one north of MKE extrapolates to the lake Michigan shoreline near MKG around 5 am and continuing ESE from there through the early morning hours. These segments are not too impressive but a swath/corridor of gusty winds to 40 mph may affect the area from I-96 south early this morning. Once the early morning storms exit, some potential exists for new storms, possibly strong or severe, to fire south and east of GRR by afternoon. SB Capes in excess of 3000 j/KG are shown to develop as dew pts near 70 push in from the southwest. Sfc convergence is decent through around 4 pm before the low level flow becomes more westerly with the cold frontal passage. So the period from about Noon to 4 pm will need closely monitored around JXN, after which time the main svr wx risk will shift south of MI where SPC has an enhanced risk. -Occasional convection Saturday through early Monday Fast west-northwest flow aloft remains over the Grtlks Rgn through the weekend. Models are in good agreement on the next shortwave in this pattern dropping through Lwr MI on Saturday, possibly triggering another round of convection. There are some slight timing differences but this feature looks to arrive already by mid morning after some sfc heating/instability has had a chance to develop. Instability Saturday will be lower than today since dew points will be a bit lower behind today`s fropa, but capes around 1500 J/kg and deep layer shear over 35 kts will still be sufficient to support the possibility of some stronger storms especially east of Hwy 131. After a brief period of quieter weather Saturday night into early Sunday, a digging nrn stream trough over the Northern Plains induces a decent low level jet from MO to srn MI by 00Z Monday. Expect convection to develop on the nose of this low level jet and returning warm front later Sunday, with some stronger storms and locally heavy rainfall possible. Could be an active period in west Michigan Sunday evening as upstream trough continues to dig/deepen and cold front approaches from the west. Convective threat looks to finally end early Monday with the passage of that strong sfc cold front. -Warm through the weekend; cool down early next week Guidance continues to support highs of 85 to 90 through Sunday although humidity not too high with dew points generally around 60 after today`s frontal passage. Deep upper trough arrives overhead by Tuesday behind the Monday`s strong cold front, resulting in chilly highs only in the 60s. That cold air doesn`t stick around long however with temps rebounding back near normal for mid week. && .AVIATION...(For the 06Z TAFS through 06Z Friday night) Issued at 146 AM EDT Fri Jun 18 2021 Showers and thunderstorms will move over the terminals from Wisconsin within the next few hours. Expect convection to persist at the eastern TAF sites through 13z or so. IFR vsbys are anticipated in storms. Conditions will improve as the morning progresses with VFR returning by the afternoon. && .MARINE... Issued at 330 AM EDT Fri Jun 18 2021 Expect occasional gusty winds and briefly higher seas over Lk MI early this morning as scattered tstms and the low level jet move through. Otherwise winds and waves remaining below advisory criteria through the weekend. We could be looking a somewhat lengthy period of rough conditions on the lake from Sunday night through Tuesday as a stronger weather system moves through and cold air pours in behind it. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...None. && $$ MESOSCALE...Meade SYNOPSIS...Meade DISCUSSION...Meade AVIATION...04 MARINE...Meade

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