Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000 FXUS63 KGRR 221932 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 332 PM EDT Fri Mar 22 2024 .KEY MESSAGES...
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- Snow Winds Down This Evening - Dry Saturday - Warm and Rainy, Then Dry Next Week
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&& .DISCUSSION...
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Issued at 331 PM EDT Fri Mar 22 2024 - Snow Winds Down This Evening A positive tilt mid level shortwave will progress eastward through the Great Lakes region this evening. It will move off to the east overnight and snow will come to an end. We trimmed back the extent of the Winter Weather Advisory prior to 200pm. We will leave what remains as is through midnight. So, the U.S. 10 and I-94 rows have been removed. Isentropic lift will continue in the advisory counties this evening, especially the Ottawa to Clinton row and Allegan to Ingham row. There is some decent mesoscale banding still occurring within this zone, but widespread impacts are dwindling by the hour. Another inch or two will occur in a few spots. The main item for folks to keep in mind is temperatures will be falling through the 20s this evening and overnight and meltwater from the snow today will refreezing into slick spots. All of that said we may be able to cancel the advisory early/before midnight. - Dry Saturday Dry weather is forecast for both Saturday and Saturday night as surface high pressure moves through the region. Deep layer moisture is not present and therefore we have high confidence in dry conditions. Normal highs this time of year are in the upper 40s with normal lows right around 30. Highs on Saturday will be in the lower to middle 30s which is 10 to 20 degrees below normals. Nothing too atypical for this time of year though. Saturday night we dip into the upper teens to middle 20s. These readings are 5 to 15 degrees below normal, but nothing we cannot handle. - Warm and Rainy, Then Dry Next Week Temperatures begin to warm Sunday as an 850mb thermal ridge moves into the central Great Lakes. Cannot rule out an isolated warm air advection based snow shower Sunday night up towards Ludington, but chances are low (20-30 percent). Temperatures climb even more Monday with highs in the 50s likely both Monday and Tuesday. Dry conditions are expected Sunday into Monday (with the exception of the aforementioned chance of snow showers towards Ludington) before rain arrives late Monday and into Tuesday, which is a trend for a later start compared to yesterday`s 12z guidance. The widespread showers will be a result of ample forcing from a coupled upper-level jet and numerous shortwaves, combined with the arrival of deeper moisture. Forecast MUCAPE and LI values support little to no thunder threat, so will keep it out of the forecast. Deterministic and ensemble guidance paints around 0.5 inches of QPF across lower Michigan providing a soaking rainfall with this system. Rain winds down Wednesday morning as the low, forcing, and deeper moisture pull away, and a cold front brings cooler air into the region. Monday also looks to be breezy given an 850mb 40-50 knot low level jet moving across the area. Numerous members of the EPS and GEFS show 30-45 mph gusts during the day on Monday, dependent on how deep we are able to mix. Conditions then dry out later Wednesday through the end of the work week as surface ridging and low level dry air come into place. Highs in the 40s are expected Wednesday and Thursday as we remain under longwave troughing.
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&& .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 132 PM EDT Fri Mar 22 2024 Primary aviation concerns are through around 03z associated with the current snowfall across the area. The primary band of IFR visby snow has moved north from the I94 corridor and will primarily impact MKG/LAN/GRR this afternoon. This band then shifts southeast this evening, causing the I94 terminals to fall back to low end MVFR to high end MVFR for a few hours before snow exits. Conditions improve from northwest to southeast starting around 00z. MKG returns to VFR behind the band while high resolution model guidance has trended towards the moisture remaining trapped under an inversion keeping MVFR stratus overnight at all other sites. Signals for areas of fog and IFR cloud cover exist south and east of KGRR associated with a few hours of NE flow off of Saginaw Bay, but low confidence keeps IFR restrictions out of the TAFs at this time. Condition then improve to VFR for the rest of the terminals just after daybreak and remain so through the rest of the TAF period. Southeast winds 7-12 knots shift to north at 5 knots or less overnight and strengthen to around 10 knots again after daybreak Saturday. && .MARINE...
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Issued at 331 PM EDT Fri Mar 22 2024 We are not expecting the need for a marine headline (Small Craft Adv or otherwise) through the day on Sunday it appears. Winds from the GFS using a BUFKIT overview at the southern buoy location show values that are mainly sub advisory. There is a brief time around daybreak on Saturday when winds increase to 20-25 knots. These winds are off shore and at this time do not look to pose to much of a threat in our nearshore water. High pressure looks to keep things tame on the big lake from Saturday afternoon into Sunday. Once we get to Sunday evening winds being to ramp up out of the south on the leading edge of a strong low moving through the Western Great Lakes. South winds will be of sufficient force for at least a SCA and most possibly a gale. At this time it looks borderline for a gale but we have plenty of time before we need to make decisions on that headline.
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&& .GRR WATCHES/WARNINGS/ADVISORIES...
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MI...Winter Weather Advisory until midnight EDT tonight for MIZ043>046-050>052-056>059-064>067. MARINE...None.
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&& $$ DISCUSSION...Duke/Thomas AVIATION...Thomas MARINE...Duke

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