Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000 FXUS63 KGRR 271923 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 323 PM EDT TUE SEP 27 2016 LATEST UPDATE... Synopsis/Short Term/Long Term/Marine .SYNOPSIS...
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Issued at 323 PM EDT Tue Sep 27 2016 A large area of low pressure over the central Great Lakes will produce cool temperatures and showery weather during the next several days. High temperatures will remain in the 60s through next Monday.
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&& .SHORT TERM...
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(This evening through Thursday night) Issued at 323 PM EDT Tue Sep 27 2016 Forecast concerns are tied to the movement of the upper low through the period. Not a lot of changes were made to the grids. Precipitation changes will remain fairly high as the upper low continues to spin over the state. Regional radar shows a large area of showers across northern Wisconsin, the UP, and northern Lower and this area is slowly moving south. The presence of the cool temps aloft will keep the region unsettled and produce showers from time to time. Lake enhancement will come into play also with h8 temps around 3c and lake temps around 20s. It`s possible a few of the stronger cells could produce thunder and we kept that in the grids. The low is progd to move slowly south through the short term and continue to affect the cwa into the long term. Temperatures will not increase much with the upper low overhead and should remain in the 60s through the period. .LONG TERM...(Friday through Tuesday) Issued at 323 PM EDT Tue Sep 27 2016 Main focus for the extended forecast centers on occasional showers with some breezy conditions possible on Friday with additional chances for showers continuing into the weekend. Improving weather conditions are anticipated after the weekend concludes. The upper low that is currently moving into the region will be fully cut off from the mid and upper level jets on Friday, leading to slow propagation. The upper low will be in the process of migrating back toward Michigan on Friday with more showers expected on the northern periphery of the system. Solid low level NE flow coming off Lake Huron and into the Grand River valley Friday will help boost wind speeds a bit, likely above the current forecast of 10 to 20 mph. Would not be surprised to see 20 to 30 mph at LAN and GRR with this type of setup. Only a slight chance for thunder across our far southern counties for Friday given very little instability. The current forecast high temps may be too optimistic (mid 60s). Could be closer to 60 if we trend wetter. By Saturday, the upper low should be over central or northern Indiana and Ohio. The surface low creeps into Michigan later in the day, continuing the threat for showers. This actually continues into Sunday as the system slowly moves over Lake Huron. Winds over the weekend should be light given the proximity to the low center. Mid level ridging Monday and Tuesday will help kick the system out of the region and dry things out. The possibility exists for highs well into the 70s on Tuesday as low level southerly flow potentially brings H850 temps into the 10C to 13C range into Lower Michigan.
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&& .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 122 PM EDT Tue Sep 27 2016 Gusty winds to 30 kts remain possible through late afternoon for LAN...AZO...BTL...and JXN. Stronger winds aloft have mixed down as a result of more prolonged sunshine in these locations. Low pressure system moving into western Lower Michigan tonight will drop cigs into the IFR range for at least MKG and GRR but perhaps AZO as well. Showers and perhaps some thunderstorms will generate in a more widespread fashion over Lake Michigan later tonight and small hail cannot be ruled out. Visibilities may occasionally be reduced to near IFR in the heaviest showers/storms as they move into MKG...GRR...and AZO. Conditions are not expected to improve out of IFR until later Wednesday morning. && .MARINE...
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Issued at 323 PM EDT Tue Sep 27 2016 We left the small craft advisory headline as is. Winds and will decrease tonight. Waterspouts remain possible through Wednesday as the upper low continues to sink south over the lake. A large lake delta t combined with a deep convective cloud depth are contributing factors.
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&& .HYDROLOGY... Issued at 140 PM EDT Tue Sep 27 2016 River levels are around normal for this time of year. Lake enhanced rain showers are possible through Wednesday. Rain showers continue to be possible into Sunday. Rainfall totals into the weekend will range from a half inch up to an inch and a half. Rivers and streams should remain below bankfull through the weekend. && .GRR Watches/Warnings/Advisories... MI...None. LM...Small Craft Advisory until 8 AM EDT Wednesday for LMZ844>849. && $$ SYNOPSIS...04 SHORT TERM...04 LONG TERM...Hoving AVIATION...Hoving HYDROLOGY...63 MARINE...04

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