836 FXUS63 KGRR 180012 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 812 PM EDT Thu Oct 17 2019 LATEST UPDATE... Update/Aviation .SYNOPSIS... Issued at 330 PM EDT Thu Oct 17 2019 - Frost and Freezing Temperatures Tonight. - Small Chances for Rain Saturday Night. - Impactful system slated for Monday into Tuesday. - Mon/Tues system to bring thunderstorms on Monday and Wind/Waves on Tuesday. && .UPDATE... Issued at 807 PM EDT Thu Oct 17 2019 Skies will be slow to scatter out with the lakeshore to be the last place. There is some potential for it to remain mostly cloudy there. Either way the cold air advection should still support temperatures close to the current forecasted values even if the cloud hang around for a few more hours. No changes planned to the headline. && .DISCUSSION...(This evening through next Thursday) Issued at 330 PM EDT Thu Oct 17 2019 High pressure settles into the Great Lakes region tonight which will yield a cold night. We are looking at freezing temperatures tonight away from Lake Michigan and have gone with a Freeze Warning away from the lakeshore. Lakeshore counties are under a Frost Advisory. Guidance numbers at Lansing for example are right around freezing which should result in a fairly heavy frost and a likely end to the growing season. Guidance numbers at HTL just north of are area are in the upper 20s. Feel with ridging tonight the cloud cover will erode after sunset resulting in substantial clearing that will aid in radiational cooling. Our next chance for precipitation comes Saturday night with a weakening cold front. In the end chances look small with this front and most areas will see little if any rainfall. We have another strong fall low that will affect the area early next week. A low around 990mb`s will move through the western Great Lakes and drive a strong cold front through the area on Monday and Monday night. The system will be dynamic enough with just enough moisture to make thunderstorms a possibility ahead of the front. Not sure there will be enough instability for any severe weather however. Winds will increase on the back side of the system with strong winds in place for Monday night into Tuesday. Lake effect rain will be likely Tuesday into Tuesday night in the cold air advection. Quieter weather is then expected for Wednesday into Thursday. Siding with the further west Euro with the Thursday system next week which would keep us dry until Thursday night. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 807 PM EDT Thu Oct 17 2019 Slow scattering out of the cloud cover is forecasted. VFR weather is expected to prevail through Friday. There is a small risk for patchy early morning fog/stratus...but that risk for too low to include it in the forecast. The pressure gradient was weakening so much less in the way of wind is forecasted through Friday. && .MARINE... Issued at 330 PM EDT Thu Oct 17 2019 Will allow the Small Craft Advisory to continue through 800pm south of Holland as Cook Nuclear buoy near Bridgman still has waves near 4 feet and there are whitecaps still at South Haven on the GLERL webcam. Conditions are clearly dampening out and waves will subside to less than 2 feet overnight. Our next wave event develops Friday night in southerly flow. We are likely going to need a Small Craft Advisory north of Holland with 3 to 6 footers likely. The waves will persist north of Holland on Saturday as well. The biggest marine item on the docket in the next 7 days is another strong wind and high wave event in the Monday/Tuesday time frame. The highest waves will occur on Tuesday, possibly reaching the 7-11 foot range once again. Gale force winds and Lakeshore Flood headlines would likely be warranted. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Freeze Warning from 2 AM to 8 AM EDT Friday for MIZ038-044-051- 052-057>059-065>067-072>074. Frost Advisory until 8 AM EDT Friday for MIZ037-043-050-056-064- 071. LM...None. && $$ UPDATE...MJS SYNOPSIS...Duke DISCUSSION...Duke AVIATION...MJS MARINE...Duke

NWS GRR Office Area Forecast Discussion

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