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Displaying AFOS PIL: AFDGRR Received: 2020-09-15 23:28 UTC
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016 FXUS63 KGRR 152328 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 728 PM EDT Tue Sep 15 2020 LATEST UPDATE... Aviation .SYNOPSIS... Issued at 225 PM EDT Tue Sep 15 2020 - Cold front drops down Wednesday afternoon/evening - Frost/freeze potential end of the week - Potential warmup for next week && .DISCUSSION...(This evening through next Tuesday) Issued at 225 PM EDT Tue Sep 15 2020 - Cold front drops down Wednesday afternoon/evening The mid level low currently dropping down the west side of Hudson Bay swings a cold front through Lower MI Wednesday afternoon/evening. A narrow band of moisture accompanies the passage of this front. The lift remains weak. Some weak instability is showing up in the models but forecast soundings do not support a risk for thunder at this time. If models trend toward more instability we may need to add a risk for thunder. We will feature only low POPs for this event. - Frost/freeze potential end of the week A large Canadian High Pressure System builds down for Thursday into Saturday. As the winds diminish and skies scatter out for late Thursday night...a risk for frost/freeze conditions could occur. Guidance continues to support near freezing temperatures for our northern zones...including Harrison. Further south...urban places like Grand Rapids and Lansing are likely not to see freezing temperatures for Thursday night. More rural locations between these cities stand a risk for patchy frost. A similar setup exists for Friday night as well. Temperatures start to go up for Saturday night with overnight lows expected to be not quite as cold. No headlines at this time but we will continue to highlight the risks in social media. - Potential warmup for next week Warm air advection develops Sunday and strengthens into Monday. This will force a moderation to the low level temperatures. At least near normal values look likely by the time we get to Tuesday. Temps at 925 mb are progged to reach 20 deg C so that should easily allow for some 70s. Monday or Tuesday could end up rather breezy depending on the timing of the next low level jet. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 728 PM EDT Tue Sep 15 2020 VFR conditions expected through Wednesday afternoon. Winds will be southwest around 10 knots tonight with some gusts over 20 knots Wednesday morning. Winds will switch to northwest behind a cold front in the afternoon. && .MARINE... Issued at 225 PM EDT Tue Sep 15 2020 The Beach Hazards and Small Craft Advisories will continue into Wednesday. We could see a lull in the winds and waves overnight...but as the front drops down Wednesday...the winds veer and strengthen again. We may need to monitor Allegan and Van Buren Counties for possible expansion of the headlines as there are some indications 4 footers and gusty winds could reach those zones/counties as well. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement through Wednesday afternoon for MIZ037- 043-050-056. LM...Small Craft Advisory until 5 PM EDT Wednesday for LMZ846>849. && $$ SYNOPSIS...MJS DISCUSSION...MJS AVIATION...Ostuno MARINE...MJS