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Displaying AFOS PIL: AFDGRR Received: 2017-11-20 17:30 UTC
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358 FXUS63 KGRR 201730 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 1230 PM EST Mon Nov 20 2017 LATEST UPDATE... Aviation .SYNOPSIS... Issued at 330 AM EST Mon Nov 20 2017 A relatively quiet period is expected into mid week as no major weather system are forecast to affect the area. We may see a bit of light rain on Tuesday along and ahead of a cold frontal passage. In its wake Tuesday afternoon into Wednesday morning a bit of lake effect snow will occur. Little to no snow accumulation is expected however. We will see highs both today and on Tuesday in the 40s. Temperatures will tumble again behind the Tuesday cold front with high on Wednesday only forecast to reach the 30s. The Thanksgiving outlook is for good travel weather across Southwest Lower Michigan with dry weather and high temperatures around 40. && .UPDATE... Issued at 1113 AM EST Mon Nov 20 2017 Quick update to the sky forecast was issued to account for the area of stratocumulus clouds north and west of a line from roughly Holland to Harrison. These clouds are related to the moist low level southwest flow off the lake but should mix out later today. && .SHORT TERM...(Today through Wednesday) Issued at 330 AM EST Mon Nov 20 2017 Limited concerns in the short term period. A southwesterly gradient builds in quickly today with breezy conditions expected. Dry weather is forecast today and tonight as we will be in the warm sector of a clipper system passing well off to our north. Highs today will push into the 40s, more typical for this time of year as compared to the colder 30s we had on Sunday. Tuesday the cold front will push southeast through the forecast area. We will likely see some scattered rain showers develop along and ahead of the front. The best chances to see showers will be in the southeast towards Jackson. The cold air advection is strong in the wake of the front with delta T's climbing to around 20C during the late afternoon. Moisture is not great but we will likely see some light lake effect snow showers developing. The snow showers will continue Tuesday night into Wednesday morning with little to no accumulation. .LONG TERM...(Wednesday night through Sunday) Issued at 330 AM EST Mon Nov 20 2017 Precipitation will be mostly toward the end of the long term as high pressure will be moving across the state during the middle of the week. Both the gfs and ecmwf are in pretty good agreement with the track and strength of low pressure as it crosses southern Ontario Friday. The trailing cold front will get some support aloft via a short wave as it moves across northern Lower. Highest pops will be Friday evening just ahead of the cold front and across the northern cwa. This is basically a rain event, although a few wet snowflakes may mix in over the far northeastern cwa late Friday night and Saturday morning. Behind the front, another shot of cold air will flow south. However, the system looks similar to the one that just moved through a couple of days ago. H8 temps fall to around -12c and moisture is shallow. We include low chc pops for snow showers...mostly over the western cwa, but we don't expect much out of this system Saturday afternoon and night. Highs will be in the 40s Thursday through Saturday before dropping into the 30s Sunday. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon) Issued at 1230 PM EST Mon Nov 20 2017 VFR conditions will continue through Tuesday afternoon. Southwest winds will gust over 20 knots today and Tuesday with some gusts to 30 knots possible this evening. && .MARINE... Issued at 330 AM EST Mon Nov 20 2017 With Gale conditions forecast within the first period have opted to drop the Small Craft Advisory and upgrade to a Gale Warning. Gale gusts may show up in the southern nearshore zones as early as late morning or midday. The core of the Gale conditions will occur tonight with 35 to 45 knot gales from the southwest. Waves will peak in the 9 to 13 foot range. Winds and waves will gradually settle down from Tuesday into Wednesday. The Gale Warning runs through mid morning on Tuesday, when we will likely need a Small Craft Advisory through midday on Wednesday. && .HYDROLOGY... Issued at 1145 AM EST Mon Nov 20 2017 Few rivers continue to rise, but rises have slowed, while others are showing signs of stabilizing. There are small chances for precipitation Tuesday afternoon and Wednesday. Amounts, if measurable, should not have any impact on rivers. Beyond Wednesday, weather looks relatively quiet. Despite elevated river levels, additional river flooding is of low concern. Rivers are likely to recede through the course of the upcoming week. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...Gale Warning until 10 AM EST Tuesday for LMZ844>849. && $$ UPDATE...Meade SYNOPSIS...Duke SHORT TERM...Duke LONG TERM...04 AVIATION...Ostuno HYDROLOGY...JAM MARINE...Duke