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Displaying AFOS PIL: AFDGRR Received: 2017-06-26 17:29 UTC
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012 FXUS63 KGRR 261729 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 129 PM EDT Mon Jun 26 2017 LATEST UPDATE... Aviation .SYNOPSIS... Issued at 330 AM EDT Mon Jun 26 2017 Another unseasonably chilly day is in store with highs only in the 60s and scattered rain showers. Temperatures will gradually moderate after today, returning to closer to normal by mid to late week. However the return of the warmer air will also result in showers and thunderstorms with a risk of some stronger storms and locally heavy rain. && .SHORT TERM...(Today through Wednesday) Issued at 330 AM EDT Mon Jun 26 2017 The last in a series of vorticity maxima/upper lows in the anomalous northwest flow pattern arrives this afternoon. Expect an increase in clouds and shower coverage as this feature drops in, with thunder probabilities also creeping up by afternoon. Since the shortwave arrival is coincident with peak heating, can't rule out a few isolated stronger cells today with strong gusty winds and small hail. Freezing levels drop to 6500-7000 ft this afternoon. The pattern is also supportive of cold air funnels as the core of the cold air with H8 temps around 3C comes overhead later today. Shower coverage will decrease after sunset, then arrival of surface ridging on Tuesday will lead to quieter weather continuing into the first half of Wednesday. However the warm air is quick to surge back in from the southwest later Wednesday as low level jet cranks up to 50 kts over WI/IL in the afternoon. Showers and tstms are likely north and west of GRR by late in the day. .LONG TERM...(Wednesday night through Sunday) Issued at 330 AM EDT Mon Jun 26 2017 Active wx is anticipated mid to late week with potential for several rounds of convection. A low pressure system will move east into the upper midwest Wednesday night and bring the first round of showers and storms. Convection will develop on the nose of a strong 45-55 kt llj. This in conjunction with increasing low level moisture and some weak to moderate instability will set the stage for convective development. Some strong to potentially severe storms are possible given this synoptic setup and fairly strong deep layer shear. Medium range guidance continues to show potential for a frontal boundary to then stall out near our just south of our fcst area Thursday through Thursday night. This would continue to focus development of more showers and storms. Another low pressure system will then move through our region Friday through Friday night and bring more convection. A few showers may linger into Saturday before a cooler and drier airmass advects in for later in the weekend. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon) Issued at 129 PM EDT Mon Jun 26 2017 Isolated showers will become more numerous this afternoon, with thunder also possible in the afternoon and evening. Some small hail could occur. Even with this, conditions will be mostly at or above VFR minimum levels through Tuesday afternoon. West winds will be gusty today at 15 to 30 kts, stronger gusts will be possible with stronger cells. Winds will decrease below 10 knots tonight. && .MARINE... Issued at 330 AM EDT Mon Jun 26 2017 Cold advection and cyclonic flow similar to a fall pattern will result in hazardous winds and waves today into the evening. Arrival of the upper low this afternoon and even colder air aloft will also the support the possibility of a few tstms and waterspouts. After a calmer period on Lake Michigan Tuesday, winds and waves will increase to hazardous levels again on Wednesday into Thursday with southwest flow. && .HYDROLOGY... Issued at 1119 AM EDT Mon Jun 26 2017 River levels are trying to return to normal across the region...with the Chippewa River at Mt. Pleasant and Pine River at Alma above flood stage. Scattered showers and thunderstorms...which will develop as an upper low moves over the state this afternoon...are not expected to produce the areal coverage or intensity of precipitation needed to slow the falling of the stages. Therefore...expect river levels to continue to fall steadily over the next 24 hours. Another round of potentially heavy rainfall will occur later Wednesday into Wednesday night. Deep moisture returns to the region...and bands of heavy rainfall may occur across central portions of Lower Michigan. Rivers in Isabella and Gratiot counties are especially vulnerable to excessive rainfall...and significant rises would likely develop on the Pine and Chippewa rivers should the heavy rainfall occur in these basins. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement until midnight EDT tonight for MIZ037- 043-050-056-064-071. LM...Small Craft Advisory until midnight EDT tonight for LMZ844>849. && $$ SYNOPSIS...Meade SHORT TERM...Meade LONG TERM...Laurens AVIATION...63 HYDROLOGY...MWS MARINE...Meade