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Displaying AFOS PIL: AFDGRR Received: 2017-07-17 01:56 UTC
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826 FXUS63 KGRR 170156 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 956 PM EDT Sun Jul 16 2017 LATEST UPDATE... Update .SYNOPSIS... Issued at 330 PM EDT Sun Jul 16 2017 The weather will stay quiet through Tuesday evening, then a chance of thunderstorms moves in from the northwest late Tuesday night. The showers should continue into Wednesday. More scattered showers and storms should arrive about every other day, Friday, and again next Sunday. After being a bit cooler than normal Monday and Tuesday, with highs in the upper 70s to lower 80s, we will see mainly 85 to 90 for the rest of the week and into next weekend. && .UPDATE... Issued at 953 PM EDT Sun Jul 16 2017 Based on the satellite trends...I decreased the cloud cover overnight. Some of the high res models do support patchy fog. Given the good radiational cooling that we are expecting...I added patchy fog to the forecast. The buoys north of Grand Haven show the waves have dropped off during the evening to under criteria for small craft advisory and beach hazards. These were cancelled for the northern two marine zones. && .SHORT TERM...(This evening through Tuesday night) Issued at 330 PM EDT Sun Jul 16 2017 Quiet and temps slightly below normal for the next couple of days. Then we will see a chance of storms return by late Tuesday night. Surface and upper ridging will build over the region through the next 48 hours. The upper ridge axis will stay to our west through Tuesday morning, so we will stay a few degrees below normal for this time of year through Monday night, then near normal by Tuesday. Once the ridge moves south and east, a cold front will approach from the northwest into Tuesday night. The front is only progged to be over Northern Lake Michigan to Central Wisconsin by 12Z Wed, so the main impact will be over the NW CWA and mainly after midnight. At this point there appears there will be a jetlet over the U.P. or Lake Superior. We will have to see if enough dynamics arrives overnight to expect showers and storms. Will keep POPs in the chance category for now. .LONG TERM...(Wednesday through Sunday) Issued at 330 PM EDT Sun Jul 16 2017 The pattern does not change during the extended period with a continuation of the fast west-northwest flow regime between a sprawling subtropical high to our south and upper troughing over central and eastern Canada. So we will continue to see the recent pattern of sfc lows tracking across the northern Great Lakes with a trailing cold front touching off showers and thunderstorms followed by a fair weather interlude as a bubble high moves in...then showers and thunderstorms returning as the cold front moves north as a warm front in advance of the next sfc low. The timing of features in this fast flow is tricky and leads to low confidence in the specifics, especially for the latter half of the week. For now highest confidence forecast for rain will be on Wednesday with a cold front. There will be a brief period of fair weather and then convection, possibly in the form of an MCS, increases along and north of the sfc warm front and rolls into Lower Michigan on either Thursday or Friday, followed by fair weather Friday or Saturday then another round of convection on Sunday. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 701 PM EDT Sun Jul 16 2017 High pressure will be building into the region tonight and into Sunday. This will result in generally clear to scattered cloud conditions and relatively light winds through the forecast period. Late night fog will be possible considering the good radiational cooling that is expected. I did add fog to the forecast for KLAN and KJXN. It is possible that sub IFR conditions could develop. && .MARINE... Issued at 330 PM EDT Sun Jul 16 2017 Buoy and webcams confirm very rough conditions on the lake this afternoon. The small craft advisory and beach hazard statement will be continue into tonight. Winds will be dropping off around midnight as the pressure gradient eases. Waves will gradually lessen toward daybreak when the headlines should be allow to expire. The lake will be calmer through the rest of the short term. && .HYDROLOGY... Issued at 330 PM EDT Sun Jul 16 2017 Much of Lower Michigan was spared of rainfall last night into this morning. A few isolated showers developed east of Grand Rapids with little in the way of measurable precipitation. The pattern remains fairly quiet through Tuesday. The midweek timeframe brings thunderstorms back into the picture, but will be isolated/scattered in nature. Limited rainfall through the next couple days will allow above normal river levels to continue to fall off. Improvement may even continue through the middle of the week with the limited aerial coverage in resulting moisture. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement until 4 AM EDT Monday for MIZ050-056-064- 071. LM...Small Craft Advisory until 4 AM EDT Monday for LMZ844>847. && $$ UPDATE...MJS SYNOPSIS...JK SHORT TERM...JK LONG TERM...Ostuno AVIATION...MJS HYDROLOGY...JAM MARINE...JK