Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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658 FXUS63 KGRR 021941 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 341 PM EDT Tue Jul 2 2024 .KEY MESSAGES... - Showers with scattered thunderstorms tonight into tomorrow - Strong storms remain possible for Friday - Unsettled weather at times next weekend and early next week && .DISCUSSION... Issued at 324 PM EDT Tue Jul 2 2024 - Showers with scattered thunderstorms tonight into tomorrow Scattered showers continue to stream through the region, mainly along and north of I 96. These showers will continue to move to the northeast as the incoming trough pushes any remaining high pressure eastward. A stronger line of showers and storms out ahead of a frontal system will move through tonight into tomorrow morning. None of the storms are expected to become severe, especially given the lack of dynamics and the time of day. Dry air will move in behind the exiting convection with clearing skies mid to late Wednesday. - Strong storms remain possible for Friday Most of the area should stay dry on Thursday, before shower/storm chances move back in for Friday. We will be in between systems for the most part on Thursday. The front that moves through on Wednesday will slip far enough south of the area to take most if not all of the rain chances with it. There is a small chance the I-94 corridor sees a brief shower on the northern edge of any complex riding along the front. There is fairly good agreement that we will have a potential period of stronger storms on Friday. Models are in fairly good agreement in bringing a healthy short wave and associated sfc front through the area on Friday afternoon. The low level jet associated with the system will help to bring a warmer and more humid air mass (implying instability) up over the area ahead of the upper and sfc features. In addition, an upper level jet max with the upper wave will help to provide plenty of deep layer shear for the storms that are looking increasingly likely to form. There are still a lot of details that have to be worked out, (exact timing, low level flow, etc...) but it is something we will continue to keep our eye on. - Unsettled weather at times next weekend and early next week The system moving through Friday looks to be the beginning of a general pattern change that is expected to hold over the Upper Midwest and Great Lakes into next week. We will see general long wave upper troughing settle in over the area as a fairly extensive upper ridge will set up over the western half of the country. The period from Saturday through next Tuesday will see chances for showers and storms at times. These chances will come via short waves that will be rotating around the long wave trough. These types of scenarios are difficult to pin down this far out due to the evolution of the upper low and where and when if it closes off or not, and the timing of the short waves. Generally speaking, temperatures should be kept down slightly with the lower heights expected. It does not look to be too cool, and could still be warm if the sfc flow ends up from the south. Even with multiple chances of rain expected off and on, much of the time will be dry. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 143 PM EDT Tue Jul 2 2024 Our focus of this forecast period will be on trends of shower activity, and any associated low clouds/fog that will be associated with them. The first main batch of rain is affecting mainly KMKG at press time, with lots of rain not reaching the sfc elsewhere further south and east. Dry air below 8-12k ft agl is holding on at all of the other sites where the rain is not as heavy. We expect a few light showers/sprinkles at the other sites, and will account for this with some VCSH/p6sm -shra wording. There will be a lull in the widespread activity then this evening and early overnight. A core of winds from the SW around 40 knots at 2k ft at the northern terminals and lighter winds at the sfc will produce enough low level wind shear to mention. The southern terminals will not see as much wind aloft. Additional rain showers will move in later tonight from west to east ahead of a front. The lower levels are expected to moisten a bit, and allow more rain to reach the ground everywhere. We do anticipate that all sites should see MVFR conditions late tonight and Wednesday morning. Clouds will lift toward and just after the end of this forecast period Wed afternoon. && .MARINE... Issued at 324 PM EDT Tue Jul 2 2024 The small craft / beach hazards threat this afternoon into tomorrow has two portions. The main question was to either wait to issue the second until the first has ended or to issue an advisory to encompass both threats. I chose the latter. South-southeast winds over Lake Michigan will continue to strengthen this afternoon as a pressure gradient continues to tighten between the exiting higher pressure and the approaching frontal system. There will be periods of gusts 25 to 30 knots mainly at and north of Whitehall. There will be a lull in the winds, mainly between 8 pm and 2 am Wednesday, then the winds will increase out of the southwest towards sunrise. These winds will coincide with showers and storms moving through overnight. After frontal passage, including the showers and storms, Winds and waves will slowly decrease Wednesday morning into the afternoon. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement until 8 PM EDT this evening for MIZ037- 043. MARINE...Small Craft Advisory from 8 PM this evening to 8 AM EDT Wednesday for LMZ844>846. Small Craft Advisory until 8 AM EDT Wednesday for LMZ847>849. && $$ DISCUSSION...NJJ/Ceru AVIATION...NJJ MARINE...Ceru