Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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471 FXUS63 KGRR 030644 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 244 AM EDT Wed Jul 3 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 && .UPDATE... Issued at 1058 PM EDT Tue Jul 2 2024 Bumped up POPs across the northern half of the forecast area the next few hours per radar trends. Expect the showers and storms to persist but diminish in coverage after midnight given lack of upper level support and instability. At least chance POPs through the overnight look good as the cold frontal passage doesn`t occur until Wednesday afternoon. && .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 /06Z TAFS THROUGH 06Z THURSDAY/... Issued at 125 AM EDT Wed Jul 3 2024 An area of showers with embedded thunderstorms stretched from western IL through northern Lower MI. The instability was decreasing as these showers were advancing east into the TAF sites here in southwest Lower MI. Based on the radar trends and latest model data, we will keep thunder out of the TAF forecasts for the remainder of the night, despite some slight instability moving in. Low level moisture will be on the increase later tonight and more so for Wednesday morning. Conditions are likely to go down to MVFR and even a period of IFR for many of the TAF sites. A cold front currently in MN will drop down into the TAF sites here in MI Wednesday morning, weakening as it does. That feature will likely generate some renewed showers/convection Wednesday morning but based off of the limited instability, the thunder risk at any particular TAF sites remains low. We will need to monitor trends though. Drier air filters in behind the front for Wednesday afternoon and that will likely support the cloud bases rising with the clouds eventually scattering out. && .MARINE... Issued at 244 AM EDT Wed Jul 3 2024 This forecast is lower than usual confidence for small craft and swimming hazards this morning, but at the very least it`s likely that moderate swim risk will be present along many beaches, with a fair enough possibility for high swim risk to issue a Beach Hazards Statement through noon. Ongoing Small Craft Advisory for gusts over 22 knots will be extended later into the morning as the wave field responds to briefly stronger southwesterly winds anticipated over the next few hours and lingers for a few more hours after the winds relax. Models have been varied in their solutions for early this morning regarding where, how strong, and for how long the stronger southwesterly surface winds will be. Stronger winds are present just 1000 feet above the lake, but it seems they will not fully mix down without the help of rain falling into the dry air at 1000 feet and cooling it down in tandem with the passing cold front. Even the most aggressive models relax the winds substantially no later than 8 or 9 AM, so any waves or currents hazardous enough for boats or swimmers should be diminishing by noon if not earlier. Independence Day will feature light winds and waves 1 foot or less. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement until noon EDT today for MIZ037-043-050- 056-064. MARINE...Small Craft Advisory until 8 AM EDT this morning for LMZ844. Small Craft Advisory until noon EDT today for LMZ845>849. && $$ UPDATE...Ostuno DISCUSSION...NJJ/Ceru AVIATION...MJS/Thielke MARINE...CAS