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Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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884 FXUS63 KGRR 150558 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 158 AM EDT Sat Jun 15 2024 .KEY MESSAGES... - High confidence for oppressive heat/humidity next week - Low Confidence on heavy rain next week && .DISCUSSION... Issued at 328 PM EDT Fri Jun 14 2024 - High confidence for oppressive heat/humidity next week Fine weather will continue through Saturday. There were a few renegade showers earlier this afternoon but those have dissipated and the diurnal cu field does not look capable of producing showers given the dry atmospheric profiles. So showers were not included in the forecast through the evening. After a stellar Saturday, the sfc high will move east and a deep southerly flow regime will be established for Sunday and into the middle of next week. The operational models continue to show an unusually strong upper high centered southeast of Lower Michigan. This creates what has been colloquially called the "ring of fire" with occasional, and in this case persistent, MCS activity to the west and north. The operational Canadian and GFS remain in line with one another on the main features with the operational EC being an outlier with stronger upper ridging. However, when looking at the NAEFS and ECMWF ensemble means and standardized anomalies, the differences of the models become smaller. So while there is some spatial temporal differences in position of the ridge and moisture advection, the pattern remains consistent. So there is high confidence in that maximum temperatures in the 90s could continue through the middle of the week. Monday and Tuesday continues to look to be the hottest days with 850mb temps ranging from +18C to +22C, depending on the model you look at. The concern along with these hot temperatures will be the dewpoints in the upper 60s to low 70s. That could bring apparent temperatures to advisory criteria, especially considering this heat could linger for days. The trend for warm overnight temperatures remains consistent as well with lows only dropping into the low 70s. This lack of recovery will be another factor along with the daytime maxes and the humidity. - Low Confidence on heavy rain next week So while there is good confidence in the upcoming heat the biggest question is whether or not there will be any precipitation to go along with it. The strength of the upper ridging and capping inversion could reduce any instability needed for showers, so while humidity may be present, there may not be enough vertical motion for showers/storms. There are constant changes run to run in the models and the best moisture to allow for rain remains north of southern Michigan. There is some potential for weak shortwave troughs and MCS/MCV effects on the western periphery of the upper high bringing more favorable conditions for showers and storms on any day next week. Confidence in the details of location and timing for those features remains low. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 158 AM EDT Sat Jun 15 2024 No major aviation concerns the next 24 hours as conditions are expected to remain VFR through 06Z on Sunday. Some mid and high clouds with bases at or above 15,000 feet will spill in from the west today. No clouds lower than that are expected. Visibilities are forecast to remain VFR as well with high resolution models not showing much of a signal for light fog this morning. Winds will generally be from an easterly direction today at 5-15 knots. && .MARINE... Issued at 328 PM EDT Fri Jun 14 2024 Winds are gradually turning onshore this afternoon but are rather weak with gusts below 15 knots at the buoys. Coastal webcams show flat waves still although there may be a slight increase late this afternoon before winds go offshore again. Winds and waves should be light for Saturday then increasing south to southwest winds Saturday night with building waves for Sunday and a Small Craft Advisory will be needed. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...Ostuno/Ceru AVIATION...Duke MARINE...Ostuno