Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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908 FXUS63 KGRR 150735 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 335 AM EDT Sat Jun 15 2024 .KEY MESSAGES... - Hotter and More Humid Sunday - Heat and Humidity Still in the Forecast for Sunday and Next Week - A Few Chances for Showers and Storms Next Week && .DISCUSSION... Issued at 335 AM EDT Sat Jun 15 2024 - Hotter and More Humid Sunday High pressure will bring fair wx today with mostly clear to partly cloudy skies and high temps in the upper 70`s to lower 80`s. Fair wx will continue tonight as the high pressure ridges moves east of our region. It will become hotter and more humid Sunday as southerly flow waa develops on the back side of the departing ridge. H8 temps moderate to 18-20 C and high temps will reach the 85 to 90 degree range tomorrow. An overall shorter range guidance consensus shows potential for scattered showers and perhaps a few thunderstorms tomorrow mainly north of I-96 as a mid to upper level disturbance moves in from the west. However convective potential will be mitigated significantly by weak instability. The 00Z HREF shows stronger instability tomorrow will stay well to the west to sw of our area. - Heat and Humidity Still in the Forecast for Sunday and Next Week So, while the heat and humidity still look on track for next week there are certainly mixed signals that lead to slightly lower confidence overall. The mixed signals are that while 500mb heights rise into the 590s dm next week there are still disparities in high temperature output. The ECMWF is still very bullish on 90s each day while the GFS holds in the 80s. 590s heights do not happen that often, so those are anomalous values. Conversely, the 850mb temperatures are not all that rare by summer standards in Michigan. A combination of the GFS and ECWMF operational 850mb temperatures range between +16C and +21C from Sunday through Friday. These are very typical 850mb numbers during warm spells, certainly not off the charts. High 850mb temperatures would be in the +22C to +26C range and we are just not seeing that. Ensemble high temperatures at GRR are completely in the 80s in the GFS over the next 10 days. The highest is 89 on Monday. The ECMWF ensemble guidance has 91 almost every day between Sunday and Friday with 94 on Monday being the only outlier. The bottom line is that it will be a warm spell with upper 80s to lower 90s temperatures for highs. Nighttime lows will remain in the 70s for days which does not happen all that often. A prolonged period of warm weather with little relief coming at night, but nothing too atypical for a mid summer warm spell. People without air conditioning will need to be checked on through the week though as the cumulative affect of the warmth will take its toll. Folks working outdoors will need to be prepared for the warmth as well. - A Few Chances for Showers and Storms Next Week The GFS and ECWMF both have a boundary that sags into the area in the mid to late week. Too early to be very confident in how precipitation chances work out though. Moisture associated with the front and potential precipitation could aid in keeping high temperatures in check a bit. We do not have any pops in the forecast that are above 20-30 percent. && .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 335 AM EDT Sat Jun 15 2024 Rather minimal wave heights and wind speeds are forecast today. Winds will veer to the southeast and begin to strengthen somewhat late tonight. Winds will become southerly and ramp up to 15 to 25 kts causing wave heights to build particularly across our northern marine zones. A small craft advisory will be needed Sunday. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...Duke/Laurens AVIATION...Duke MARINE...Laurens