Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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135 FXUS63 KGRR 240534 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 134 AM EDT Tue Sep 24 2024 .KEY MESSAGES... - Rain Tonight through Tuesday - Dry and mild Wednesday into Friday - Rain chances arrive for next weekend with uncertainty && .DISCUSSION... Issued at 325 PM EDT Mon Sep 23 2024 - Rain Tonight through Tuesday Shortwave trough amplifies across the Great Lakes region tonight and Tuesday with a surface low tracking across Lower Michigan. Leading edge of steadier rain is currently across central and southern Ill/Ind and moving northeast. Just a slightly slower adjustment for the arrival of the rain was made in the grids with the rain arriving just after midnight across the south and reaching the northern zones by daybreak. The path of the surface low suggests the better warm sector instability should remain south and east of the forecast area on Tuesday although there could be some embedded thunder across roughly the southeast half of the forecast area. The deeper moisture moves east with the steadier rain ending during the evening. Showers and drizzle could linger past midnight along with lake effect rain showers near Lake Michigan in northerly flow. - Dry and mild Wednesday into Friday The vast majority of the rain chances with the Tuesday wave should have moved out by Wednesday morning. An isolated shower can not be ruled out in the morning as the upper trough axis will be swinging through at that time. Conditions will be drying out and temperatures will warm into the 70s. We should then see dry and mild conditions persist through at least Friday. We end up in a col region for this period with the low departing to our NE, upper ridging to our NW and SE, and a low complex to our SW. This pattern with amplified features will get blocked up for a bit as they will all be battling each other. It seems that the ridge to our NW will be the dominating feature for our area. 850 mb temperatures in the low to mid teens C will support highs well into the 70s approaching 80. - Rain chances arrive for next weekend with uncertainty How long the dry weather remains and when the rain starts moving in are a bit uncertain. What looks to bring the next chance of rain in will be what is left of the tropical system that is forecast to develop and move through the Gulf. This system will eventually be absorbed by the upper low complex that is forecast to dig over the Arkansas region. How this interaction takes place, and how each system rotates around each other is the biggest uncertainty. There does seem to be a decent amount of agreement that the main upper low will rotate the leftovers of the tropical system to the NW before it can reach our area. There are many various solutions to when the rain moves in, and even if it does. Rain chances in the official forecast begin Friday night and continue into next Monday with this in mind. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 131 AM EDT Tue Sep 24 2024 Local radar shows light rain moving north toward the terminals. Along with the rain, MVFR/IFR ceilings will develop within the next few hours. Look for showers throughout the day. An isolated thunderstorm is possible too, but given low instability, we left TSRA out of the TAFS. Once the rain ends around 00z, fog and IFR/LIFR cigs will develop. && .MARINE... Issued at 325 PM EDT Mon Sep 23 2024 Winds will be mostly northerly the next couple days and remaining below 20 knots for the most part. There could be some choppy waves near Big and Little Sable Points otherwise winds and waves should not pose a hazard to small craft. Instability over the lake on Tuesday and Tuesday night could be favorable for waterspouts but those have not been added to the forecast at this point. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...Ostuno/NJJ AVIATION...04 MARINE...Ostuno/Thielke