Area Forecast Discussion
Issued by NWS Gaylord, MI
Issued by NWS Gaylord, MI
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847 FXUS63 KAPX 201741 AFDAPX Area Forecast Discussion National Weather Service Gaylord MI 141 PM EDT Fri Sep 20 2024 .KEY MESSAGES... - Rain/thunder chances return today - Chances for widespread rain and isolated thunder Sunday - Cool down next work week && .UPDATE... Issued at 920 AM EDT Fri Sep 20 2024 Scattered to numerous showers will continue to work across parts of northern Michigan today. Best chances for rain will come across the eastern U.P. and Tip of the Mitt where the greatest shower coverage currently resides, with lesser chances with southward extent. Current confidence is that additional showers and a few storms will develop later this morning and early afternoon. A few hundred joules of MLCAPE and around 30 kts of deep layer shear make chances for a strong storm or two non-zero, but confidence in any strong storms today is currently decreasing as it appears best activity will be disjointed from a more favorable environment -- better instability and shear is expected to work into northern Michigan this evening, after the frontal passage and when rain chances are diminishing. Rainfall totals are still expected to remain light with most areas seeing less than 0.25" through today. Otherwise, patchy fog development will be possible once again tonight. && .SHORT TERM /THROUGH TONIGHT/... Issued at 333 AM EDT Fri Sep 20 2024 Pattern/synopsis: An upstream cold front has pushed into western WI and eastern IA. Decaying pre-frontal convection extends from the WI/IL border up thru central Lk Superior. The front is progged to slow as it crosses eastern WI today, and then moves into northern MI tonight. Forecast: Cloud cover has increased in nw lower MI, and will become somewhat more extensive as the morning proceeds. However, that cloud cover will also thin with time. Some showers will likely reach the nw lower MI coast, and western Chip/Mack Cos this morning. But otherwise, this initial push of precip will struggle in our initially dry air. Diurnal instability then starts to kick in, and by midday convection will start to regenerate locally. MlCape values of 600-800j/kg can be achieved. Those higher pops will start in western areas at midday, expanding toward and east of I-75 thru the afternoon and into early evening. 0-6km bulk shear reaches of 30-40kt in southern areas, where instability should also be on the higher side. This is into a parameter space where a few strong storms are possible. Maybe even a stray severe? But probably not. (SPC did push the marginal svr risk northward to about GRR, but not this far north.) 500mb trof axis pushes across the area tonight, with mid-level subsidence/drying/warming pushing into western areas. Chance for showers and a few storms will still be present in central and especially eastern areas this evening. By overnight, pops linger only in the far north and east. Without a significant push of cooler/drier air down low, partial clearing will lead us prone to seeing fog late, especially in the west (and perhaps near Lk Huron). Max temps today mostly in the 70s, perhaps hitting 80f near Saginaw Bay. Lows tonight mid 50s to near 60f. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Issued at 333 AM EDT Fri Sep 20 2024 Saturday, skies will clear through the morning hours and lead to a mostly sunny and warm afternoon. Clouds will begin to build back in Saturday evening/night as the next system approaches the state. An upper level trough over central south Canada will close and start to tilt negatively Sunday. This upper level jet will meet with a SW upper jet over MN/WI, and aid in moisture advection northward towards the Great Lakes Region (PWATs ~1.4 by Sunday afternoon over northern MI). A deeper cold front will move through the state Sunday, as some shallow upper waves move up from the south. All in all, there should be enough larger scale forcing present for scattered to even widespread wetting rain Sunday. At this time, weak instability is present in the mid to lower part of the column, meaning it will be harder for storms to grow. It will likely be widespread light to moderate rains with a handful of embedded low topped cells producing some lightning. Higher uncertainty in actual moisture amounts play into this as well, if there is a little more dry air to work with then gusty winds could be seen with some of that embedded convection. GFS/high res Canadian show saturation through much of the column (after top down moistening), with the NAM hinting at some drier air. After the ~1015mb air mass moves through, temperatures will start to decrease. Forecasted high temps remain in the mid to high 60s Monday through the end of next week. Winds will be breezy at times, with chances for rain here and there. Low confidence in details for after Sunday rain chances due to chaotic pattern. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 141 PM EDT Fri Sep 20 2024 Mainly VFR conditions are expected to persist across northern Michigan TAF sites through this evening. Showers and a few embedded thunderstorms will continue to work across the area this afternoon before chances wane this evening. Any heavy showers/storms that pass over TAF sites could briefly drop VSBYs to MVFR/IFR. Otherwise, rainfall today followed by clearing skies and weak/calm winds tonight is expected to lead to patchy/areas of fog development across northern Michigan tonight. Drops to IFR/LIFR VSBYs will be possible late tonight/early Saturday morning before lifting after sunrise. && .APX WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ UPDATE...DJC SHORT TERM...JZ LONG TERM...ELD AVIATION...DJC