Area Forecast Discussion
Issued by NWS Gaylord, MI
Issued by NWS Gaylord, MI
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387 FXUS63 KAPX 071801 AFDAPX Area Forecast Discussion National Weather Service Gaylord MI 201 PM EDT Sun Jul 7 2024 .KEY MESSAGES... - Mainly quiet weather today with rain chances, rumbles of thunder returning tonight. - Rain/storms Monday and Monday night/Tuesday. - Potential for Beryl`s Remnants to Impact Northern Michigan Wednesday and Beyond. && .SHORT TERM /THROUGH MONDAY/... Issued at 316 AM EDT Sun Jul 7 2024 Pattern Synopsis: Short wave ridging will continue to slide over the Great Lakes this morning into this afternoon, providing subsidence aloft that will slowly build surface high pressure east of the region through the period. Meanwhile, longwave troughing will progress from the Great Plains over the Midwest by Monday morning, generating enough forcing aloft to create a weak, broad surface pressure response across the region. Forecast Details: Mainly quiet today, rain chances/thunder tonight -- With high pressure in place across the Great Lakes, mainly quiet weather is expected through this evening. Morning fog should dissipate shortly after sunrise as diurnal heating/mixing ensues. While a few showers cannot be entirely ruled out during daylight hours, subsidence aloft and relatively dry low-level profiles lead to very low chances (10% or less) at this time. The main chances for rain and the potential for a few rumbles of thunder will return late this evening and tonight as aforementioned troughing/surface pressure falls work into the Great Lakes. Severe storms are not expected with weak buoyancy and shear in place. Otherwise, temperatures look to warm into the low 80s for most areas this afternoon with mild overnight temperatures in the low to mid 60s. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Issued at 316 AM EDT Sun Jul 7 2024 PATTERN SYNOPSIS/FORECAST: Longwave troughing continues to overtake the central continent...with rather nebulous flow/generalized high pressure overall hanging over the northern US/southern Canadian Prairies, including northern Michigan. Even so, a handful of pv niblets in the flow, including a well-defined swirl over SD/MN with attendant convection ahead of this...and a surface cold front stretching back into WY. Additional niblet over the central Plains with better theta- e advection and 20+kt LLJ with its own surface reflection over Nebraska/KS. Otherwise...primary BCZ over the nation stretches from New England down to southern TX with a 100+kt upper jet stretching up into the eastern CONUS; bulk of the deep moisture (pwats greater than 2in) along and south of this from the Gulf Coast up into the Mid Atlantic. BCZ extends back northwestward into the Canadian Rockies, with additional niblets being funneled into the NW US along that portion of the flow ahead of anomalous ridging over the West Coast. Otherwise...eyes remain on T.C. "Beryl" in the western Caribbean as it eyes the TX coast. This same general pattern to remain largely the idea going into the start of the workweek...as upstream troughing looks to firm up over the central Plains as Beryl makes landfall Monday morning. General idea attm is that our upstream troughing will ultimately scoop up Beryl and allow it to hitch a ride northeastward into the OH Valley for midweek. While the general idea keeps it over southern Michigan and the OH Valley...will be something to keep an eye on going forward given some uncertainty in that portion of the forecast attm. In the meantime...will look for a wad of PV and moisture to slip northeastward over the Upper Midwest Monday, which should drive some shower/tstorm activity in our general region going into Monday night. Potential break in the action Tuesday before Beryl`s remnants begin to track up the BCZ into the OH Valley going into midweek. Additional energy dives into the back of troughing over the Upper Midwest Wednesday...which looks to keep the troughy idea in place over the region through much of the upcoming week. Meanwhile, upstream pattern should begin to break down, with ridging looking to spread eastward over the central continent going into the latter half of the week, driven by a system crossing central Canada. A lot of questions yet with the end of the forecast for the upcoming weekend, given the potential for troughing to hold over the Great Lakes...as well as our proximity to the eastward-expanding heat dome. While nothing is certain by any means, suspect things should remain generally unsettled (perhaps more than is currently in the forecast) over some portion of the Midwest right on into next weekend. Stay tuned. Primary Forecast Concerns: Rain/storms Monday and Monday night... Expecting an initial round of elevated, warm advection convection to slip through during the morning hours Monday. Some uncertainty in the timing/position of this, though, with potential for the primary bout of rain to stay further north across the Yoop...or further south, more or less focusing over central Lower and West Michigan. Either solution is possible from the pessimistic viewpoint that convection tends to split around northern Michigan (and Gaylord in particular)...though in this case, not so sure it will be a split as much as dependent on timing...and could honestly see it going either way: a quicker solution would have a tendency to trend more south and east (particularly if convection is at all organized and the right- leaning Coriolis force comes into play, though signals for well- organized convection are not strong attm), while a solution that slows the wave would more likely focus rain/storms across the eastern/central Yoop, perhaps as far south as NW Lower into the Tip of the Mitt region. Given the wildcard of Beryl...do have to wonder if the slower solution will ultimately win out...but for now will lean a little more toward the quicker/more southern solution. Think we`ll be looking at potential for redevelopment in the afternoon with increased diurnal heating and continued slow movement of a weak SW-NE oriented BCZ ahead of the trough aloft. Deep layer shear attm appears a little better, perhaps approaching 20- 30kts...but think that low-level wind fields will be weak enough to support lake breeze development (particularly along the Lake Huron coast), which could further focus mesoscale convergence over NE Lower. The slightly better deep layer shear suggests convection may try to get a little more beefy/better organized, which could be problematic along the lake breeze boundary with an increased potential for turning of the low- level winds with height (i.e., more potential for rotation) and perhaps enough low-level instability to accelerate upward motion/boost stretching of vorticity. For now, though, think any tornadic threat is on the lower side...but will be something to keep an eye on, particularly given that the last couple tornadic events up here haven`t necessarily been classically impressive. Otherwise, do think gusty winds could be a threat again with some potential for low-level dry air that could enhance evaporative cooling/downbursts with convection, despite winds aloft not being terribly impressive as far as exact severe thunderstorm (50kts/58mph) wind criteria goes. Hail threat may not be overly impressive with a lack of sub-freezing cloud depth...but certainly even small/sub-severe hail could help the cause of downbursts. Other threat with the activity Monday is heavy rain, with warm rain processes remaining in play amid increasingly anomalous moisture over the area. While slightly better wind fields aloft could certainly lead to slightly quicker storm motions than we`ve seen the last couple days or so...do think it`s not out of the question some areas could see training/backbuilding storms along mesoscale boundaries (e.g., the Lake Huron lake breeze)...which could produce a localized significant amount of rainfall in a short period of time. Probabilistic guidance suggests that 24-hr rainfall totals by 8am Tuesday could be an inch or greater on the worst case scenario end of things. Think the broader focus for these heavier rainfall totals will be NE Lower Monday into Monday night...and think activity should hang on into at least part of Monday night, with the boundary likely a bit slower to move through over there. If the boundary ends up hanging out over NE Lower...think another round of pop-up showers/storms could be in the works for Tuesday. Potential for Beryl`s Remnants to Impact Northern Michigan?... This may be the trickiest part of the forecast attm...given uncertainty as it gets scooped up by our northern stream troughing early this week. There are decent signals for additional northern stream energy to dive into the back of the trough Wednesday...which could buckle things further northwest than currently anticipated (at worst case scenario). Do think there could be a tight gradient on the north side of this system...with high pressure potentially settling in to our north...which bears watching as well, as it could help drive the northern edge of the precip shield further south. Even so...with tropical moisture and well-organized surface system crossing the Ohio Valley...think at least some portion of our area (even our more vulnerable hydrological areas toward Saginaw Bay) could be in a favorable position for a prolonged period of steady/heavy rain. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 139 PM EDT Sun Jul 7 2024 Currently VFR conditions over most terminals with lake breeze winds. Skies could fill in more for terminals near the boundary this afternoon with chances for ISO -RA/VCSH low and mostly near the tip of the mitt terminals. Skies will fill in and lower after 06Z with chances for VCSH approaching the state from the W/SW. Winds will start to turn S/SW 06Z - 12Z with better chances for -RA/VCSH. Chances for ISO TS after 12Z with chances too low for mention in TAF yet, which will likely lead to periods of MVFR/IFR cigs and vis. Chances for SCT VCTS/TSRA near the end of the period and into Monday afternoon. && .APX WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ SHORT TERM...DJC LONG TERM...FEF AVIATION...ELD