Area Forecast Discussion
Issued by NWS Gaylord, MI
Issued by NWS Gaylord, MI
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320 FXUS63 KAPX 120741 AFDAPX Area Forecast Discussion National Weather Service Gaylord MI 341 AM EDT Sun May 12 2024 .KEY MESSAGES... - Thunderstorm potential late this afternoon into tonight. A few strong/severe storms possible, mainly this evening. - Continuing rain/thunderstorm chances for central Lower Monday/ Monday night. - Rain chances return Thursday and beyond. && .SHORT TERM /THROUGH TONIGHT/... Issued at 340 AM EDT Sun May 12 2024 Synopsis/pattern: Yesterday`s system of concern is near Niagara and heading east. A surface ridge axis extends northward across Lake MI and eastern upper MI, providing brief benign wx here. Our next system is over far nw Ontario, with a cold front trailing off into nw MN and eastern ND. This front moves into the area late tonight. Forecast: Dealing with some shallow ground fog in the usual sheltered locales. That should erode fairly quickly past sunrise. There have been some weak warm-advection-forced showers/sprinkles early this morning in parts central/western upper MI and northern WI. This is ahead of an elevated warm front, and behind the surface ridge. These will continue to migrate eastward, reaching western Chip/Mack Cos toward mid- morning. Sct showers will continue to develop eastward across the UP, far northern and ne lower MI, late morning to mid afternoon. Trailing this, partial sunshine will break out, especially in nw lower MI. That will help warm nw lower into the lower 70s today, with 60s to upper 50s elsewhere (coolest near Lakes Huron and Superior). Surface moisture does not recover (yet), with dew points in the low-mid 40s most commonly. So available Cape is minimal thru, say, 21Z/5pm. But a surface warm front then pushes east into the area, heading into this evening. Moisture in the BL jumps, with dew points climbing to around 50f. That gives a narrow window (before diurnal cooling kicks in) to boost MlCape values to 300-500j/kg. That corresponds with 0-6km bulk shear of 30-40kt, and sw winds at 1km also of 35-40kt. So it`s another event with reasonable shear and wind fields, but unimpressive instability. Kind of wish either shear or instability were a little bit stronger to get real excited. But SPC has a marginal svr risk late today in a good portion of northern lower MI, and that isn`t unreasonable. Main hazard is wind and perhaps hail, between 6 pm and midnight. So likely pops develop initially in eastern upper MI, the Straits, and far nw lower MI, by early evening. That expands se-ward thru the evening and early overnight, before pops start to diminish and exit closer to morning. A chance for showers/ storms lingers in the far se thru 12Z. Localized QPF will exceed 0.50" Min temps tonight from the lower 40s n to lower 50s se. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 340 AM EDT Sun May 12 2024 Pattern Forecast: Large scale pattern for this week starts with a northern branch short wave trough/upper low over northern Manitoba tracking east across James Bay...though it will slow/stall there as heights build downstream over the Atlantic. Meanwhile a southern branch low over the Four Corners this morning crosses the central/ southern Plains Monday and into the southeastern U.S. by Wednesday. Great Lakes remains in between these two features through midweek... then another split trough coming in off the Pacific and into central North America Thursday...and spreading height falls across the region for the end of the week. Northern branch wave passing by well to the north of the Great Lakes has an associated surface cold front that will drop into Lower Michigan Sunday night...and then stall across central Lower Michigan as front parallels upper level flow. Eventually this front should be given a nudge south by high pressure over Hudson Bay/Baffin Island ridging south into the upper Lakes Monday night/Tuesday with north/northeast boundary layer flow setting up across Michigan. Southern branch short wave trough over the mid/lower Mississippi Valley Tuesday will have a surface reflection that tracks across the Ohio Valley with eventual secondary cyclogenesis over the mid Atlantic...while surface ridge continues to hang on over the upper Lakes. Pattern evolution gets more muddled toward the end of the week but the idea in general for height falls and some resultant low pressure moving through the Great Lakes perhaps in the later Friday/Saturday time frame. Primary Forecast Concerns: Continuing rain/thunderstorm chances for central Lower Monday/ Monday night: Cold front will arrive in western Upper Michigan late this afternoon and work its way into Lower Michigan after midnight. Front looks like its going to get hung up south of M-72 Monday morning...there may some showers along the low level theta-e axis coincident with the boundary at the start of the day. Some low level instability will develop with diurnal heating which will bubble up additional convection south of an MBL-APN line during the afternoon. Meanwhile...southern branch short wave trough moving out of the central/southern Plains expected to have a developing deformation rain band that will spread into central/southern Lower Monday afternoon/evening with a surge of deep layer moisture into the southern half of the state (precipitable water 1.25-1.50 inch). Northern edge of this precipitation shield will probably scrape areas south of that same MBL-APN line...overnight mid level winds shift more northwest across the northern half of the state which is forecast to push the deformation zone farther into southern Lower. As long as this pans out expectation is that rain threat should come to an end by sunrise Tuesday. Rain chances return Thursday and beyond: After a couple of dry days with high pressure ridging in from the north...split Pacific trough moves into the Plains/Midwest Thursday. The majority of Thursday may end up staying dry...better rain probabilities look to be occur on Friday. And Saturday right now is a bit of a toss-up. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 136 AM EDT Sun May 12 2024 Shallow fog has formed at APN and MBL. These could last a bit past dawn. There is a chance for showers Sunday, but a better chance for showers and perhaps a few TSRA Sunday evening, as a cold front goes thru. Brief cig/vsby restrictions possible then. S to sw winds getting a little breezy this afternoon, weakening tonight. && .APX WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ SHORT TERM...JZ LONG TERM...JPB AVIATION...JZ