Area Forecast Discussion
Issued by NWS Gaylord, MI
Issued by NWS Gaylord, MI
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977 FXUS63 KAPX 121030 AFDAPX Area Forecast Discussion National Weather Service Gaylord MI 630 AM EDT Wed Jun 12 2024 .KEY MESSAGES... - Warmer yet with chances for showers and storms tonight. - Chances for marginal severe storms Thursday - Heat builds in this weekend and early next week && .SHORT TERM /THROUGH TONIGHT/... Issued at 235 AM EDT Wed Jun 12 2024 Pattern Synopsis/Pattern Forecast: Weak (and weakening) shortwave trough in the process of working east across the area early this morning...becoming increasingly detached from rapidly decaying cold front working into the western Great Lakes. Just enough forcing/mid level moisture convergence to kick off a few sprinkles and light showers across the Northwoods... although those continue to decay as forcing and convergence do the same. Definitely a much milder night, with current readings mostly in the 50s. Shortwave and attendant disjointed moisture plume will work east of the area early on this morning, with remnant weak surface trough following in their wake. Next shortwave trough will sharpen some as it races east/southeast...reaching vicinity southwest Ontario and the northern Mississippi Valley region by sunrise Thursday. North/south oriented cold front will work out ahead of this wave, expected to reach western upper Michigan down into central Wisconsin by Thursday morning. Organizing pre-frontal moisture plume will spread across our area tonight, bringing the next threat for showers and thunderstorms along with it. Primary Forecast Concerns/Challenges: Cloud/temperature trends and addressing shower and thunderstorm potential tonight. Details: Any lingering showers/sprinkles expected to come to an end early on this morning, leaving behind partly to mostly sunny skies. Airmass continues to modify, and when combined with that sunshine...will support high temperatures this afternoon reaching into the lower 80s across much of northern lower Michigan...with readings just a touch cooler right near those big waters and across eastern upper Michigan. Will likely see some afternoon cumulus develop, particularly across northeast lower Michigan where convergence will be maximized. Not out of the realm of possibility for a stray shower or two to develop out of this cu field, but probabilities are simply too low to include in the forecast at this time. Deep layer moisture advection ramps up tonight out ahead of that approaching wave. Expect upscale growth to showers and thunderstorms off to our northwest later this afternoon and evening, with favorable mass convergence along veering of 40+ knot low level jet helping drive at least some of that activity into the region tonight. Not overly confident on how organized and widespread showers will remain as they depart much more impressive instability plume to our west. Still, axis of elevated instability (several hundred joules/kg cape) and forced convergence along the leading edge of that low level jet definitely supports at least some maintenance of showers and thunderstorms. Despite increasing wind fields through the vertical, surface based instability is lost...negating any real severe weather concerns. Suppose a more organized updraft through that elevated instability plume would support some brief gusty winds, but any severe threat most definitely appears minimal at this time. Even milder tonight, with lows likely not even dropping out of the 60s for most areas south of the big bridge. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Issued at 235 AM EDT Wed Jun 12 2024 Pattern Synopsis and Forecast: A weak surface feature will be moving over northern MI Thursday morning around sunrise. Mostly stratiform rain with a few spots of embedded thunder and more moderate rain showers will be generally exiting to the east. Southwest winds will prevail and will strengthen as we head into midday. Moisture from the recent rain and continual moisture advection will allow surface dewpoints to reach into the mid 60s over much of the area Thursday afternoon. An upper level short wave will track to clip the Great Lakes region, trending upper heights down while surface temperatuers warm. This leads to good chances for around 1000 - possibly 2000 j/kg SBCAPE (00Z HRRR and NAM most agressive) Thursday afternoon. Better mid level shear exists (mostly speed and less directional) which will help storms get organized. This (and a few other details discussed below) will lead to good chances for a severe environment Thursday afternoon and evening. A cold front will be approaching from the north, possibly moving through the CWA late afternoon/evening to even early Thursday night. At this time, CAMs depict more discrete convection forming along the boundary as it moves through the CWA. Model sounding profiles depict better chances for hail and wind threats with storms, as we lack stronger lower level shear. Northwest winds and upper level heights starting to rise Friday. Temperatures will dip around 10 degrees with the cooler and drier Canadian air settling in. Upper level ridging building over the easter CONUS coast will keep the warming trend in place through the end of the period. Moisture will eventually be advected northward, rising heat indices even more for early next week and introducing more rain chances. Primary Forecast Concerns/Key Messages: Short range CAM guidance has been trending up for available instability Thursday. The mean HREF SBCAPE for Thursday afternoon is around 900 j/kg. 00Z Sounding traces from the HRRR depict a healthy part of that instability within the HGZ, even with drier mid level air. CAMs more consistently show an elongated hodograph trace, indicating weaker low level shear but enough mid level shear to organize storms. LCL heights will generally be around 2 - 3.5 kft, and combined with weaker low level shear will be less favorable for tornadic activity. The more likely threats will be hail and wind with storms that do form. Now do form is the key there, as there is uncertainty in the timing of the cold front. Some guidance moves it through eastern upper more in the afternoon hours, and some guidance shows it slightly later (especially previous runs). If there is ample afternoon sunshine after the morning rain moves out Thursday, isolated to scattered storm formation won`t need the boundary and will likely fire off somewhere over northern lower (convective T is around 83 degrees, which northern lower will likely reach in the mid afternoon hours). The front will likely aid in storm initiation over eastern upper sometime Thursday afternoon, and these storms have chances for producing severe hail and/or winds. Enough instability (elevated at least) should stick around for the frontal passage once it reaches northern lower, meaning storm chances will continue through Thursday evening and maybe night (depending on the frontal timing). && .AVIATION /12Z TAFS THROUGH 12Z THURSDAY/... Issued at 627 AM EDT Wed Jun 12 2024 VFR conditions expected into this evening. Threat for showers (and perhaps embedded thunderstorms) arrives from west to east overnight, perhaps producing MVFR conditions with any heavier showers. Otherwise, trends support maintenance of a VFR producing cloud deck. Southwest winds expected to become a bit gusty today. && .APX WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ SHORT TERM...MSB LONG TERM...ELD AVIATION...MSB/MLR