633 FXUS63 KAPX 220725 AFDAPXArea Forecast Discussion National Weather Service Gaylord MI 257 AM EDT Mon Sep 22 2025
.KEY MESSAGES...
- Showers and thunderstorms today and on Tuesday. A few stronger storms not out of the question.
- Fog potential again tonight. Fog could be locally dense in spots with significant reductions in visibility.
- Seasonable to seasonably warm temperatures through much of this week.
- Recent trends suggest a better chance for showers mid week, although uncertainty remains.
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.SHORT TERM /THROUGH TONIGHT/... Issued at 253 AM EDT Mon Sep 22 2025
Pattern Synopsis and Forecast:
Slow meandering upper low/trough (picturesque looking feature on WV satellite) continues to move eastward with time today and tonight, from N WI/W UP to near/just north of the eastern UP. There could be an embedded perturbation or two (perhaps of convectively agitated origin) on the southern periphery of the western flow which could aid shower and storm development later today and into portions of the overnight. Weak stationary boundary also remains draped across northern lower due to the very minimal meridional movement of upper level features across the Upper Midwest/Great Lakes region through the daytime hours.
Primary Forecast Concerns:
Thunderstorm potential: Showers and thunderstorms remain possible on Monday, especially during the afternoon as daytime heating is maximized. Couple of triggers that may allow for scattered thunderstorms during the day, one being the lake breeze across northeast lower, another the breaching of convective temperatures assuming daytime heating is able to maximize (although going back and looking at the latest 00Z point soundings does show a bit of warm air just above the boundary layer which could stifle development), and any subsequent outflow/differential heating boundaries. Additionally, few pieces of guidance (RAP/HRRR for ex) are also trying to hint at a convectively charged feature (from the current convection across MN) on the southern periphery of the trough center moving west to east across northern lower Michigan during peak heating. This scenario would result in quite a bit of thunderstorm coverage across northern lower, but could in theory materialize slower/less impactful given the sensitivity of these features.
Instability pushing ~1000+/- j/kg and modest mid level southwesterlies will support a threat for a couple of stronger storms, think especially along the lake breeze if convection fires off. Given the CAPE profiles, locally heavy rain and gusty/damaging winds will be the primary concern with the strongest storms, although some brief marginal hail cannot be ruled out given the modest bulk shear and increasing winds above 6km. If there is a little cap, then perhaps a good chunk of real/robust convection struggles, and much of the gibberish above was for naught. Conceptually think there is a decent chance for at least lake breeze convection though during the afternoon and at least isolated coverage elsewhere. Showers/rumble of thunder look to remain into portions of the overnight, esp early and close to the upper low center.
Fog development:
Recent rains, a relatively cool night, and light winds suggest an environment conducive for fog development late tonight. Despite the fact that there will likely be clouds and at least some precip chances lingering, it will still likely be cool and moist enough for fog development. Certainly is supported when looking at the HREF/NBM statistical/probability guidance, in addition to deterministic HRRR visibility, which suggests the potential for areas of significant visibility reduction.
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.LONG TERM /TUESDAY THROUGH SUNDAY/... Issued at 253 AM EDT Mon Sep 22 2025
Day 2 (Tuesday):
Not really a tremendous difference on Tuesday in regards to the upper pattern and expected weather. Upper low to the north across the E UP begins to drift a tad bit south/southwest to some extent. Environment remains characterized by ~1000 j/kg of CAPE and similarly modest shear and thus the chance for showers and thunderstorms will remain on Tuesday. Shower and storm coverage may be perturbed a little to the south comparatively, but again a stronger storm or two would be possible given the environment.
Days 3-7 (Wednesday - Sunday):
Although details still a little fuzzy, perhaps garnering a little better picture on the pattern for mid to late week, albeit plenty of uncertainty remains. On Wednesday, aforementioned upper low across the E UP begins to retrograde to the southwest over N MI/Lake MI. At the same time, upper low and embedded short waves across the center/southeastern portions of the country will begin to interact with the Lake MI upper low. Potent short wave will lift northward around the circulation of the Lake MI upper low, with a moisture filled low pressure system producing a swath of precipitation. Latest culmination of guidance vary but several pieces of guidance keep the main precipitation swath to the east of N MI for the most part. That being said, the upper low slowly drifting to the south does keep shower chances into mid week (~Wed-Thurs). There is still plenty of uncertainty with this pattern, as is the case usually with upper low interactions and potential phasing. There has definitely been a trend northward within the ENS over the last several runs though, with a little wiggle in the ENS sfc low pressure centers to the east this evening, and worth monitoring closely in the coming days. Either way, temperatures do look to remain near to slightly above normal for late September.
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.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1258 AM EDT Mon Sep 22 2025
Mixture of MVFR to LIFR producing fog/mist and stratus expected through early this morning. Gradually improvement expected after sunrise, with most locations likely trending to VFR conditions during the afternoon. Likely to see some scattered showers with a few embedded thunderstorms impact the taf locations today into this evening...although uncertainty is still significant with regards to overall shower/storm coverage and exact timing. Light winds through the period...with perhaps some brief gusty winds with any thunderstorms.
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.APX WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None.
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SHORT TERM...JLD LONG TERM...JLD AVIATION...MSB
NWS APX Office Area Forecast Discussion