960 FXUS63 KAPX 132154 AFDAPXArea Forecast Discussion National Weather Service Gaylord MI 554 PM EDT Sat Sep 13 2025
.KEY MESSAGES...
- More clouds north/less clouds south tonight/Sunday.
- Mid September warm spell continues Sunday.
- Well above normal temperatures through midweek...next chance for rain likely not until Friday.
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.SHORT TERM /THROUGH SUNDAY/... Issued at 310 PM EDT Sat Sep 13 2025
Pattern Synopsis/Forecast: Split flow pattern persists across North America to start this weekend; northern branch flow emanates from a trough over the Pacific...extends north around a strong upper ridge across the Canadian territories...then dips around an upper low east of Hudson Bay. Southern branch flow comes around a broad upper low over the northern Rockies/Great Basin...with a narrow but amplified ridge over the Plains (that extends north toward the northern branch ridge separated by a col region)...and a narrow trough axis along the mid Atlantic and southeast coast. Part of the northern branch upper low east of Hudson Bay is an elongated PV filament moving south across northern Michigan...behind which drier air is moving southward into the upper Lakes (at least higher up...still a good bit of absolute moisture at and below 850mb). At the surface...high pressure encompasses much of New England/mid Atlantic/lower Great Lakes...surface low over South Dakota has a warm front extending east into southern Wisconsin...with a cold front associated with the northern branch flow over northern Ontario.
PV anomaly/short wave trough coming in from the north will be south of the forecast area by this evening...trailing cold front will cross Lake Superior tonight and slow/become stationary across eastern Upper/northern Lake Huron Sunday. No real wind shift will exist with this feature by Sunday but there is still a bit of fingerprint in some of the low level thermodynamics. Meanwhile upper level ridge continues to build east and expand into the Great Lakes.
Primary Forecast Concerns:
More clouds north/less clouds south tonight/Sunday: Will be watching cold front that is still north of Lake Superior at mid afternoon... as it sinks into Upper Michigan tonight. While clouds have been mixing out ahead of the front this afternoon over Lake Superior... there will still be low level moisture along/ahead of the boundary as more significant drying occurs higher up. So the expectation is that clouds will redevelop ahead of the boundary this evening from the Straits north...with less cloud cover south. Some indications that low level moist layer may be thick enough to squeeze out some drizzle across eastern Upper overnight/Sunday morning. Clouds across eastern Upper should eventually mix out into Cu deck though it may take some time. Will mention some fog potential as well for overnight into Sunday morning.
Mid September warm spell continues Sunday: As mentioned yesterday combination of easterly flow off Lake Huron and more cloud cover across eastern Upper will set up an east-west temperature gradient across the forecast area. Warmest temperatures expected along and west of the I-75 corridor in northern Lower with highs from the mid 70s to lower 80s. Coolest readings likely around Drummond Island where temperatures may not get out of the 60s.
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.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... Issued at 310 PM EDT Sat Sep 13 2025
Days 2-3 (Monday-Tuesday): Long-advertised upper level anticyclone will be pretty much parked over the upper Great Lakes Monday and Tuesday...500mb heights in the vicinity of 590dam would be nearly a +2 sigma standardized anomaly for mid September. Overall pattern becoming a bit more Rex block looking as lower heights along the mid Atlantic/ southeast coast get cut off and caught beneath the positive height anomaly over the Great Lakes. Surface high pressure will be over eastern Canada to start the week...expanding south into New England and the mid Atlantic Tuesday. High temperatures likely to be a degree or two warmer each afternoon...with the idea of more widespread temperatures in the 80s on Tuesday. As mentioned in this space yesterday: Tuesday records range from 86 (ANJ) to 91 (TVC) both set just last year. Don`t see those being in jeopardy right now.
Days 4-5 (Wednesday-Thursday): Great Lakes region will be caught in a weak flow pattern for the midweek between troughs along the east coast and over the northern/central Plains. Highs in the 80s across much of northern Lower still in the offing for both days; also still a mostly dry forecast though areas south of the M-72 corridor in northern Lower could use some precipitation.
Days 6-7 Outlook (Friday-Saturday): Height falls associated with plains trough/upper low may eventually make their way into Michigan to end the week. This should bring an end to the big warm up and a return to something closer to normal...though there is a pretty big spread in probabilistic temperature guidance starting Friday. The forecast trend will be cooler but remains to be seen by how much. Rain chances will return Thursday night into Friday.
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.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 551 PM EDT Sat Sep 13 2025
Conditions look pretty favorable for more MVFR to IFR producing fog/mist and stratus development during the early morning hours of Sunday...especially at locations other than KTVC. Still some uncertainty in overall extent and duration, so will continue to use tempo wording to convey these impacts. Any fog/mist and stratus expected to burn off quickly after sunrise, leaving behind VFR conditions under what should be mainly sunny skies Sunday. Light/calm winds with local lake breeze development expected Sunday afternoon.
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.APX WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None.
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SHORT TERM...JPB LONG TERM...JPB AVIATION...MSB
NWS APX Office Area Forecast Discussion