430
FXUS63 KAPX 271018
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
618 AM EDT Mon Jul 27 2026

.KEY MESSAGES...

- Showers and thunderstorms through tonight with strong/severe
  thunderstorm potential along with a heavy rain threat.

- A little cooler and a little breezy Tuesday with an
  increasing Great Lakes swim risk.

- Maybe more unsettled weather for next weekend.

&&

.DISCUSSION...
Issued at 318 AM EDT Mon Jul 27 2026

Pattern Synopsis/Forecast: Broad upper ridge encompasses the
southwest/southern Plains and the lower Mississippi Valley...with a
split trough long wave trough across eastern North America. Closed
low in the northern branch of the split trough is part of a high-
latitude block from Hudson Bay eastward across the North Atlantic.
Long wave trough off the west coast is firing pieces of energy over
the top of the western ridge...one such wave was moving into
northern Manitoba with a second over southern Saskatchewan.
Elongated latent PV anomaly around the fringes of the upper ridge
associated with the cyclonic shear side of an anticyclonically
curved jet extending from off the California coast...up and around
the periphery of the ridge and diving across the Great Lakes/mid
Atlantic.  Steep mid level lapse rates/elevated mixed layer
spreading into the Great Lakes from the northwest...700mb
temperatures at or above +12C knocking on Michigan`s doorstep.
Sunday evening surface analysis shows the usual summer mesoscale
chaos: 1002mb surface low along the North Dakota/Minnesota border
with a wavy frontal boundary extending to a 1005mb frontal wave over
Lake Superior.  A second warm front extends southeast across
Minnesota/Wisconsin/Illinois and into the Ohio Valley...with 70s-
lower 80s dew points pooled along and on the warm side of this
front.  Michigan is in a narrow wedge between these two boundaries.

Northern Manitoba short wave trough digs southeast across the Great
Lakes today...reinforcing the southern branch of the split long wave
trough downstream.  Overall pattern configuration doesn`t look to
change much through midweek; forecast trends continue to show a more
blocky pattern across the Atlantic basin...with more agreement on a
closed low developing in the southern branch over the mid Atlantic/
southern New England...as well as more agreement that height rises
will push into the Great Lakes for midweek.  For the latter half of
the week...energy undercutting the ridge may allow for some height
falls across the eastern CONUS and some overall retrogression of the
pattern as the ridge amplitude sharpens across the Rockies in
response to a strong upper low moving into the Pacific Northwest/
British Columbia next weekend (an impressive 600dam 500mb high
centered in the vicinity of the Four Corners next weekend).

Low pressure moving across the Great Lakes later tonight will become
better organized as it moves into the lower Lakes tonight...with a
stronger pressure gradient setting up across Michigan for Tuesday as
a result.  High pressure nudges into the upper Lakes Wednesday/
Thursday along with rising heights as the downstream pattern gets
backed up.  Looking at some height falls and possibly a frontal
passage for Friday/Saturday.

Primary Forecast Concerns:

Showers and thunderstorms through tonight with strong/severe
thunderstorm potential along with a heavy rain threat: As of this
writing (0630Z)...a narrow northwest-southeast line of convection is
developing from southern Lake Winnipeg to northeast Wisconsin.  A
smaller cluster of thunderstorms is dropping southeast across
eastern Upper Michigan....also getting some radar returns east of I-
75 in northern Lower.  All of this is developing along an elevated
instability gradient... which will be shifting across the upper
Lakes today. Current thinking is that upstream convection will
propagate east during the overnight hours (mid level winds are
backing more west)...and eventually spread into northern Michigan
this morning. It is quite possible that with surface low approaching
this afternoon...along with larger scale forcing with digging short
wave trough/left front quadrant jet forcing...there may be several
clusters of storms impacting northern Michigan throughout the day
into tonight.  Severe threat will certainly be in play today given
magnitude of the instability and deep layer shear...have already
popped off a few SVRs across eastern Upper this morning.  Other
concern is heavy rain potential...especially the way upstream
convection is lining up. As a result not going to get too cute with
PoPs and timing...if there is a larger break in the precipitation
then so be it...otherwise one is just asking for trouble.  Plan to
have an explicit mention of heavy rain in the forecast through this
evening.

A little cooler and a little breezy Tuesday with an increasing Great
Lakes swim risk:  Tighter pressure gradient and some momentum to mix
down expected to result in gusty winds Tuesday from the north/
northwest...on the order of 20-30mph.  Higher waves in a more
limited northerly fetch would be south of Grand Traverse Light on
Lake Michigan (high swim risk for Manistee County...moderate for
rest of northwest Lower shoreline counties)...and south of Thunder
Bay Island on Lake Huron (moderate swim risk for northeast Lower
shoreline counties).  Cold water upwelling also a concern on the
Lake Michigan side. Highs Tuesday should be mostly in the 70s.

Maybe more unsettled weather for next weekend: After tonight next
threat for rain arrives on Friday as short wave energy cuts
underneath the western ridge and dives across the Great Lakes/Ohio
Valley.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 618 AM EDT Mon Jul 27 2026

Multiple rounds of storms will be possible across northern Michigan
today ranging from this morning into this evening, making it
difficult to pin-point precise timing at specific locations in the
TAFs. That said, highest confidence in best storm coverage across
the area comes later this afternoon and early evening. Otherwise,
patchy FG/BR across parts of the area is expected to burn off
shortly after sunrise. Southwest to west winds around 5-10 kts are
anticipated for most areas today with lake breeze formation likely
pushing inland from Lake Huron this afternoon. Drops to MVFR/IFR
CIGs will be possible with any storms later today and may linger
into tonight with low-level moisture hanging around after a cold
front swings through this evening.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement from Tuesday morning through Tuesday
     evening for MIZ031.
MARINE...None.

&&

$$

DISCUSSION...JPB
AVIATION...DJC