959
FXUS63 KGRR 182320
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
720 PM EDT Thu Jul 18 2024

.KEY MESSAGES...

- Dry and pleasant next few days

- Daily chances of summer pop-up showers/storms next week

&&

.DISCUSSION...
Issued at 245 PM EDT Thu Jul 18 2024

- Dry and pleasant next few days

Upper-level flow and dynamics will be weak over the next few days,
with one jet rounding a low over northern Ontario/Quebec and
another faint jet over the mid-southern CONUS. High pressure in
the lower levels will be in place over the Midwest and Great Lakes
through Saturday while slowly weakening.

Patchy fog is possible in southern Michigan late tonight with the
center of the high moving closer. Dew points tomorrow will be in
the 50s again, quite comfortable, with temperatures a little
cooler than normal for mid July. Some daytime cumulus clouds are
expected to develop away from Lake Michigan.

- Daily chances of summer pop-up showers/storms next week

Despite fairly weak flow overhead through much of the troposphere
early next week, the tendency for broad upper-level troughing over
the Midwest will erode the surface high, favoring slightly better
dynamics for lift as well as weaker capping atop the diurnal
boundary layer. Moisture content of the lower troposphere may
creep up slightly each day, presumably in part due to
evapotranspiration across the region. A reinforcing shortwave
trough is likely to dive into the midwest from central Canada
midweek.

Shower and thunderstorm chances will increase between Sunday and
the middle of next week, peaking daily each afternoon-evening.
Slight chances begin in Central Michigan on Sunday. Better
instability and dynamics around Tue-Wed-Thu will support higher
chances for scattered storms.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 720 PM EDT Thu Jul 18 2024

Light winds and clearing skies on the way this evening. This
could bring some MVFR visibilities in fog between 06z and 12z.
Otherwise, expect VFR conditions.

&&

.MARINE...
Issued at 245 PM EDT Thu Jul 18 2024

Moderate to high swim risk at Lake Michigan beaches, and hazardous
winds and waves for small craft, are expected to persist into
Thursday evening south of Whitehall toward South Haven. High
resolution models including the HRRR have been indicating north
winds (due to high pressure west of us), combined with a daytime
lake breeze circulation, will pull the wind direction northwest
and intensify the wind speeds slightly this afternoon. North sides
of north piers will be particularly hazardous due to stronger
currents. On Friday, lighter west winds are expected with waves
around 1 foot.

&&

.HYDROLOGY...
Issued at 245 PM EDT Thu Jul 18 2024

Lingering water swamping of low-lying and slow-draining areas in
locations near and south of I-94, following the Monday night
thunderstorms, will very gradually improve through a dry weekend.
This includes river forecast points at Comstock Twp, Vicksburg,
Burlington, Marshall, and Jackson.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement until 8 PM EDT this evening for MIZ050-
     056-064-071.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LMZ844>847.

&&

$$

DISCUSSION...CAS
AVIATION...Maczko
MARINE...CAS
HYDROLOGY...CAS