555
FXUS63 KDTX 270709
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
309 AM EDT Mon May 27 2024

.KEY MESSAGES...

- Cooler for Memorial Day with scattered morning showers and a few
  thunderstorms transitioning to mainly dry and breezy conditions
  this afternoon.

- Continued unsettle tonight into midweek with periodic showers and
  average to below average temperatures in the 60s to lower 70s.

&&

.DISCUSSION...

Scattered showers and a few thundestorms will pivot through the area
this morning as an upper level shortwave and associated low pressure
lifts into northern lower MI and a cold front wraps west to east
through the area. Mainly dry conditions are expected for much of the
afternoon with gusty westerly winds as the cooler air is ushered in
behind the front.

Showers will pivot back southeast into the area this evening into
tonight and persist into Tuesday as this upper level system opens
and shifts back through the area on its way to the eastern Great
Lakes. A fast moving Pacific shortwave will merge with this MI
system tonight and help re-invigorate the rain shower potential to
some degree and will increase pops just a bit overnight into early
Tuesday.

In the meantime, an upper low pressure system positioned east of
Lake Winnipeg will pivot southeast into the area in the wake of both
of these merging upper waves from Tuesday into Tuesday night. This
will result in a continuation of unsettled weather with periodic
scattered showers into early Wednesday. As the colder upper level
core of this northern stream system works over the area, instability
will increase enough to warrant a thunderstorm mention as well.
While this will be most prevalent during peak heating from Tuesday
afternoon into early evening, a small chance of a thunderstorm or
two will persist overnight Tuesday night into early Wednesday as the
upper low/trough crosses the area.

Thereafter, upper ridging will expand into the area late this week
once the upper trough that results from these various shortwaves
shifts off to the east. This will bring dry conditions from late
Wednesday on through at least Friday with temperatures gradually
moderating from the mid 60s to lower 70s in the Tuesday-Thursday
time frame back into the middle 70s by Friday.

By next weekend, the surface high pressure system that coincides
with the upper level ridge will shift off to the southeast with
south to southwest flow becoming established over the area. This
will lead to further warming with high temperatures into the upper
70s to lower 80s. By this point in the forecast, the next stream of
Pacific origin shortwaves begin to impact the Great Lakes and this
brings a return of at least scattered/widely scattered shower and
thunderstorm chances.

&&

.MARINE...

Low pressure brings the first round of storms into the area this
evening. Strong low level easterly flow has already been able to mix
down 30 knot gusts, so a Small Craft Advisory has been issued for
the nearshore area of Lake Erie through 8pm tonight. Winds will
briefly die down overnight to 10-15 knots, but return to strength on
Monday evening with the passage of a cold front. Abundance of Small
Craft Advisories with this system, beginning with western Lake Erie
currently in effect through 8pm tonight. Conditions around the tip
of the thumb are expected to pick up tonight, so Small Craft
Advisory will go into effect beginning at 6pm tonight. All zones are
up to criteria by noon tomorrow, with the zones of Lake Erie, Lake
St. Clair, and nearshore areas of Lake Huron from Harbor Beach to
Port Huron expected to drop below criteria overnight Monday into
Tuesday. These advisories are set to drop off at 4am Tuesday.
Gustier conditions are expected to hang around a little bit longer
around the thumb, so the Saginaw Bay and Port Austin to Harbor Beach
zones have the advisory active until 4pm. Gale potential out over
the open waters looks marginal for now, and have decided not to go
with a gale watch at this time. Cooler conditions with westerly flow
are expected behind the front.

&&

.HYDROLOGY...

Periodic scattered showers and a few thunderstorms will impact the
region into Tuesday night and early Wednesday. Additional rainfall
will generally remain light to occasionally moderate. However, a few
localized downpours early this morning may bring one quarter of an
inch of rain to some locations. Otherwise, the highest precipitation
totals of one quarter to one half an inch from tonight into Tuesday
night and Wednesday morning will focus especially over the Saginaw
Valley and Thumb regions with perhaps one to two tenths of an inch
possible further south. Rises on local rivers associated with Sunday
evening rainfall will peak and subside today into tonight with this
additional early week rainfall having little to no additional
impact.

&&

.PREV DISCUSSION...
Issued at 1153 PM EDT Sun May 26 2024

AVIATION...

Prevailing MVFR cigs of approximately 2.0 kft agl are expected in
the wake of the convection from this evening. A convective vorticity
maximum will lift out of the Ohio River Valley and support an
additional round of showers and thunderstorms between 10-14Z Monday
morning. A cold front will sweep across Southeast Michigan between
15-19Z. West southwest winds of 20 to 35 knots will be possible late
Monday afternoon.

For DTW/D21 Convection...Another round of thunderstorm activity is
possible between 10-14Z.

DTW THRESHOLD PROBABILITIES...

* Moderate in thunderstorms between 10-14Z Monday morning.

* High in ceilings aob 5000 feet tonight and Monday.

* Low in crosswind thresholds being exceeded Monday afternoon.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory from noon today to 4 AM EDT Tuesday for LHZ442-
     443.

     Small Craft Advisory until 4 PM EDT Tuesday for LHZ421-441.

     Small Craft Advisory from noon today to 4 PM EDT Tuesday for LHZ422.

Lake St Clair...Small Craft Advisory from noon today to 4 AM EDT Tuesday for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory from noon today to 4 AM EDT Tuesday for LEZ444.

&&

$$

DISCUSSION...DG
MARINE.......BC
HYDROLOGY....DG
AVIATION.....CB


You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.