789
FXUS63 KDTX 151950
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
350 PM EDT Wed May 15 2024

.KEY MESSAGES...

- Dry conditions through today and much of tomorrow.

- Increasing precipitation chances Thursday night with scattered to
  numerous showers and possible embedded thunderstorms Friday.

- Low chances for showers and thunderstorms over the weekend, mainly
  Saturday, with an active weather pattern setting up early to middle
  of next week.

&&

.DISCUSSION...

A surface low pressure will continue the slow progression eastward
today with northeast winds gusting to around 15 knots across most of
southeast Michigan this afternoon. Drier air filtering into the
region has brought decreasing clouds north of I-96 with lingering
clouds to the south with even a hint of elevated smoke from
wildfires present across parts of central Michigan. Any low chance
of precipitation this afternoon has come to an end with dry
conditions expected to hold through this evening and overnight.

Surface high pressure center over Hudson Bay and shortwave ridging
aloft passing through Michigan early in the day will help maintain
dry conditions through much of the day tomorrow, but high falls will
be encroaching into the western/central Great Lakes associated with
an upper Midwest trough. Increasing clouds will arrive downstream of
this feature during the afternoon into the evening. Lower level
moisture advection will ramp up throughout the day as well. Marginal
instability tries to develop along the southwestern fringes of the
CWA during the afternoon, but synoptic lift is rather weak. This
should keep any isolated or scattered showers and possible
thunderstorms that may develop during the afternoon to the west of
the forecast area. Warm advection throughout tomorrow will bring
afternoon high temperatures up a few degrees compared to today into
the mid 70s. Weak shortwave energy over Michigan tomorrow night will
bring increasing precipitation chances during the overnight period,
but any activity should be scattered.

The weakening trough lifting into the northern Great Lakes/Ontario
will drag a weakening frontal boundary through the central Great
Lakes on Friday with more appreciable chances for rainfall during
the morning and afternoon. Models have some increasing instability
into the afternoon ahead of this front. MLCAPE values generally
around 500-750 J/kg are forecast by the RAP for Friday afternoon.
Bulk shear at 0-6 km will be around the 25-40 knot range. Though,
steep mid level lapse rates will be lacking based on the forecast
right now. This environment will be supportive of mainly general
thunderstorms given the lack of strong forcing.

The start of the weekend will see a southern stream shortwave lift
out of the southern plains and into the central/northern Appalachian
Mountains while the northern stream jet situates west to east from
the PacNW through the upper Midwest. Saturday will see weak surface
flow with a relatively warm and moist airmass residing across
Michigan. Weak lift in the vicinity of the southern stream trough
combining with the diurnal instability may be enough to generate
some isolated to possibly scattered convection, though much of the
area probably remains dry. Will maintain lower end PoPs of 20-30%
for Saturday afternoon. Lead shortwave trough at the front end of
the northern stream jet will help drive a cold front through
Michigan on Sunday. Confidence decreases in regards to precipitation
chances along this front, but it looks like chances will be limited
as deeper forcing holds off to the north. Zonal flow pattern sets up
for early next week setting up a possible active stretch of weather.

&&

.MARINE...

Low pressure exits the Ohio Valley today, keeping fresh northeast
flow in place. Small Craft Advisories are in effect for Saginaw Bay
through 8pm and for the nearshore zones between Port Sanilac and
Port Huron through 11pm tonight. Northeast wind over the bay up to
25 knots will continue to die down through the evening hours, and
peak hazard conditions have already occurred for that area. High
waves are the concern for the Port Sanilac to Port Huron near shore
zone. High pressure briefly influences the area Thursday morning,
before showers return on Thursday evening into Friday due to low
pressure dragging a front across the Great Lakes. Thunderstorms are
also possible with this event, but other than localized impacts due
to these showers/storms, winds are expected to remain gentle at 10
knots, with waves expected to remain low through Friday and into the
weekend.

&&

.PREV DISCUSSION...
Issued at 149 PM EDT Wed May 15 2024

AVIATION...

Split upper level flow will bring a period of shortwave ridging
across Southeast Michigan the remainder of today and tonight.
Easterly wind trajectories will be in place in response to strong
surface high pressure in northern Canada. Boundary layer cloud and
saturation is forecasted to push toward the taf sites after 07Z
tonight, then persist and lift by midday Thursday. MVFR ceiling
heights are possible Thursday morning.

DTW THRESHOLD PROBABILITIES...

* Moderate for ceiling 5000 ft or less early after 09Z Thursday
  morning.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory until 8 PM EDT this evening for LHZ421-422.

     Small Craft Advisory until 11 PM EDT this evening for LHZ443.

Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

DISCUSSION...AA
MARINE.......BC
AVIATION.....CB


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