Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 152305
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
705 PM EDT Fri Sep 15 2017

.AVIATION...

Boundary layer moisture adequate for broken coverage of cumulus
during the afternoon hints that fog will once again be possible
tonight. As clouds dissipate, light southerly wind will become
variable or calm and allow radiational cooling to accelerate.
Temperatures will start down tonight from warm afternoon readings
once again today with some dewpoint recovery likely after the loss
of daytime mixing. This is expected to allow low end MVFR fog to
develop overnight through mid Saturday morning. Model soundings do
indicate a very shallow saturation that could produce a brief IFR
visibility around sunrise. Another fast trend of improvement is then
expected during mid to late morning leading to VFR with light south
wind during Saturday afternoon.

For DTW... As afternoon clouds dissipate, fog will become a concern
once again overnight through Saturday morning. Plan to hold the line
on expectations of low end MVFR restriction and monitor surface
observations during the evening for moisture contribution from Lake
Erie. This could make a short period of IFR fog or stratus possible
around sunrise through mid Saturday morning.

//DTW THRESHOLD PROBABILITIES...

* Low for visibility 1/2SM or less around sunrise.

* Low for ceiling 5000 ft or less Saturday afternoon.

&&

.PREV DISCUSSION...
Issued at 322 PM EDT Fri Sep 15 2017

Discussion...

With very little change in the overall airmass across the region,
this afternoon`s conditions will basically be repeated on Saturday.
There will be a little less residual low level moisture around, so
shallow fog during the early morning hours will be more limited in
most locations. Once that burns off, mostly sunny skies and south
winds 5 to 10 mph will bring temperatures into the lower 80s across
most of the region by afternoon.

The high pressure ridge will shift slightly east late Saturday into
Sunday as a weak cold front approaches from the west. This will lead
to additional warm air advection as south-southwest flow increases
somewhat. So, even with an increase in upper level cloud cover by
late in the day, expect temperatures to climb into the lower 70s
once again with some locations most likely reaching 85 degrees for
high temperatures.

The cold front then works into Southwest Lower Michigan from Sunday
evening into the overnight, bringing a chance of showers or isolated
thunderstorms to the area. Lack of quality moisture across the area
should limit coverage substantially and have no plans of increasing
precipitation chances above the going 20-30 percent in any notable
way.

After the front passes through in the morning, Monday`s high
temperatures will moderate slightly lower, particularly for areas
north of the I-69 corridor where highs will be in the lower 70s. For
the southern counties, upper 70s are expected Monday. Slight chance
for a round of showers on Tuesday as a weak mid-level disturbance
moves over the southern Great Lakes. Following this, an upper ridge
will build into the region Wednesday and into the weekend. With this
setup, SE Michigan can expect a mainly dry period with daily high
temperatures in the upper 70s. Overnight lows will fall into the
upper 50s to lower 60s.

MARINE...

High pressure remains over the region heading into the weekend
resulting in favorable boating conditions. Winds will be out of the
south through the weekend, mainly at or below 15 knots which will
keep waves heights in check. A weak cold front will swing through
the Central Great Lakes Sunday evening and night, triggering
scattered showers and possibly a thunderstorm. Winds will shift
northerly behind the front early next week, but still at or below 15
knots.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.

&&

$$

AVIATION.....BT
DISCUSSION...DG/TF
MARINE.......SF


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