Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 130948

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
548 AM EDT Sun Aug 13 2017


High pressure building into the region will result in VFR conditions
for most of the forecast. Winds will be 5 knots or less under this
high with mainly only mid or high clouds passing over. One concern
early this morning is the fog potential as radiative cooling peaks.
Thus far it has been a struggle to sustain fog at any one location,
with primarily patchy MVFR around. Still narrow window for better
coverage this morning, but should be short lived as the diurnal
cycle will quickly burn off this shallow fog layer. With low level
moisture around, a few afternoon cu should pop up.

For DTW... Watching fog potential through the early morning. Still
think MVFR is possible for a brief period before sunrise. Light
westerly wind will become variable or light onshore with weak lake
breeze influence this time of year.


* None.


Issued at 301 AM EDT Sun Aug 13 2017


Mid level subsidence will persist through the day amidst subtle mid
level height rises. This will sustain a large region of sfc high
pressure across the southern Great Lakes. Diurnal mixing will erode
early morning fog with continued drying the boundary layer into the
afternoon, leading to ample sunshine. Mixing depths expected to rise
up toward 5-6k ft will support afternoon highs in the upper 70s to
low 80s.

A fairly compact mid level low now churning over North Dakota is
forecast to rotate into the western Great Lakes late tonight into
Monday, transitioning into a broader open wave. A region of weak mid
level isentropic ascent ahead of this features will lead to an
increase in mid and high level clouds. The wave is forecast to
dampen as it rotates across Lower Michigan late Mon and Mon night.
This and lingering dry low level air will be substantial limiting
factors for much if any precip. Model soundings and plan views do
however suggest the development of weak instability Mon afternoon,
primarily in the vicinity of Saginaw Bay and the higher terrain in
north central Lower Mi. This instability, with the possibility of an
embedded weak short wave feature, will support a low chance of
convection across the Saginaw Valley and thumb region Monday into
Mon night. Despite the greater cloud coverage on Monday, slight low
level warm air advection within the return flow of the sfc high will
support high temps near 80.

Lingering entrance region jet dynamics late Mon night into early
Tues will support a slight chance of showers. Otherwise, a region of
mid level anticyclonic flow will overspread the Great Lakes,
supporting dry conditions through most of Tues into Wed. The 00Z
model solutions continue to show a mid level wave ejecting out of
the central Rockies and lifting into the northern Great Lakes in the
Wed to Thurs time frame. The latest model trends are for a little
less amplification, leading to a faster progression. This system is
expected to force sn influx of moisture and instability into Se Mi
in the late Wed to Thursday time frame, supporting the next good
chance for showers/thunderstorms.


High pressure building into the region will bring light winds to the
eastern lakes to finish the weekend. The region will remain under
the influence of this high through early next week keeping light
winds and favorable marine conditions in place.


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



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