Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 221407

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1007 AM EDT SAT OCT 22 2016


A forecast update was issued to adjust for latest cloud trends.
Some fairly significant clearing has occurred over portions of the
area since daybreak. The 12Z DTX sounding did show a deep
inversion based at 860MB, much deeper than the bulk of most of
the 06Z model suite suggested, including several hi res
solutions. The moisture under the inversion is however very
shallow. Subtle downslope into the Saginaw Valley and ongoing
large scale subsidence has supported some areas of clearing. The
low level flow will continue backing toward the west today. This
will bring some remnant lake clouds into Se Mi. There will also be
some diurnal cloud enhancement. Low level warming across Lake Mi
today will however suppress the lake response. Increasingly
divergent low level flow across Se Mi will also lead to an
overall tendency toward mixing out some of the clouds. Taking all
of these factors into consideration will likely result in a mix of
sun and clouds through the first half of the day. The more
widespread mid cloud deck now over ern Wisconsin and wrn Lake Mi
is associated with mid level warm air advection and will
eventually overspread the forecast area late this afternoon into
the evening.


Issued at 659 AM EDT Sat OCT 22 2016


Mostly cloudy skies (low VFR) expected today as cool airmass remains
in place. Warm advection this evening into tonight is then
expected to support an extended period of mid clouds before skies
clear toward sunrise Sunday. Northwest winds today topping out
around 20 knots by afternoon, becoming very light westerly this

For DTW...If anything, could see ceilings develop/move in quicker
(late this morning) than the taf indicates.

//DTW Threshold Probabilities...

* Low confidence in ceilings aob 5000 ft this morning, medium this

Issued at 325 AM EDT Sat OCT 22 2016


Slow release of the existing mid level cyclonic flow within the
trailing section of the departing mean trough periphery will leave
SE Michigan under generally benign northwest flow today.  Cloud
trends the primary challenge through the daylight period.  A
gradually drying north-northwest gradient this morning promoting a
slow clearing process of the existing stratus, although satellite
trends still present a mixed signal as to exactly how much clearing
will commence yet this morning.  Model evidence then continues to
point toward the eventual eastward expansion of the residual lake
Michigan moisture plume now tucked closer to the coastline.  This
advective process occurs in response to general backing of the mean
flow toward the west with time, with this moisture capitalizing on a
sufficiently steep lapse rate environment as diurnal heating takes
hold.  Increasing upper heights will yield a natural increase in mid
level temperatures relative to yesterday, but expect lower levels to
respond more slowly.  Highs arrive in close proximity to yesterday,
with readings in the vicinity of 50 degrees.  There will be a noted
diurnal uptick in northwest winds as well, with a gust component
into the 25 mph range this afternoon.

Pocket of higher mid level moisture will lift across the region
tonight, as the surface ridge slips through and mid level flow
briefly transitions to weakly anticyclonic.  Presence of at least
some degree of cloud cover and the eventual emergence of a light
southwest flow will cap the cooling potential.  Coldest locales
could potentially achieve the mid 30s /thumb/ should a greater
window of clear sky develop, but generally favor lows in the upper
30s/near 40F for many locations.

Pattern of weak low level warm air advection develops on Sunday,
existing low level southwest flow increasing immediately downstream
of an inbound cold front.  Mixing potential perhaps compromised some
as mid level warm air advection remains stronger, but the noted
warming across the lowest levels should still support readings into
the 60 to 65 degree range.  Compact shortwave will quickly track
from the Upper MS Valley Sunday morning into central/southern Lake
Huron by early Sunday night. Model response remains rather muted
as this wave clips across central lower Michigan 21z-04z Sunday
evening/night. Best response locally tied to the attendant cold
frontal boundary, with frontal convergence increasing with time as
trailing stronger height falls eventually catch the boundary. A
simple chance pop mention still warranted for areas mainly M-59
northward during this time.

Cooler post-frontal environment will define conditions Monday under
prevailing northwest flow.  Little expectation for the ambient
airmass to moderate much heading into the midweek period.
Extended guidance projects the development of low level easterly
flow locally, downstream of a dynamic system organizing across the
Plains. This tends to limit the diurnal response, particularly if
an increasing coverage of cloud cover further caps an already
meager mixing profile. This points to below normal temperatures
across the Monday to Wednesday period. Dry conditions through at
Tuesday under confluent mid level northwest flow and high pressure
at the surface.


Northerly winds mostly in the 20 to 25 knot range over Lake Huron
will become northwest Today, with just a slow diminishing trend
Tonight. Small craft advisories remain in effect for the nearshore
waters of southern Lake Huron, including Saginaw Bay. Winds will
decrease to 15 knots or less on Sunday as the gradient finally
relaxes across the region. This will be brief however as another
push of cold air will support a reintesification of the northwest
winds by Monday, with gusts around 30 knots over the open waters
of Lake Huron.


Lake Huron...Small Craft Advisory until 4 AM EDT Sunday FOR LHZ421-441>443.

     Small Craft Advisory until 10 PM EDT this evening FOR LHZ422.

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



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