Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 270710

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
310 AM EDT THU OCT 27 2016


Compact shortwave over northern Lower Michigan tracking off to the
East. Meanwhile, Upper level wave along the southern
Manitoba/Ontario border early this morning, tracking southeast and
reaching Lake Huron by this evening. Southeast Michigan will be
influenced by the mid level dry slot (700 mb dew pt depressions of
10 to 20 C) working into the State this morning. As of 7z, low
pressure located along the southern Michigan border, and will be
exiting the state around 12z, taking most of the measurable
precipitation with it. There is actually a good deal of mild air
on the backside of the low (around 50 degrees in Chicago), and
Detroit area and points south will likely hit 50 degrees or
slightly better (almost there already), even with low clouds
trapped underneath dry slot. Across the far north, temps probably
won`t get out of the lower 40s with northerly winds developing.
Main surge of cold advection does not occur until late day, with
850 mb temps falling to -5 C, but could be devoid of ice nuclei
(per nam soundings) as saturation fails to reach -10 C isotherm.
Either way, 850 mb temps then quickly warming overnight as
subsidence and pronounced upper level ridging builds into Lower
Michigan promoting clearing (outside of warm advection high
clouds toward morning).

Excellent warm advection pattern Friday into Saturday, with 850 mb
temps pushing into the low to mid teens by Saturday Morning ahead of
a cold front. Strong Upper level Jet forcing still looks to reside
just north of the Northern Great Lakes, and thus front will likely
be mainly dry as it comes through with the limited moisture and lack
of upper level support. Any light rain showers/sprinkles will have
to be generated down low with the low level convergence, and at this
point the prospects for measurable rainfall looks very low, as nam
likely overzealous with the low level moisture/qpf noise.

Temperatures look to be well into the 60s on Saturday, and still
reasonable shot at 70 degrees for Detroit Metro area depending on
the timing of the front and low clouds.

Not a great southward push to the front over the Weekend, and with
Upper Level Energy off the California coast progged to move into the
area Saturday Night, good chance the low level front will get going
and generate showers, especially near the southern Michigan border
into Sunday Morning...per 00z Euro. Clouds and cold advection
through the day on Sunday holding maxes in the low to mid 50s.



Strong east to northeast winds north of low pressure tracking across
Lake Erie will maintain gusts to near gales across portions of Lake
Huron this morning.  The persistent onshore flow will maintain large
wave action over Lake Huron, leading to extended small craft
conditions across the nearshore waters.  Winds and waves will
diminish late today and tonight as high pressure works across the
region.  Southerly flow then quickly ramps up on Friday, peaking
late Friday into Friday night.  The potential exists for gusts to
reach gale force during this time, prompting the issuance of a gale
watch central portions of Lake Huron.


Issued at 1155 PM EDT Wed OCT 26 2016


Low pressure will track along the Mi/Oh border early this morning.
Widespread IFR ceilings extend along and north of this sfc low with
the influx of moisture along and north of the low track. Recent
model soundings along with area observations suggest IFR ceilings
will prevail through mid to late morning. Mid level dry air will
continue to overspread Se Mi during the early morning. This will
cause the residual light rain showers to diminish to drizzle. Cold
air advection in the wake of the departing sfc low later in the
morning will allow a slight upward trend in ceiling heights during
the day Thurs.

For DTW...Observations indicate the IFR ceilings will move back into
metro by TAF issuance. The easterly winds will slowly weaken heading
toward daybreak as the sfc gradient relaxes with the approach of the
sfc low.

//DTW Threshold Probabilities...

* High in ceilings below 5000 feet today.


Lake Huron...Small Craft Advisory until 10 PM EDT this evening FOR LHZ421-422-

     Gale Watch from Friday evening through late Friday night FOR LHZ362-

Lake St Clair...Small Craft Advisory until 4 AM EDT early this morning FOR LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 4 AM EDT early this morning FOR LEZ444.




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