Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 190757

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
257 AM EST Sun Nov 19 2017


Sprinkles and flurries were moving across the forecast area early
this morning in the wake of the strong storm over the St. Lawrence
Valley. As the colder air continues filter into the area, expect all
of these to change to flurries/scattered snow showers.  Today will
feature cyclonic flow in the wake of the storm with some help from
the lakes, diurnal response giving some boundary layer instability
with convective depths up to around 8000 feet and a shortwave moving
over the region. Therefore will keep the 30 to 40 POPs in the
forecast for those snow showers today. Will also keep the high
temperatures closer to the mid 30s with plenty of clouds, raw model
output colder than guidance and the cooler trend in that guidance.

High pressure ridge folds over Lower Michigan this evening which
will not only end the cyclonic flow but also introduce some drier air
in the boundary layer. Expect some partial clearing tonight, but
there is a jet streak diving down into the lakes late tonight with
some modest jet support and 500 mb Fgen and deformation. This will
support some mid and high clouds from about 09z to 15z.

After that skies will be mostly sunny for the bulk of the day on
Monday. Southwest gradient strengthens as the high moves east and
the next potent system heads toward the northern Great Lakes.
Subsidence inversion is very low which will keep us from mixing too
much wind, but will also keep the temperatures in check in the mid
to upper 40s.

The cold front moves through Lower Michigan on Tuesday. There is
decent dynamic support through a very good depth on Tuesday, but it
takes time for the response since the moisture is marginal. Will
have just chance POPs for the eastern portions of the forecast area
Tuesday afternoon.

Seasonably cool high pressure builds into the region on Wednesday
and for Thanksgiving. This high will keep it dry enough for a fair
amount of sun on Wednesday and Thursday to offset the cooler regime.
Friday will be a transition day before the next system on Friday
night and Saturday which will bring our next chance of rain and/or



Northwest gusts to gales over the open waters of Lake Huron will
diminish through the morning as high pressure works into the area.
A period of moderate to fresh westerlies will then take hold through
Monday followed by the the development of strong southwest flow
Monday night into Tuesday as low pressure tracks across northern
Ontario. Gusts to low-end gales will be possible during this time
and a fresh gale watch is now in effect.


Issued at 1146 PM EST Sat Nov 18 2017


While winds have been slow to increase this evening, a push of low
level cold air overnight will support increasing mixing depths. This
will sustain northwest winds gusts in the 20-30 knot range. The
increasing depth of the cold air will lift inversion heights, which
in turn will result in steadily rising ceilings. With inversion
heights forecast to exceed 6k ft by late Sun morning, ceilings
should trend VFR by daybreak. Some lake effect showers may break off
into Se Mi from northern Lower. Expect the brevity of any snow
showers through daybreak will be enough to leave the mention out of
the terminals.

For DTW...There will be a slow backing of the winds from 320/310 deg
toward 280/290 deg through daybreak. Speeds will slowly drop during
the early morning. Thus the chances for crosswind thresholds to be
exceeded are looking low. There is a chance for some snow showers to
release off Lake Michigan and impact metro Sun afternoon. No
accumulations are expected.


* High for cigs aob 5kft tonight and Sunday.

* High for precip type being all snow Sunday.

* Low in crosswind thresholds being exceeded Sunday morning.


Lake Huron...Gale Warning until 7 PM EST this evening for LHZ361>363-462>464.

     Gale Warning until 10 AM EST this morning for LHZ421-441>443.

     Gale Warning until 7 AM EST this morning for LHZ422.

Lake St Clair...Small Craft Advisory until noon EST today for LCZ460.

Michigan waters of Lake Erie...Gale Warning until 10 AM EST this morning for LEZ444.




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