Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 180745
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
345 AM EDT Wed Oct 18 2017

.DISCUSSION...

Quiet weather pattern through the upcoming weekend as ridging aloft
and at the surface reside over the region for the most part. Some
slight eastward drift with the surface ridge centered to our SE will
occur as a mid level shortwave passes over Wednesday night into
Thursday, but it looks to build back west for the weekend. Next
notable system doesn`t look to arrive til Sunday into Monday.

Today will largely be dry and sunny as shortwave ridging split flow
region slides over the state immediately in advance of a weak
trough. Very dry airmass and subsidence region will keep the skies
clear. Will get some gusty winds as the gradient between the
approaching trough and surface ridge tightens/compresses overhead.
One limiting factor to winds will be the low mixing heights which
are forecast to rise to around 3kft. Most model soundings show this
cap gusts off around 25-30 mph but a couple higher gusts can`t be
rules out. Temperatures today will again rise to around 10F above
normal which is around 70F. As mentioned in the previous discussion,
temperatures slightly over achieved and the thermal profile looks to
warm slightly over yesterday so should only add to the confidence of
achieving these temperatures with the warm SW flow.

The strength of the ridge will steer the next upper level wave well
north of the Great Lakes through northern Ontario and James Bay. The
weakening cold frontal trough extending southward from this system
will sweep across Lower MI Wednesday night into Thursday. Little
fanfare with the trough as the airmass is so dry and surface ridge
still remains in place. Looks like at best we`ll see a period of
enhanced cloud cover with the trough but that should be about it.
Highs will fall back into the mid/upper 60s in responds to the weak
thermal trough as well.

Surface high builds back over the area Friday into the weekend,
still positioned for us to receive a favorable SW flow. Upper level
ridge amplifies over the eastern conus in response to the strong
trough coming ashore the west coast. Though the trough looks to
fracture as a potential 140+ kt jet surges east through southern
Canada, a cold front should track across lower MI sometime Sunday
into Monday bringing the next chance of showers. With the jet
quickly refocusing back to our north, warm westerly flow will
continue behind the front keeping near normal temps across southern
MI.

&&

.MARINE...

A pressure gradient between surface high pressure slowly moving east
through the Ohio Valley and low pressure in central Canada will
maintain gusty southwest winds through the midweek period. Small
craft advisories are again in effect today and tonight for Saginaw
Bay and the nearshore waters of Lake Huron from Port Austin to
Harbor Beach. Southwest winds will then diminish slightly this
evening below 20 knots before maintaining around 20 knots over Lake
Huron on Thursday.

&&

.PREV DISCUSSION...
Issued at 1158 PM EDT Tue Oct 17 2017

AVIATION...

Moderate southwest wind will persist and be the main impact on
aviation conditions over the next couple of days. This will occur as
SE Michigan remains in between surface high pressure over the Ohio
Valley and a track of low pressure systems through far northern
Ontario, north of Lake Superior. Boundary layer decoupling during
the night will leave just the gradient wind through mid morning.
Gusts near 25 knots will then once again be likely through
afternoon. Conditions will otherwise be VFR in varying coverage of
high clouds.

//DTW THRESHOLD PROBABILITIES...

* None.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Small Craft Advisory from 10 AM this morning to 10 AM EDT Thursday
     for LHZ421-422-441.

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

$$

DISCUSSION...DRK
MARINE.......CB
AVIATION.....BT


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at www.weather.gov/detroit.



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