Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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603
FXUS63 KDTX 301951
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
251 PM EST Wed Nov 30 2016

.DISCUSSION...

Large stacked low is centered over northern Wisconsin with an
occluded front arcing to just east of Michigan. Most of the area
experienced a fair amount of sunshine today in a zone of
subsidence and drier air. There were pockets of low clouds and
light fog mainly across the far western forecast area and Saginaw
valley resulting from moisture trapped under strong low level
inversion. Expect areas of clear skies and clouds for the rest of
day into the evening. Exception will be a few light rain showers
or sprinkles possible through evening along the far eastern
portion of the forecast area as weak elongated pva rides northward
along departing front just to the east.

The stacked low will drift east northeastward tonight and to the
northeast of Lake Huron by late Thursday.  Plenty of low level
moisture wrapping around this low will begin advecting into the area
tonight and will continue into Friday.  Cold air advection will also
begin tonight on a westerly flow which will pick up additional moisture
from Lake Michigan. Airmass is not terribly cold for this time of
year and mixing depths will not be too deep. Expect lake effect
showers to develop aided by mid level troughing and advect into
southeast Michigan later tonight and continue through Thursday.
Precipitation will be light with the heaviest and most coverage to
occur across the far western CWA and Saginaw Valley/Thumb.
Boundary layer will remain relatively mild with lows dropping
into the 30s tonight and highs in the 40s Thursday. Could see some
snow flakes mix in with any showers late tonight through shortly
after sunrise Thursday. Winds will also pick up from the west
southwest in the 10 to 20 mph range which will add a bite to the
air Thursday. Clouds will linger into Friday but any lake effect
precip will slowly dissipate as much drier air will be advecting
in.

High pressure and upper level ridging builds in for much of the
weekend keeping the area dry as temperatures remain slightly above
normal for the beginning of December.  The next system looks to then
develop late Sunday as a shortwave comes across, bringing the next
chance for rain and snow showers.  High pressure then follows in the
wake of the system bringing drier conditions back to the area for
the start of next week.

&&

.MARINE...

Cold front clearing the Central Great Lakes this afternoon, with
westerly post front winds in the 15 to 25 knot range, strongest
winds occuring over southern Lake Huron. This stronger winds will
continue tomorrow and even increase a bit more Thursday Night and
Friday as colder air filters into the region with winds becoming a
bit more northwest on Friday. High pressure for the weekend will
allow winds to become light and variable.

&&

.PREV DISCUSSION...
Issued at 1151 AM EST Wed Nov 30 2016

AVIATION...

Dry cold front clearing southeast Michigan this afternoon, with
narrow Area of IFR/MVFR clouds tending to mix out/lift and slide off
to the east. Confidence in ceilings this afternoon across
southern taf sites is low. Post frontal Low level cold advection,
helped out by moisture off Lake Michigan, will assure low clouds
(low VFR to MVFR) will return to southeast Michigan, but timing of
this is uncertain, as mid level dry slot looks to be persisting
into early this evening. As cold pool settles over Lower Michigan
Tonight into Tomorrow, there will be increasing chance of rain
(possible snow mixed in) showers as low level lapse rates steepen
up, with trajectories off lake Michigan favoring MBS/FNT early
tomorrow morning, with low chance across the southern taf sites by
late morning.

For DTW... Upstream IFR ceilings/fog likely dissipating, not
advancing past the higher terrain of the Irish Hills. Any cigs below
5 kft ceilings at Metro this afternoon should be brief, as drier air
seen over northern Indiana works in from the southwest behind the
front. Targeting mid evening hours for low vfr ceilings arriving,
with MVFR ceiilngs settling in overnight, and persisting through
tomorrow. Chance of showers tomorrow too low to introduce in Taf at
this time.

//DTW Threshold Probabilities...

* Low for ceilings aob 5000 feet through early this evening, then
  high late evening through Tomorrow.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Small Craft Advisory from 10 PM this evening to 10 PM EST Thursday
     FOR LHZ421-441.

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

$$

DISCUSSION...DRC/SS
MARINE.......SF
AVIATION.....SF


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