Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
FXUS63 KDTX 010121
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
821 PM EST Wed Nov 30 2016
Steepening mid level lapse rates this evening resulted from the
approach of a 500mb thermal trough. These steepening lapse rates
interacted with the back edge of the deep moist axis now moving
east of the area and actually triggered a cluster of thunderstorms
from roughly Armada to Port Huron. This convection is now well
east of the forecast area.
Attention now turns to a second region of moisture moving into the
forecast area from the west within the post frontal cold air
advection. Water vapor imagery actually shows numerous mid level
short wave impulses embedded within the broad upper low over the
western Great Lakes and upper Midwest. The short wave feature now
rotating into wrn Illinois will lift into Se Mi late tonight,
providing some larger scale forcing. This combined with the low
level moisture will support scattered showers. The better coverage
will be north of Detroit and Ann Arbor due to some modest lake
enhancement under sw flow. The degree of low level cold air
advection is not terribly strong, but will drop temps into the 30s
overnight. While this will allow some snow to mix in, the
relatively mild boundary layer temps will likely keep precip type
mainly liquid. An earlier update to the forecast nudge overnight
pops up slightly. So no additional forecast updates are needed
Issued at 553 PM EST Wed Nov 30 2016
Cold air advection will be ongoing during the course of the night.
This will sustain some degree of gustiness to the west-southwest
winds through daybreak. Ample low level moisture advection within
the cold air upstream will support a solid strato cu field through
the day Thurs. Cloud bases will initially be VFR early this evening,
then drop to MVFR as lower level moisture advects in from the west
within the colder air. This moisture combined with some upper level
forcing and over lake instability will support some rain and snow
showers late tonight, primarily over FNT and MBS. The better chances
for showers will then shift south toward metro Detroit on Thurs as
winds over Lake Mi turn more westerly.
For DTW...Some showers (a few thunderstorms) have erupted along the
back edge of the deep moist axis just east of metro. This moisture
and associated showers will exit east of D21 airspace between 00 and
02Z. The onset of cold air will be marked by a shift in the wind
toward 280 deg around 02Z. Winds will then gradually back more
toward 240 to 260 deg during the overnight.
//DTW Threshold Probabilities...
* High in ceilings below 5000 ft tonight through Thursday.
Issued at 251 PM EST Wed Nov 30 2016
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
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.
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.
Lake Huron...Small Craft Advisory until 10 PM EST Thursday FOR LHZ421-441.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
You can obtain your latest National Weather Service forecasts online