Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 271934

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
334 PM EDT SAT AUG 27 2016


Strong corridor of southwest flow will remain over the area through
the near term, funneling additional mid-level energy across the area
tonight. Fairly strong right entrance support will remain over the
Central Great Lakes during this time as the height gradient
contracts in response to the shortwave entering Minnesota this
afternoon. High moisture content will ensure low levels of
instability persist tonight and this should be sufficient for
regeneration of a few showers along the developing nocturnal LLJ
axis. Maintained a 40 pop roughly north/west of I-69 with just a low
schc elsewhere as theta-e advection could still kick off a few
isolated showers or storms.

Sunday will feature building high pressure as the Minnesota
shortwave tracks north of Lake Superior and upstream height rises
commence. Flow will veer to the northwest as the surface high takes
hold over the Northern and Western Great Lakes, forcing the moisture
axis and instability gradient south. 12z progs hang up this boundary
right along the Ohio border, so have introduced a low chance pop
there as solenoidal component of forcing during peak heating could
certainly ignite a few thunderstorms. Severe concerns remain low at
this time owing to marginal shear, although an isolated wind gust to
60 mph in Lenawee or Monroe County is not out of the question.

Flow continues to gradually veer into Sunday night, setting the
stage for a marine inversion to advect from northeast to southwest
across the CWA. NAM12 soundings appear quite favorable for a very
shallow inversion and the potential for marine stratus development
for the latter half of Sunday night. Bumped up sky cover and
overnight lows accordingly. Suppression of the instability gradient
and zonal flow aloft will sustain dry conditions through monday with
highs slightly above average values as H5 heights rise into the low
590s. Any marine stratus that forms will clear early and give way to
just passing high clouds embedded within flat flow aloft.

Surface cold front will move through the area on Tuesday and
Wednesday. A fairly moist airmass ahead of the front will allow for
scattered showers and thunderstorms to develop over portions of
southeast Michigan. As the cold front passes through on Wednesday,
above average temperatures should drop near to slightly below normal
for the remainder of the period. High pressure is expected to build
over the area Thursday and continue through the weekend.



Rapidly diminishing potential for thunderstorms through the evening,
leading to a quiet overnight period.  Modest southeast winds
shifting to southwest through this time.  Winds then becoming
northwesterly on Sunday as a front lifts through.  Strongest winds
expected across northern Lake Huron, but still at or below 20 knots.
High pressure will then bring a light and somewhat variable flow for
early next week.


Issued at 118 PM EDT Sat AUG 27 2016


Steady expansion in coverage of showers and thunderstorms across the
SE Michigan airspace will present a solid window for TSRA at all but
MBS moving forward through the mid-late afternoon period.  Greater
uncertainty on the prospects for additional/renewed development
beyond this lead activity /after 21z/.  Most recent model guidance
suggests greater stability will ensue with rapidly diminishing
potential by evening.  Moist low level conditions augmented by any
rainfall will then support some degree of fog and/or low stratus
formation during the early morning hours.  Moisture may linger into
early Sunday as low stratus before mixing out and drier air works in
by afternoon.

For DTW...Radar trends provide growing confidence for thunderstorms
to expand east-northeast into the airspace within the 18z-21z
window.  Confidence drops off beyond this time, with the potential
for increasing stability to limit chances thereafter this evening.
Residual low level moisture will then support some combination of
low clouds and fog during the early morning period.

//DTW Threshold Probabilities...

* Medium in thunderstorms through 21z, low 21-23z.

* High in CIGS aob 5000 feet this afternoon.  Low confidence tonight
  into Sunday.


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



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