Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 271710

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
110 PM EDT Tue Jun 27 2017


Residual mid-level cyclonic flow in conjunction with daytime heating
has and will continue to produce high based VFR cu throughout the
afternoon. Isolated shower develop will still continue to be a
possibility during daylight hours (18 - 00Z), however, opted to
leave the mention of it out of the TAFs as coverage and duration
will be limited. Otherwise, high pressure moving across the Ohio
Valley throughout the day will act to keep winds westerly, with
isolated gusts peaking at 20 kts possible due to daytime mixing.
Gusts will diminish after sunset as nocturnal stability acts to
scour out remaining cloud cover.




Issued at 335 AM EDT Tue Jun 27 2017


Low pressure tracking into Georgian Bay will continue to drag an
axis of moisture across Southeast Michigan early this morning. This
will generate a few light showers, primarily north of M-59. The
showers should exit the thumb by about 8AM, allowing the atmosphere
to recover a little through the mid-morning hours before shower, and
possibly thunderstorm, chances are renewed.

Upper shortwave diving through Ontario and away from St James Bay
will clip across northern and central Michigan today. This should
help generate showers and a few thunderstorms again during the
afternoon and evening. Weak theta-e advection and only modest
instability should limit coverage to lower-end scattered. Low
freezing level (6-7kft) will once again bring the risk for small
hail with any thunderstorm that develops. The wave will exit east
during the late evening, leaving subsidence and drier air in its
wake. The remainder of the night and most of Wednesday look dry as
high pressure centered over the Ohio Valley extends northward into
Lower Michigan. Temperatures will undergo a moderating trend over
the next few days, with max temps reaching back into the upper 70s
by Wednesday as southerly flow increases.

Active pattern then setting up from Wednesday night through the end
of the week as upper energy now pushing through Oregon tracks
through the Upper Midwest and Great Lakes, and is followed by the
upper low now over British Columbia and Alberta. Strong low-level
jet will usher warmer air and moisture into the area Wednesday
night, spiking PW values up close to 1.75 inches. Idea is still for
storms to develop over the Upper Midwest Wednesday, and lift across
Michigan Wednesday night, with better chances for showers/tstorms
over central and northern Lower Michigan. Steep mid-level lapse
rates and 0-6km bulk shear around 30 knots could favor hail with
stronger storms, but elevated nature of storms would limit damaging
wind gust threat. Occluded surface low will track near the U.P. on
Thursday, dropping a weak front through southern Michigan. This
boundary will then serve as a focus for additional showers/tstorms
Thursday. While best chance for strong to severe storms looks to be
just south of the area, cannot rule out a few severe storms over
southern Michigan. Main concern with convection during the middle to
end of the week will be potential for storms to produce very heavy
rainfall in a short period of time. Areas where flood waters are
still receding will be most vulnerable.


A period of moderate west-northwest winds will exist today as mid
level troughing slowly relinquishes control.  Winds will ease
tonight under weak high pressure.  Moderate southerly winds then
emerge on Wednesday in the wake of this high.  South to southeast
winds will persist through Thursday, as low pressure tracks through
the northern great lakes.  Increasing stability as warmer air
returns under this pattern will limit the gustiness.  There will be
a chance of thunderstorms Wednesday night through Friday.


The next chance for organized rainfall will exist Wednesday night
into Thursday.  The latest forecast indicates up to one half inch of
rain will be possible through this time.  However, localized higher
amounts in excess of one inch could occur within any heavier
thunderstorms.  This would result in rises on area rivers and
streams, while potentially creating some minor flooding.  The
extremely saturated conditions still existing across the Tri-Cities
and northern thumb will make these locations even more susceptible
to a period of heavy rainfall.  In the meantime, area river flooding
continues to gradually ease. The Titabawassee has now fallen below
flood stage, with the Saginaw River forecast to fall below flood
stage Wednesday morning.


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



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