Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 270802

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
402 AM EDT WED JUL 27 2016


Upper energy dropping through Ontario will continue to push a
surface trough and cold front now over Lake Huron down into central
Michigan today, while gradually displacing surface high pressure
south into the Ohio Valley. Weak theta-e advection ahead of the
front and steepening mid-level lapse rates will support a chance for
showers and thunderstorms over south-central Lower Michigan as the
front settles into the area. Activity along the front weakened
overnight as it lost support from the low-level jet. While a few
showers/tstorms will be possible early, we can mostly expect to see
an uptick in activity as low-level lapse rates steepen with the
diurnal cycle today. Best chance for rain/storms looks to be from
Saginaw northward where greater instability will reside. ML CAPE
near 1500 J/kg may support a few brief strong updrafts with storms,
but with 0-6km bulk shear only around 20 knots, not expecting
anything to become organized for long. With fairly neutral thermal
advection, temperatures today will be similar to yesterday, in the
mid/upper 80s with a few 90s sprinkled in. Chances for
showers/storms will linger through the late evening as the surface
trough axis drops across Southeast Michigan. Cold front looks to
pretty much wash out however with lack of upper support and as it
becomes parallel to upper flow. Given this and very dry air in place
currently over Southeast Michigan, will keep the forecast south of M-
59 dry today and through the evening. Plenty of clouds expected by
this evening and overnight however, both with moisture associated
with the surface trough and from debris clouds arriving from
overnight convection over the Dakotas and Minnesota. This activity
is firing ahead of the next shortwave that will move across the

Forecast for Thursday is a little more complex as two more
shortwaves have an impact on the area. Next upper wave dropping
through northern Ontario will push another cold front down into
Michigan. Models are struggling a little with how they handle this
energy, specifically with how quickly and how far southward to drop
it, and this affects the timing of the cold front sliding through
Michigan. Upper wave over the Dakotas/Minnesota will meanwhile track
east into the western and central Great Lakes very late tonight and
Thursday. This introduces some uncertainty to the forecast as the
highest POPS need to be positioned where the upper wave rides over
the frontal boundary, but the front`s position is still a little up
in the air. Coverage of showers and thunderstorms overall should be
higher on Thursday, but thunderstorm potential should be reduced by
early day arrival of precip. and clouds as they inhibit surface
heating and overall instability. This and a light wind field will
mitigate severe threat. Temperatures will be cooler Thursday as
slightly cooler air arrives behind the front, flow turns north off
Lake Huron, and skies remain mostly cloudy. This should limit max
temps into the low/mid 80s for inland locations, and mid/upper 70s
over the northern thumb. Latest round of models settle the front
near the Ohio border late Thursday night into Friday, keeping
chances for showers/thunderstorms low and closer to the Ohio border
as high pressure builds into the northern Great Lakes.

High pressure will remain centered to our north through the weekend,
and potential to see showers/thunderstorms near the Ohio border now
looks very low. Temperatures will run fairly close to seasonal

Main story for next week looks to be the resurgence of upper ridging
over the central and then eastern part of the country, which will
again lead to rising temperatures here in Michigan.



Outflow associated with the cluster of storms which moved across
northern Lake Huron overnight will push south across the rest of the
lake during the pre dawn hours. A brief period of light to moderate
winds from the north-northeast will result. Winds will quickly
transition back to light and variable by mid morning. A cold front
will move across Lake Huron from the north this afternoon. This
front will provide a chance for thunderstorms. The front will sink
south into Lake Erie late tonight. There is a chance for some short
duration gusty winds out of the northeast across Saginaw Bay and the
southern Lake Huron basin this evening following the passage of the
front and/or any organized thunderstorm clusters that are able to
develop. High pressure will expand across the northern Great Lakes
from the northwest on Thursday, establishing a north-northeast
gradient across the lakes. This may lead to some gusty winds and
choppy seas across the nearshore areas and especially Saginaw Bay
late Thursday through Friday.


Issued at 1153 PM EDT Tue Jul 26 2016


Light southwest winds will persist overnight into Wednesday between
high pressure settling to the southeast and a weak frontal boundary
dropping south towards the region. Diurnal cumulus, SCT to perhaps
BKN, will develop within warm sector south of this front. Late in
the day, scattered shras/tsras will likely form along this boundary
near KMBS 20z-22z and shift south to KFNT after 22z. Confidence is
low in this activity surviving long enough into the evening to reach
south of KPTK.

For DTW...VFR conditions are expected into Wednesday afternoon with
SW return flow behind exiting high pressure and approaching surface
front. Isolated to scattered convection may encroach on terminal
after 00z as this front settles south.

//DTW Threshold Probabilities...

* Low in thunderstorms affecting terminal 00z-02z Wednesday.


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



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