Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 230409

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1209 AM EDT Sat Sep 23 2017


Upper ridge will remain anchored over the area, providing nearly
calm wind conditions (outside late day lake breeze considerations)
and mainly clear skies. The warm, humid airmass associated with the
ridge will allow for some patchy fog development overnight
with MVFR to perhaps a BRIEF period of IFR vsbys near sunrise,
mainly DTW/YIP/PTK.


* None.


Issued at 304 PM EDT Fri Sep 22 2017

The first day of fall is probably warmer all around then any day
this past summer.  This persistence will continue through the
weekend as the center of the upper level ridge will remain parked
over lower Michigan.  Highs and lows will be about the same
as today`s through the weekend with heat indices in the low to
mid 90s along with mainly clear skies and light winds.  With this
heat and moisture comes some rather large diurnal cape values
especially for this time of year. However with very warm mid levels
comes strong capping that will continue to impede convection
development for the most part.  There is still a very small chance
for some convection development this evening across the western
forecast area where broad and weak low level convergence is
occurring from lake breezes from Lake Michigan and Lake Erie/Huron
across the center of lower Michigan.  Satellite shows a wide band of
cu development in this area up to about Saginaw Bay. If the cap can
get punched convection could fire up with locally heavy rain and
possibly small hail but activity would not move much as wind through
the column is very light and variable.  Other then that there will
be patchy light fog again around sunrise.

The extended stretch of above normal temperatures will continue
through Tuesday as the upper level ridge slowly translates east.
With mainly clear skies and light southerly flow continuing, expect
a continuation of highs in the mid to upper 80s. A wave ejecting
northeastward from the Southwest US will help pull a cold front
through the region during the midweek period. Model solutions
continue to vary on the timing of the frontal passage with the ECMWF
showing an earlier passage late Tuesday/early Wednesday while the
GFS shows a later passage on Wednesday. Regardless of timing, the
next chance for showers and thunderstorms will accompany the frontal
passage. Much cooler air will then filter into the region on
Wednesday and remain in place through late next week as temperatures
fall closer to average with highs returning to the mid 60s to near
70 on Thursday.


Extended stretch of very warm and humid conditions will exist
through the upcoming weekend as the region remains under the
influence of strong upper ridging. This pattern will support light
winds - under 15 knots - and low waves during this time. These
conditions will persist into early next week.


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



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