Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 201041

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
641 AM EDT Fri Oct 20 2017


Departing high pressure will still be able to maintain clear skies
(below 25 kft) today and tonight. Southerly winds look to reach
around 10 knots this afternoon, dropping off during the evening.


* None.


Issued at 301 AM EDT Fri Oct 20 2017


There will be a slight amplification to the mid level ridge axis
extending from the Se US into the ern Great Lakes today as a
progressive mid level trough axis moves into the nrn Rockies. The
influence of the low level anti cyclone across the Upper Ohio Valley
and Mid Atlantic will sustain very dry air across Se Mi today, while
southerly return flow advects a little warmer air mass into Lower
Mi. In fact, upstream high temps yesterday were well into the 70s.
Despite the relatively cold early morning temps, the low level warm
air advection under full sun today should boost highs into the low
to mid 70s. The southerly gradient will increase tonight as the low
level anticylone shifts toward the east coast. This will suppress
the degree of radiation cooling, supporting min temps mainly in the
50s. Despite some occasional high clouds on Saturday, the southerly
gradient will offer a little better mixing and thus support very
warm conditions, with highs well into the 70s.

The 00Z model suite indicate the cold front associated with the
progressive mid level trough will push across Se Mi late Sun/Sunday
night. Energy within the base of this trough is forecast to cut off
across the Lower Ms Valley, while the better northern stream energy
lifts well north of the Great Lakes. Nonetheless, a narrow plume of
deep layer moisture along/behind the surface front and some upper
jet support likely sustaining some degree of mid level fgen will
support rain across the area during the late Sunday to early Mon
time frame. Warm and breezy conditions can be expected through much
of Sun in advance of the sfc cold front.

While the GFS and ECMWF agree in northern stream trough
amplification on Monday, there are differences with respect to the
timing and degree of phasing with the remnant upper low over the
deep south. The Ecmwf phases this energy more quickly, the result
being a prolonged period of rain across Se Mi Monday into Tues. The
GFS on the other hand is slower to phase the systems, resulting in
the better rain potential well east of the forecast area. Obviously
with these differences, chance type pops will be maintained in the
forecast Mon into Tues. The northern stream trough will drive colder
air into the region during the early portion of the work week.
Current forecast projections suggest the flow will remain
progressive, with a brief warm up possible on Thurs before the next
northern stream wave drives another influx of cold air into the


High pressure sliding east will allow for southerly winds right
through the Weekend, topping out between 20 to 25 knots over the
second half of the weekend, ahead of a cold front. This cold front
looks to be moving through Sunday night, bringing with it showers
and wind shift to the west early next week, and topping out around
30 knots by Tuesday.


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



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