Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 212256

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
656 PM EDT Fri Apr 21 2017


There is a definite diurnal component to the strato cu field across
Lower Mi. For this reason there has been a decrease in the cloud
cover as the diurnal heating cycle wanes. This is likely to support
some breaks in the cloud cover this evening. A low level thermal
trough will however slide from cntl Mi across Se Mi this evening
into the early portion of the overnight. The depth of the low level
inversion under this cooler air should at least sustain a prevailing
cloud base into the night. Subtle lowering of the inversion may also
cause cigs to dip back down below 3k ft. Sfc high pressure and drier
air will then build into the region from the north during the
overnight, supporting a north to south clearing trend.

For DTW...Can not rule out some longer duration cloud breaks this
evening before the thermal trough slides through around midnight.
The bulk of the 18Z guidance bring the clearing through metro
Detroit shortly after 07Z.


* Moderate in ceilings below 5000 ft through 07Z.


Issued at 303 PM EDT Fri Apr 21 2017

Mid level trough axis and weak surface troughing extends back from
yesterday`s system across central lower Michigan.  This combined
with plenty of low level moisture wrapping behind this system is
producing extensive cloud cover and some light rain showers earlier.
The trough will gradually swing through over night bringing gradual
clearing from the northwest to about the northern burbs of the
Detroit metro area by morning. Gradient wind will remain about 5 to
10 mph as surface high pressure center approaches.  This combined
with cloud cover for a good part of the night should hold temps up
in the upper 30s preventing any frost formation.

Upper level ridging and surface high pressure will slide in for the
weekend bringing plenty of sunshine and relatively light winds.  The
exception will be the southeast corner, from about the Detroit area
south for most of Saturday.  Large elongated closed 500mb
circulation across the Tennessee Valley will slowly push east with
mid and high level cloud shield extending north into the southeast
corner.  Depending how thick whether mostly cloudy or filtered
sunshine in that area.   Highs Saturday will be a few degrees below
average in the mid to upper 50s.

For Saturday night, large surface high pressure will be moving in
with weak surface gradient and plenty of dry air.  Winds  will
go near calm and with clear skies and dew points around or slightly
below freezing, expect possibility of frost, mainly west and north
of Detroit area. High pressure overhead Sunday will bring a wonderful
weather day with sunshine, light winds and highs mostly in the mid

Dry air is expected to hold in place throughout Monday as
temperatures rise into the mid-60s for a daytime high , with a
decent amount of sunshine expected through the afternoon. Cloud
cover will gradually increase as early as Monday evening, with
clouds filtering in through Tuesday as a weak low travels from the
North Central plains into southern Ontario. As the low travels north
of Michigan, winds will start to take on a S/SW component, pushing
temperatures into the lower 70s by Tuesday afternoon. Strong WAA in
addition to a series of upper-level disturbances will also bring the
chance for rain showers starting Tuesday afternoon. A second weak
low will then push in from MO/IL into MI Tuesday night through
Wednesday morning, bringing the continued chance for rain throughout
most of Wednesday.

Another round of rain and potential thunderstorms will be possible
by Friday, however, confidence remains low at this time track and
timing differences exist between the GEM and ECMWF models with the
associated low. Additionally, the GFS keeps the low pressure system
over the Central Plains, where-as the GEM and ECMWF models push the
low from around MO into Eastern WI by roughly Friday into Saturday.
PoP values will remain low through Friday as a result.


West to northwest winds will continue to decrease overnight as low
pressure lifts through Quebec. The Small Craft Advisory will be
cancelled as winds have already decreased below thresholds. Wave
heights will build into the 2 to 4 foot range for southern Lake
Huron this evening and late tonight as winds turn north, then
subside for Saturday as high pressure provides light winds. High
pressure over the Great Lakes will keep a quiet weather pattern and
favorable marine conditions over the area through the weekend.


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



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