Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 191120

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
720 AM EDT Thu Oct 19 2017


Frontal boundary pushing southward through southeastern Michigan
this morning will lead to additional drying sub 800mb to an airmass
that had already been lacking moisture. A well developed, compact
anticylonic circulation will then roll across Lower Michigan this
afternoon and tonight. Nil moisture and dynamic support for
subsidence will bring little cloud outside of thin cirrus canopy.
There is moderate to high confidence that westerly wind gusts will
reach and exceed 15 knots.


* None.


Issued at 348 AM EDT Thu Oct 19 2017


A dry cold front is beginning to march across the Great Lakes as
advertised with little in the way of even clouds with it.
Compression of the the SW gradient is keeping winds elevated through
the rest of the night/morning. Afternoon mixing will keep some gusts
through the afternoon, otherwise winds will die off tonight. A
narrow band of clouds will slide across MI with the front, but will
impact the forecast minimally. Most notable change to the forecast
in the near term is the downward adjustment to dewpoints into the
afternoon. Obs show the dry air and subsidence over WI resulting in
quick drops in dewpoints from 40s into the upper teens. With the
front weakening, the driest air more to the north, and airmass
modification over the lakes, we shouldn`t be getting that dry but
could flirt with values near 30F across the north. Otherwise,
another day with temperatures rising into the mid/upper 60s.

Friday and Saturday will continue the pleasant weather we`ve been
experiencing for the last week or so now. Large area of surface high
pressure quickly builds back into southern Great Lakes while we
still reside on the western side of the ridge with warm
southwesterly flow. Longwave ridge will undergo strong amplification
Friday in response to strong troughing moving inland off the
Pacific. The pattern will stall temporarily as it continues to
deepen but will eventually get forces east by the next strong wave
surging across southern Canada. This will send a stalling frontal
boundary into southern MI late Sunday and overnight. Models begin to
diverge significantly heading into the start of the new week. Euro
wants to stall the front over southern MI while the GFS keeps it
more progressive. So will continue to forecast precipitation
centered around Sunday night and will adjust as necessary in the
coming forecasts.

Model do tend to agree that cooler weather looks to be in store for
the middle of next week.  An upper level trough will drop into the
region with northerly flow originating from northern Canada. This
would bring one of the coldest airmasses of the season into the
region likely lingering through the end of the week.


Gusty southwest winds have persisted overnight over much of the
central Great Lakes ahead of an approaching cold front. Widespread
observations have been reported with southwest winds of 25 to 30
knots. Winds will begin to ease late this morning and afternoon in
response to increasing high pressure behind a shallow cold front.
Winds this afternoon will still range between 15 to 20 knots in many
areas. Dry conditions are expected for the end of the week and for
much of the upcoming weekend. However, southwest winds are expected
to remain in the 15 to 20 knot range in response to strong gradient
ahead of a northern Plain States low pressure system.


Lake Huron...Small Craft Advisory until 10 AM EDT this morning for LHZ421-422-

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



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