Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 191059
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
659 AM EDT Thu Apr 19 2018


.AVIATION...

The departure of the upper wave to the southeast of the area this
morning has produced a drying trend from north to south, leading to
some scouring out of the clouds. An influx of low level cold air
under a deepening inversion with remnant moisture will however lead
to an uptick in diurnal cloud enhancement later this morning. These
clouds should be more abundant from the thumb region into the
northern and eastern portions of metro Detroit, where some MVFR
based cloud development is possible. High pressure and drier air
will advance into the area from the west this afternoon, supporting
an overall clearing trend. There is already decent n-nw gradient in
place. Ongoing cold air advection combined with diurnal mixing will
lead to strengthening northwest winds by afternoon, gusting at time
over 20 knots.

For DTW...There will be a slight backing of the winds from north
this morning, to northwest during the afternoon. During peak daytime
heating through the afternoon, wind directions should hold between
310 and 330 deg.

/DTW THRESHOLD PROBABILITIES...

* Moderate in ceilings at or below 5000 ft this morning. Low this
  afternoon.

&&

.PREV DISCUSSION...
Issued at 337 AM EDT Thu Apr 19 2018

DISCUSSION...

Much quieter stretch of weather coming up after the backside of the
upper low drifts southeast of the area this morning. The surface low
raced well east of the upper low center cutting off much of the
moisture from lifting north into southern MI. The 700mb front did
supply some light snow showers overnight with about a half inch on
grassy and elevated surfaces, but contracted and scoured out to
about nothing by the time it traveled from Flint to Pontiac. Still
some light showers will be possible as it gets pulled through
Oakland, Macomb and southern St Clair counties over the next couple
hours. Looking at mainly a dusting from this. The upper low center
passing through northern Indiana at the moment is responsible for
the broader swath of light precip over that area. The low will be
drifting south of east through the early morning as a trough
rotating around the large east coast low drops through the eastern
Great Lakes and starts to absorb it. This will push the area of
precip south with it as well. Will keep a low chance pop going as
satellite does show some moisture lifting up into southern MI so
some light snow can`t be rules out. The whole area looks dry by 12Z
this morning. The caveat to that is the Lake Huron shoreline this
morning as the trough picks up some lake moisture and could produce
some light showers as low level lapse rates spike with the cold air
advection. Inversion up to around 5kft will limit activity.
Northerly winds backing northwesterly will force any activity off
shore by this afternoon.

Other that POPs this morning, main concern will be gusty northerly
winds as a fairly tight pressure gradient sets up between the
departing trough and approaching ridge. Gusts around 20 to 30 mph
will be common which will make our low to mid 40 high temps feel
like they are only in the mid 30s.

Forecast get much quieter after the trough rotates east of the
region by this evening. Eastern edge of the upper level ridge
building up through the plains into Canada will nudge eastward into
the Great Lakes by Friday while a large surface high centers itself
over MI. Heights will only slowly increase as flow becomes split
with an upper low cutting off over the central Rockies then drifting
through the central Plains through the weekend. The low will prevent
any real southerly flow and warm air advection from occuring but
temperatures will slowly climb through the weekend as late April sun
helps modify the airmass each day. Upper level ridge axis is
forecast to fold across the region Sun/Mon which would bring a boost
to the thermal field. Temperatures should climb into the upper 50s
by Sunday with low/mid 60s coming for Monday and Tuesday. Next
chance of precipitation does not arrive til Tuesday night or
Wednesday as the next trough finally swings through.

MARINE...

The region will lie between departing low pressure off the east
coast today and building high pressure across the upper Midwest.
This will sustain gusty northerly winds today, leading to hazardous
conditions for small craft on southern Lake Huron. There will be
some backing of the winds toward the northwest during the afternoon,
allowing the strongest winds to affect mainly the open waters of
southern and central Lake Huron. Probabilities are high that gusts
on Lake Huron will achieve 25 knots. There has however been a noted
downward trend in wind gusts approaching 30 knots. The period of
strongest winds will occur this afternoon and evening. Winds and
waves will slowly decrease overnight into the day Friday as large
high pressure expands into the region from the west. This high
pressure will reside over the region through the weekend, thus
maintaining light and variable winds.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Small Craft Advisory until 4 PM EDT Friday for LHZ421-441>443.

     Small Craft Advisory until 4 PM EDT this afternoon for LHZ422.

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

$$

AVIATION.....SC
DISCUSSION...DRK
MARINE.......SC


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