Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 281709
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
109 PM EDT Tue Mar 28 2017


.AVIATION...

Extensive MVFR stratus sustained under a colder and sufficiently
moist north-northeast flow will remain prevalent through the latter
half the daylight period, augmented by diurnal heating.  Drier air
working southward across Lake Huron this afternoon will begin to
encroach on the southeast Michigan terminals this evening.  This in
combination with the loss of diurnal support should support a
gradually clearing trend tonight.  Lower confidence yet on the exact
timing, but recent model guidance continues to favors this process
unfolding 02z-06z.  Expanding high pressure will then maintain a
generally clear sky across the lowest 10k ft into Wednesday.


For DTW...MVFR stratus to hold tight through the latter half of the
daylight period.  Arrival of drying air will allow skies to
eventually clear tonight, currently timed around midnight.
Maintenance of 7-10 kt wind from a northerly direction will continue
through this evening.  Winds speeds ease slightly overnight.

//DTW THRESHOLD PROBABILITIES...

* High for cigs below 5000 feet through this evening.  Low after
  midnight.

&&

.PREV DISCUSSION...
Issued at 322 AM EDT Tue Mar 28 2017

DISCUSSION...

Quiet forecast through the midweek period as high pressure aloft and
at the surface build into the region. The last of whatever light
showers can develop over the far southern CWA will move off early
this morning but only a slow improvement in cloud cover will be
realized. The surface high currently over Manitoba, will track
across Ontario and Quebec through the week which will place us in
the southern periphery of the ridge resulting in drier and cooler
easterly flow. Expect a cooling trend through Thursday in response
to this sustained easterly flow. Stronger subsidence aloft due to an
amplifying ridge ahead of the next southern stream trough will dry
the column out from the top down. Basically we`ll end up with a low
stratus deck around 2-3kft by this afternoon that should scour out
from north to south allowing some sun by nightfall.

Will keep with the cool easterly flow in the low levels on Wednesday
but a drier airmass will result in plenty of sun through the day.
Could see some cirrus debris ahead of the next system and also a few
diurnal cu early in the diurnal cycle before scattering out. The
next system will be over the southern Plains Wednesday, pinching off
from the northern jet. Southern jet tries to absorb it but some
energy in the trough remains tied to the northern jet which isn`t
doing the models any favors. Overall they are pretty well in sync but
the setup could turn one way or the other pretty quick. As for now
will go with persistence forecasting with the steady model output.

The low will lift northeast Wednesday night with good warm air
advection centered around 5-10kft ahead of it into the region. Low
level easterly flow from the surface high will hold through the day.
Looks like the initial rain will stay to our west late Wednesday
night and Thursday morning as the 850mb jet surges northward over
Wisconsin. This would all be elevated showers on the lead isentropic
leaf but gets a little complicated by the right entrance region of
the northern stream jet max over northern lower. Models are trying
to light up this eastward extension of the elevated front Thursday
morning from about Flint northward. Dry air in the lowest ~8kft will
make it tough for this to reach the ground but will be something to
watch. Better precip chances come Thursday afternoon as the 850mb
jet slides over lower MI bringing a surge of better theta E into the
area. This in conjunction with upper level diffluence and isentropic
ascent looks to produce a broad coverage of showers across the area.
There does remain a chance of some mix precip at the lead edge if it
can get going early enough Thursday morning as dry, cool surface
layer will wet bulb, but overall think best precip chances will come
after diurnal heating commences.

Rain will taper off overnight as the system progresses eastward with
the last of the showers exiting the area Friday morning. Ridging
will build back into the region Friday for the weekend. This will
bring quiet weather and a slight warming trend back to the mid 50s.

MARINE...

Northerly winds will increase during the day as strong high pressure
expands across the northern Great Lakes. Wind gusts may reach 20
knots across the southern Lake Huron basin and possibly Saginaw Bay
where northeast winds will funnel into the bay. The high will expand
into the eastern Great Lakes by Wednesday. Modest northeast winds
will be sustained as a result. Low pressure is forecast to lift into
the Ohio Valley on Thursday before pushing into the southern Great
Lakes on Friday. This system combined with strong high pressure to
the north will lead to increasing east-northeast winds Thursday into
Friday, possibly resulting in the development of small craft
advisory conditions.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&

$$

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


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