Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 290739

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
339 AM EDT Wed Mar 29 2017


Quiet day today with really only minor temperature and cloud trend
concerns as surface high pressure sliding across northern Ontario in
conjunction with mid level ridging stay in control of the weather.
Temperatures will stay similar to Tuesday with highs around 50,
except in the shadows of the lakes where cool easterly flow may keep
them in the 40s. Even with a slightly cooler thermal profile due to
continued east/northeast flow into the region around the area of
high pressure, a good deal of late March sun with diurnal mixing up
to around 900mb should get us a degree or so above Tuesday highs.
Some possible stratus off Lake Huron may stall the warming trend
across the north, but will have to wait and see the extend and
thickness of those clouds. Otherwise may just see some cirrus
sliding in later in the day ahead of the next system.

The next low pressure system is currently over the southern plains
embedded in a deep closed upper low. A strong jet rounding the base
of the upper level trough will start to shear some energy
northeastward into the western Great Lakes later tonight. The low
itself will then track up through western Lake Erie on Friday. With
the system originating so far south with strong 850mb moisture
transport ahead of the trough, should get a widespread region of
soaking rain. Model estimates for Thursday morning through Friday
afternoon are around 0.75 to 1" of rainfall. Models have been locked
onto this system for a few period now but there are a few questions
that remain, mainly ptype at the onset Thursday morning, and how
long does precip linger on Friday on the backside?

Thermal profile Wednesday night is cold enough for some snow across
the north and surface dew points around 30 will aid in that with wet
bulb cooling. Models hold off on the better moisture and forcing til
after 12Z Thursday but do continue to advertise a lead 700mb fgen
band with a midlevel pv filament getting shed from the low still to
the south. Right entrance region of the upper level jet will be a
bit further north but still close enough to support the forcing.
They`ve held firm on this and current IR satellite images over Iowa
are showing hints of this feature. If this forcing can set up over
the area while the cold air is still in place, locations north of
about I69 could end up seeing some wet snow before the changeover to
rain. Introduced some light accums (less than 1 inch) to start
giving credit to this. The 850mb jet will slide through lower MI
around 15-18Z Thursday bringing with it a slug of moisture and
warmer air aloft which should result in all rain.

The deformation band will linger over SE MI on Friday as the low is
slow to exit east. Always a question of how fast the ridge and drier
air behind it can scour things out but for now will keep rain going
through the day. After having temperatures bottom out on Thursday,
likely in the low/mid 40s, temperatures will trend back up through
early next week as high pressure through the weekend with periods of
southerly flow allow for a steady increase. Next chance of rain
looks to be Monday/Tuesday as the southern stream remains active,
sending the next system through the Ohio Valley once again.



Modest north-northeast winds will persist through the day as strong
high pressure expands from the northern to the eastern Great Lakes.
Gusts will continue to top 20 knots at times across the southern
Lake Huron basin and Saginaw Bay. A tightening of the easterly
gradient will take hold tonight into Thursday night as low pressure
lifts into the Ohio Valley and strong high pressure holds to the
northeast of the region. Shallow cold air across Lake Huron will
support neutral to slightly unstable low level conditions, allowing
winds to increase. Small craft advisory conditions are likely to
develop on Thursday and possibly persist through Friday as winds
back to the northeast. The low level wind field will be strongest
across northern and central Lake Huron, where there is a high
probability that wind gusts will reach 30 knots. There is a chance
that gale force gusts will develop Thurs night into Fri morning.
This will be monitored over the next couple forecast cycles in the
event some gale warnings need to be issued. The surface low will
pass east of the region Fri night, with a diminishing trend to the
winds following in its wake.



A slow moving low pressure system will bring a few rounds of
precipitation to the region Thursday through Friday. Precipitation
will arrive on Thursday along a lead warm front. While most of this
will fall as rain, some snow is possible across the northern Saginaw
Valley and thumb region. Additional rainfall will then occur on
Friday as the main low pressure system lifts across the eastern
Great Lakes. Two-day total rainfall amounts from this system are
forecast to range from three quarters of an inch to one inch. These
amounts spread over two days should result in just minor rises to
area rivers and streams.


Issued at 1155 PM EDT Tue Mar 28 2017


VFR conditions are expected throughout the forecast period as dry
NNE flow maintains generally clear low levels. Upper clouds will
begin to increase Wednesday afternoon/evening as low pressure lifts
into the mid Mississippi Valley, but ceilings should remain above
10kft for this forecast.

For DTW...VFR conditions are expected this forecast period now that
stratus is well south of the terminal. Otherwise, NE flow in the 4-7
knot range will persist into Tuesday around high pressure.


* None.


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



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