Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 281051
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
651 AM EDT Tue Mar 28 2017


.AVIATION...

Ongoing shallow cold air advection within a moist low level
environment has led to widespread IFR stratus with some LIFR/VLIFR
cigs as well. Some subtle low level drying and cold air advection
along with daytime heating will gradually lift the cloud bases to
MVFR, likely late this morning or early afternoon. There will be a
push of drier air from the north later in the day that will erode
the stratus deck during the evening.

For DTW...The gradient will support a steady north-northeast wind
during the entire day. Boundary layer growth due to daytime mixing
will sustain the wind speeds around 10 knots. Timing of the lifting
of cloud bases to MVFR carries some degree of uncertainty, but
should occur sometime between 15Z and 17Z.

//DTW THRESHOLD PROBABILITIES...

* High for cigs below 5000 feet this morning through mid evening.

&&

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


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