Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 161820

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
220 PM EDT Fri Mar 16 2018


Latest surface analyses have ridge of surface high pressure in place
over the western and central Great Lakes. Very dry and stable air
mass will preclude much in the way of aviation weather and clouds.
Clear skies anticipated tonight with an increase in some transparent
high cloud late tonight. Surface wind directions are forecasted to
remain relatively light, backing to the west with time.

For DTW...Light and variable winds tonight with surface high
pressure. Bulk of moisture/clouds will remain south of DTW on


* Low in ceilings at or below 5000 ft tonight.


Issued at 357 AM EDT Fri Mar 16 2018


A broad region of surface high pressure will build from central
Canada over Lower Michigan today. It will allow a decrease of clouds
and some flurries lingering during morning for a generous dose of
sunshine by afternoon. The resulting mid March surface heating will
then battle the polar nature of the incoming air mass for
temperature dominance to finish the day. The brisk northwest
gradient flow during the night was sustained by strong low level
cold advection that brought surface temperatures down into the upper
teens to mid 20s early this morning. This marks the southward
intrusion of the low level thermal trough that will be directly
overhead prior to sunrise and then move quickly eastward through the
day. Except for in the Thumb region where colder readings will
linger, the progression will return afternoon boundary layer
temperature to about the same level as yesterday. Model 925 mb temps
averaged -4C at 18Z yesterday, dropped to about -11C at 09Z this
morning, and then warm up toward -5C this afternoon over interior
sections. The difference from yesterday will be much more sunshine
to help with surface heating and diminishing wind that will take the
edge off the feel of the cooler air mass. This will be opposed by
shallower boundary layer mixing as indicated in model soundings that
show a mid level subsidence inversion setting up that holds the
surface based mixed layer to about 900 mb. As a result, a few of the
typically warmer locations around the Detroit metro area could touch
40 while another round of mid to upper 30s is in store for the rest
of SE Michigan. Normals for mid March are in the lower to mid 40s.

Clear sky and calm wind during the evening will set up efficient
radiational cooling and a sharp drop in temperatures during the
evening. A meaningful increase in high clouds is expected after
midnight but likely remaining south of the I-69 corridor setting up
the Tri Cities and Thumb region to make another run into the teens
for low temperatures by sunrise Saturday.

The high clouds streaming over south sections of the area will be
associated with the central Plains upper low that is projected to
shear south of the area during Saturday. There is good agreement
among the 00Z models on holding QPF south of the Ohio border through
the day. Weakening surface high pressure over Lower Michigan and low
level dry air will be sufficient to hold off any mid level moisture
straying farther north. Model soundings indicate dry air holding
strong below 700 mb even as far south as Toledo. Late breaking mid
and high clouds will then allow high temps to reach the lower to mid
40s except for 30s across the Thumb due to onshore flow from Lake

Sunday will be the warmest day of the weekend as more of a Pacific
high pressure air mass follows the Saturday short wave. Northerly
low level flow is also projected to back west and provide some low
level warm advection as the high settles into the Ohio valley and
the next northern stream wave moves into the northern Great Lakes.
Assuming passage of the associated cold front holds off until
evening, then high temps have potential to make a run toward 50,
especially in the Detroit area as cloud cover would be limited to
gradually increasing high variety. The forecast will hold
temperatures in the lower 40s across the Thumb region to allow for a
late afternoon frontal passage where the shallow nature of the front
will be augmented by renewed cold onshore flow.

The passage of this front Sunday night will usher in another air
mass of polar origin that will take temperatures back below normal
to start next week. There is some consolation in that the front will
be very moisture starved and so no precipitation is expected with
its passage. High pressure will then reinforce dry conditions
through Monday.

Model solutions look solid through Monday but lower predictability
is anticipated during the middle of next week. Global models
indicate a transition out of the recent blocking configuration in
the large scale upper level pattern. This will send the remnants of
the western U.S. trough into the Plains Monday and Ohio valley by
Tuesday. Some phasing with the northern stream has potential to
alter the development and track of the system which could affect our
area by Wednesday but again expect quite a bit of model variation
during that time period over the next several model cycles.


High pressure building across lower Michigan today will bring
relief to cloud cover and winds. Satellites already show drier air
associated with the high reducing the coverage of clouds across the
region. Some lake stratus will persist through the morning hours
before scouring out as the high centers over the area. Winds will
decrease through the day while backing more westerly in response to
the high sliding in west of Lake Huron. The westerly flow will push
the highest waves off shore allowing the small craft advisories to
end this afternoon. A broad region of high pressure will linger over
the region through the weekend, leading to generally light winds.


Lake Huron...Small Craft Advisory until 4 PM EDT this afternoon for LHZ421-422-

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



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