Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 181923

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
323 PM EDT Sun Mar 18 2018


A low pressure center at 950-850mb is currently pushing southward
from Lake Huron and into sections of southwestern Ontario this
afternoon. The low is weak and appears to be a surface reflection of
lower tropospheric warm advection in the presence of a greater
baroclinic zone. Daytime heating to the south of this feature has
allowed temperatures to climb into the middle 50s for many areas of
Southeast Michigan away from the larger bodies of water. The
diabatic heating response has led to a surface troughing bubble over
Lower Michigan. As daytime heating wanes and the mixed layer begins
to shrink, models are advertising a shallow cold front, or density
current dynamics that will rapidly push southward through the
forecast area into northern Ohio. Will likely see temperatures drop
this evening of 10 degrees or more in a 2 hr period or so. In fact,
much of the northern forecast area will likely be in the upper 20s
by midnight. Lows are expected in the lower to middle 20s.

Surface ridging will steadily expand southward through the Great
Lakes tonight due to increase in confluent flow aloft and the deep
cold air advection. Main story will be cold conditions Monday as
850mb temperatures are forecasted to drop into the -4 to -9C range
by midday. Cloud concerns enter the picture as models suggest
midlevel moisture will break on the anticyclonic shear side,
streaming directly into Lower Michigan. Nam solution is likely
overdone on the amount of clouds but expecting some coverage,
nonetheless, particularly early Monday. Brisk conditions, with wind
chills remaining in the teens for the Thumb and upper 20s to lower
30s for the remainder of the areas.

Tuesday...Fairly strong signal exists that maximum of upper level
ridge will be drawn directly over the state in response to the upper
level entrance region to the jet streak pulling eastward. All signs
indicate that fresh, strong, deep column subsidence will wash
southward directly into the state. This ridging and very strong east
component will keep moisture well south of the region. No concerns
for the larger low pressure system to affect the area. The only
impact will be increasing easterly gradient flow which will make the
weather again very brisk. Highs in the 30s, with wind chills again
ranging from the upper teens to near 30 far south.

Quiet conditions with light northerly flow will persist Wednesday
through Friday. The longwave trough axis will push to the east of
the Great Lakes by Wednesday evening and surface high pressure will
return to the area. Mostly cloudy skies look to hold on Wednesday in
the cold air advection behind the Tennessee Valley low moving off to
the east. The thermal trough left in this system`s wake will linger
over the area through the end of the week, continuing the pattern of
below average temperatures. Gradual modification of the air mass
will bring high temps from the mid to upper 30s on Wednesday to the
low to mid 40s by Friday.

Best chance for the return of precipitation remains Saturday. A
Pacific shortwave will lead to cyclogenesis over the plains by
Friday; this cyclone will track through the Ohio Valley on Saturday.
With Michigan on the cool side of this system, a snowy start with a
transition to rain with daytime heating will be possible. This
system will be quickly ushered over the Mid-Atlantic states and
deepen into another nor`easter while high pressure fills in behind
it, resulting in another quiet and cool Sunday for our area.



High pressure transiting Ontario will force a long duration of fresh
onshore flow through the midweek period. Significant wave heights
will build to several feet with maximum wave heights approaching 10
feet in the nearshore zones of Lake Huron beginning as early as
Monday morning before expanding into the remainder of the waters and
persisting through Wednesday. Small craft advisories are in effect.
An advisory will be under consideration for the Michigan waters of
Lake Erie in subsequent forecast packages.


Issued at 1153 AM EDT Sun Mar 18 2018


SKC with wind gradually backing from WSW to WNW during the afternoon
and turning NE overnight as high pressure transits Ontario. There
may be just enough moisture in NE flow to support SCT low VFR, but
meaningful CIG not anticipated attm.

For DTW...Noise abatement issues with marginal NE flow will become
increasingly likely after about 23z and will continue through Monday.


* None.


Lake Huron...Small Craft Advisory from 10 AM Monday to 4 PM EDT Wednesday for

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



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