Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 160507
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1207 AM EST Thu Feb 16 2017

.AVIATION...

Stubborn flurries and lake effect snow showers will continue for a
few more hours during the early morning thanks to some
preconditioning off Lake Superior. There has been a gradual upward
trend in ceiling height during late evening that is expected to hold
through the early morning and make VFR more of the prevailing
condition while northwest wind remains on the gusty side in the 20
to 25 knot range. Incoming model data strongly favors channels of
clearing to develop toward sunrise which matches climo for dry
northwest low level flow and is supported by the latest satellite
trends over the northern Great Lakes. Some breaks are then expected
to develop into SE Michigan during the morning before the western
edge begins to move eastward. A more convincing diminishing trend is
then projected during the afternoon as surface high pressure slides
into and through the region.

For DTW... Flurries or scattered snow showers for a few more hours
will only produce a trace of accumulation while northwest wind
diminishes from gusts generally under 25 knots. Ceiling of stratocu
will persist through the night around the MVFR/VFR threshold. There
is improving confidence in potential for breaks or prolonged VFR
ceiling through the morning and especially during the afternoon as
high pressure moves into the region.

//DTW THRESHOLD PROBABILITIES...

* High for ceiling 5000 ft or less through mid morning.

* Low for exceeding crosswind threshold through early morning.

&&

.PREV DISCUSSION...
Issued at 945 PM EST Wed Feb 15 2017

UPDATE...

A quick update to maintain scattered snow showers and flurries into
the overnight hours along and south of the I-96/696 corridor.
Upstream radar composite over SW Lower Michigan remains active within
the moist and unstable convective layer extending up to about 800 mb
and well into the favorable zone of the DGZ around -15C. That
corridor of instability extends eastward into SE Michigan as shown
nicely by the 00Z DTX sounding, so there should be some persistence
into the overnight hours with at least scattered coverage of snow
showers and flurries. After that, there is good agreement in model
soundings that show lake effect potential diminishing from west to
east as the surface high approaches. Lapse rate remains favorable but
convective depth is pushed below -10C which should bring an end to
lake production of snow showers later in the night through Thursday
morning.

PREV DISCUSSION...
Issued at 307 PM EST Wed Feb 15 2017

DISCUSSION...

Lake effect snow shower activity will slowly wane late today into
tonight as a ridge of high pressure builds east into the region.
This trend will accelerate late tonight into Thursday as upper
troughing shifts east and H85 temperatures warm substantially,
especially to the west over Lake Michigan. So, the general trend
will be for scattered light snow showers late this afternoon to
diminish to little more than a few flurries tonight and then some
partial clearing by midday Thursday as drier low level airmass
begins to spread into area from the west.

Temperatures will be chilly tonight with teens expected for lows,
and despite a warm air advection pattern setting up on Thursday,
temperatures at the surface will remain cold as it will take some
time to scour out this dome of cold, dense air. So, highs will be
limited to upper 20s to lower 30s again on Thursday.

A substantial shift eastward in the northeast CONUS upper trough into
Friday will allow significant mid level heights rises as upper ridge
translates east into the Mississippi Valley and western Great Lakes.
This will lead to temperatures climbing back into the 40s by midday
under partly cloudy skies.

With the upper level ridge axis over the Great Lakes on Saturday
morning southwest flow will allow 850 mb temps approaching 10 C over
SE Michigan. Under limited cloud cover, high temperatures on
Saturday could approach record values in the mid to upper 50s at
Saginaw and Flint and near 60 at Detroit. A weak cold frontal
passage on Saturday night will usher in slightly cooler air mass on
Sunday but sunny skies will allow diurnal warming with highs
remaining well above average in the 50s over much of SE Michigan.
Ridging then builds again over Michigan on Monday with increasing
southerly flow ahead of an approaching low pressure system. While
increasing cloud cover might limit diurnal warming high temps could
again approach near record values across SE Michigan with warm air
advection in place. The next chance for rain returns early next week
as low pressure passes to the north of the Great Lakes region.

MARINE...

Northwesterly winds will continue to usher cold and unstable air
over the eastern lakes resulting in gusts around 25 knots through
tonight. Small craft advisories will continue for a portion of the
Lake Huron nearshore waters that are not ice covered to account for
this. A ridge of high pressure will then slide over the area on
Thursday which will allow the winds to decrease.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...NONE.

Lake Huron...Small Craft Advisory until 10 AM EST this morning for LHZ441>443.

Lake St Clair...NONE.

Michigan waters of Lake Erie...NONE.

&&

$$

AVIATION.....BT
UPDATE.......BT
DISCUSSION...DG/JD
MARINE.......DRK


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at www.weather.gov/detroit.



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