Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 191027

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
627 AM EDT Mon Mar 19 2018


High pressure building into the northern Great Lakes and low
pressure moving through the Ohio Valley will set the stage for
aviation weather in SE Michigan to start the week. These weather
features will combine to generate increasing northeast surface wind
while conditions will otherwise be VFR. Clouds will consist of
scattered to broken mid level coverage today followed by potential
for a few streamers of stratocu from Lake Huron tonight. The air
mass crossing Lake Huron from Ontario is very dry which suggests
coverage will be less than indicated in model data through Tuesday

For DTW... Northeast surface wind increasing into the 10-20 kt range
will require planning for northeast traffic flow operations today
through Tuesday morning.


* None.


Issued at 352 AM EDT Mon Mar 19 2018


A weak surface cold front has pushed through southern MI displacing
the surface high that was spread across the region to the southwest.
The front is largely uneventful featuring a wind shift to NE last
evening with a thermal boundary lagging behind a few hours, now
starting to make its way across Lake Huron. We are currently
dealing with an narrow band of elevated clouds which is tied to a
weak mid level wave working through the confluent flow overhead. The
wave will skirt east by this afternoon which should result in skies
clearing, especially considering the dry air and increased
subsidence from the high pressure system building into Ontario and
the northern Lakes today. Temperatures will feel the effect of the
front and increased northeast flow today as highs struggle to get
out of the 30s for most locations. 850mb temps will quickly fall to
around -5C today with already cool air advecting over the cold
waters of Lake Huron assisting in dropping highs from the 50s seen
on Sunday.

Quiet stretch of weather in store for the week with a few systems
brushing MI just to the south leaving us otherwise under the
dominate surface high stalling over Ontario through mid week.
Looking aloft, the southern stream of the jet remains very active
and to out south but the northern stream is quite weak and to our
north leaving us in the void of the split flow pattern which phases
to our east. First glancing system will be late tonight into Tuesday
as a main piece of the western conus trough shoots east along the
Ohio Valley with a stacked surface low along with it. Models have
been consistent with a sharp northern edge to the precip shield
owing to the strong high to the north with a deep layer of dry air
in place. Will keep the area dry as nothing has shown this precip
leaking north yet.

Surface high pressure will expand quickly southward through the
plains in the wake of this system as the longwave trough axis passes
to the east on Wednesday. The thermal trough will linger through the
end of the week as upper level ridge starts building into the
western Great Lakes. This will keep below average temperatures going
into the weekend with highs hovering around the mid 30s to low 40s.
Looks like the stretch of dry weather will carry us through the end
of the week with the next chance of precip holding off til Saturday.
Models still trying to come together on this system but they have
been advertising the northern edge of the precip shield clipping at
least a portion of southern MI Saturday producing a rain/snow mix
across the area.


High pressure will build from northern Ontario into the central
Great Lakes today. It will combine with low pressure moving through
the Ohio Valley and sharpen low level gradient flow from the
northeast today through Wednesday. The incoming air mass will also
be cold enough to produce an unstable thermal profile over the
water. This, along with the long northeast fetch, will lead to
favorable conditions for high waves across central and southern Lake
Huron into Saginaw Bay. The fetch will be shorter over western Lake
Erie but gusts will approach 30 knots by Tuesday morning. Both wind
gusts and wave height will be marginal for small crafts on Lake St
Clair. The slow progression of the low pressure system through the
Ohio valley will set up persistence of the wind pattern through
Wednesday. Small craft advisories remain in effect during this time
for outer Saginaw Bay and southern Lake Huron, and are added for the
Michigan waters of Lake Erie.




Lake Huron...Small Craft Advisory until 4 PM EDT Wednesday for LHZ421-441>443.

Lake St Clair...NONE.

Michigan waters of Lake Erie...Small Craft Advisory from 4 PM this afternoon to 4 AM EDT Wednesday
     for LEZ444.




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