Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 261107
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
707 AM EDT THU MAY 26 2016

.AVIATION...

Mid level subsidence trailing the early morning shower/storm complex
will maintain a quiet period for the remainder of the morning into
early afternoon. That will leave the question of lower cloud
coverage across the terminal corridor with MVFR observed out of
Indiana and portions of western lower Michigan. Expect there will be
intervals of restriction before boundary layer mixing carries bases
into VFR by late morning.

The larger convective complex in progress at press time over
Wisconsin/Illinois is worthy of monitoring for impacts in SE
Michigan later in the day. This activity could be sustained by
renewed surface based instability downstream and/or produce a
remnant MCV that could organize new development over our area mid to
late afternoon. There is enough confidence for a prob30 mention to
cover this scenario.

FOR DTW... A quiet morning period complicated only by potential for
MVFR ceiling from Indiana/western lower Michigan mixing to VFR below
5000 ft through early afternoon. Afternoon thunderstorm potential
could be enhanced by ongoing morning activity from Wisconsin to
Illinois and/or its remnants.

//DTW Threshold Probabilities...

* Moderate for ceiling 5000 FT or less today.

* Moderate for thunderstorms affecting DTW/D21 airspace mid to late
  afternoon.

&&

.PREV DISCUSSION...
Issued at 339 AM EDT Thu May 26 2016

DISCUSSION...

Currently on radar we have a line of showers, with isolated
thunderstorms, working slowly northeast through western and central
Michigan. These showers went up on shortwave trough lifting through
the longwave flow with a lobe of vorticity associated with it.
Though the showers are moving into a less favorable environment, it
appears there is a weak MCV embedded which is likely providing it
the forcing it needs to progress further across the state through
the early morning hours. Updated pops across the Saginaw Valley to
categorical with the increased confidence that it will at least hold
together into the area. With such slow forward motion, it could
still fall apart before reaching the bay.  Regardless, any precip
that falls will likely be light and not amount to much as upstream
observations suggest.

In the wake of the early morning showers it looks like we should
dry out once again, at least for several hours. Fairly strong
subsidence behind the passing shortwave should be enough to suppress
any activity til later this afternoon. At that point, there is no
real forcing mechanism in terms of shortwaves, fronts, etc., but
there is a great deal of CAPE as a hot humid airmass persists over
the region. Model average puts max CAPE values around 1500 J/Kg by
late this afternoon. Soundings are quite stable in the low levels as
warm SW flow keeps a warm layer from about 3-6kft capping the
atmosphere. Still with that much CAPE around this warm humid airmass
(dew points in the 60s) can`t rule a few pop up showers from
occurring.

Looking forward, the overall pattern changes very little through the
weekend. Ridging will hold over the Great Lakes and actually looks
to strengthen on Saturday in response to a stronger wave deepening
in the base of the trough. This will push the jet and corridor of
better forcing further north and west. With the warm and humid
airmass holding firm over the area, chance pops will be featured
most days. This does not mean everyone will see rain everyday. Any
activity will be quite scattered with the lack of forcing mechanisms
thus it is difficult to impossible to zero in on any area days in
advance.

There are a couple opportunities in the coming days for more
widespread thunderstorm activity. First will be Friday afternoon as
the trough strengthens and sends a few weak waves northward up
through the area. Current timing looks to coincide with peak heating
which would then be able to utilize the +1000 J/kg of MUCAPE
available. Then on Sunday the main vorticity max at the base of the
trough looks to get picked up by the jet and pass up and around the
ridge. This would take it west then north of the area with the
trailing front swinging up through southern Michigan. This again
could be a day to watch for more widespread thunderstorm activity.

As for next week the pattern breaks down a bit becoming more zonal.
Could start Memorial Day off with some lingering showers but that
looks to get forced eastward by high pressure building in at the
surface and height increasing aloft. This will likely dry the region
out for a few days before the next trough approaches.

MARINE...

Low pressure moving through the western Great Lakes will pull a warm
front through lower Michigan and Lake Huron today. Clusters of
showers and thunderstorms will be most numerous along the front
early in the day. Light south wind will then maintain warm
temperatures and favorable marine conditions through Friday other
than areas of fog resulting from the warm air moving over the cold
lake water. Showers and thunderstorms will remain possible but will
be less organized and mainly confined to areas near land until
Friday night into Saturday. The next low pressure system is due in
the region by then and expected to produce greater coverage of rain
activity. Light south wind will shift light west as the low moves
through the western Great Lakes and pulls a weak front through lower
Michigan and Lake Huron by Sunday.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

AVIATION.....BT
DISCUSSION...DRK
MARINE.......BT


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