Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 261657
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1257 PM EDT THU MAY 26 2016


.AVIATION...

The development of an MVFR/low end VFR strato cu deck has resulted
from low level moisture and the onset of daytime heating. Continued
heating during the course of the afternoon will slowly lift bases.
Weak to moderate afternoon destabilization may lead to some
scattered thunderstorms late this afternoon/evening...aided by mid
level moisture pooling with the passage of a a weak trough axis in
the 21Z to 01Z time frame. Given that the strongest ascent will be
sliding north of the area and in light of recent regional radar
trends...the chances of thunder at PTK/FNT/MBS look to be less than
30 pct.  Low level moisture will linger across the region through
the night. This may support some fog and/or low stratus development
late tonight into early Fri morning.

FOR DTW...The most recent regional radar loop is suggesting some
redevelopment on the northern edge of the convection now tracking
across Indiana. There is a chance that some of this convection will
push into metro in the 21Z to 00Z time frame. If it does not reach
the airport, there is at least a good chance that the southern
sections of the D21 airspace will be impacted.

//DTW Threshold Probabilities...

* Moderate for ceiling 5000 FT or less this afternoon and evening.

* Moderate for thunderstorms affecting DTW/D21 airspace late this
  afternoon and evening.

&&

.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.....SC
DISCUSSION...DRK
MARINE.......BT


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