Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 190735
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
335 AM EDT Mon Jun 19 2017

.DISCUSSION...

An upper level trough has set up over the Great Lakes and will hold
through mid week while several shortwaves track through it. In
addition, a trailing surface trough extending back from the strong
surface low now over eastern Ontario, will linger over the region
with a few troughs rotating around it. Though not an idea setup for
severe weather, should be enough support for scattered showers and
isolated thunderstorms.

First opportunity for precipitation will come this afternoon as a
surface trough swings through during the afternoon hours with weak
mid level energy moving in aloft. Post cold frontal airmass is
notably cooler (70s) and drier (mid 50 dewpoints) than the previous
few day, but still enough boundary layer forcing to produce some
showers. Cooler air advecting in aloft with 850mb temps falling to
around 10C today will produce healthy low level lapse rates in
addition to around 500 J/kg of CAPE during peak heating. Lack of
shear (sub 20 knots) will prevent storms from organizing but any
rapidly developing updrafts could produce some small hail as
freezing heights fall to around 700-750mb.

Thermal trough slides over on Tuesday with 850mb temps falling
further to around 8C. Stronger shortwave drops through the trough
across lower MI again during peak heating in the afternoon. Models
advertise slightly lower CAPE (sub 500 J/kg) but higher bulk shear
values (model average around 30 knots) as 50 knot flow aloft sinks
lower in the column to around 10kft. Expect a decent coverage of
showers with the compact wave overhead, but should again result in
scattered to possibly numerous coverage with brief heavy showers and
small hail possible. With coldest airmass overhead, expect highs to
fall slightly further into the low-mid 70 range Tuesday.

Heights start to increase on Wednesday as the next jet max relocates
over the northern plains. This will bring about more westerly flow
and help temperatures start to rebound back into the upper 70s. High
pressure will slide across the region as well which will keep the
area dry through the day. Precip chances do return on Thursday as a
warm front tries to lift, and possibly settle, over the area. This
combined with any shortwave activity could lead to periodic chances
for showers and thunderstorms through the end of the week. Better
return flow from the southwest will help temps rise back into the
80s as well.

&&

.MARINE...

An upper level trough will build across the region during the first
part of week, bringing scattered showers and possibly a few storms.
This activity will be focus mainly during the afternoon and early
evening hours during peak daytime heating. Winds during the period
will generally be light and westerly. However, a bit of an uptick in
wind gusts can be expected late Tuesday into Tuesday night as a
shortwave trough sweeps through area around the base of the slowly
exiting upper level trough. No headlines are anticipated at this
time.

&&

.PREV DISCUSSION...
Issued at 1153 PM EDT Sun Jun 18 2017

AVIATION...

A cooler and drier post-frontal environment will maintain control
through the overnight period. Generally clear skies with a modest
southwest wind will exist.  Steep lapse rates under daytime heating
will lead to a steady expansion of VFR cu by midday Monday. This
will also bring a scattered coverage of showers, with isolated
thunderstorms possible.

For DTW...Clear skies across the lowest 5000 ft through Monday
morning.  Development of scattered showers within a bkn coverage of
cumulus Tuesday afternoon.  Isolated TSRA a possibility.

//DTW THRESHOLD PROBABILITIES...

* Low for thunderstorms Monday afternoon and evening.

* Medium for cigs aob 5000 ft Monday afternoon.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&

$$

DISCUSSION...DRK
MARINE.......DG
AVIATION.....MR


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