Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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155
FXUS63 KDTX 242335
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
735 PM EDT SUN JUL 24 2016

.AVIATION...

Upward trend in shower/storm activity from NW lower MI into central
IL matches up with axis of instability in hourly mesoanalysis.
Recovery of instability has been substantial during late afternoon
into early evening and expect the axis to move eastward along and
ahead of the cold front and continue to support showers and
thunderstorms with modest coverage and intensity. Timing at the
terminals is mid to late evening at MBS and progressing farther
south to DTW through the overnight hours. There is also a generous
amount of MVFR ceiling over northern lower MI that will likely
develop southward along the front as it moves through SE MI. All
precipitation is expected to be east of the region by shortly after
sunrise Monday with improving aviation conditions in all areas
during the day.

For DTW... Storms over northern IL are expected to develop more into
Indiana than SW lower Michigan. Showers/storms over northern and
west-central lower Michigan have a better chance of developing
southward during the night. These are timed into DTW in 05-08Z time
range as best estimate at issuance. MVFR ceiling/visibility in fog
will be swept in by the cold front with or shortly after the main
area of showers/storms followed by improvement by late Monday
morning.

//DTW Threshold Probabilities...

* Moderate for thunderstorms between 05-08Z.

* Moderate for ceilings at or below 5kft late tonight/Monday
  morning.

&&

.PREV DISCUSSION...
Issued at 311 PM EDT Sun Jul 24 2016

DISCUSSION...
MCs that has been slowly passing across southeast Michigan will
continue to weaken this afternoon as it exits. Temperatures remained
quite steady during the day a bit far from forecasted highs but as
clouds thin, several hours of decent amount of sunshine the rest of
this afternoon and evening will push most location into the 80s.
Two boundaries remain across the area that will be the main focus for
convection the rest of the day.  One outflow boundary is laid out
across central lower from about Saginaw bay/Thumb westward and the
other is from about Toledo back to southern Lake Michigan.  Broken
line of showers and thunderstorms have developed along the northern
boundary but have been weakening somewhat as it pushes southward away
from main cold pool aloft. Expect this boundary to make it near i69
corridor before stalling this evening.  The better chance for shower
and thunderstorm development will be more westward were the better
instability lies.  The southern boundary is a bit stronger as
a result from the cooler air from todays MCs and substantial heating
across northern Indiana as this area has had a good amount of
sunshine all day.  Expecting regeneration of storms along this
boundary from nw Ohio back into sw lower Michigan.  Most activity
should remain south and west of the cwa but some showers could spill
over into Lenawee and Monroe counties as main flow aloft is from the
southwest.

Main cold front is moving through eastern Wisconsin and that will
push slowly through the area overnight. Not much dynamical forcing
with the front, just mainly surface convergence.  Southeast
Michigan will not likely get into the good deep instability as that
will remain to our south, shunt off by todays MCs and boundary to
the south.  Only expecting scattered showers and thunderstorms to
accompany fropa. The front should be close to exiting the area
around sunrise.  Will still carry a chc for precip far southeast
corner Monday morning as this area will still be close to the front.
Drier air will slowly work in behind the front with dewpoints
starting off the day still in the upper 60s in the north to lower
70s south but dropping a 10 or so degrees by end of day.  With
plenty of moisture in the boundary layer, expect a rapid
development of cu shortly after sunrise with clouds slowly
thinning and diminishing throughout the day from nw to se.   It will
still be quite warm Monday as airmass behind front more drier then
cooler.

Zonal upper flow Wednesday over the Great Lakes will transition to
cyclonic by the end of next week/weekend as a series of shortwaves
act to carve out a trough. Midrange deterministic models time the
lead disturbance for Thursday, so Wednesday will likely be another
dry and warm day. Then, indications are that a low-level circulation
attendant to the upper height falls will slowly track across the
lower Great Lakes. This could focus a more well-defined period of
precipitation, but still significant model spread with respect to
the timing and placement, so have kept general chance PoPs Thursday
through Saturday. Temperatures are expected to trend back toward
normal late next week.

MARINE...

A cold front will move across the region tonight turning the winds
from south/southwest to west/northwest. Speeds are expected to
remain below 15 knots. High pressure will set the stage for light
and variable winds on Tuesday.

HYDROLOGY...

Additional showers and thunderstorms are possible in advance of a
cold front tonight. Widespread rainfall is not expected - however
localized downpours are still possible, capable of totals up to an
inch.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

AVIATION.....BT
DISCUSSION...DRC/DT
MARINE.......Mann
HYDROLOGY....Mann


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