Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS63 KDTX 182346

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
746 PM EDT TUE OCT 18 2016


With the main surface baroclinic zone over portions of Ohio and
Indiana, the secondary cold front has been pushing steadily
southward across southeastern Michigan. The ling of showers over
portions of Lenawee and Monroe Counties is in line with the
secondary cold front a significant wind shift. The shower activity
across the far south developed more out of midlevel altocumulus and
its been difficult to get MVFR. So, will be looking at VFR sky
conditions right at the start of the period. The exception is
farther north where some saturation occurred in and near Saginaw Bay
due to cold advection. Model data does not support this lingering
much moving forward. Aggressive surface ridging to build into the
state tonight allowing wind speeds to fall off rapidly. Will be
watching guidance this evening on overall fog potential late
tonight. Latest model data suggests some better potential perhaps in
the higher terrain but any surface saturation will be extremely
shallow supporting nothing more than patchy fog right at daybreak.

For DTW...Lingering midlevel VFR cloud will scatter out during the
remainder of the evening. Low confidence in fog formation in the
urban heat island environment. High confidence in insignificant
wind Wednesday.

//DTW Threshold Probabilities...

* None


Issued at 347 PM EDT Tue OCT 18 2016


Surface cold front will continue its passage through southeast MI
through the remainder of the afternoon, with the last of the showers
exiting the area around 23Z. The front is tied to a low pressure
system well removed to the northeast passing just south of James
Bay. Some earlier showers over Northern MI did produce thunder as
tops grew to near 20kft. Stout warm layer above 700mb over the
immediate area will reduce chances for convection even though low
level lapse rates will be favorable with strong southwest flow at
the surface warming us into the mid 70s and skinny CAPE below the
cap. Best chance of seeing a thunderstorm would be across far
southeastern MI later this afternoon as the area will have more time
to destabilize. Still probably an isolated lightning strike at best.
Any shower that can develop any depth will be able to produce gusts
up to 50 mph as the low level jet is still fairly stout at the top
of the mixing layer.

Tight gradient ahead of the front resulted in elevated synoptically
forced winds gusting to around 35 mph this morning and into the
afternoon hours. Relief will come with the frontal passage as
gradient relaxes and the low level jet gets pushed east. Could see a
quick pop of winds out of the northwest behind the front up to
around 25 mph but winds will quickly fade through the rest of the

High pressure will build into the region tonight at the surface
bringing dry air, clear skies, and light winds. Temperatures however
will remain above average as the upper levels hold nearly zonal,
slight positive slope, through the night as the next trough has
already begun to dig into the plains. With the jet stream staying to
our north, the colder air will remain locked up in Canada.

The next trough will continue to dig through the Tennessee Valley
through Thursday night. This will result in an extended period of
wet weather Wednesday night through Thursday night as a lead surface
low lifts north along the old cold front lingering across the Ohio
Valley. The low track will be to our south but this will allow the
main deformation band fueled by moisture overrunning the front to
lift into southeast MI late Wednesday night. This track will favor
southeast MI staying under the precip shield through Thursday as the
long axis of the deformation zone is aligned parallel with the

A few lingering showers are possible Friday, depending on the track
of the low as its moisture pulls away. Otherwise, expect a cool day
Friday and Saturday as the thermal trough with 850 mb temps around
-5C settles overhead. A bit warmer Sunday into early next week
beneath fast upper WNW flow. 12Z ECMWF brings a quick-moving
shortwave embedded in this flow which would allow for a chance of
showers, but will opt for a dry forecast this cycle as it appears to
be an outlier at this point.


A cold front will exit Lake Huron and lower Michigan by evening and
leave moderate northwest wind to diminish quickly overnight. The
decreasing wind and lowering waves will allow the expiration of all
marine headlines. Favorable marine conditions will then continue
through Wednesday as high pressure settles over the southern Great

The cold front passing through the region today will stall over the
Ohio valley Wednesday. The next low pressure system will develop
along this front Thursday and begin a round of northerly wind over
all marine areas. Moderate speed will develop as the system moves
toward Lake Ontario through Friday which will build waves on the
south half of Lake Huron. Small Craft Advisories may be needed
during this time.


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



You can obtain your latest National Weather Service forecasts online
at is the U.S. government's official web portal to all federal, state and local government web resources and services.