Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
FXUS63 KDTX 191939
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
339 PM EDT WED OCT 19 2016
The next system to target southeast MI is coming together as planned
thus far. Upper level trough is digging through the Central Plains
this afternoon and will continue to deepen and amplify through
Thursday night as it travels further east, when the axis aligns with
the Appalachians. Cyclogenesis ahead of the trough is well underway
with a strung out surface low developing over the Mid Mississippi
Valley. Models have been very consistent with the track of this low
NE through the Ohio Valley tonight through Thursday, with the
deformation zone and elevated fgen band passing through southern MI.
Enhancing this region of fgen will be a cold front currently
dropping through WI which will reach mid MI early Thursday morning.
This will encourage some compaction of the elevated front around
700mb over Saginaw Valley. High res models are advertising this but
questions remain as to whether it will be too far removed from the
lower end of the front with the deeper moisture to actually result
in much precip. Also working against the north end of the CWA will
be persistent northerly flow bringing in drier air, reinforcing the
already dry boundary layer. Soundings show the dry layer to be
around 10kft deep which matches well with the ceilings reported from
current METARS across mid MI. Top down moistening will drop ceilings
toward 5-6kft so expectations are for light rainfall tonight,
tapering off later Thursday. Further south around Metro Detroit, the
fgen will be stronger and lower on the frontal surface with more
moisture to work with as the theta e plume slides across far SE MI.
Light rain should begin after 03Z this evening with the steadier,
moderate rain mainly falling between 12-18Z. This will be when the
right entrance region of the approach jet slides through lower MI.
Overall looks to be a longer duration rainfall for SE MI starting
tonight and finally tapering off early Friday morning. Rainfall
amounts will approach 0.75 inches across the south, tapering off as
you head north. Could be a tight gradient around PTK to FNT where
the qpf drops off quick.
The cold front will usher in a colder airmass for Thursday, and
combined with ample cloud cover will result in highs only in the
mid/upper 50s. A backdoor cold front could then brush SE MI on
Friday bringing even cooler air into the Great Lakes. 925mb temps
will fall to around 2C through this time keeping temps in the low
50s. High pressure building into the region with the thermal trough
overhead will allow temps to fall into the mid 30s Friday night.
Another chilly but dry day Saturday with the thermal trough
overhead. Back to seasonable temperatures on Sunday with rising
heights. Medium-range models depict a quick-moving shortwave in
northwest flow Sun/Sun night, however current consensus favors the
best forcing remaining north of our CWA. High pressure builds back
in for early next week, with seasonable temperatures continuing.
Light southwest winds will veer to the north and strengthen through
Thursday. Moderate to fresh winds will continue out of the north to
northwest Thursday evening through Saturday as cooler air spreads
over area waters. The persistent N to NW fetch will build waves to
hazardous levels in the nearshore zones of Lake Huron as early as
Thursday night. An extended period of Small Craft Advisories for
both winds and waves is likely between Thursday night and Saturday.
A frontal zone will slowly move through the area as low pressure
lifts from Paducah to Buffalo. Light to occasionally moderate rain
will develop on the northwest side of this system bringing up to one
half inch of rain to areas along and south of I-69 between late
tonight and Thursday evening. The heaviest rain is forecast to be
the heaviest between approximately 8am and 2pm Thursday during which
time at least half of the forecast amount of rain is expected to
Issued at 1252 PM EDT Wed OCT 19 2016
VFR and light wind through early evening. Attention is on the
expanding batch of clouds and showers lifting northeast out of
Missouri and Illinois. This is associated with a deep layer of
isentropic ascent will spread into the area between 03-06z.
Generally expect high-based showers at the onset as resident dry air
indicated on the 12z DTX sounding will be reinforced by developing
dry NE flow even as top-down saturation tries to commence. Showers
are forecast to become MVFR and moderate intensity by early Thursday
morning. Heaviest rain rates expected in the 12-18z time frame
Thurs. MBS likely to escape most or all rain but will see
enroaching MVFR cloud behind the cold front early Thurs.
For DTW...Developing N-NE wind component may result in noise
abatement concerns by Thursday morning.
//DTW Threshold Probabilities...
* Low confidence in cig below 5kft through 12z. High confidence
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
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