Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
FXUS63 KDTX 131657
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1157 AM EST Fri Jan 13 2017
With a large area of high pressure building into the area, expect
generally VFR conditions with just a FEW-SCT stratus this afternoon
near 2500 feet. Otherwise, CIGS will thicken and lower closer to
10kft late tonight -vs- 20kft this afternoon. Winds under 10 knots
will veer from N to NE with approach of the high and then become
For DTW...FEW-SCT 2500 stratus possible this afternoon, otherwise
just thickening/lowering mid/upper clouds within subtropical plume
funneling east into the area. Period of ~7 knot NE flow afternoon
into early evening, then light/variable later tonight.
//DTW Threshold Probabilities...
Issued at 311 AM EST Fri Jan 13 2017
The upper wave now rotating into northern Quebec drove arctic air
across the Great Lakes region yesterday afternoon through last night
and forced the low level moisture gradient well south of the state.
The departure of the aforementioned upper wave will leave zonal and
confluent flow across the Great Lakes through the weekend,
supporting a modest thermal gradient across the state. High temps
today will struggle to break 20 across the tri cities/thumb region
(closer to the deeper arctic air), while highs should push upper 20s
near the Ohio border.
An upper jet max (150 knots) over the northern Great Lakes today
will become centered over New England tonight. A narrow region of
enhanced mid level frontal forcing within the entrance region is
forecast to traverse the forecast area late tonight through the
first half of the day Saturday. Overall, the mid level moisture
quality will not be too bad (2 g/kg). Fairly stable mid levels and
the brief nature of the forcing (not to mention the dry arctic air
in the low levels) will support just a slight chance for some light
snow late tonight into Sat morning with this feature. Otherwise,
extensive mid/high cloud cover will mitigate the nocturnal drop in
temps tonight. Sfc high pressure will then support dry conditions
through the rest of the weekend, with a slight warming trend as the
arctic air slides well east of the region.
There are differences among the model suite in timing of the wave
forecast to eject out of the swrn US late in the weekend and with
its subsequent phasing of northern stream energy dropping across the
central Rockies. The GFS is faster than both the ECMWF and Canadian
and suggests a better response along the mid level front across the
Great Lakes on Monday. Wet bulb cooling associated with lingering
dry air will support a chance of light snow and even freezing rain
on Monday based on the earlier GFS timing. Thermal profiles then
become warm enough to support all rain by Monday night. Despite the
timing differences, all model solutions suggest the strongest
forcing and moisture transport (and thus highest QPF) will occur on
Tues as the wave lifts up through the western Great Lakes, with
thermal profiles remaining warm enough to support all rain. With
arctic air will north of the lower 48, a modified Pacific airmass
will support very mild air for the remainder of next week.
Strong west to northwest winds early this morning will be
diminishing through the day, becoming light and variable by evening
as high pressure arrives. This high will slide off to the east,
allowing for modest increase in southwest winds on Saturday, topping
out around 20 knots as a weak front moves through. Light winds
return for Sunday, lingering into Monday as milder air streams into
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
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