Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
FXUS63 KDTX 221922
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
322 PM EDT MON AUG 22 2016
Much drier air in place today over southeast Michigan, as afternoon
dew pts reside in the 50s, setting up cool night with comparable
The Strong upper level wave/PV anomaly over southern Alberta will
continue to track east, moving into southern Manitoba on Wednesday.
Upper level ridge axis ahead of this feature will build over the
Central Great Lakes tomorrow, providing another mostly sunny day
with warmer temperatures, exceeding 80 degrees as 850 mb temps
forecasted to be in the 14-16 C range with favorable low level
southwest flow developing.
Strong moisture transport looks to take place on Wednesday, with
a shortwave coming out of the Four Corners Region or an MCV
progged to eject out of the Southerns Plains and lift into the
Western Great Lakes. Still, there are questions on how fast
moisture will surge up through the plains, as moisture plume then
folds over into more of a west to east fashion across Great Lakes
Region Wednesday night. 12z GFS/NAM are faster with the deeper
moisture (PW values of 2 inches) established over southeast Michigan
Wednesday Afternoon already, and with MLCAPES of 1000-1500 J/kg,
seems worthy of chance pops late in the day. Strong low level Jet
(45-55 knots) supports a chance of damaging winds with any evening
convection, with high 0-1 KM Bulk shear supportive of rotating
updrafts as well, but generally low instability (showalter -1 to -2
C with around 500 J/kg of Cape) expected with relatively stable near
surface layer along with diminishing 0-6 KM Bulk shear as shortwave
quickly exits the Northern Great Lakes Wednesday Night. At this
point, bulk of forcing and low level jet looks to be tracking
through Northern Lower Michigan, and thus reason not to increase
pops to likely just yet.
Medium-range global model consensus keeps warm/moist airmass around
into Thursday before drier air filters in. Lift will be enhanced by
equatorward entrance region of upper jet. Upshot is a likelihood of
showers and thunderstorms, especially for the SE half of the
forecast area. Milder and drier air for Friday and Saturday under
surface high pressure (temperatures near normal values). Return flow
will once again result in warm/moist advection for Sunday, but for
now will hold precipitation chances off until Sunday night/Monday.
Area of high pressure centered over the Ohio Valley will slowly
drift eastward reaching the east coast Tuesday evening. This will
open the door for increasing southwesterly flow Tuesday afternoon
which will persist through Wednesday. Winds will reach 15 to 20
knots in the afternoon, possibly reaching 25 knots at times. Off
shore flow will limit wave potential in the nearshore zones but
can`t rule out a low end small craft advisory for winds being
needed. Shower and thunderstorm chances will increase Wednesday
Issued at 109 PM EDT Mon AUG 22 2016
VFR conditions should prevail through the taf period as high
pressure slowly drifts across the Great Lakes. A weak southwest wind
field this afternoon will go variable tonight, before picking back
up out of the southwest on Tuesday. Clouds will be limited to some
diurnal cu around 4-5kft through this evening before clearing out
tonight. CU field will develop again early Tuesday afternoon.
//DTW Threshold Probabilities...
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
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