FXUS63 KDTX 242305
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
705 PM EDT Thu May 24 2018
High pressure will maintain VFR conditions this forecast period with
mainly clear skies and light winds (variable to southerly overnight
and south/southwest 8-12 knots by midday Friday.
.DTW THRESHOLD PROBABILITIES...
Issued at 346 PM EDT Thu May 24 2018
Friday will remain warm with plenty of sun through the day as
surface high remains in control while it drifts over the mid
Atlantic states. Upper level ridge axis will be passing east in the
morning which will open the door for deep layer southwest flow into
the state, granted flow throughout most of the column will remain
below 20 knots. 850mb temps will be up around 16C which combined
with cumulative heating effects from Thursday should easily allow
temps into the mid to upper 80s.
Weekend becomes a bit more active as the remnants of the west coast
trough that became more progressive, track across southern Canada
around the ridge. Main cold front is locked north of Lake Superior
which will have mid level wave support for an extended period of
showers and storms. Our concerns farther south begin early Saturday
morning as hires models hint at a convective cluster developing over
MN/WI then tracking south along western Lake MI following the better
moisture and instability gradient. Will keep an eye out to see how
far east it can push but at this point the morning looks to start
off dry. A shortwave trough then swings across lower MI in the
afternoon/evening which will present a chance of showers and
thunderstorms. Models show high levels of CAPE building through the
afternoon as dewpoints increase into the mid 60s. A model average of
1500 J/kg is in the mix with a few models reaching up near 2000
J/kg. Moisture profile is thin down low but overall PWATs will be at
or above 1.3 inches. Shear is lacking due to weak flow throughout
the column with only around 20 knots to be expected. The jet being
hung up well to the north will provide no support across the local
area. A popular scenario with latest models is have the trough axis
initiate convection over SE MI late in the afternoon or evening
aided by peak heating. Not expecting severe weather at this time due
to lack of shear and upper level support, but heavy rain will be
likely with any storm. As previously mentioned, if CAPE really does
flirt with 2000 J/kg, pulse severe storms could occur.
Height rises will begin Sunday as midlevel trough axis moves off to
the east. A secondary midlevel trough will swing through the
northern Great Lakes Sunday afternoon, but model guidance is in
disagreement as to how far south its influence will reach - latest
ECMWF run hints that this feature will be unable to contend with the
height rises over our area. Regardless of good midlevel support,
there will be plenty of instability for SE Michigan with MLCAPE
advertised to reach 1500+ J/kg. Thus, scattered thunderstorms will
remain a possibility Sunday but tweaks will need to be made to the
forecast as we continue to evaluate how the trough will evolve.
Ridging aloft fully takes over and surface high pressure moves
through for the early week. Memorial Day weather looks dry and warm.
Highs through the extended period will reach the 80s each day with
overnight lows in the 60s. The next best chance for rain will come
Thursday as a trough and associated cold front push through.
Strong surface high pressure center will push southeastward out of
Lower Michigan and into the Mid Atlantic tonight. Light southwest
return flow will develop over the central Great Lakes with time. A
modest increase in southwesterly flow is expected for Friday and
Saturday. Southwest winds ranging between 10 to 20 knots will be
possible. A slow moving front will then slide into the northern
Great Lakes from the north on Saturday, bringing occasional showers
and thunderstorm activity. The front will wash out over the region
toward the end of the weekend as high pressure expands back into the
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
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