Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 242257

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
657 PM EDT Sun Sep 24 2017


Ridge of high pressure will maintain quite conditions through the
forecast period with light winds. Slowly increasing boundary layer
moisture on southeast flow may lead to several hours of MVFR fog,
mainly KDTW/KYIP and perhaps a slight uptick in diurnal cumulus
coverage, FEW-SCT, on Monday.


* None.


Issued at 330 PM EDT Sun Sep 24 2017


Record highs continue to fall here in southeastern Michigan with the
upper level omega block/ridge in place over virtally all of eastern
North America. The centroid to the upper level ridge axis has now
drifted to the east, but wavelength is large enough that a main
chunk continues to grip the area. Local maximum in thermal ridge
supported temperatures running over 90 degrees in many locations.
Record highs have been broken outright today at both MBS and FNT,
with the most recent temperature back to within one degree at DTW.
The exception has been the immediate shoreline areas adjacent to the
local waterways where a southeasterly wind trajectory has resulted
in some relief.

The thermal ridge axis will drift away from the state Monday
allowing southwesterly return flow to finally set up over the area.
The arrival of return flow is usually a harbinger of warmer weather
with warm air advection, but for this particular scenario the area
will actually see some cooling. The cooling may potentially be as
much as 2 to 3 degrees C at 850mb. Will continue to favor a warmer
solution with some increase in mixing heights. The forecast will
continue to call for upper 80s to around 90 degrees for maximum
temperatures at all locations both Monday and Tuesday.

Cold frontal passage remains progged to occur through the first half
of Wednesday with highs ranging from the mid 70s across the Tri
Cities to the low 80s across Metro Detroit where the frontal passage
will occur later. With better forcing staying well to the north of
SE Michigan and limited moisture ahead of the front, only a slight
chance of showers and thunderstorms will accompany the frontal
passage. Surface high pressure then builds into the region on
Thursday yielding pleasant weather as cooler 850 mb temps near 5 C
will limit highs to the mid 60s. A shortwave dropping southeast
through the Great Lakes on Friday will bring increased clouds and a
chance for showers along with a reinforcing shot of cooler air
keeping highs in the low to mid 60s to end the week.


Strong upper ridging will continue to influence the weather pattern
across the Great Lakes through Tuesday with dry weather and light
south or southeast winds, generally around 10 knots or less. A cold
front crossing the Central Great Lakes Tuesday night will bring a
low chance of shower and thunderstorm activity. Winds behind this
front become northwest on Wednesday and increase to around 10 knots
for Lakes St. Clair and Erie, but in the 15 to 20 knot range for
Lake Huron.


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



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