Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 190353

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1153 PM EDT Sun Jun 18 2017


A cooler and drier post-frontal environment will maintain control
through the overnight period. Generally clear skies with a modest
southwest wind will exist.  Steep lapse rates under daytime heating
will lead to a steady expansion of VFR cu by midday Monday. This
will also bring a scattered coverage of showers, with isolated
thunderstorms possible.

For DTW...Clear skies across the lowest 5000 ft through Monday
morning.  Development of scattered showers within a bkn coverage of
cumulus Tuesday afternoon.  Isolated TSRA a possibility.


* Low for thunderstorms Monday afternoon and evening.

* Medium for cigs aob 5000 ft Monday afternoon.


Issued at 330 PM EDT Sun Jun 18 2017


Surface cold front just about to slip east at press
time, with latest water vapor imagery showing mid level dry air
becoming well established over southeast Michigan, which has/will
allow skies to become mostly clear. Mostly clear skies will then
persist through the evening and most of the night, but continued
cold advection and next series of upper level waves tracking through
Midwest late tonight helping to amplifying the longwave trough axis
further, with colder 500 mb temps of -18 C spilling over southeast
Michigan late Monday. MLcapes of 400-700 J/kg, coupled with steep
mid level lapse rates approaching 7 C/KM should be sufficient to
generate scattered showers and isolated thunderstorms. Severe
thunderstorms not expected with meager instability and 0-6 KM bulk
shear dropping off through the day, but small hail remains possible
with favorable freezing levels around/just under 10 kft.

Yet another strong upper wave embedded within the northeast flow
looks to be tracking through southern Lower Michigan during Tuesday,
with another repeat performance with scattered showers/isolated
thunderstorms. With the stronger wave (-20 C at 500 mb) and more
direct hit, coverage may end a bit higher on Tuesday compared to
Monday, which is also indicated by the slightly higher pops
indicated by local probabilistic SREF guidance. Similar MLCapes, but
jet forcing/0-6 KM bulk shear of 50+ knots toward Ohio border draws
ones concern for severe storms. However, strength of the updrafts
will probably end up being too weak to overcome the increased wind
shear. Highs in the 70s both days, with Tuesday a couple degrees
cooler with corresponding slightly lower freezing levels as well.

High pressure will act to keep conditions dry throughout Wednesday
as west to northwesterly flow keeps temperatures capped in the mid
to upper 70s for a daytime high, just below seasonal normal for this
time of year. Zonal flow will persist Thursday and will remain in
place for the remainder of the week as temperatures slowly creep
back into lower 80s for a high. In addition to the slightly warmer
temperatures, confidence continues to increase regarding rain and
thunderstorm chances for both Thursday and Friday. Winds will shift
westerly to southwesterly through Thursday morning which will allow
warm, moist air to flow into the region, providing lift for isolated
to scattered showers. A weak cold front is then expected to push
through early Friday providing additional chances for rain and
thunder. Dry conditions are expected to move in behind the front,
minimizing rain chances Saturday into early Sunday, with daytime
highs remaining sub-80 as cooler air settles in place.


West to southwest winds will continue to gust between 20 and 30
knots behind a cold front, with highest speeds focused over Saginaw
Bay due to the funneling effect. Dry weather is expected this
evening and overnight, however the presence of upper level low
pressure over the region will bring renewed chances for
thunderstorms Monday and Tuesday. Winds during this period will
remain fairly light and out of a westerly direction.


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



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