Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 231756
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
156 PM EDT Wed Aug 23 2017


.AVIATION...

The combination of cool northwest flow with relatively moist
antecedent boundary layer moisture and full vegetation green-up has
led to a bkn layer of boundary layer cumulus over all of southeastern
Michigan today. The area remains under a favorable sector for strong
upper level confluence as evidenced in recent water vapor imagery.
Progged moisture progs depict a high amount of lower theta e
advection from the due north overnight off of a backdoor type frontal
structure. This drying in concert with loss of diurnal heating will
cause cumulus dissipation this evening. One question for Thursday
morning is prospects of near surface radiation fog development with
cool temperatures at daybreak. The unknown with fog potential hinges
on the the amount of high cloud that will be in place ahead of
the shortwave set to  dig through southeastern later Thursday
afternoon. Attm, preference was to hold back on fog given the tenuous
dependence on said cloud deck in forecast soundings. The forecast
sides with more of an opaque midcloud Thursday.

//DTW THRESHOLD PROBABILITIES...

* Moderate for ceiling 5000 feet or less this afternoon.

&&

.PREV DISCUSSION...
Issued at 327 AM EDT Wed Aug 23 2017

DISCUSSION...

After some active and warm weather, dry and quiet conditions will
commence for the majority of the forecast period. Temperatures will
cool off noticeably, as temps come in just below normal through the
end of the week and into the weekend. Upper level troughing will
continue to hang around today as surface ridging begins to slowly
build in. This will allow for a continuation of cold air advection
with northwesterly flow. With troughing and some low level moisture
still in place over the area, there will some strato cu development
during the afternoon. There may be some potential for a brief
sprinkle during the afternoon hours, but that is about it.
Temperatures at 850mb drop into the single digits before cooling off
a little more on Thursday. This extra little cool down will come as
a shortwave moves down across the area bringing a chance for some
shower activity to the Thumb area during the day on Thursday.  More
expansive high pressure and upper level ridging build back behind
the quickly exiting shortwave bringing dry conditions all the way
into the weekend. Changes to the quiet conditions do not come back
into play until into next week.

MARINE...

Moderate northwest wind will continue over marine areas early today
before easing slightly by late afternoon and evening. Gusts to
around 30 knots will be common over the open waters of Lake Huron
where the long fetch will build the highest waves toward the
Canadian border. Wind speed will diminish tonight while a secondary
front/trough reinforces cool air over the warm lake water through
Thursday. This will be a favorable condition for waterspouts,
especially where any land breeze development is possible. High
pressure settling overhead by Friday will bring in enough dry air to
inhibit cloud formation and produce favorable wind and wave
conditions through the weekend.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&

$$

AVIATION.....CB
DISCUSSION...SP
MARINE.......BT


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