Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 201700

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
100 PM EDT FRI MAY 20 2016


High VFR clouds will continue to work in from the south this
afternoon before mid VFR clouds start working into the area this
evening and tonight.  There is a chance for some high based showers
(6-10 kft) along the I-94 corridor and south by early tomorrow
morning. Light easterly winds expected today...becoming
variable/shifting to the northeast tonight.

//DTW Threshold Probabilities...

* Medium confidence in ceilings above 5k tomorrow morning


Issued at 246 AM EDT Fri May 20 2016


Surface ridge and shortwave ridge aloft will bring one more very
quiet weather day to Southeast MI. Upper low spinning from the
central Plains will send a spoke of vorticity across Lower MI this
afternoon.  Accompanying that will be decent forcing at 500mb,
certainly enough to bring high opaque cloudiness to areas south of I-
69 during the afternoon. Those clouds should keep temperatures down
just a degree or two from today`s highs which is in line with
guidance temps.

This afternoon`s clouds is just the start of a slightly more
pessimistic forecast for tonight through Saturday night.  That upper
low wobbles just south of the state through Saturday.  Forcing
continues to be very weak on the northwest flank of this upper low
with just some 700-500mb deformation and very weak 850-700mb
moisture advection and isentropic lift brushing the far southeast
portion of the forecast area. Airmass remains dry below 800mb which
should result in some light rain showers from cloud bases of 5000 to
10000 feet. End result will be the addition of chance POPs for the
second half of Friday night and Saturday along and southeast of an
PHN to ARB line. Expect warmer temps for the Tri Cities region with
more sunshine on Saturday which guidance temps handle well.

Shortwave moves mainly across Lakes Huron and Erie Saturday night
with a weak back door type of cold front. Any chance of showers will
be east of the area closer to the better moisture and forcing. Then
Sunday will see the return of mostly sunny skies for Southeast MI.
Just enough of a north-northeast kick to the wind on Sunday to
expect cooler conditions for the eastern portions of the forecast
area near the Great Lakes.

Upper ridge builds over the lakes for Monday and into Tuesday.
Should be dry both days as temperatures make a run at 80, especially
for Tuesday. As that ridge breaks down late Tuesday, deep but only
modest southwest flow develops for Wednesday and Thursday and
beyond. This will keep the region in a warm and relatively humid air
mass for much of the later half of next week. A series of weak
shortwaves embedded in this deep southwest flow will act upon the
air mass with rounds of showers and storms.


High pressure and a weak pressure gradient will sustain light winds
and tranquil weather across the marine waters through the
weekend...with light southerly winds and warmer temperatures
arriving early next week...leading to a chance of showers and
thunderstorms by mid week.


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



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