Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 261705
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1205 PM EST Sat Nov 26 2016

.AVIATION...

The wedge of open sky over central portions of Lower Michigan during
the morning will continue to fill in through early afternoon.
Surface heating will reinvigorate stratocu development while backing
low level flow directs stratus eastward from Lake Michigan. Expect
ceiling to lift into VFR during mid to late afternoon with a little
more surface heating and factoring in that the morning lake stratus
was at the upper end of MVFR. Passage of the surface ridge axis
should then promote a fragile clearing trend during the evening
before low cloud potential increases again overnight. Incoming model
data is less aggressive at displacing the lake clouds north and east
of the terminal corridor and is more bullish on prospects for
northward expansion of low level moisture from the mid Mississippi
valley overnight. The moisture from the south will be feeding into a
loosely organized warm front/trough over the southern Great Lakes
that may already be preserving the lake clouds late tonight through
Sunday morning, mostly likely in the lower end of MVFR. Should
clouds fail to materialize or hold in place, then a window of MVFR
fog would be likely instead before southerly surface wind increases
more convincingly by Sunday afternoon.

//DTW Threshold Probabilities...

* High for ceiling 5000 ft or less today... medium late tonight
  through Sunday morning.

&&

.PREV DISCUSSION...
Issued at 349 AM EST Sat Nov 26 2016

DISCUSSION...

Deep layer west-northwest flow still locked in through the daylight
period, the surface ridge axis holding firm across the Lake Michigan
corridor during this time.  While the overall advective process now
stands at neutral, the existing colder thermal profile will maintain
some degree of moisture flux off Lake Michigan.  This will
effectively solidify an already moist sub-inversion boundary layer,
with the added diurnal contribution ensuring plenty of cloud cover
for today.  Ascent through this layer will otherwise be lacking,
still supporting a dry forecast once any residual light shower/
drizzle activity fades this morning.  Rather seasonable late
November temperature regime, readings again topping out in the lower
40s.

Backing upstream low level flow as the surface ridge settles through
the region tonight will begin to disrupt both the moisture supply
and depth.  Subsequent reduction in inversion heights as subsidence
increases and drier air works over the top suggests a trend toward
diminishing cloud coverage overnight.  With that said, still some
concern that this process takes a good portion of the night to
unfold.  In terms of low temperatures, will continue to lean on the
prospects of seeing a greater period of open sky by the early
morning period, netting a more sizable nocturnal cooling response
within an otherwise favorable radiational cooling profile (dry mid
levels & weak/decoupling flow).

Outside of managing any pesky near term cloud trends, benign weather
conditions to finish off the holiday weekend as the region settles
within low level southerly flow beneath building upper ridging.
Developing pattern of warm air advection across this timeline
relatively weak initially, simply augmenting the climb in mean
thicknesses to nudge highs upward a category relative to Saturday
/mid-upper 40s/.

Increasingly energetic southwest flow will emerge immediately
downstream of a strong mid level system that takes residence over
the eastern Dakotas by Sunday Night/Monday.  Anchored by a 150+ knot
upper jet, increasing upper diffluence and warm frontal dynamics/low
level jet forcing, an arc of strong ascent will quickly funnel
downstream during this time.  Main question locally will be the
integrity of this forcing as it works into the slowly departing
upper ridge still hanging across the region.  Recent model guidance
suggests SE Michigan may very well be the end point for this forcing
field Monday, with the resultant linear axis of precipitation fading
in coverage upon entry.  Greater opportunity for widespread rainfall
centers on the Monday night period, as a secondary strong wave
pivots through the base of the lead wave and provides a renewed
source of strong ascent and moisture transport.  Setup points toward
seeing a good soaking rainfall all locations during this time.
Modified warm sector will engulf the region in the wake of this
moisture plume for Tuesday.  This will yield the warmest day of this
forecast cycle, with readings pushing well into the 50s.

MARINE...

Moderate westerly winds will persist until passing high pressure
turns winds southeasterly sunday night. Deepening low pressure will
support a fresh southeast breeze on Monday becoming strong into
Monday night. Wind gusts will be limited due to the stable southerly
fetch but gusts to low-end gales are possible Monday night into
early Tuesday. This period will be monitored for a potential gale
watch over central Lake Huron in future forecasts. Small craft
advisories for wind and waves will likely be needed for wind and
waves will likely be needed for the nearshore zones of Lake Huron
Monday into Tuesday.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

AVIATION.....BT
DISCUSSION...MR
MARINE.......JVC


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