Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 290704
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
304 AM EDT MON AUG 29 2016

.DISCUSSION...

The 00z DTX sounding revealed good mid level drying, extending down
to 850 mb, as the dew pt checked in at -7 C. However...still have
some lingering moisture from surface up to around 900 mb, and this
has lead to some fog formation, locally dense, especially toward warm
waters of Lake Huron/Saginaw Bay. With further expansion expected,
will issue dense fog advisory for Tri-Cities and Thumb region.

With continued dry advection today (925-850 mb theta-e trough over
eastern thumb region) and increased daytime boundary layer mixing
taking place, dew pts should take noticeably dive to around 60
degrees, with highs in the low to mid 80s based off 925 mb temps of
20-22 C. Mixing depths during the daytime hours to 850 mb is no
longer a done deal as we approach September with less insolation/longer
nights.

Big pattern shift for the end of the work week as upper level trough
develops over the Eastern United States. Surface cold front tracking
through southeast Michigan appears to be on track for Tuesday Night.
It also appears there will be sufficient instability/low level
fgen/converge to support some shower and thunderstorm activity, but
less than ideal night time timing and just modest 6 hr height falls
tracking through supports holding onto just low chance pops in light
of dry nam solution vs wetter Euro/Canadian solutions. Much cooler
air (850 mb temps of 7-8 C) to settle over the Central Great lakes
on Thursday. With water temps around 21 C, Isolated Lake Huron
enhanced showers could come into play as spoke of energy rotates
through backside of the upper level trough.

Building heights and sprawling surface high will then set us up for
large diurnal temperatures swings and gradually warming temperatures
as we head into the Weekend as pronounced upper level ridge axis
(588+ DAM AT 500 MB) returns, with mean 1000-500 mb RH progged
around 30 percent supporting plenty of sunshine.

&&

.MARINE...

Northerly winds across the lakes this morning will weaken during the
course of the afternoon as high pressure builds into the region from
the west. This high will sustain light and variable winds through
the evening. A cold front will drop into western Lake Superior
tonight, supporting the development of south-southeasterly winds
across Lake Huron. This front will push across Upper Michigan on
Tuesday, causing an uptick in south-southwest winds across Lake
Huron. This front will push south across Lake Huron Tuesday night
before advancing into Lake Erie Wednesday morning. In addition to a
chance of thunderstorms along and ahead of this front, winds will
veer to the northwest with its passage.

Post frontal north-northwest winds Wednesday into Thursday will
usher in cooler air across the region. The resulting reduction in
stability over the warm lakes and the tight gradient will likely
support frequent gusts over 20 knots during this period.
Probabilities of small craft advisory conditions across the lakes
Wed through Thurs is quite high.

&&

.PREV DISCUSSION...
Issued at 1208 AM EDT Mon AUG 29 2016

AVIATION...

Clear sky other than some thin cirrus debris will contribute to
favorable conditions for continued fog and stratus development
during the night. High pressure shifting from northern lower
Michigan to Lake Huron will line up to direct some marine moisture
inland. Surface moisture conditions are already be favorable for
borderline LIFR/IFR fog and the marine moisture will enhance both
the fog and LIFR/IFR stratus potential through morning. While
prospects are good for restrictions, observational trends will be
required to refine timing and coverage at each terminal location.
Conditions will then follow a standard improving trend through late
morning and lead to clear sky and light wind through afternoon into
Monday evening.

For DTW... Borderline LIFR/IFR restriction in fog and stratus or
obscuration remains likely late tonight through mid morning with
improvement to VFR by late morning/early afternoon. Clear sky and
light wind will then persist into Monday evening.

//DTW Threshold Probabilities...

* High ceiling aob 5000 feet late tonight through mid morning.

* Low for ceiling/visibility below 200 ft or 1/2 sm late tonight
  into early morning.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Dense Fog Advisory until 10 AM EDT this morning FOR MIZ047>049-
     053>055-062-063.

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

$$

DISCUSSION...SF
MARINE.......SC
AVIATION.....BT


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