Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 010355
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1155 PM EDT WED AUG 31 2016


.AVIATION...

Northerly flow will continue into Thursday on leading edge of high
pressure. VFR conditions will be replaced by some degree of MVFR
stratus at times, mainly KPTK north late tonight into early Thursday
as cool flow picks up moisture from Lake Huron. Lower VFR to MVFR
stratus may affect southern tafs by Thursday morning. From midday
Thursday into Thursday evening, skies will trend from BKN to SCT
with cigs mixing slightly higher.

For DTW...Generally expect VFR conditions overnight with cigs below
5000 feet expect again at times by Thursday morning with stratus and
strato-cu funneling south towards the terminals on northerly flow
from Lake Huron.

//DTW Threshold Probabilities...

* Moderate in ceilings below 5000 feet Thursday.

&&

.PREV DISCUSSION...
Issued at 338 PM EDT Wed AUG 31 2016

DISCUSSION...

Cold front currently across far se corner of state slowly pushing
southward.  Dewpoints ahead of the front in the low 70s lead to
afternoon cape values 1-1.5k joules, resulting in a thin line of
showers/thunderstorms to develop across southern Wayne and Washtenaw
counties.  These storms will continue southeastward and should exit
the state completely before 5pm.  Behind the front cooler and drier
air is filtering with back edge of post frontal clouds now along the
I-69 corridor.  Should see gradual clearing this evening from north
to south with diurnal cu north dissipating toward sunset.

Tonight through Friday morning,  sharp 500mb trough will slowly
swing southward across the area bringing the first fall like airmass
of the season as 850 temps fall to the single digits.  Wind flow
will become north-northeast over Lake Huron and forecast area.  Sfc-
850 delta-T of around 20C over Lake Huron will lead to several
hundred joules of cape and lake effect clouds that will advect over
most of southeast lower Michigan.  Some lake convergence banding and
sharp 500mb cyclonic flow with trough will lead to a slight chance
for showers beginning in the Thumb region and expanding southward
through the day.  A fair amount of clouds and mixing into 850mb
temps around 7c will yield highs Thursday in the upper 60s Thumb
Region to the low 70s far south and west.

Clouds will quickly dissipate toward sunset Thursday evening with
loss of heating and passage of 500mb trough axis leading to
mostly clear skies, though there will still be patches of lake
effect clouds as flow above boundary layer inversion will remain
rather strong from the northeast.   Surface winds should decouple
allowing for good radiational cooling sending temps down in the
upper 40s in the normally cooler locations to low to mid 50s
elsewhere.

Surface High pressure and 500mb ridging will provide clear skies,
low humidity and seasonably cool temps for the beginning of Labor
Day weekend.

All indications are for a quiet Labor Day weekend as the Great
Lakes remains under upper ridging between a western CONUS trough and
TS Hermine, which is forecast to track up the Eastern Seaboard.
Temperatures are expected to warm from near normal values on
Saturday to well above normal by Labor Day as a surface high shifts
east and southerly flow increases. Humidity values are expected to
be rather low during Labor Day weekend.

MARINE...

Northerly winds will increase tonight and Thursday as a second cold
front drops through the Central Great Lakes. Winds will be strongest
over Lake Huron, where gusts will reach between 25 and 30 knots. In
addition to the gusty winds, the long fetch over the length of the
lake will allow wave heights to build between 3 to 5 feet over
Southern Lake Huron by late tonight. A small craft advisory remains
in effect for the Southern Lake Huron nearshore waters with the
exception of inner Saginaw Bay. Winds will gradually decrease over
the region Thursday night and early Friday as high pressure slowly
builds into the area. High pressure will remain in control through
the weekend, bringing dry quiet weather and no marine concerns.

The deep layer of cold air surging southward over the warm lake
waters will also support waterspout development over all of the
Central Great Lakes both tonight and Thursday. Multiple waterspouts
were already observed Wednesday afternoon over Lake Superior.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement from 8 AM EDT Thursday through Thursday
     evening FOR MIZ049-055-063.

Lake Huron...Small Craft Advisory until 8 AM EDT Friday FOR LHZ421-441>443.

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

$$

AVIATION.....DG
DISCUSSION...DRC/DT
MARINE.......HLO


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