Small Craft Advisory 52, NWS Detroit, MI

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
147 PM EDT FRI SEP 9 2016

.AVIATION...

Lingering low-level moisture and daytime heating will allow
afternoon cu to develop under a subsidence inversion. Coverage will
predominantly be scattered, but cannot rule out broken ceilings for
an hour or two in the late afternoon. Conditions will remain VFR
through much of tonight, although high/mid clouds will thicken and
lower as the next low pressure system approaches. Upper disturbance
lifting out of the Southern Plains is expected to ride over the top
of a warm front as it lifts into Lower Michigan late tonight and
early Saturday morning. This will provide a good chance for showers
and MVFR ceilings and visibility (rain/BR), primarily after 08Z per
latest model consensus. Limited instability will limit coverage of
thunderstorms late tonight/early tomorrow and will leave mention out
of the TAFS. Low-level jet surging up into the area along/behind the
front will also increase low-level wind shear through late morning
until mixing increases. We may then see a break in activity from mid-
morning through early afternoon before the cold front arrives and
increases chances for showers and thunderstorms again after 18Z.
Southwest winds will also increase tomorrow ahead of the cold front.
There is potential for gusts to reach 30-35 knots in the late
afternoon.

For DTW...VFR conditions are expected this afternoon and most of
tonight, although we could see an hour or two with ceilings at low-
end broken between 3500-4000 feet. First round of precipitation
associated with approaching low pressure looks most likely to affect
the terminal between 09-13Z. This should mostly consist of rain
showers, but cannot rule out an embedded thunderstorm. Second round
of showers and storms looks to hold off until just after 18Z.

//DTW Threshold Probabilities...

* Low for thunderstorms late tonight and early Saturday morning.
  Moderate Saturday afternoon.

* High for ceilings below 5000 feet late tonight through Saturday
  morning.

&&

.PREV DISCUSSION...
Issued at 307 AM EDT Fri SEP 9 2016

DISCUSSION...

Warm and humid weather will persist today and to some degree into
Saturday as broad southwesterly upper level flow in advance of an
approaching shortwave promotes a continuation of above average
temperature conditions. While dry conditions are expected through
the day today and most likely through the evening hours, surface low
pressure will develop over the upper midwest in response to the
digging shortwave energy.

As this low lifts into the northern Great Lakes, a warm front will
be forced northward through the area with shower and thunderstorm
chances increase overnight into Saturday morning with the passage of
this frontal boundary. Rain chances will then continue much of the
day until trailing cold front sweep across the area around departing
low pressure late in the day and sweeps most remaining activity to
the east. See no reason to lower likely precipitation chances that
are already in place. In fact, will edge up chances just a bit on
Saturday with this forecast.

After another day in the 80s today with modest humidity levels and
temperatures approaching 80 on Saturday within an increasingly humid
airmass, expect somewhat cooler readings and much less humid weather
during the Sunday/Monday time frame as surface high pressure builds
into area from the west. While trajectory of this system northeast
into eastern Canada will limit any real cool air punch from central
Canada, the drier airmass will lead to significantly cooler nights
and daytime temperatures back to near average in the middle 70s.

The next significant northern stream shortwave in this somewhat
active early fall upper level pattern will cross southern Canada and
tap colder air than the first system and lead to much more fall-like
conditions from mid to late next week. Daytime high temperatures in
the Wednesday to Friday time frame are currently expected to range
in generally in the upper 60s to lower 70s with widespread 40s
expected for overnight low temperatures during the same period. In
general, the cold front responsible for this change will cross the
area late Tuesday/Tuesday night, bringing at least a chance of
scattered showers/thunderstorms to the area.

MARINE...

High pressure will result in quiet marine conditions today before
the next low pressure system moves through the region tonight and
Saturday. Southerly winds will start to increase Friday night in
response to the developing low and gusts will approach 25 knots
Saturday ahead of the cold front. Showers and thunderstorms will
also develop in the early afternoon in advance of the front which
will sweep through the Eastern Great Lakes Saturday
afternoon/evening. Winds will turn northwesterly behind the front
Saturday night ushering in a colder airmass. This colder, more
unstable air, will result in an uptick in wind speeds where gusts
could reach 30 to 35 knots Saturday night over Lake Huron. Winds
will decrease on Sunday as high pressure builds back into the
region.

&&

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

AVIATION.....HLO
DISCUSSION...DG
MARINE.......DRK

You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
404 AM EDT FRI SEP 9 2016

MIZ047>049-053>055-060>063-068>070-075-076-082-083-100830-
MIDLAND-BAY-HURON-SAGINAW-TUSCOLA-SANILAC-SHIAWASSEE-GENESEE-LAPEER-
ST. CLAIR-LIVINGSTON-OAKLAND-MACOMB-WASHTENAW-WAYNE-LENAWEE-MONROE-
404 AM EDT FRI SEP 9 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST
MICHIGAN.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS ARE POSSIBLE LATE TONIGHT AS A LOW PRESSURE SYSTEM
DEEPENS OVER THE NORTHERN GREAT LAKES AND PULLS A WARM FRONT NORTH
THROUGH THE AREA. THERE WILL BE A MARGINAL RISK OF SEVERE STORMS
WITH A FEW STORMS POSSIBLY PRODUCING LARGE HAIL OR DAMAGING WIND
GUSTS TO AROUND 60 MPH. STORM MOTION WILL BE TO THE NORTHEAST AT
30 MPH.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE CHANCE OF THUNDERSTORMS WILL CONTINUE ON SATURDAY IN ADVANCE
OF AN APPROACHING COLD FRONT. STRONG TO POSSIBLY SEVERE STORMS
WILL REMAIN POSSIBLE INTO THE LATE AFTERNOON HOURS BEFORE THE COLD
FRONT SWEEPS EAST.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED FROM EARLY SATURDAY MORNING INTO
SATURDAY AFTERNOON.

LCZ460-LEZ444-LHZ361>363-421-422-441>443-462>464-100830-
LAKE ST. CLAIR-
MICHIGAN WATERS OF LAKE ERIE FROM DETROIT RIVER TO NORTH CAPE MI-
LAKE HURON FROM 5NM EAST OF MACKINAC BRIDGE TO PRESQUE ISLE LT
BEYOND 5 NM OFF SHORE-
LAKE HURON FROM PRESQUE ISLE LIGHT TO STURGEON POINT MI BEYOND 5NM
OFF SHORE-
LAKE HURON FROM STURGEON POINT TO ALABASTER MI BEYOND 5NM OFF SHORE-
OUTER SAGINAW BAY SW OF ALABASTER TO PORT AUSTIN MI TO INNER SAGINAW
BAY-INNER SAGINAW BAY SW OF POINT AU GRES TO BAY PORT MI-
PORT AUSTIN TO HARBOR BEACH MI-HARBOR BEACH TO PORT SANILAC MI-
PORT SANILAC TO PORT HURON MI-
LAKE HURON FROM PORT AUSTIN TO HARBOR BEACH BEYOND 5NM OFF SHORE-
LAKE HURON FROM HARBOR BEACH TO PORT SANILAC BEYOND 5NM OFF SHORE-
LAKE HURON FROM PORT SANILAC TO PORT HURON BEYOND 5NM OFF SHORE-
404 AM EDT FRI SEP 9 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF LAKE ERIE...LAKE
HURON AND LAKE ST CLAIR.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS ARE POSSIBLE LATE TONIGHT AS A LOW PRESSURE SYSTEM
DEEPENS OVER THE NORTHERN GREAT LAKES AND PULLS A WARM FRONT NORTH
THROUGH THE AREA. THERE WILL BE A MARGINAL RISK OF SEVERE STORMS
WITH A FEW STORMS POSSIBLY PRODUCING LARGE HAIL OR DAMAGING WIND
GUSTS TO AROUND 50 KNOTS. STORM MOTION WILL BE TO THE NORTHEAST
AT 25 KNOTS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE CHANCE OF THUNDERSTORMS WILL CONTINUE ON SATURDAY IN ADVANCE
OF AN APPROACHING COLD FRONT. STRONG TO POSSIBLY SEVERE STORMS
WILL REMAIN POSSIBLE INTO THE LATE AFTERNOON OR EARLY EVENING HOURS
BEFORE THE COLD FRONT SWEEPS EAST.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED FROM EARLY SATURDAY MORNING INTO
SATURDAY AFTERNOON.

YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

DG