Beach Hazards Statement 10, NWS Detroit, MI

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1158 PM EDT Fri Aug 17 2018

.AVIATION...

Wind directions have uniformly turned to the northwest or west in
all location which has begun the drying out process of the
atmosphere. Plan view progs suggest a slow drying response this
evening, increasing now after 06Z. Deep downward motion is
forecasted with building surface high pressure. However, subsidence
inversion is not overly impressive and some diurnal instability will
exist Saturday afternoon. Model trends are now suggesting some
greater static stability in the midlevels. Dry conditions
anticipated today.

.DTW THRESHOLD PROBABILITIES...

* Low for cigs aob 5kft overnight, medium Sat afternoon.

&&

.PREV DISCUSSION...
Issued at 338 PM EDT Fri Aug 17 2018

DISCUSSION...

Extensive cloud cover remains in place over the area as the upper
low near Chicago slowly makes its way east. Clearing over northern
IN and southwest Lower MI has fostered modest destabilization and
subsequently allowed showers and thunderstorms to develop in that
area. This activity will spread into the the Detroit Metro area and
points south and west into the evening as renewed warm and moist
advection lifts into the area and larger scale dynamic forcing
increases. In the meantime, mediocre convection will likely continue
to flare up at times within areas of enhanced boundary layer
convergence. Further north, more organized mesoscale forcing will
still pose a threat for locally persistent heavy rain. However, the
lack of destabilization to this point, HRRR analysis indicates just
a few hundred J/KG MLCAPE, suggests the outcomes indicated by the
12z suite are highly unlikely. Instead, maintained likely to
categorical pops and will simply highlight a locally heavy rain
threat potentially leading to poor drainage or urban flooding.

Little in the way of airmass change between now and Sunday as H850
temps hover in the mid teens within mean troughing regime. Scouring
out of today's moisture will limit convective potential,
particularly as mid-level temperatures warm, favoring just diurnal
cu-up Sat and Sun aftn as high temps settle in the low 80s with a
decent coverage of upper atmosphere smoke worthy of an upward nudge
in the sky grid.

Midlevel ridging will remain in place on Monday as surface high
pressure drifts northeast into New England, allowing for a dry
Monday morning and afternoon for our area. Highs near normal in the
lower 80s and light southeasterly winds expected. A shortwave
currently moving over the Pacific Northwest will make its way into
the central Plains by this weekend and interact with additional
upper energy dropping in from the Canadian Prairie provinces on
Tuesday, resulting in a strengthening mid-latitude cyclone moving
into the Great Lakes by late Monday night. Long range guidance has
begun to converge on a solution suggesting the center will track
through lower Michigan during the day Tuesday. Chance for showers
and thunderstorms increases Monday evening and lasts through the day
Tuesday.

A broad area of high pressure will build back in on Wednesday and
maintain influence over the area through the rest of the work week,
allowing quiet weather to prevail. The early week system will pull a
good amount of cooler and drier air southward from Canada, leading
to highs in the mid to upper 70s Tuesday through the end of the week.

MARINE...

A weak secondary area of low pressure tracking across Lower Michigan
will maintain showers and thunderstorms this evening before exiting
the region tonight. In its wake, weak high pressure will build
across the Great Lakes bring dry weather for the weekend. Light to
moderate northerly flow will prevail through the weekend, with peak
gusts limited to around 15 knots.

HYDROLOGY...

A secondary low pressure system moving across Lower Michigan will
bring scattered to numerous showers and thunderstorms through this
evening. Rainfall amounts will generally range from a quarter to a
half of an inch, with locally higher amounts associated with
thunderstorms. The flooding threat will be minimal, with ponding of
water on roadways and localized minor poor drainage flooding briefly
possible where the heaviest rainfall occurs. Outside of an isolated
shower Saturday afternoon, the weekend will feature dry weather with
weak high pressure building across the region.

&&

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

AVIATION.....CB
DISCUSSION...JVC/TF
MARINE.......JD
HYDROLOGY....JD

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

Hazardous Weather Outlook
National Weather Service Detroit/Pontiac MI
342 PM EDT Fri Aug 17 2018

LCZ460-LEZ444-LHZ361>363-421-422-441>443-462>464-181945-
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-
342 PM EDT Fri Aug 17 2018

This hazardous weather outlook is for portions of Lake Erie, Lake
Huron and Lake St Clair.

.DAY ONE...This Afternoon and Tonight

Showers will produce locally heavy downpours this afternoon. Poor
drainage flooding such as ponding on roadways will be possible. A few
rumbles of thunder are also possible.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today and tonight.

MIZ047>049-053>055-060>063-068>070-075-076-082-083-181945-
Midland-Bay-Huron-Saginaw-Tuscola-Sanilac-Shiawassee-Genesee-Lapeer-
St. Clair-Livingston-Oakland-Macomb-Washtenaw-Wayne-Lenawee-Monroe-
342 PM EDT Fri Aug 17 2018

This hazardous weather outlook is for portions of southeast
Michigan.

.DAY ONE...This Afternoon and Tonight

Showers will produce locally heavy downpours this afternoon. Poor
drainage flooding such as ponding on roadways will be possible. A few
rumbles of thunder are also possible.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today and tonight.

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