Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 281859
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
259 PM EDT Sun May 28 2017

.DISCUSSION...

Scattered thunderstorms over far southern lower Michigan on into
northern Indiana and Ohio will gradually expand in coverage as they
move northeast into area along an advancing warm front. MLCAPES of
near 1000 J/kg along with deep layer shear of 30-35 knots will help
maintain some storm organization (as is evident by several of the
pulse type cells already garnering some structure this afternoon).
This will lead to primarily a risk of large hail and eventually
isolated damaging wind gusts if cells are able to organize into
small clusters. While low level shear is generally very weak, there
will be a small window for an isolated tornado threat along the warm
front as it edges into the far southern forecast area. Initial risk
of thunderstorms will generally be limited to the M-59 corridor on
south late this afternoon.

The approaching shortwave through and associated surface low forcing
this warm front northward will move into area this evening and bring
additional scattered showers and thunderstorms to a broader portion
of the area. While some strong storms still may occur, a lack of any
notable instability by that time should limit severe threat. This
activity will work east of area with the shortwave in the 10pm to
midnight time frame.

For the upcoming work week, there will be a general trend to cooler
weather into the Wednesday/Thursday time frame as a broad upper
level trough expands over the area as large upper low over south
central Canada wobbles southeast into the northern Great Lakes in
the wake of this current passing shortwave.

On Monday, mild weather with temperatures into the 70s is expected
as mean upper trough axis remains west of area during the day and
cold air advection does not begin until late in the day. In fact,
upped temperatures a degree or two from previous forecast. Expect
temperatures to back into the 60s Tuesday/Wednesday as the upper low
settles into the vicinity. As this system lifts back into the mean
Hudson Bay position by late week, a moderation back into the 70s is
expected. Weather will be rather dry for much of the week, but may
become more active once the upper low does re-position further north
and more zonal looking upper flow develops and allows for better
moisture return into area with several shortwaves riding through the
mean westerlies.

&&

.MARINE...

Numerous showers and strong thunderstorms late today and this
evening over the marine waters. Storms over Lake St. Clair and Lake
Erie may be severe.  West to southwest winds will then develop
behind a cold front tonight, then strengthen Monday and
Tuesday as low pressure becomes stalled over northern Ontario. Gusts
both days look to just top 20 knots for most marine areas, with
stronger speeds over Saginaw Bay possibly necessitating a Small
Craft Advisory Monday and Tuesday.

&&

.HYDROLOGY...

Numerous showers and strong thunderstorms tracking through late
today and this evening. Basin average rainfall amounts are forecast
to range between one-quarter and one-half inch, but precipitation
totals will vary widely from location to location due to the hit and
miss nature of showers and thunderstorms. The more intense storms
will have the potential to produce isolated rainfall amounts of one
inch or greater, which could cause minor flooding in the low lying
and poor drainage areas. Showers and thunderstorms should end around
midnight, before scattered activity redevelops Monday afternoon.

&&

.PREV DISCUSSION...
Issued at 1242 PM EDT Sun May 28 2017

AVIATION...

CU field has struggled to get going thus far, but should see
ceilings in the 3-7 kft range by late afternoon. Weak and chaotic
surface wind field this afternoon as weak surface reflection tracks
through southeast Michigan late today, helping to trigger numerous
showers and strong thunderstorms, with greatest concentration of
thunderstorms and possible severe cells across southern TAF Sites.
Westerly winds to become established early this evening, but still
struggling to reach 10 knots, and then dropping off slightly and
becoming southwest overnight. Amount of rainfall that falls late
today/early this evening will determine if there is any light fog
and/or low ceilings to worry about overnight. Whatever fog that
attempts to develop will burn off quickly shortly after sunset
Monday, with increasing southwest winds through the day, topping out
around 25 knots in the afternoon. Scattered showers and isolated
thunderstorms developing in the afternoon, but coverage too low to
include in TAFS at this time.

For DTW...Outside of the possible short period of borderline
MVFR/VFR ceilings to start taf period as warm front lifts north,
ceilings around 5000 feet expected late this afternoon. Lower
ceilings (MVFR) in and around thunderstorms, which look to arrive
around 21z, and ending during early evening hours.

//DTW THRESHOLD PROBABILITIES...

* Moderate in ceilings at or below 5000 ft late this afternoon and
  into this evening.

* Moderate in thunderstorms between 21-02Z.


&&

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

$$

DISCUSSION...DG
MARINE.......SF
HYDROLOGY....SF
AVIATION.....SF


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



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