Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 161913
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
313 PM EDT Mon Oct 16 2017

.DISCUSSION...

12Z DTX sounding revealed a lot of dry air in the 925-800 MB layer,
which has allowed for a good deal of sunshine today as the 700 MB
cold pool (-12 C)/thermal trough has just pulled east, and allowed
Lake Michigan clouds to finally be released and track into the CWA
late this afternoon, which should help hold max temps in the
mid/upper 50s.

Further mid level warming will take place tonight as rather flat
upper level ridge builds into the Central Great Lakes this evening.
Pretty good low level warm advection as well with the southwest
gradient developing tonight, as cold front tracks through Lake
Superior. With the gradient and warm advection, low temperatures
expected to hold around 40 degrees, despite the current dew pts in
the lower 30s. With surface high along the Ohio River, locations near
the Ohio Border will probably come in with the coolest readings, as
there is an opportunity for winds to decouple around midnight.

Weak 925-850 MB theta-e ridge axis to drop south into southern Lower
Michigan Tuesday afternoon, but too dry and stable (showalter index
around 10 C) to worry about many clouds, much less any precipitation
concerns. 925 mb temps reaching 13 C (per 12Z nam/euro) suggest highs
in the upper 60s, with Wednesday looking just as warm, if not
slightly warmer, as renewed increasing southwest flow gets going
ahead of another shortwave trough/cold front tracking through Lake
Superior Wednesday evening. This front will be stronger, but moisture
axis is still pretty lean tracking through Wednesday night, with PW
values getting up around three quarters of an inch. Another dry fropa
appears likely with majority of the upper level forcing displaced
well to the north.

Upper level ridging to move in Thursday and persist into the first
half of the weekend. Southerly flow around the high pressure center
over the eastern CONUS and warm air advection will help keep temps
above average and support a slight warming trend. Conditions will be
very pleasant with mostly sunny skies and highs reaching the low 70s
by Saturday.

Potent energy moving into the Pacific northwest will work to push
this ridge out of the area beginning Sunday. The next chance of
widespread rain returns to the area late Sunday into early Monday as
an upper trough digs through the Great Lakes. This trough is progged
to stick around the area through mid next week, leading to much
cooler temps and unsettled conditions.

&&

.MARINE...

Moderate westerly flow through the early afternoon across the Lakes
through this afternoon as the upper trough exits further to the
east. Surface high pressure will build in across the Ohio River
Valley and southeastern US as another low pressure system to our
north pass through northern Ontario. Michigan will be placed in
between these two system and it allow the gradient flow to
strengthen out of the southwest late tonight through tomorrow
afternoon. A long fetch of gusty winds out of the southwest at 20-30
knots will set up for much of Lake Huron basin and Saginaw Bay.
These winds should persist over the next couple of days as gradient
winds will remain elevated within this regime.

&&

.PREV DISCUSSION...
Issued at 150 PM EDT Mon Oct 16 2017

AVIATION...

Mostly VFR conditions for all sites through this TAF period with
light westerly to southwesterly winds this afternoon. There are
pockets of MVFR CIGS moving across far southern Michigan, but expect
those to lift throughout the afternoon. Winds will become light
after 0Z and clouds will also begin to clear out. A tightening
surface pressure gradient will allow winds to pick up overnight into
tomorrow morning and could bring gusts up to 20 knots out of the
southwest.

For DTW...CIGS will hover right around 5000 feet this afternoon as
clouds move in from the west. The cloud deck could dip below 5000
feet from time to time throughout the afternoon.

//DTW THRESHOLD PROBABILITIES...

* Low in ceilings at or below 5000 ft today.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Small Craft Advisory from 6 AM to 6 PM EDT Tuesday for LHZ421-422-
     441.

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

$$

DISCUSSION...SF/TF
MARINE.......AA
AVIATION.....AA


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