Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 150455
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1155 PM EST Sat Jan 14 2017

.AVIATION...

The sky will be clear until about mid morning and then only fragile
coverage of high clouds is expected through much of the day. This
will be thanks to a new round of high pressure building from the
Plains into the Great Lakes that will maintain very favorable
aviation conditions for mid January. Westerly low level wind will be
just strong enough to keep an eye on Lake Michigan for any stray
stratocu but the lake has been unproductive compared to low level
model RH depictions and this is expected to continue through the
day.

//DTW Threshold Probabilities...

* None.

&&

.PREV DISCUSSION...
Issued at 317 PM EST Sat Jan 14 2017

DISCUSSION...

Stagnant upper air pattern over the Great Lakes into Monday as upper
jet remains parked over the area, waiting for ejection of energy
over the SW US. Until then, forecast is more or less modified
persistence with no airmass change and episodic mid/high level cloud
cover. Visible satellite indicates thicker portion of cirrus
beginning to settle south of the state. This will continue as subtle
low amplitude height falls translate across the area. Along with
high pressure providing a light gradient at the surface, all
locations should decouple eventually tonight - northwestern
locations first. Thin cirrus will prevent optimal radiating, but
suspect the Saginaw Valley will still make a run into the upper
single digits.
Teens to around 20 degrees elsewhere. 925mb temps continue to hover
around -4 to -5C for Sunday. Primary driver of max temps will
therefore be cirrus coverage and opacity. Upper-level moisture
modeled to be thinner than today with no mid-level clouds to speak
of, so generally expect a partially transparent cirrus shield
impacting the southern CWA the most. Temps should moderate at least
3 to 5 degrees over today. A return to overcast mid/high cloud in
store for Monday, but a warming column and developing return flow
support potential for highs approaching 40 degrees regardless.

Clouds rapidly thicken and lower by late Monday Warming temps Monday
night as deep layer theta-e advection commences in response to
ejection of the closed low over the southwest. Increasing isentropic
ascent aided by weakly coupled jet overhead will push pwats toward
one inch and support categorical pops. Brief period of negligible
fzra possible during initial saturation...otherwise all rain.

Low pressure crossing the Great Lakes region on Tuesday will bring a
surge of warm, moist air northward with widespread rainfall during
the first half of Tuesday and unseasonably warm temperatures with
highs approaching 50 in Metro Detroit. There remain some slight
differences between model solutions regarding how the low exits the
Great Lakes region. GFS favors a second northern wave pushing into
the Great Lakes late Tuesday with the low exiting more slowly on
Wednesday. ECMWF and CMC solutions favor the initial shortwave
quickly crossing the Great Lakes on Tuesday with the low well east
of the Great Lakes by Wednesday while the second northern wave dives
further south into the Central Plains. Thus some uncertainty remains
as to how long showers may linger late Tuesday into Wednesday.
Unseasonably mild conditions then prevail for the latter half of
next week as a ridge amplifies over the Eastern US in response to a
deepening trough over the Western US.

MARINE...

Moderate westerly winds late today shifting to northwesterly this
evening.  Strongest winds positioned across northern sections of
Lake Huron, reaching up to 25 knots at times before diminishing
overnight.  Extended period of light winds and modest wave action
expected Sunday and Monday as high pressure drifts through and
warmer conditions return.  Southerly winds increasing to around 20
knots on Tuesday will allow for ever milder air to reach Lake Huron,
resulting in precipitation type falling as all rain.

HYDROLOGY...

Low pressure coming out of the Southern Plains will spread rain into
southeast Michigan Monday Night into Tuesday. This system will have
a good deal of moisture to work with, but at this point, rainfall
totals are expected to range in the quarter to half an inch
range. Heavier convective showers or even a slight chance of
thunderstorms could produce localized higher totals, but no flooding
is anticipated.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.

&&

$$

AVIATION.....BT
DISCUSSION...JVC/JD
MARINE.......MR
HYDROLOGY....MR


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