Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 252045
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
345 PM EST Sun Feb 25 2018

.DISCUSSION...

The remaining wind advisory for the Tri Cities and northern Thumb
will be cancelled at 4 PM as peak wind gusts continue to diminish.
An isolated 40 mph wind gust remains possible at locations favored
in southwest flow, such as Tri Cities and Detroit Metro, but the
overall trend will diminish rapidly with decreasing pressure gradient
and with the approach of sunset.

Diminishing wind during the evening will lead to a period of dry and
pleasant weather to start the week. Mild temperatures are also
expected by late February standards after lows tonight in the mid
and upper 20s most locations, and even those values are above normal
for the date. Incoming surface high pressure is solidly of Pacific
origin and will shift the low level thermal trough out of lower
Michigan during Monday. This will allow already modest cold
advection to quickly transition neutral to warm and produce a
surface temperature rebound solidly into the 40s across the area.
Warmer guidance choices are preferred considering snow cover is gone
and sunshine will be plentiful during Monday afternoon.

The warming trend will gain even more momentum Tuesday as southwest
flow increases across the Great Lakes. This will be driven mainly by
the low pressure system moving through central Canada and as high
pressure remains anchored to the Atlantic coast sharpening the
gradient flow across the Great Lakes. Strong west to southwest flow
aloft over the Rockies will also force lee side surface trough
development over the Plains to enhance low level flow during this
time. The NAM and GFS model soundings in are good agreement with
starting out the day strongly stable and decoupled in the low levels
before building a mixed layer to near 850 mb during Tuesday
afternoon. This, along with wind direction minimizing cold lake
influence, will help temps make a run at 60 subject to just some
high clouds filtering full sun. Record highs are in the upper 50s
for MBS and FNT, and in the lower 60s at DTW.

Increased cloud cover and scattered showers will arrive by Wednesday
courtesy of increased moisture south of a weak frontal boundary
across mid Michigan and a shortwave lifting through the northern
Ohio Valley. Temperatures will again remain 10-15 F above average on
Wednesday with highs in the upper 40s to mid 50s. A southern and
northern stream wave ejecting from the Western US will then phase
over the mid Mississippi Valley Wednesday night bringing the next
low pressure system to the region on Thursday. This system is
expected to bring widespread precipitation to Southeast Michigan on
Thursday. With temperatures in the 40s at onset, expect mainly rain
across the region before cold air wrapping into the system will
bring the potential for a changeover to snow late Thursday. Precip
type will remain sensitive to the eventual track of the low with a
more southern track favoring a higher chance for snow while a more
northern track would favor rain. Drier weather is then expected to
end the week as ridging builds into the region and temperatures fall
closer to average with highs in the lower 40s and lows in the mid
20s.

&&

.MARINE...

Southwest gales will continue to diminish late this afternoon and
evening, with winds dropping below 30 knots over all of Lake Huron
toward Midnight. Winds will continue to diminish overnight into
Monday as high pressure slides across the Ohio River Valley.
Southwest winds behind the high on Tuesday will remain moderate,
holding in the 15 to 25 knot range, with a weak cold front passing
through during the mid week period leading to shift to the north.

&&

.HYDROLOGY...

Dry weather through Wednesday will continue to allow river
levels to lower, with just the Hamburg, Shiawassee, and Saginaw
Rivers left to drop below flood stage over the next couple of days.

&&

.PREV DISCUSSION...
Issued at 1149 AM EST Sun Feb 25 2018

AVIATION...

Low clouds (2500-3500 feet) will continue to mix out early this afternoon
with skies becoming clear by sunset. Clear/mostly clear skies then
persisting this evening through the end of the taf period. The
exception may be across MBS, as modestly cold westerly flow off Lake
Michigan may support a high MVFR deck over northern Lower Michigan
late tonight into tomorrow morning, which may extend far enough south
to impact MBS.

The strong southwest winds this morning around 20 knots sustained
and gusts of 30-40 knots will diminish this afternoon, with
sustained winds lowering to around 10 knots this evening with gusts
ending. Winds then mostly below 10 knots late tonight into tomorrow
morning.

/DTW THRESHOLD PROBABILITIES...

* Medium for cigs below 5 kft until 19z.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...None.

Lake Huron...Gale Warning until 10 PM EST this evening for LHZ361>363-421-422-
     441>443-462>464.

Lake St Clair...Gale Warning until 4 PM EST this afternoon for LCZ460.

Michigan waters of Lake Erie...Gale Warning until 4 PM EST this afternoon for LEZ444.

&&

$$

DISCUSSION...BT/JD
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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