Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 250402
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1202 AM EDT Wed Apr 25 2018

.AVIATION...

Steady northward expansion of low level moisture now translating
into widespread low stratus carrying 400 to 600 ft ceiling heights
throughout the Detroit and Pontiac corridors.  Further expansion
likely to impact FNT yet early this morning, leaving MBS as the only
southeast Michigan terminal absent of LIFR/IFR conditions going
forward through the pre-dawn hours. The passage of a cold front will
bring improving conditions late morning /12z-15z/. Window will exist
during the latter half of the morning for a limited coverage of
cloud coverage, before a diurnally invigorated MVFR or low VFR
stratus emerges for the afternoon. Post-frontal daytime winds turn
northwesterly, with a modest gust component expected to remain below
20 kts.

For DTW...Low stratus holds firmly in place during the early-mid
morning period, only lifting with a cold frontal passage after 12z.
Post-frontal winds turn northwesterly and increase to 10-12 kts
Wednesday.

.DTW THRESHOLD PROBABILITIES...

* High for ceiling 5000 ft or less through 12z Wednesday.

* High for rain as precipitation type.

&&

.PREV DISCUSSION...
Issued at 313 PM EDT Tue Apr 24 2018

DISCUSSION...

Should see blossoming radar coverage early this evening (supported
by latest HRRR/RAP/12z NAM) over the Central Great Lakes, as sharp
northern stream trough tracks into the western Great Lakes,
interacting with moisture in place (12z DTX indicated PW value of
0.92 inches/184 percent of normal), as surface dew pts are also
climbing to around 50 degrees at press time.

Consolidating of upper level PV at base of trough will lead to
slowing down of the PV anomaly as it tracks through lower Michigan
tomorrow morning. 12z Ukmet/Euro remain slower and farther south
compared to GFS/NAM, but still should have enough forward momentum
to clear southeast Michigan by early evening, with post wave
subsidence and drying taking place to clear skies out for Wednesday
night. With an added boost from Lake Huron, as 850 mb temps slip
below zero tomorrow, appears showers are likely for eastern Thumb
Region during the day.

Favorable radiating conditions Wednesday night, with mins
predominately in the 30-35 degree range.

Good shortwave ridging on Thursday ahead of next trough will support
sunshine and temperatures back around normal, lower 60s, with very
light westerly wind advertised.

A chance for rain showers returns on Friday as an upper trough and
cold front push through from west to east. Depth of moisture is not
looking particularly impressive with this system, so it`s possible
just a few sprinkles will result Friday afternoon. High temps Friday
look to reach about 60 degrees before cold advection takes over. 500
mb vort max pushing in behind the front will wrap around the trough
and help it linger over the eastern Great Lakes through the first
half of the weekend. Northwest flow and cold pool aloft (850 mb
temps falling to around -5 C) will limit Saturday highs to the mid
50s.

By Sunday, the upper trough will move out and strong ridging through
the column will arrive. Dry conditions and clear skies will prevail
through the early week. Full late April insolation and thermal ridge
over the region will allow high temps to rise from the mid to upper
50s on Sunday to the lower 70s by Tuesday.

MARINE...

An advancing cold front will produce breezy northwest winds ranging
between 20 - 25 knots across Saginaw Bay and Lake Huron overnight,
subsequently increasing wave heights up to 4-5 feet across the Lake
Huron shoreline. High pressure is then expected to influence the
Great Lakes region which will relax wind gusts late Wednesday into
Thursday morning. Calm to light winds will continue through the
weekend as high pressure moves across the Ohio Valley. Overall,
small craft advisories will go into effect Wednesday morning and
afternoon for the Saginaw Bay and Lake Huron shoreline for wave
concerns.

HYDROLOGY...

Low pressure situated across the Ohio Valley in conjunction with an
approaching cold front will increase coverage of rain showers across
SE MI. The bulk of precipitation is expected to fall across the
Metro region with totals ranging between .10 - .25 inches, with the
higher end totals accumulating down river. Flint up into the Tri-
Cities and Thumb will see up to .10 - .15 inches of rainfall. Rain
chances will end Wednesday morning, where conditions will remain dry
until Friday, where a quick moving cold front could provide a slight
chance for precipitation through the morning and afternoon.
Otherwise, the forecast calls for dry conditions into the weekend.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Small Craft Advisory from 8 AM this morning to 10 PM EDT this
     evening for LHZ421-441>443.

     Small Craft Advisory from 8 AM this morning to 6 PM EDT this
     evening for LHZ422.

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

$$

AVIATION.....MR
DISCUSSION...SF/TF
MARINE.......AM
HYDROLOGY....AM

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



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