Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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424
FXUS63 KDTX 241913
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
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.

&&

.PREV DISCUSSION...
Issued at 125 PM EDT Tue Apr 24 2018

AVIATION...

Low pressure situated across the Ohio Valley will continue to advect
moist air across the terminals, bringing the chance for light rain
showers through the remainder of the afternoon and evening. As the
low levels continue to saturate, cloud bases are expected to lower
from VFR to MVFR. Periods of more consistent rainfall forecasted for
the evening hours may also lower cloud bases to IFR heights. A cold
front will then push through tonight and overnight, causing winds to
back from the east to the northwest. Additional rain showers will be
possible ahead of the front, however, as cooler air is advected
behind the front, cloud ceilings are expected to increase through
the mid to late mornings are diurnal mixing processes start, right
around sunrise. This will also act to bring stronger winds aloft
down to the surface, with gusts up to 20 kts possible during
daylight hours.

For DTW...

ESE winds off of Lake Erie have brought in IFR ceilings and
scattered showers across the Metro terminals. IFR ceilings and
visibilities will continue through the afternoon and evening as low
pressure centered across the Ohio valley continues to produce ESE to
E flow across the terminals. A cold front will then push through
overnight, turning flow to the NW with dry but breezy conditions
filtering in behind the front.

DTW THRESHOLD PROBABILITIES...

* High for ceiling 5000 ft or less today and tonight.

* High for rain as precipitation type.


&&

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

     Small Craft Advisory from 8 AM to 6 PM EDT Wednesday for LHZ422.

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

$$

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


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