Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

661
FXUS63 KDTX 241053
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
653 AM EDT Tue Apr 24 2018

.AVIATION...

Flight category will trend more firmly down into MVFR during the
morning as showers add moisture to the boundary layer. The onset of
IFR is a more difficult call outside of the stray 2sm visibility in
a heavier rain shower. Early morning observations suggest IFR is
favored over Illinois where the inverted surface pressure trough is
sharper. Conditions are not as low over Lower Michigan and Ohio
where low level flow has a more uniform easterly component. The
inverted trough is expected to develop into Lower Michigan during
the afternoon as the cold front approaches from upper Michigan and
Wisconsin. Coverage of showers will also be on the increase and
combine with the trough to make IFR more likely later in the day,
and possibly at MBS before DTW, and then last through tonight until
the cold front moves past. Even then, expect low end MVFR to hold
through Wednesday morning.

For DTW... Expect the wind to have a light SE component much of the
day as MVFR ceiling and visibility become more persistent. A brief 2
mile restriction is possible early and then IFR is more likely
toward mid afternoon as the wind turns NE and as showers increase
coverage and intensity. IFR will then last through tonight until the
passage of a cold front late.

.DTW THRESHOLD PROBABILITIES...

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

* High for rain as precipitation type.

&&

.PREV DISCUSSION...
Issued at 333 AM EDT Tue Apr 24 2018

DISCUSSION...

Weak radar returns are attempting to work their way northward into
lower Michigan early this morning, but are struggling to produce
much in the way of precipitation at the moment with resident dry
airmass. These showers are associated with a large upper low
currently moving through the TN Valley. As this low slowly slides
east towards the Central Appalachians, it will open up and begin to
merge with a northern stream wave as it swings across the upper
Great Lakes through mid-week. The resident dry airmass will
eventually moisten up the mid and lower levels as moisture is
advected into the region under southerly flow. Precipitable Water
values increase to around an inch across much of the area by 12Z
this morning. Height falls along with some mid level forcing will
support increasing rain chances this morning and into tonight. This
event will feature likely PoPs with low QPF as showers are expected
to remain light and scattered in a way that any one location will
also see dry conditions throughout the day.

The mid/upper level shortwave trough will begin digging through the
western Great Lakes tonight into tomorrow morning bringing greater
height falls. However, the deeper moisture will also be pushed out
of Michigan with decreasing Precipitable Water values and surface
dewpoints by 06Z tonight while a surface cold front progresses
south through Michigan as well. The front will help keep some rain
chances in through the overnight hours with rain showers remaining
light.

The evolution of this trough looks like it will close off tomorrow
over the central Great Lakes but keep a somewhat progressive track.
This will likely lead to precipitation coming to an end by tomorrow
morning. Recent Euro solution still wants hold precip into tomorrow
afternoon, but is the outlier. Cold pool assoicated with this trough
will move in by tomorrow afternoon and drop high temperatures into
the lower 50s inland and mid to upper 40s towards the lakeshores of
the Thumb.

Mid/upper ridge and surface high pressure will build across the
region tomorrow night into Thursday. Post frontal dry conditions
will help scatter out clouds and allow for good radiational cooling,
which will result in overnight temperatures tomorrow dropping towards
freezing in the mid to lower 30s for much of southeast Michigan. On
the plus side, sunny skies on Thursday will help high temperatures
rebound back into the upper 50s and low 60s. Another trough digging
through central Canada on Friday will send another cold front through
Michigan on Friday and bring quick passing line of showers before
another post frontal surface high arrives. Fairly calm weather for
the weekend with cooler northwest flow mitigating a strong warm up.
High temperatures look hold in the 50s.

MARINE...

Scattered to numerous rain showers will spread northward across the
central Great Lakes today and tonight. The moisture is streaming
northward from the Tennessee Valley low pressure system and ahead of
a weak cold front moving into the western Great Lakes. The front
will sweep the rain eastward early Wednesday and be followed by
moderate north wind into Wednesday evening. Light and variable wind
is projected to turn north over all marine areas by sunrise and
quickly increase to gusts around 25 knots Wednesday morning. Small
craft advisories are likely for outer Saginaw Bay and southern Lake
Huron due to both the wind and waves building in excess of 4 feet
through Wednesday afternoon into Wednesday evening. Wind and wave
conditions then diminish overnight through Thursday as high pressure
builds into the region. The next cold front remains on track to
arrive Thursday night into Friday and is also projected to be on the
weak side in terms of both rain and wind potential.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

AVIATION.....BT
DISCUSSION...AA
MARINE.......BT


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



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.