Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 270343
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1143 PM EDT Tue Mar 26 2024

.KEY MESSAGES...

- Cooler and drier weather returns Wednesday through Friday.

&&

.AVIATION...

A steady increase in low level moisture occurs overnight in the wake
of cold frontal passage. This will lead to widespread stratus
carrying MVFR restrictions overnight through Wednesday morning. This
moisture maintained within ongoing cold air advection in low level
southwest flow. Some intervals of gustiness may persist overnight as
the advective process unfolds, but with a decline in overall wind
magnitude and gust frequency expected during the morning hours.
Daytime heating will bring increasing mixing depth with time on
Wednesday, effectively lifting cloud base into VFR heading into the
afternoon. Some degree of clearing potential may emerge by late in
the day. Winds prevailing from the southwest, perhaps turning
modestly gusty during peak heating.

.DTW THRESHOLD PROBABILITIES...

* High for ceilings at or below 5000 feet through Wednesday
  afternoon.

&&

.PREV DISCUSSION...
Issued at 334 PM EDT Tue Mar 26 2024

DISCUSSION...

Active afternoon unfolding as a strong shortwave lifts across the
area, inducing weak/shallow instability within the ambient high
shear environment in place and helping force a line of showers
across Lower MI. Thunder has been sporadic so far as the convection
remains low-topped but several gusts of 50+ mph were observed
upstream near Chicago where linear segments were able to organize
more orthogonal to the 0-3 km shear vector (which is SSW at 50+ kt).
Despite a lack of cloud clearing today, latest SPC mesoscale
analysis places about 100 of MLCAPE within a narrow corridor just
ahead of the line now extending from Montcalm to Branch County,
mainly due to theta-e convergence ahead of the front. So, do expect
the line to continue east into the local area with an attendant
threat for isolated damaging wind gusts to 60 mph.

CAMs have favored a continued north-south organization of convection
along the cold front which is largely parallel to the effective
shear and should limit a more widespread damaging wind threat.
Should any rightward/northeastward bulges develop along the line,
those areas would have a locally higher risk for damaging gusts or a
brief tornado. Showers/isolated storms will move through from
roughly 21z/5pm to 02z/10pm before departing east. The primary
severe threat area remains west of I-75/US-23 where instability will
be in place from daytime heating. Farther east carries less
confidence in a severe threat as post-sunset timing leans toward a
more stable profile less conducive for downward momentum transfer of
strong winds aloft.

Strong NVA in the wake of the shortwave brings a quick end to precip
late this evening with cooler air filling in behind the cold front.
Remnant low-level moisture within the cool advection may produce
some spotty showers or drizzle overnight with lows settling into the
mid to upper 30s by sunrise Wednesday. Winds will remain breezy but
taper off to around 15 to 25 mph quickly after the front clears the
area. Cooler conditions Wednesday with a glancing shot from the
arctic air mass, with highs in the 40s and a breezy WNW wind around
15 to 20 mph.

Near seasonal average conditions on Thursday as the now broad
barotropic low drifts over Hudson Bay and slowly fills in. In the
meantime, a ridge of high pressure will build in from the south to
promote mainly dry conditions with a better shot at some sunshine.
Mid-level height rises take over for Friday, reinforcing the surface
ridge in place with modest 1000-500mb thickness advection promoting
a slight warming trend across the area. A low amplitude shortwave
originating from the northern Rockies tracks overhead within the
larger scale ridge on Saturday, producing a compact surface low that
tracks in the vicinity. This will have potential to bring a
concentrated band of rainfall within the corridor of isentropic
ascent along its leading warm front. Relatively seasonable
conditions expected to continue through the weekend and into early
next week with an active jet pattern bringing additional rain
chances by Monday.

MARINE...

A very strong and shallow low level jet (45 knots down to 300 ft)
will hold into the evening hours, however, extremely stable over-
lake conditions has prevented persistent mixing into the wind maxima
aloft. Surface observations and sparse ship observations have
reported sustained winds and gusts generally below gales, however,
some sporadic gust to gales have been reported. That said, strong
showers and possibly some embedded thunderstorms will move over the
Great Lakes this evening along a cold front, which will bring the
chance to pull some of the stronger wind gusts down to the surface.
Thus have opted to continue to gale warning into tonight. Shower and
thunderstorm potential will exit the region between 10 PM - 12 AM
EDT. Special Marine Warnings may be needed for areas under Small
Craft Advisories, as these showers will have the potential to
briefly pull down wind gusts to or in excess of 40 knots.

High pressure will build in through the midweek period behind the
cold front, and will bring a period of lighter winds to the Great
lakes.

HYDROLOGY...

After morning rainfall ranging between 0.10 and 0.40 inches, a
second round of showers and isolated storms will occur from late
afternoon to mid evening as a cold front tracks eastward across SE
MI. Some of these showers/storms may produce heavy rainfall, but
should be fairly progressive with short residence time. Additional
rainfall amounts of a quarter to half inch will be possible before
rain ends late this evening. Flooding is not likely but ponding of
water will be possible where heavier downpours occur. The passage of
this front will usher in cooler and drier conditions for Wednesday.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory from 8 AM to 10 PM EDT Wednesday for LHZ421.

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

$$

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

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at www.weather.gov/detroit.


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