597
FXUS63 KDTX 282246
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
646 PM EDT Fri Mar 28 2025

.KEY MESSAGES...

* Well above normal temperatures filter in through the weekend,
  outside of the northern Thumb and northern Tri-Cities.

* Widely scattered to widespread rainshowers with embedded
  thunderstorms expected Sunday into Sunday night. There is a slight
  risk (2/5) of severe weather and potential for heavy rainfall.

* Seasonable temperatures return Monday into Tuesday before the next
  warm-up arrives Wednesday.

&&

.AVIATION...

The warm front has cleared all the terminals except MBS. The front
is forecast to become nearly stationary in the vicinity of MBS
tonight, placing it just south of the low low level moisture axis.
This frontal placement will leave the terminals within the warm
sector through the night, maintaining VFR conditions with just some
occasional mid and high level clouds. The ongoing influx of mild air
will sustain some degree of gustiness to the surface winds past
sunset. With the expectation for at least some degree of nocturnal
boundary layer decoupling and considering an impressive west-
southwesterly wind field of 50 to 60 knots at 2-4k feet, the mention
of low level wind shear will be maintained in the TAF through
daybreak Saturday. The front will slowly sink southward as a cold
front on Saturday, likely to reach FNT (or possibly PTK) during the
afternoon. The marine modified post frontal airmass will be
characterised by northeast winds and increasing chances for a low
cloud deck.

For DTW...Strengthening of the low level wind fields during the
evening will warrant low level wind shear through 12-14Z Saturday.
The front is forecast to remain north of Detroit through the TAF
period, keeping metro in the warm sector. The advection of low level
moisture from the southwest Saturday afternoon will however result
in increasing chances for a sub 5000 foot deck after 21Z Saturday.

.DTW THRESHOLD PROBABILITIES...

* Low in ceilings aob 5000 feet Saturday morning and afternoon. High
  Saturday evening.

&&

.PREV DISCUSSION...
Issued at 258 PM EDT Fri Mar 28 2025


A stationary front that was draped over southern Michigan this
morning is now in the process of traversing north through the
northern fringe of the cwa in response to the upstream ejection of a
shortwave over the northern plain and gradual push of a diffuse low
pressure system across the west-midwest. Moist low-level system
relative isentropic ascent will be maximized along/north of the I-69
corridor this evening along the front, coincident with the ongoing
precipitation chances. The elevated instability with steep lllr will
support thunderstorm chances through the early evening. Low end
chances for a spotty shower will hold for locations south noting the
open flow of gulf moisture that will persist through the weekend,
but limited forcing outside weak unbalanced flow within the llj will
preclude mention of any widespread coverage.

A rapid push of warm air advection in the wake of a warm front will
reinforce a strong cap characterized by h925 temperatures of 15C
late tonight through tomorrow morning. The aforementioned warm front
will again become quasi stationary along or briefly just north of
the northern Thumb and northern Tri-Cities, bringing a window for
dry weather across most of not all of the cwa through the night. The
nocturnal waa will nullify overnight cooling and will likely
challenge or break record hi-lows for KDTW and KFNT (see climate
section). The Metro Detroit region and locations north through I-69
will remain well entrenched in the warm sector tomorrow, bringing
above normal temperatures well into the 60s. The exception will fall
along the frontal boundary, which will create a stark temperature
gradient where delta Ts of 20-25F over a 50mi span will be likely by
early tomorrow afternoon. As is typical with springtime modeling,
the exact position and initial translation speed of front will be
poorly modeled as it begins to traverse south again, but the thermal
gradient will likely set up somewhere across the northern Thumb to
northern Tri-Cities. The HREFs unusually large Day 2 25th-75th 2m
temperature spread lends credence to this. Otherwise within the warm
sector, there will be a window during daylight hours focused in the
afternoon where shallow mixing can bring some sporadic wind gusts
around 35 mph.

The stationary turned cold front will initially reintroduce
precipitation chances from north to south, with the boundary hanging
up around the I69 corridor as a shortwave and associated low
pressure system across the central Rockies starts to maneuver east
into the Midwest. This will lead to backed southwest flow over
southern Great Lakes, offsetting the push of the front while
amplifying Gulf moisture. This positive theta-e advection coupled
with a glancing shortwave will then bring in the likely chance for
showers across the remainder of SE MI as early as the late
afternoon, but more likely leading into the late evening and
overnight hours. The likely potential for widely scattered to
numerous showers and some embedded thunderstorm activity will
continue through Sunday as the surface low paths across northern
lower Michigan into Lake Huron Sunday afternoon and evening, with
the trailing trough following into Monday morning.

Position of the low will place SE MI in a precarious spot for severe
weather potential. The strengthening llj leading with low will
lengthen the hodograph in the low to mid levels and latest time-
lagged LREF output still has a crosshair of sufficient deep layer
bulk shear combined with at least 500 J/kg SBCAPE. Still outside the
bulk of the hi-res output, but some of the longer range models
(RGEM) shows some possible amalgation of storms with cold pool
generation. The trailing trough brings lingering precipitation
chances through Monday, with Tuesday being the next likely chance
for sustained dry weather.

MARINE...

Slow moving warm front has just begun to lift through southern lower
MI this afternoon generating numerous showers and scattered
thunderstorms over the southern Great Lakes. Front gradually pushes
into the central lakes this evening-tonight shifting this shower/t-
storm activity northward over Lake Huron. With this slower than
originally anticipated track, front now looking to stall just north
of the tip of the Thumb late tonight. East-northeast winds north of
the front strengthen this evening through the first half of the
night with favorable fetch out of the Georgian Bay supporting gusts
between 25-30kts. First of a series of surface lows then tracks
along the frontal boundary early Saturday shifting main region of
showers back south from northern towards central/southern Lake Huron
as the frontal boundary is pushed back towards Port Huron. This
passage also shifts winds north of the front to more true
northeasterly while largely maintaining strength.

Another surface low rides along the front Sunday morning generating
widespread showers as well as increasing thunderstorm chances for
all waters south of Sturgeon Point Sunday late afternoon/evening-
these storms could be strong to severe. Final surface low lifting NE
out of southern WI finally forces the lingering warm front back to
far northern Lake Huron setting up southerly for the majority of the
region lake Sunday-early Monday. With this warmer flow, winds likely
remain at or below 25kts. Low vacates the area first half of Monday
supporting a transition towards snow as precip finally tapers off in
addition to redeveloping colder northwest winds. With the rapid pace
this low tracks into Quebec, the local gradient is expected to
weaken fast enough to keep peak NW gusts sub-gales at around 25-
30kts.

HYDROLOGY...

A cold front sinks south tomorrow night before a low pressure system
tracks into the area on Sunday. This system will usher in Gulf
moisture with higher moisture content supporting potential for
heavier showers and storms Saturday night into Sunday night. Rainfall
totals during this period are forecast to range between 0.75 and
1.00" but locally higher totals will be possible if multiple storms
track over the same locations. These amounts will bring minor ponding
and rises in area creeks and streams, but flooding is not likely at
this time.

CLIMATE...

The record high minimum temperatures for Saturday, March 29th:

Detroit: 54 Degrees (Set in 1910)
Flint:   52 Degrees (Set in 1986)
Saginaw: 52 Degrees (Set in 1981)

PREV DISCUSSION...
Issued at 253 PM EDT Fri Mar 28 2025

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory from 11 AM Saturday to 4 PM EDT Sunday for
     LHZ421-441.

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

$$

AVIATION.....SC
DISCUSSION...AM
MARINE.......KDK
HYDROLOGY....AM
CLIMATE......AM


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at www.weather.gov/detroit.