155
FXUS63 KDTX 261948
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
348 PM EDT Sat Apr 26 2025

.KEY MESSAGES...

- Frost Advisory late tonight outside of metro Detroit.

- Dry weather with progressively warmer temperatures Sunday and
  Monday.

- Scattered showers move in late Monday night and Tuesday morning.

- A cold front arrives with showers and thunderstorms likely Tuesday
  afternoon and evening.

&&

.DISCUSSION...

A classic spring season temperature swing is in progress from
Friday`s highs near 80 inland from the shorelines to a struggle into
the 50s today. Gusty north wind is ensuring an effective supply of
cooler air trailing low pressure as it exits the eastern Great
Lakes. A considerable diurnal cloud component also lingers to
further limit temperatures. Both the wind and clouds begin a
decreasing trend this evening as high pressure builds in from the
Midwest and settles nearly overhead by Sunday morning. This sets up
efficient radiational cooling conditions for a temperature drop into
the mid and upper 30s outside of the larger metro areas. There is
also not much dry air advection left to occur this afternoon and
evening based on upstream surface observations. Surface Td hovering
in the mid 30s then sets up frost formation as increasing high clouds
are too late arriving after sunrise Sunday morning. Warmer ground
temperatures are a consideration but not trustworthy enough to be a
limiting factor in more rural or sheltered areas. A Frost Advisory
then includes SE Mi where the growing season has been declared;
Saginaw, Genesee, Lapeer, St Clair counties and southward except
warmer Wayne county and just patchy coverage in Monroe county.

Expansive high pressure remains centered across southern Lower Mi
through Sunday which allows nearly full sun to quickly lift
temperatures out of the 30s during the morning. High clouds remain
slow to arrive as flow aloft is still strongly NW and more on the
western fringe of the Quebec closed low vs downstream of the Plains
ridge. Guidance high temperatures rebounding into the 60s are then
on target. The exceptions will be in all of the lake breeze zones
from western Lake Erie, southern Huron, to Saginaw Bay as pronounced
onshore wind occurs during peak late April daytime heating and as
the surface high center shifts eastward.

Still under patchy high clouds, wind picks up from the south Sunday
night as the main support for holding temperatures in the 40s into
Monday morning. Temperatures then continue the classic spring season
swing in the warmer direction as the weather highlight for Monday.
Lower to mid 70s afternoon highs are reachable away from the
shorelines and even as clouds gain ground in a profile of deepening
moisture transport aloft. Mid time range deterministic models agree
on holding off or limiting precipitation to a few sprinkles in this
initial warm advection phase followed by a stronger push and a
better chance of showers with the primary moisture axis Monday night
into Tuesday morning. This moisture/instability axis sets the stage
for a possible round of strong to severe thunderstorms Tuesday with
the potential strongly tied to timing of the afternoon/evening cold
front. Consensus of deterministic solutions favors faster/farther
east timing but which still shows wider spread considering the lone
NAM solution that is earlier with more direct SE Mi impact.
Refinements on the short wave character in the northern stream mid
and upper level flow will help refine expectations in the next few
forecast cycles.

&&

.MARINE...

Low pressure reaching New England gives way to high pressure
arriving from the Midwest tonight. This transition maintains a
tightened pressure gradient over the central Great Lakes this
afternoon which gradually relents through the overnight as the high
builds in. Small Craft Advisories remain in effect through this
evening for gusty northwest wind to around 25 knots and waves 4 to 6
feet. The high pressure promotes dry weather and light wind through
Sunday. A warm front then lifts across the region on Monday with
milder southerly flow leading up to the arrival of low pressure on
Tuesday. The warm air arriving over the cool lakes will result in
strong stability and limit wind magnitude to a degree but periods of
gusty 20+ kt wind will be likely, especially in the nearshore areas.
Low potential (25 percent chance) exists for a brief period of gusts
to gales over Saginaw Bay. Scattered thunderstorms are expected to
accompany the system`s cold front on Tuesday with potential for some
strong to severe storms in the south.

&&

.PREV DISCUSSION...
Issued at 153 PM EDT Sat Apr 26 2025

AVIATION...

The MVFR stratus has been slowly lifting and scattering out today as
high pressure brings drier air into the region. MBS has lifted above
3kft and the rest of the sites will be soon to follow as most are
already above 2500ft. The rest of the clouds will scour out by this
evening leading to clear skies tonight. Gusty northwesterly winds
will relax through the late afternoon and eventually fall below 5
knots tonight as the high centers itself over lower MI. Heading into
Sunday, winds will become northeasterly with some cirrus starting to
move in.

DTW THRESHOLD PROBABILITIES...

*  High for ceilings aob 5000 feet today.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...Frost Advisory from 2 AM to 8 AM EDT Sunday for MIZ053-060>063-
     068>070-075-082.

Lake Huron...Small Craft Advisory until 10 PM EDT this evening for LHZ421-422-
     441>443.

Lake St Clair...Small Craft Advisory until 8 PM EDT this evening for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 8 PM EDT this evening for LEZ444.

&&

$$

DISCUSSION...BT
MARINE.......TF
AVIATION.....DRK


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