Expert Forecast Opinion

964
FXUS63 KDTX 251649
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1249 PM EDT Fri Oct 25 2024

.KEY MESSAGES...

- Numerous rain showers impact the area this morning, with a low
chance for a rumble of thunder near the Ohio border.

- A cooler airmass filters in for the weekend with daytime highs in the
mid to upper 50s and lows Sunday morning dropping below freezing
in some spots.

- Warmer weather looks to return next week with 70s Tuesday and
Wednesday.

&&

.AVIATION...

Rain showers should be east of terminals by beginning of the
forecast cycle as cold front shifts through the region. MVFR to
lower VFR cigs will persist for a few hours post-front (with a few
IFR patches possible KMBS/KFNT). Skies will then clear into evening
with VFR conditions on through Saturday. Southwest winds will veer
to west and northwest with fropa during the afternoon with general
northwest flow persisting for the remainder of the forecast. A brief
period of minor gusts may occur immediately behind the front and
also in better mixing by midday Saturday.

For DTW/D21 Convection...No thunderstorms are expected during this
forecast.

DTW THRESHOLD PROBABILITIES...

* High for cigs aob 5kft into this evening.

&&

.PREV DISCUSSION...
Issued at 346 AM EDT Fri Oct 25 2024

DISCUSSION...

A band of showers has just started to move onshore from Lake
Michigan, on track to reach southeast Michigan around 10z (6am local
time). First thing to note about these showers is that they have
lost organization over time. This is partially due to a weakening
low level jet, and also in part due to outrunning low level theta-e
support. Most locations will see measurable precipitation through
late morning, however QPF is expected to hold under a tenth of an
inch. The other thing to note is a swath of embedded thunderstorms
on the southern flank of this band. There is a slight chance (15%)
for a rumble of thunder to survive over extreme southern portions of
the area (namely Lenawee/Monroe Counties), as mid level lapse rates
are quite steep (over 7 C/km).

The frontal zone begins to slide through early this afternoon, which
will bring an end to the widespread precipitation. Thermal profiles
quickly lose saturation as steep isentropic downglide helps dry air
surge in aloft. Just a shallow moist layer will remain in the lowest
5.0 kft or so. This moist layer will maintain cloud cover while cold
advection will establish enough instability at the top of the
boundary layer to squeeze out additional isolated showers throughout
the afternoon and evening.

Remnant boundary layer moisture clears out overnight with high
pressure filling into the Ohio Valley for the weekend. The inbound
airmass is notably dry--forecast PWAT values of ~0.25" fall in the
tenth percentile for this time of year. Do expect some degree of
lake effect stratocumulus response this weekend given the cool
inbound airmass (850mb temperatures in the negative single digits)
and northwest flow, although the dry synoptic pattern should limit
coverage to few or scattered at best. Combined with seasonal daytime
highs in the mid to upper 50s, expecting another pleasant fall
weekend across southeast Michigan. The most noteworthy aspect of the
weekend forecast is the potential for overnight lows to bottom out
below freezing Sunday morning. Based on extended MOS and
probabilistic guidance, the most likely (60-70% confidence) area to
see sub-freezing lows will be across the Irish Hills.

The upper level height field exhibits very little shortwave activity
over the next few days, affording another prolonged period of
longwave ridging through early next week. The next system to watch
will be a low pressure system that glances across the Canadian
provinces Monday-Tuesday of next week. Return flow feeding into its
cold front may trigger precipitation, while a constricting pressure
gradient will result in gusty conditions developing mid-week. This
system sets up a baroclinic zone that will be the focus for a more
uncertain late week period next week.

MARINE...

Southwest winds 10 to 20 knots this morning ahead of a wave of low
pressure which will produce scattered to numerous showers. A solid
surge of cold air and northwest wind gusts to follow for this
afternoon afternoon/evening. Probabilistic guidance and soundings
continue to suggests wind gusts in the 25 to 30 knot range over Lake
Huron, which looks to carry through the day on Saturday. Despite the
mostly offshore northwest flow, enough wave build up over the
southern Lake Huron for some 4+ waves expected to clip the nearshore
waters around the northern Thumb region by Saturday morning.

Winds diminish for the second half of the weekend as the airmass
modifies and a surface high/ridge traverses the Central Great Lakes.

Strengthening southwest flow early next week ahead of a strong low
tracking through the Midwest will bring the potential of 30-35 knot
wind gusts by Tuesday.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory from 6 PM this evening to 10 PM EDT Saturday
for LHZ421-441-442.

Small Craft Advisory from 6 PM this evening to 4 PM EDT Saturday
for LHZ422.

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

$$

AVIATION.....DG
DISCUSSION...MV
MARINE.......SF


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