600
FXUS63 KDTX 181054
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
654 AM EDT Tue Mar 18 2025

.KEY MESSAGES...

- Warming trend today and Wednesday with highs generally in the low-
mid 60s.

- Rain chances being Wednesday evening with precipitation expected
overnight into Thursday morning; a few storms are possible Wednesday
evening and early Wednesday night which could produce strong wind
gusts.

- Precipitation likely changes over to a period of melting snow
north of I-69 with time Thursday.

- Gusty winds in excess of 30 mph are probable Wednesday and
Thursday.

&&

.AVIATION...

VFR conditions expected through the taf forecast as high pressure
tries to hold over the region. A frontal boundary draped to the west
will stay nearly stationary through tonight which will allow the
gradient to tighten over the region resulting in southwesterly flow.
With only mid/high clouds generally above 15kft expected through the
overnight, the main concern looks to be another round of low level
wind shear tonight as the low level jet increases to around 45 knots
down to 2kft.


.DTW THRESHOLD PROBABILITIES...

*  None

&&

.PREV DISCUSSION...
Issued at 354 AM EDT Tue Mar 18 2025

DISCUSSION...

Resident surface ridge axis has been shoved toward Appalachia this
morning as the pressure field responds to deepening surface low over
The Plains. Corridor of resultant confluent southerly flow acts to
moderate 2M temperatures today, but the real thermodynamic
adjustments come in the form of an elevated warm front that is
progressing into Lower Michigan. 925 mb temperatures jump into the
9C to 13C range by 21Z today, driven by respective pressure-height
wind enhancements tied to a low amplitude shortwave trough
transiting Lake Superior and The UP. The peak of today`s warm
advection won`t occur until closer to 00Z this evening, but
nonetheless, high temperature should easily top-out in the 60s for
nearly the entire CWA before an easterly on-shore flow change arises
along the western Lake Huron coast (northern half) as the
aforementioned low quickly intensifies, and broadens (west-east).
Should also note that the co-dependent LLJ structure between the
primary circulation and the northern stream disturbance do lend
potential for 35-45 knot flow at 5 kft AGL locally, but forecast
soundings show just enough an inversion based on the MaxT aloft/925
mb temperature to prevent sufficient mixing depths which keeps gusts
AOB 20 knots late this afternoon. Should mid-high level clouds
arrive/develop late and diabatic process overachieve, there could be
a two or three hour period of late day gustiness. Clouds aloft
linger overnight while the lower portion of the column remains
largely subsaturated. Column winds gradually back southwesterly,
from the bottom up, while energetics improve into Wednesday with
notable uptick in gradient winds.

Increasingly wind and mainly dry through the midday hours as the
higher quality moisture gets hung up over the Mid-Mississippi
Valley. The narrow ThetaE plume of concern releases northward after
18Z with peak 925-850 mb layer dewpoints of 2-3C overhead between
21Z and 03Z (Thursday). CAM window is limited beyond 00Z Thursday,
but prior to F48, the convective response appears rather muted,
likely tied to stubborn capping (and dry air) near 8 kft AGL. Any
precipitation during this time will struggle to overcome general
moisture deficiencies and unfavorable instability profiles.
Regardless, the synoptic-scale dynamics will be impressive and
should have no problem forcing ascent, therefore any
remnant/decaying convection that spills in from west should be
supported for at least a little while. Non-convective gusts of 35+
mph remain possible while the primary evening convective threat
should mainly be convective gusts in excess of 50+ mph given 0-3 km
shear of 50+ knots.

Nocturnal response appears more robust with mid-level
cooling/moistening helps steepen lapse rates. There are even some
indications of a potential window of 100-200 J/kg of SBCAPE, around
03Z Thursday. Most of the rainfall should occur between
approximately 03Z and 09Z as the surface low rips northeast across
Lower Michigan and Lake Huron. Trailing attendant cold front leads
to a swift changeover to cold advection with a period of deformation
rain/snow Thursday. Material snowfall generally holds north of I-69,
but should melt on contact. Further south, rain mixes with snow
before changing to all snow, northwest of Metro Detroit. Prior wet
surfaces and air temperatures still in the mid-upper 30s should lead
to melting before precipitation comes to an end around 00Z for
Southeast Michigan. As was the case on Sunday, high temperatures
likely verify prior to 12Z Thursday with differential cooling
through the daylight hours given the post-frontal environment. This
ensures non-diurnal 2M temperature curves across the region.
Expected additional gusty winds Thursday with some to 35 mph,
especially with the post-frontal WSW to WNW wind shift.

Height rises build in Friday with the next composite ridge axis,
although the amplitude of this feature becomes more muted with time
as a northern-stream trough drops through central Canada.
Ageostrophic response to a progressive shortwave trough moving into
the Ohio Valley Friday night into Saturday could suffice in some
light rain before a more typical temperature trend settles in for
the weekend.

MARINE...

Weak low pressure washes out over the Straits this morning, with its
attendant front dropping across lower Michigan and eventually
stalling between Saginaw Bay and Port Huron by evening. Northeast
winds develop poleward of the boundary, with southerly flow
persisting elsewhere. Meanwhile, strong low pressure ejects out of
the Plains and takes on a northeastward trajectory toward the Great
Lakes. Ahead of the system, a strong low level jet response brings
plentiful moisture into the region and pushes the front back to the
north as a warm front. This generates widespread showers across the
area and a return to southerly flow. Despite the strong jet aloft,
nocturnal timing and cool water temperatures (2-4 C) favor stable
profiles that prevent gusts from exceeding 30 knots in the warm
sector. The possible exception to this would be along the shoreline
of Lake Erie/St. Clair/southern tip of Lake Huron where the jet
arrives slightly earlier. Passage of the low early Thursday morning
initiates cold advection and eventual transition from rain to snow
in the colder airmass. Additionally, a boost in mixing depths and
shift to northwest flow becomes more favorable for wind gusts to
reach gale force by Thursday afternoon.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

AVIATION.....DRK
DISCUSSION...KGK
MARINE.......MV


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