Pontiac, Michigan 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

298
FXUS63 KDTX 301911
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
311 PM EDT Sun Mar 30 2025

.KEY MESSAGES...

* Potential for severe weather exists between 6 and 10 pm this
  evening. There is an Enhanced Risk (3/5) of severe thunderstorms
  south of a line from Saginaw to Cass City, with a Slight Risk
  (2/5) north of this line. Damaging winds, large hail, heavy
  rainfall, and an isolated tornado are all possible.

* High temperatures mostly in the 40s for Monday into Tuesday before
  the next round of warmer weather with showers and thunderstorms
  returns Wednesday.

&&

.DISCUSSION...

Severe weather threat window remains 6 to 10 pm this evening.
Convective initiation and organization underway as expected across
eastern IL, within an axis of weak to moderate instability derived
within a greater corridor of pre-cold frontal clearing. To the
extent this clearing arrives locally remains somewhat uncertain
given pockets of cloud debris still embedded within this warm
sector, but a noteworthy period of low level moisture advection
/lower 60s dewpoints/ as temperatures continue to moderate will
contribute to steady boundary layer destabilization by early this
evening. MLCAPE values ranging from 700 to 1300 j/kg still projected
by hi res model guidance, with upwards of 200 j/kg across the lowest
3 km. Inbound activity likely to maintain a linear mode with
clusters of higher magnitude updrafts as the shear vector becomes
increasingly parallel to the governing forced ascent along the
advancing boundary. Damaging wind gust potential highlighted as the
greatest threat within the expansive SPC enhanced risk under this
environment. A tornado risk does exist noting maintenance of a
slightly veered profile with height and accompanying increase in
adequate SRH. Potential exists for the warm front to stall over the
Saginaw valley and northern thumb, so any intersection of incoming
activity with this feature could offer a heightened risk for
updrafts to quickly attain greater structure and rotate.

Cold frontal passage brings a swift end to the convective threat by
02z, with lingering potential for light shower production through
the latter half of the night as the trailing mid level trough pivots
through. This occurs within a gusty post-frontal west to northwest
wind, as ensuing cold air advection increases in magnitude. Peak
gusts reaching 30 to 35 mph. Airmass change completes heading into
Monday as low level thermal troughing takes residence within a
broader region of mid level troughing. The timing and magnitude of
the advective process will effectively minimize the diurnal recovery
in temperature Monday, placing a ceiling for highs at low to mid
40s. Stretch of dry and stable conditions exist Tuesday as high
pressure builds across the northern great lakes. Full insolation
potential given the profile, but with low level flow holding out of
a cold northeasterly direction. This ensures seasonably cool
conditions prevail again Tuesday.

Yet another dynamic mid level wave of central pacific origin
projected to strengthen while ejecting northeast out of the plains
Wednesday. Expansive corridor of warm air advection along the
downstream flank will initiate deeper moisture advection with the
northward advancing warm frontal slope. Inbound arrival set locally
for early Wednesday, bringing a good chance of rain with the
possibility for elevated thunder given quality of the theta-e
advection. Steady late day/evening boundary layer destabilization as
the warm sector makes greater inroads will lead to a thermodynamic
environment not unlike today, as temps peak in the 60s and dewpoints
approach this mark. Given the underlying wind field currently
projected, this again brings potential for a higher magnitude
convective episode to emerge along an attendant cold front/trough.
Depending on pace and positioning of the frontal zone relative to
the upper level dynamics, possibility for axis of heavy rainfall
also exists. Prevailing mid level southwest flow left behind in the
wake of the system maintains milder conditions through the end of
the week.

&&

.MARINE...

Warm frontal boundary currently over the northern Thumb continues to
gradually lift north in response to low pressure reaching the western
Great Lakes. The warmer, moist airmass behind this front is
supportive of areas of fog development with webcams near Port Huron
showing patchy fog post frontal passage. This low will drive a cold
front across the region this evening as the low center tracks
directly over Lake Huron. A line of thunderstorms likely develops in
advance of this front, tracking through the central and southern
Great Lakes between roughly 6pm and midnight. Storms may be severe,
particularly over waters south of Port Austin, where the main hazard
is strong gusts in excess of 34kts and frequent lightning.
Secondary, lesser chance, hazards are hail and an isolated tornadic
waterspout. Colder northwest flow then redevelops by Monday
following the passage of the low/cold front tonight. Given the low
rapidly pushes into eastern Canada, a weakening gradient over the
central Great Lakes is expected to keep NW gusts below 30kts. This
does lead to larger waves around the Thumb nearshore waters with
Small Craft Advisories up through Tuesday morning. High pressure
builds over the region for Tuesday bringing drier conditions and
lighter winds.

&&

.HYDROLOGY...

An area of showers and thunderstorms will expand across the area
this evening. Potential exists for locally heavy rainfall within the
strongest and most persistent storms. Rainfall totals from one
quarter to one half inch possible. Minor ponding of water of prone
areas along with rises on area creeks and stream are possible.
Rainfall tapers off quickly as a cold front moves across the area
overnight.

&&

.PREV DISCUSSION...
Issued at 153 PM EDT Sun Mar 30 2025

AVIATION...

With fog/drizzle finally started to depart southeast Michigan this
afternoon and SSW winds increasing in speed, ceilings will gradually
lift into the MVFR range. These SSW winds have started to increase
across the area, especially across terminals that are south of the
stalled frontal boundary draped across Mid-Michigan and the Thumb
Region. Continue to expect SSW winds to gust upwards of 20-25 knots
this afternoon. The above mentioned stalled frontal boundary is
currently sitting in the vicinity of MBS, with is still being
impacted by 200 ft ceilings and 1/2 SM vsbys. As the surface low
lifts northeast across the state later this afternoon and evening,
this will eventually help veer winds with northeast winds becoming
easterly, then southeast, and eventually southwesterly by tonight.
As these winds veer and the stalled front lifts north, ceilings
should also slowly improve into the MVFR range by later this
evening.

Heavy rain and thunderstorms are expected to move through the area
as the low tracks through this evening. All terminals will likely
see thunderstorm activity, as the broken line of storms move
through. These storms look to impact terminals mainly between 22Z
and 03Z, with the main hazard being damaging winds. After convection
clears southeast Michigan, a cold front moves through and brings
additional stratus and wind shifts overnight and into Monday morning.

For DTW/D21 Convection...IFR stratus is expected to lift into the
MVFR range this afternoon as south/southwest winds increase. These
south/southwest winds will usher in better low-level moisture to
help fuel a broken line of storms this evening, which is expected to
move west to east across the D21 airspace. Timing looks to remain
close to the previously mentioned window, with convection moving in
from the west around/shortly after 22Z and exiting to the east of
the terminal/D21 airspace by 02/03Z. Damaging winds are the main
concern with this broken line of convection, and may pose a threat
for winds up to 60 mph as it moves through. All other severe weather
hazards are possible, but the damaging wind threat is of greatest
concern. A cold front follows the passage of convection late tonight
and into Monday morning. Winds veer and become WSW late tonight and
eventually NW on Monday morning. Until we get the drier, post
frontal air mass to move in on Monday, MVFR ceilings likely remain
in place overnight tonight.

DTW THRESHOLD PROBABILITIES...

* High in ceilings aob 5000 feet today.

* Low in ceilings aob 200 feet today.

* Moderate to high in thunderstorms this evening.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory from 8 AM Monday to 4 PM EDT Tuesday for
     LHZ421-441.

     Small Craft Advisory from 2 PM Monday to 4 PM EDT Tuesday for
     LHZ442-443.

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

$$

DISCUSSION...MR
MARINE.......KDK
HYDROLOGY....MR
AVIATION.....JA


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