Pontiac, Michigan 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

315
FXUS63 KDTX 290246
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1046 PM EDT Sat Jun 28 2025

.KEY MESSAGES...

- Warm and muggy conditions return Sunday and Monday with highs on
Sunday near 90 degrees.

- Showers and thunderstorms likely on Monday, mainly during the
afternoon and evening. There is a low probability for an isolated
severe storm.

&&

.AVIATION...

A period of shallow fog formation remains plausible overnight as
winds go calm and encourages modest near surface saturation.
Forecast will continue to highight a VFR visibility restriction
attm. Any fog rapidly lifts with sunrise, leaving mostly sunny skies
with limited cloud potential given lack of meaningful moisture
within the column. Modest winds from the southwest expected Sunday.

For DTW/D21 Convection...No thunderstorms expected through the TAF
period.

 THRESHOLD PROBABILITIES...

* None

&&

.PREV DISCUSSION...
Issued at 334 PM EDT Sat Jun 28 2025

DISCUSSION...

A progressive, low amplitude upper air pattern dictates this
weekend`s weather. A shortwave ridge axis within a relative weakness
in the jet stream passes overhead tonight into Sunday to maintain
dry and stable conditions. Advection of lower boundary layer dew
points into the 50s and lower 60s behind this morning`s cold front
has brought some relief from the recent muggy conditions with dry
air throughout the mid and upper troposphere offering mostly sunny
skies into this evening. This leads into mostly clear skies through
tonight with lows settling into the 60s.

Burgeoning southwest flow ensues by Sunday afternoon as the ridge
axis passes east with a warm front bringing in the next round of
heat and humidity. Temperatures upstream over the Midwest support
highs around 90 with dew points creeping back toward the upper 60s
to around 70 degrees by late in the day. This will bring increasing
instability through the late afternoon. However, capping and
convective inhibition is also expected to increase as an EML advects
in from the northern plains - sending 850mb temps to near 19 C. Also
of note is the lack of support for ascent with system relative flow
trajectories exhibiting lingering anticyclone influence beneath the
ridge. A convective shortwave is progged to track across northern MI
during the evening which will be a feature to monitor as several hi-
res runs continue to show some signal for isolated, disorganized
convection in the vicinity of the Tri-Cities and Thumb. Effective
bulk wind difference is progged to be below 20 knots supporting
short lifespan and low severe risk from any convection.

The hot and muggy conditions persist into Monday amidst continued
southwest flow ahead of an amplifying mid-level trough dropping in
from the upper Midwest. Minimal capping is shown in model soundings
with increasing support for ascent via DCVA as a shortwave tracks in
ahead of the trough. Surface moisture convergence progs show ample
convergence for storm initiation along a pre-frontal trough during
the late afternoon/evening. As a result, numerous showers and
scattered thunderstorms will become likely. Dew points hanging in
the upper 60s to lower 70s with modest mid-level lapse rates around
6 C/km will support MLCAPE on the order of 1000 J/kg which can lead
to some strong updrafts. Low-level shear is weak but southwest flow
at 500mb will trend up to around 30 kt to support potential for some
updraft organization. PWAT around 1.75 inches suggests any mature
convection will be capable of producing heavy downpours with precip-
loaded downdrafts bringing an isolated damaging wind threat.
Available machine learning guidance shows increased severe wind gust
probabilities for parts of the Lower Peninsula on Monday and this
will be something to monitor.

The cold front passes through the area Monday night with showers and
storms likely to taper off during the late evening. The inbound air
mass has Canadian continental origins with 850mb temp around 14 C. A
cutoff low over coastal CA induces downstream ridging over the
Rockies which maintains relative troughing over the Great Lakes to
hold a similar air mass in place through the week. Temps and
humidity should hold near typical early July values. An upper low
arrives within the NW flow on Thursday to bring the next chance for
unsettled weather. Ensemble guidance then leans toward producing a
mid-level ridge over the SE CONUS by next weekend, signaling a
return of above normal temps to the Great Lakes.

MARINE...

A ridge of high pressure will provide light winds and low waves over
the Central Great Lakes through tomorrow morning. Light southerly
flow under 20 knots develops tomorrow afternoon ahead of the next
low pressure system, which enters the northern Great Lakes Sunday
night into Monday driving a stronger cold front through the region.
This cold front will provide additional storms Monday and a stronger
post-frontal wind field Tuesday, around 20 knots

&&

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

$$

AVIATION.....MR
DISCUSSION...TF
MARINE.......SF


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at www.weather.gov/detroit.