496
FXUS63 KDTX 140948
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
548 AM EDT Mon Jul 14 2025

.KEY MESSAGES...

- A sunny and warm start to the week with less humidity today and
  Tuesday.

- Showers and thunderstorms return Wednesday through Thursday. Heavy
  rainfall becomes the primary weather hazard during this time.

- A cold front sweeps through the area early Friday followed by
  cooler and less humid air next weekend.

&&

.AVIATION...

Morning satellite imagery shows last of the mid-high cloud exiting
east while the lower portion of the column remains subsaturated.
This ensures VFR ceilings for today and tonight with minimal diurnal
cumulus. Main forecast consideration is the accumulation of near-
surface wildfire smoke within a subsident column. HRRR/RAP smoke
models are not clear as to whether or not smoke density will suffice
in causing MVFR obscuration. This will need to be monitored as the
day progresses. WNW winds should be kept in check by weak gradient
flow as speeds hold AOB 10 knots before trending toward calm
overnight with SKC. Expect dewpoint depressions to remain large
enough to preclude any MVFR fog mentions into Tuesday.

For DTW/D21 Convection...No thunderstorms expected this TAF period.

THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 352 AM EDT Mon Jul 14 2025

DISCUSSION...

Great Lakes high pressure is weak but established enough to maintain
dry weather and slightly less humid conditions compared to recent
days. Larger scale subsidence follows the eastward 500 mb trough
departure this afternoon leaving zonal northern stream westerlies
displaced well north across Canada. The resulting excellent
prospects for full sun support leaning high temperatures toward the
warm end of the guidance range, in the upper 80s with a few reports
touching 90.

Relatively comfortable temperature and humidity conditions continue
tonight as surface Td holds below 70, and this is now projected to
be the case for most of Tuesday. HREF mean surface Td available out
into Tuesday evening holds in the 60s as does the usually bullish
NBM guidance. This makes a slight uptick in temperature easier to
take with a few more 90s expected for afternoon highs.

Tuesday ends up being the transition day into increasing SW flow
ahead of the next Plains frontal system that is set to return an
active late week period of showers and thunderstorms to SE Mi. The
14/00Z deterministic solutions are in good general agreement on the
large scale pattern by 12Z Wednesday. The mid time range projections
bring the current Ohio valley front and associated moisture
transport back into Lower Mi Wednesday morning. Strong 850-700 mb
theta-e advection quickly lifts PW back to about 1.75 inches and
sustains numerous showers and thunderstorms across the area during
the day. This phase helps fully establish the large scale moisture
axis out ahead of the impressive frontal system stretching from
Quebec to the upper Midwest and into the central Plains. There is
abundant model QPF and vorticity evidence of convective clusters
occurring along and ahead of this system as it advances eastward
Wednesday night and Thursday, and across Lower Mi centered on
Thursday night into Friday morning. At this point in the forecast,
heavy rainfall is set to be the primary hazard vs severe thunderstorm
potential. Consensus of extended time range projections then bring
the front through SE Mi Friday morning for a chance to start off next
weekend with cooler and less humid conditions.

MARINE...

A high pressure system will bring light winds and mostly dry weather
today into Tuesday, outside for a very low chance of a stray shower
across northern Lake Huron this afternoon and evening. The next
chance for showers and thunderstorms will enter Wednesday through
early Friday as a series of upper-level disturbances and cold front
pass over the Great Lakes. This brings the chance for some localized
stronger wind gusts with any thunderstorm development, but otherwise
winds remain light given the weaker pressure gradient in place.

&&

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

$$

AVIATION.....KGK
DISCUSSION...BT
MARINE.......AM


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