069
FXUS63 KDTX 191650
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1250 PM EDT Fri Jul 19 2024

.KEY MESSAGES...

* Seasonably cool and dry conditions today and most of the weekend.
  High temperatures warm gradually into the mid 80s by Sunday.

* Low chance for showers Sunday and Monday afternoon north of I-69,
  with more widespread precipitation possible middle of next week.

&&

.AVIATION...

High pressure drifts overhead through the period maintaining light
winds and VFR cloud. SCT-BKN cumulus that developed late morning
dissipates with the loss of diurnal heating this evening setting up
another clear night.

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

DTW THRESHOLD PROBABILITIES...

* Medium for ceilings aob 5000ft early this afternoon. Low by late
  afternoon.

&&

.PREV DISCUSSION...
Issued at 326 AM EDT Fri Jul 19 2024

DISCUSSION...

Surface high pressure slowly inches eastward into the Great Lakes
today, affording another day of deep static stability and
corresponding dry weather. Observed 850mb temperature of 9 C, per
the 00z KDTX sounding, is in the 10th percentile for this time of
year (NAEFS/SPC climo) as daytime highs fall a few degrees short of
normal around 80 degrees. Forecast soundings are notably drier in
the boundary layer than yesterday, so expecting a muted diurnal
cumulus response in comparison, yielding mostly sunny skies.

The semi-permanent high over the Four Corners region and column
winds under 15 knots in the lowest 20.0 kft agl create little
opportunity for thermal advection. This equates to a gradual warmup
through the weekend as temperatures climb a couple degrees each day
due to airmass modification. Daytime highs by this weekend settle in
the low to mid 80s, which hold through middle of next week.

The weak flow pattern aloft allows a cutoff low to develop and stall
over the upper Mississippi Valley by Saturday morning. Precipitation
from this system will stay to our southwest, but its presence will
halt southward advancement of a Canadian cold front this weekend.
The stalled front acts as a deformation axis, most notable in the
850-700mb layer, which will engage existing frontal moisture and
weak instability (~500 J/kg MLCAPE) to create isolated showers and
perhaps a thunderstorm for the Tri Cities/Thumb both Sunday and
Monday afternoon. The low dislodges by mid-week in response to an
inbound northern stream shortwave, increasing chances for widespread
precipitation toward the end of the forecast period.

MARINE...

Expansive high pressure over the Midwest into the Great Lakes region
will lead to light winds (under 20 knots) right into early next
week. The next chance of showers and thunderstorms does not look to
arrive until Tuesday, with a low chance continuing through Thursday.

&&

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

$$

AVIATION.....KDK
DISCUSSION...MV
MARINE.......sf


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