124
FXUS63 KDTX 200339
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1139 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 afternoon north of I-69, with more
  widespread precipitation possible for the middle of next week.

&&

.AVIATION...

High pressure extending across the southern Great Lakes will
maintain light and variable winds through the morning. This high
pressure system will dominate into Saturday night. The associated
dry air will limit cloud coverage to just scattered diurnally driven
cu.

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

DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 321 PM EDT Fri Jul 19 2024

DISCUSSION...

Broad high pressure remains in place today and will slowly make its
way east through the weekend. Near-full insolation today hindered
only by a patchy cumulus deck has helped push temperatures into the
low 80s across the CWA. Light and variable winds through the evening
hours today before southwesterly flow of 5-10 knots takes hold
overnight. Slightly below normal temperatures are expected both for
the lows and for the highs tomorrow, dipping below 60 and reaching
the low to mid 80s respectively. Weak high pressure continues to the
east allowing winds to veer westerly and maintain strength of 5-10
knots.

Cut off upper level low will develop to the west through the
weekend, which will wrap up and slowly help increase 1000-500mb
heights by a couple dam. This will have enough of an impact in
combination with high insolation to bring highs up to the mid-80s
this weekend. At the same time, frontal boundary to the north will
gradually lower, making its way to the northern Lower Peninsula by
Sunday afternoon/evening. Forcing from the boundary in combination
with modest CAPE of 500-1000 J/kg give chances for shower
development Sunday evening. Best chances for rain are in the Tri-
City area followed by the Thumb. Rain is not currently expected in
the metro area, but a unexpected forward progression of the boundary
would make that possible. Thunderstorms are possible with this
development, but severe weather is not expected at this time.

Upper level high over the southwestern United States shows no
indications of movement next week. This maintains the temperature
regime and holds highs in the low to mid 80s next week, hovering
around climatological normals. Another cut off upper level low will
develop in the Tuesday/Wednesday time frame. Deterministic guidance
is fairly confident in the low moving overtop Michigan. ECMWF places
the trough axis further west than the GFS, leading to a jet streak
directly overhead. The GFS on the other hand gives a stronger jet
streak but sets up further east. With model drift tendencies this
far out it is difficult to say anything concrete on such a small
scale, but higher than normal confidence in the upper level setup
makes it clear that there is shower and storm development potential
for the mid- to late-week period.

MARINE...

A broad expanse of surface high pressure continues to produce
favorable marine conditions across Great Lakes tonight and Saturday.
Benign conditions then continue even as a weak cold front settles
into northern Lake Huron Saturday night and into the south half by
Sunday. The front brings a minimal temperature change and supports
just a stray shower along and near the boundary leaving the SW to NE
wind shift as the weather highlight. The directional wind shift is
notable but wind speed remains light for a low impact wave pattern
Sunday followed by the return of weak high pressure by Monday.

&&

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

$$

AVIATION.....SC
DISCUSSION...BC
MARINE.......BT


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