767
FXUS63 KDTX 151031
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
631 AM EDT Sat Jun 15 2024

.KEY MESSAGES...

- Dry with seasonable temperatures today before abnormally warm
conditions commence Sunday through much of next week.

-Temperatures likely peak in the mid to upper 90s next week with
maximum heat indices near/above 100F.

- Low confidence thunderstorms could offset some of the warming,
depending on coverage and timing.

&&

.AVIATION...

High pressure will be centered over the eastern Great Lakes today.
This system will sustain a light easterly wind component through the
day. Dry air circulating around this high will also maintain clear
skies other than some late day cirrus.

For DTW/D21 Convection...No thunderstorms are expected.

 DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 353 AM EDT Sat Jun 15 2024

DISCUSSION...

Atmospheric state is currently characterized by a longer wavelength
ridge across the north-central tier of CONUS, flanked by a Pacific
low descending along the coast of British Columbia and broad upper
low over Hudson Bay that has begun to eject east. 15.00Z RAOBs
reveal a region of +591 dam at H5 over the southern Plains which
marks the infancy of a highly anomalous ridge that will build
northeastward with time and bring dangerous heat to Southeast
Michigan by Monday. As for conditions today, flow trajectories flip
from cyclonically curved to anticyclonically augmented due to the
approach of the aforementioned northern stream ridge. Stabilizing
omega response noted with forecast soundings responding through
warming/drying within the mid-levels, especially into the afternoon
hours. Effectively clear skies offer broad insolation potential as
the days creep toward the summer solstice. High temperatures will be
tempered by the presence of veering low-level winds toward the ENE
which promotes advective cooling, helped further by the influence of
Lake Huron. Highs should largely hold in the upper 70s outside Metro
Detroit (near 80 for the metro region).

The southern ridge closes off and centers a bit further east Sunday,
primarily over northeast GA and the western Carolinas while surface
high pressure over the Great Lakes slides into The Northeast,
strengthening to 1025 mb. This realigns sub-H9 winds southeasterly
with warming conditions under the return-flow configuration. H8
temps jump significantly as the elevated portion of an approaching
warm front lifts through from the southwest. Favorable model
consensus of +18C by 18Z supports highs well into the 80s for most
locations. A shortwave feature embedded within the mean flow will
lift across northern Lower Michigan Sunday evening. The 15.00Z
deterministic GFS has now fallen in-line with the corresponding
ECMWF/CMC/NAM runs in keeping the precipitation just north of the
CWA.  Latest PoPs offer some minor refinements with a shift to only
Slight Chance wording and a re-focus on Midland/Bay/Huron counties
during the late evening timeframe. Overnight temperatures stay
rather warm as lows hold near/above 70F.

Record-setting heat remains a possibility Monday and at various
points throughout next week as the mid-level portion of the ridge
builds to 594 dam over North Carolina. Highs temperatures locally
are still expected to peak in the upper 90s for most urbanized
locations while confidence increases for similar readings for the
outlying areas. Heat indices should break into the triple digits as
max 0-3 km ThetaE values approach 360K with surface dewpoints in
excess of 70F. The combination of +100F heat indices, overnight
lows above 70F and the multi-day impact of highly anomalous prolonged
late-spring heat warrants discussion of Excess Heat Watches/Warnings
within the next update cycle. From an impacts perspective, the
effects of this heat wave become more amplified for areas with
higher population density. This is supported by the Experimental NWS
HeatRisk tool where widespread Extreme Risk for Heat-Related Impacts
(Level 4 of 4) could be reached.

The ridge is expected to strengthen as it broadens northeastward
along the Mid-Atlantic, peaking near 599 dam at H5 by Wednesday.
EPS/CMCE/GEFS remain on-board with highs in the 90s through
Thursday. Uncertainty festers wrt convective potential and
subsequent modulation of thermodynamic profiles. MEX and GEFS
datasets hint at slightly more "cooling" potential with various
shortwave perturbations along the western periphery of the ridge.

MARINE...

High pressure remains in control this weekend, bringing gentle winds
across Lake Huron. Conditions hold ahead of a warm front moving
across the area Sunday evening. Chances for showers and storms
accompany the front, mainly over northern Lake Huron. Southeasterly
winds will veer southwesterly behind the front, increasing to 10-15
knots. Gentle to moderate winds alongside chances for unorganized
showers will persist through the rest of the week.

&&

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

$$

AVIATION.....SC
DISCUSSION...KGK
MARINE.......BC


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at www.weather.gov/detroit.