697
FXUS63 KDTX 120803
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
403 AM EDT Wed Jun 12 2024

.KEY MESSAGES...

- Warming trend continues through mid-week with high temperatures in
  the mid 80s today and nearing 90 degrees for Thursday.

- Scattered showers and thunderstorms arrive Thursday. Strong to
  severe storms will be possible during the afternoon and evening
  with damaging winds and large hail the main threats. Southeast MI
  is outlined in a Marginal to Slight Risk from SPC.

- Higher than usual confidence in hot and humid conditions next
  week. Temperatures into the 90s Monday and Tuesday with relatively
  high humidity will likely bring the highest heat indices we have
  seen so far this year.

&&

.DISCUSSION...

A weak shortwave is passing over the region this morning with an
associated tongue of theta-e responsible for the area of mid-level
clouds passing overhead. The low levels remain dry evidenced by sfc
dew point depressions of about 10 to 15 degrees, so the weak radar
returns noted this morning have largely been virga save for a few
light showers in the Thumb. Height rebounds commence around daybreak
with a low amplitude shortwave ridge building directly overhead
today. Steady southwest flow and increasing sunshine offer a net
boost in mean thickness with 850mb temps rising to around 15C by 00z
this evening. This supports high temps in the lower to mid 80s this
afternoon. Surface dew points will likewise rise to near 60 degrees
and provide a noticeably more humid feel than previous days. Did add
a slight chance for a shower for interior areas as a weak surface
trough/wind shift may produce enough convergence for disorganized
convection during peak heating.

A zonal jet streak crossing the northern Plains today will be the
impetus for a round of convection over the upper Midwest this
afternoon and evening as a cold front tracks across the region.
Model guidance continues to offer moderate confidence that some of
this convection will sustain itself along a veering 40 kt LLJ,
reaching Lake Michigan tonight and eventually moving into northern
Lower MI early Thursday morning. Elevated instability looks to
advect in locally with 700-500mb lapse rates nudging up to around
6.5 C/km across the north. This would support MUCAPE of a few
hundred J/kg and a chance for elevated thunder with highest
confidence north of I-69 during the pre-dawn hours.

Uncertainty remains with convective trends during the day Thursday,
but generally expect any morning activity to wane in vigor as the
convective shortwave passes east and favors a pocket of subsidence
through midday. Continued southwest flow ahead of the inbound cold
front will bring dew points into the mid 60s with temps rising into
the mid to upper 80s. Forcing associated with the inbound upper jet
exit region and attendant shortwave then begins to arrive during the
afternoon and evening bringing better opportunity for convective
redevelopment along/ahead of the cold front. This window offers
potential for isolated to scattered severe storms with MLCAPE on the
order of 1000 to 2000 J/kg (assuming early/mid day convection
doesn`t stabilize the environment) and bulk 0-6km shear increasing
to around 50 kt which would be supportive of damaging wind gusts and
large hail as the primary threats, though an isolated tornado cannot
be ruled out. Areas south of I-69 and west of I-75 are highlighted
in the SPC Day 2 Slight Risk (2/5) with the rest of SE MI in a
Marginal Risk (1/5). The front pushes across the area during the
late evening and brings an end to any showers and thunderstorms
around midnight.

Cooler, drier, and more seasonable air settles in behind the front
to bring comfortable conditions Friday and Saturday. High pressure
will dominate the region, bringing mostly sunny skies and light
winds. The next opportunity for showers and storms arrives Sunday as
the ridge axis passes east and a shortwave lifts in from the central
Plains. There are still significant timing differences among
deterministic solutions stemming from this wave`s ejection speed out
of the Four Corners region on Friday.

A significant warm-up is still on track for next week with model
guidance supporting a 592 dam 500mb ridge setting up across the SE
CONUS Sunday and gradually expanding to encompass much of the
eastern half of the continent through the week. Ensemble guidance
shows mean 500mb height anomalies near 2 sigma by mid-week which
supports a prolonged period of well above normal temps with
potential for record heat. This is corroborated by ensemble progs
showing 30 to 50% of LREF membership with apparent temps above 95
degrees each day from Monday to Thursday. Available soundings
continue to suggest only weak capping, so the temperature forecast
for any given day will remain subject to any MCS activity that rolls
through.

&&

.MARINE...

Tranquil weather will continue through the mid week as a ridge of
high pressure continues to shift eastward.  Southerly winds will
slowly shift to the southwest as the gradient becomes more
established for the second half of the week. A low pressure system
is projected to arrive on Thursday into Friday which could support a
period of Small Craft Advisory conditions with several opportunities
for showers and thunderstorms.

&&

.PREV DISCUSSION...
Issued at 1203 AM EDT Wed Jun 12 2024

AVIATION...

Broken to overcast mid and high clouds precede the Midwest frontal
system as a plume of elevated moisture moves across Lower Mi late
tonight. Upstream observations support lower ceiling but still above
5000 ft while also presenting some virga indications from radar and
possibly a stray sprinkle reaching the ground through early morning.
The cold front weakens but still remains the focus of cumulus
enhancement while moving west to east across Lower Mi during the
afternoon. The cumulus component contributes to broken ceiling
around 5000 ft into Wednesday evening.

For DTW/D21 Convection...Thunderstorms are not expected late tonight
through Wednesday evening.

 DTW THRESHOLD PROBABILITIES...

* Moderate for ceiling 5000 feet or less in the afternoon.


&&

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

$$

DISCUSSION...TF
MARINE.......SS
AVIATION.....BT


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