295
FXUS63 KDTX 111941
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
341 PM EDT Tue Jun 11 2024

.KEY MESSAGES...

- Warming trend through mid-week with high temperatures possibly
  reaching 90 degrees for Thursday.

- The next chance for rain and thunderstorms will be Thursday.
  Isolated strong to severe thunderstorms will be possible with a
  Marginal Risk in place across much of southeast Michigan.

- Higher than usual confidence in hot and humid conditions early
  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...

Lake aggregate stable high pressure parked over the Central Great
Lakes this afternoon will maintain a predominate dry southeasterly
flow influence through tonight. Very pleasant and comfortable
weather is in store through this evening with temperatures falling
back into the 60s after sundown.

The next upper level jet packet (exit region) will push into the
western Great Lakes late tonight touching off the lead edge of warm
advection. Models resolve a fairly abrupt bout of 850-650mb thetae
return prior to 12Z Wednesday, however, organization to any warm
front structure is poorly defined. A high based sprinkle will
certainly be possible the latter half of tonight with some help from
cloud top cooling, but confidence is too low to include. A modest
boost in surface dewpoints into the middle to upper 50s will yield
warmer conditions Wednesday afternoon. Heat indices are forecasted
to be well into the lower 80s.

The southern edge of a deep midlevel trough will force a cold front
through Southeast Michigan during the late afternoon and evening
hours on Thursday. Moisture return in advance of the cold front is
forecasted to be disjointed with only the low level thetae content
arriving in a very narrow axis from north to south after 18Z. Note
any sub 700mb thetae early Thursday is positioned within the
anticyclonic flow trajectories which will ensure the column starting
from a baseline of high static stability in the lowest 5.0 kft agl.
The modeled UVV signal suggests there will be two potential forcing
mechanisms of interest. The first is high based convective remnants
coasting into the northern forecast area from the Upper Mississippi
River Valley after 09Z. Relatively high confidence exists in
weak/lack of vigor to vertical motion early.  The second potential
forcing mechanism will be shortwave energy attendant to the
anticyclonic shear side of the upper level jet that could arrive
after 18Z at or around the time of the front. The details for
Thursday afternoon are going to matter as some forecast data
suggests that active midlevel subsidence between 4.0 and 12.0 kft
will arrive coincident with increasing shear. Kinematics certainly
become impressive during the afternoon with a midlevel jet exceeding
50 knots yielding 0-6km bulk shear increasing to nearly 50 knots.
Hires modeled storm motion relative to the shear vector is generally
parallel during the Thursday afternoon period here in Michigan with
some greater updraft/shear balance potential over Ontario south of
the Bruce Peninsula. MLCAPES are expected to reach 1000 J/kg so an
isolated large hail/strong wind gust severe thunderstorm will be
possible sometime between 18Z-00Z Thursday. The latest Swody3 has a
Marginal designation for Severe Weather north of Metro Detroit.

Surface high pressure and strongly anticyclonic flow trajectories
are expected to result in comfortable summer weather conditions
Friday and Saturday with limited humidity.

Longwave ridging is then expected to amplify rapidly Sunday and
early next week with H5 geopotential heights reaching above 580dam
as far north as James Bay. Everything is shaping up to be a notable
time period for heat by Monday as 850mb temperatures easily exceed
20C. Current forecast soundings do not show a considerable amount of
midlevel warm air so there is some question to how capped off the
environment will be. As a result, could see some convective
complex(es) short circuit daytime heating for a day or so, but given
the setup and potentially multiple days of heat it should be rather
noteworthy. The current forecast has heat indices in the upper 90s
next Monday and a NWS HeatRisk as a Category Red.

&&

.MARINE...

Tranquil weather will continue through the mid week as the ridge of
high pressure continues to shift eastward.  This will bring a return-
flow setup, veering winds southerly as the gradient slowly becomes
more established into the second half of the week. A low pressure
system is projected to arrive late Thursday into Friday which could
support a period of Small Craft Advisory conditions with several
opportunities for showers and thunderstorms.

&&

.PREV DISCUSSION...
Issued at 120 PM EDT Tue Jun 11 2024

AVIATION...

VFR conditions are expected through the rest of the forecast as both
high and low clouds currently approach the area. Low clouds come
from developing diurnal cumulus making its way northeast. Confidence
is low on the final areal extent of this cloud deck before it
dissipates later today. High cirrus from the west continue to make
their way southeast through this evening and tonight. Ceilings will
gradually lower overnight as a cold front moves closer to the area
through Wednesday. No rain is expected to impact the CWA with this
system, with ceilings reaching 5000 feet at their lowest tomorrow.

For DTW/D21 Convection...Thunderstorms are not expected through the
TAF period.

 DTW THRESHOLD PROBABILITIES...

* Moderate for ceilings aob 5000 feet Wednesday afternoon.


&&

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

$$

DISCUSSION...CB
MARINE.......SS/KGK
AVIATION.....BC


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at www.weather.gov/detroit.