109
FXUS63 KDTX 021658
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1258 PM EDT Tue Jul 2 2024

.KEY MESSAGES...

- Seasonable conditions today as clouds thicken through the day.

- Potential for showers to develop tonight, mainly across the
  Saginaw valley and thumb region. An isolated non-severe
  thunderstorm also possible.

- Chance of showers and thunderstorms will continue into Wednesday
  as conditions turn more humid. An isolated strong to severe storm
  will be possible during the afternoon, capable of producing strong
  wind gusts.

- Typical heat and humidity for the 4th of July holiday.

&&

.AVIATION...

Central Plains to Midwest low pressure draws warmer air with
elevated humidity into Lower MI tonight and Wednesday. The air mass
change is preceded by greater coverage of mid and high clouds this
afternoon while higher based showers are directed west and north of
the terminal corridor. The MBS area could be an exception, although
with just a sprinkle of light rain possible there through this
evening. Conditions are otherwise VFR above 5000 ft until the
trailing cold front moves in from the west during Wednesday.
Borderline MVFR/VFR stratus and light rain showers are likely in the
warm sector/moisture axis prior to the frontal passage. Thunderstorm
potential also returns but mainly during daytime peak instability
and as the front moves west to east across Lower MI Wednesday
afternoon.

For DTW/D21 Convection... Thunderstorms are not expected this
afternoon and tonight. Storm potential returns with the passage of a
cold front Wednesday afternoon.

DTW THRESHOLD PROBABILITIES...

* Low for ceiling 5000 ft or less in the morning, moderate Wednesday
  afternoon.

* Low for thunderstorms Wednesday afternoon.

&&

.PREV DISCUSSION...
Issued at 358 AM EDT Tue Jul 2 2024

DISCUSSION...

Low and mid level ridging entrenched locally early this morning.
This pattern effectively solidifying a profile characterized by a
rising thickness field, dry ambient environment particularly below
700mb and a high degree of stability captured through a deep layer.
Upstream satellite trends lend support for a steady increase in mid
level cloud with time today, as mid level southwest flow yields
better moisture transport above 700 mb. Some hints within recent
model guidance for some sprinkles or very brief light showers to
materialize late today as this advective process gets a boost from
shortwave energy, possibly convective induced, lifting toward
northern lower. Very low confidence that any activity actually leads
to a measurable amount of rain, so tentatively plan to hold with a
mainly dry forecast. General moderation of the thermal profile
despite the inbound cloud nets a return to seasonable temperatures
today. Highs around 80 degrees.

Low amplitude mid level wave shearing through the mean southwest
flow will track into the northern great lakes overnight into
Wednesday. Steering flow generally ensures greater precipitation
potential tied to the main area of dcva/height falls remain
northwest of the area through the night, with some potential mainly
across the Saginaw valley. Trailing cold front arrives Wednesday.
Frontal convergence remains weak as the boundary becomes parallel to
the mean flow, but interaction with a moistening boundary layer
condition provides a window for convective development. Higher
precip chance with eastward extent, with overall pace of the front
relative to daytime destabilization dictating whether a more
organized convective episode can manifest locally or remain to the
east/southeast. Targeted conditional marginal risk offered by the
SPC Day 2 outlook for the eastern zones highlights the isolated
stronger wind gust potential in this environment. Drying conditions
within veering low level post-frontal flow from northwest to
southeast late in the day.

A seasonably warm/moist and unstable thermodynamic profile maintains
residence for the 4th of July holiday. Model consensus offers a high
temp forecast of mid 80s. Maintenance of an energetic lower
amplitude southwest flow complicates the precipitation forecast this
period, as there remains some potential for a still ill-defined wave
to engage this profile favorably during the peak heating cycle.
Forecast outlines a more conservative/drier stance overall at this
stage, simply offering a lower end mention focused across southern
sections. An upward revision remains possible should a more
definitive signal emerge.

A much better convective signal exists for the Friday period,
anchored by the arrival of organized forced ascent associated with a
deeper mid level wave/low. Typical summertime conditions then
expected for the upcoming weekend, with temperatures near or just
above average and some shower/t-storm potential within broad mid
level troughing.

MARINE...

A high pressure system will depart into the continental northeast
today while a low pressure system arrives into Lake Michigan late
tonight into early tomorrow morning. This will veer wind direction
from the southeast to the southwest. Wind speeds and gust potential
will increase slightly with the departure of high pressure, with
gusts increasing to around 20 to 25 knots across Lake Huron. A cold
front is then expected to move over the Great Lakes tomorrow, which
will bring increasing chances for showers and thunderstorms both
ahead and along the front. The southwest fetch across the Saginaw
Bay will also bring a window to see gusts around 25 knots tomorrow
afternoon and evening. Small Craft Advisories for the bay may be
needed. A weak area of high pressure will then build in Thursday,
relaxing wind speeds and decreasing gust potential.

&&

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

$$

AVIATION.....BT
DISCUSSION...MR
MARINE.......AM


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