062
FXUS63 KDTX 181651
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1251 PM EDT Sat May 18 2024

.KEY MESSAGES...

- Warm and muggy conditions continue through early next week. Chance
(35-40 percent) for showers and thunderstorms Sunday afternoon and
evening.

&&

.AVIATION...

Morning fog and LIFR/IFR low clouds have dissipated (outside of
DET), and looking at just a bit of diurnal CU development this
afternoon, mainly in the 5000-6000 foot level. The rest of the mid
levels look very dry, and not anticipating convective development.
Enough low level drying during the day and a subtle southerly wind
tonight to help limit fog potential compared to this morning.
However, leaning toward fog/moisture from Lake Erie to make inroads
into the southern TAFS late tonight, and have put tempo LIFR cigs in
for DTW/YIP/DET. A weak surface cold front should allow for light
winds to flip to southwest, helping to accelerate the mixing out of
the low clouds and fog with diurnal CU (around 5000 feet) likely in
the afternoon. Lake breeze convergence and instability will bring
the potential for scattered thunderstorms during the late afternoon.

For DTW/D21 Convection...Potential for FEW-SCT clouds flirting with
the 5000 foot level much of the period. Fog/LIFR low cloud concerns
late tonight as light southeast flow off Lake Erie exists.

Thunderstorms are not expected this afternoon, but there is a chance
of thunderstorms Sunday afternoon, with lake breezes serving as the
focus.


DTW THRESHOLD PROBABILITIES...

*  Low for ceilings aob 5kft.

*  Low for ceilings and visibilities to drop below 200ft or 1/2SM
   8-14Z Sunday.

*  Low for thunderstorms Sunday afternoon.

&&

.PREV DISCUSSION...
Issued at 333 AM EDT Sat May 18 2024

DISCUSSION...

The culmination of the past 24 hours of precipitation accumulation
coupled with a surge of very shallow low level moisture coming off
the Great Lakes have resulted in extensive low-level stratus and
areas of dense fog across portions of SE MI. Both fog and cloud
coverage will quickly dissipate after sunrise once the mid-May sun
angle works to lift cloud depths and mix out the moisture. Some
scattered cu will likely re-form in the wake of the stratus, but
clearing trends will allow temperature trends to or above the 80
degree mark, outside of the immediate nearshore locations. Cannot
completely rule out a fleeting diurnally fueled shower, but very
limited instability and weak kinematics support dry conditions for
most locations.

A series of upper-level waves will travel across the northern and
central Plains through the weekend and into early next week while a
secondary upper-level trough builds in through the Tennessee Valley
by this afternoon. This will enhance ridging across the Great Lakes
and will pool in warm air from the continental SW into Michigan,
characterized by h850 values between 14-16C. This will support
daytime highs in the 80s Sun - Tue, likely pushing into the mid-80s.
Warm overnight lows will also accompany the warming trend given the
constant stream of warm air advection. Overnight lows in the mid 60s
are likely Tuesday morning and Wednesday morning.

There will be multiple chances for showers and thunderstorms during
this warm stretch, with PoPs increasing by the mid-week period. The
notable change for the near-term will be increasing PoP chances for
showers and thunderstorms for tomorrow afternoon and evening.
Surface based instability will return on Sunday under the warm and
moist airmass with CAPE building up to 1,500 J/kg. There will be a
cold front that washes out across central Michigan by Sunday
afternoon which will be one possible point of CI, mainly over the
Tri-Cities, but the most probable focal point for initiation will be
multiple lake breezes that push inland off of Huron/St.Clair/Erie
accounting for the large surface deltaT. Surface convergence can
capitalize on the building instability, bringing the chance (35-40%)
for showers and thunderstorms. The limiting factor will be the meager
deep layer shear values with 1-6 km shear holding aob 15 knots.
Convective mode will be pulse thunderstorms. Strong 0-3 km lapse
rates around 9 C/km, DCAPE aoa 1000 J/kg, and PW values above 1" will
bring the chance to see heavy downpours with highly localized wind
gusts up to 45-50 mph with the more vigorous activity. Weak mean
boundary layer flow will be favorable for outflow boundaries, which
can also support renewed neighboring t-storm development. Showers
and storm chances wane after sunset with the loss of daytime
heating.

Upper-level waves riding within the longwave ridge will bring the
additional chance for showers and storms Monday afternoon and
evening and again for Tuesday, most favorable over the northern half
of the cwa where the best moisture axis resides. The upper-level
trough will amplify across pacific west early next week, while a
potent mid-level wave derived around Baja California targets the
Texas Panhandle, which will strengthen a weak surface low and drive
it northeast into the western Midwest and up towards the northern
Great Lakes. The EPS and NAEFS both show excellent agreement
regarding cyclone centers holding northeast of the cwa which will
push a cold front across SE MI likely on Wednesday. This will
provide another chance for showers and storms, and pending the
timing of the front, could bring strong to severe thunderstorm
potential as 0-6 km shear values increase to 35-40 knots. A daytime
passage would be more favorable for stronger storms. Cooler
temperatures filter in behind the front, dropping temperatures back
into the 70s by the late week period.

MARINE...

Showers in the area as a high pressure system briefly takes control
today. Moist profile and southeasterly winds around 5-10 knots
through the day today allow for areas of fog over Lake Huron to
stick around into the early afternoon. A dense fog advisory is in
effect for Lake Huron, and may need to be expanded into Lake St.
Clair and western Lake Erie. Benign and predominantly southerly
winds persist through the rest of the weekend into Sunday, where a
shortwave brings the next low pressure system across to the north.
The system will drag a cold front across the region Sunday with no
inclement weather expected, before giving way to a second disturbance
behind it. This second disturbance brings chances for showers and
storms, but aside from inside any such storms, winds and waves are
expected to remain below SCA criteria at this time.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Dense Fog Advisory until 4 PM EDT this afternoon for LHZ361>363-
     441>443-462>464.

Lake St Clair...Dense Fog Advisory until 4 PM EDT this afternoon for LCZ460.

Michigan waters of Lake Erie...Dense Fog Advisory until 4 PM EDT this afternoon for LEZ444.

&&

$$

AVIATION.....SF
DISCUSSION...AM
MARINE.......BC


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