754
FXUS63 KDTX 151000
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
600 AM EDT Thu Aug 15 2024

.KEY MESSAGES...

* Increasing cloud cover today with periods of showers this evening
  through Sunday.

* Chance of strong thunderstorms Friday and Friday night.

&&

.AVIATION...

A very dry low level environment remains entrenched throughout the
daylight period as high pressure slowly relinquishes control. This
maintains VFR conditions under a thickening high based cloud. The
increase in mid level moisture will lead to some pockets of rain
this evening and tonight. Some reduction in cloud base during this
time, but with conditions holding at VFR outside any heavier
showers. Diminishing stability aloft could prove sufficient for an
isolated thunderstorm overnight and early Friday, but limited
potential precludes a defined mention attm.

For DTW/D21 Convection...Very low probability for an isolated
thunderstorm late tonight and Friday morning.

DTW THRESHOLD PROBABILITIES...

*  Low for thunderstorms late tonight and Friday morning.

&&

.PREV DISCUSSION...
Issued at 300 AM EDT Thu Aug 15 2024

DISCUSSION...

Upper level storm system organizing over Minnesota/Midwest this
morning, with the closed 500 MB low on track to move through Lower
Michigan on Saturday. Lead spoke of energy/upper level PV filament
moves through this evening, with good moisture advection bringing
the likelihood of high based showers. Looking at the 850-700 MB
Theta-E ridge fully entrenched Friday morning, with PW Values around
1.5 inches. Weakening 500 MB height fall center to move through
during early Friday afternoon, out of sync with peak heating of the
day. A second round of height falls then arrives Friday night.

Still could be enough destabilization on Friday (MUcapes 1000-2000
J/kg) with 0-6 KM bulk shear around 30 knots to support a marginal
risk of severe thunderstorms. This also includes the late evening-
early morning activity/second round of height falls.

Continued occasional showers and possible thunderstorms on Saturday
as the nearly stacked lows (sfc-700-500 MB) slowly track through the
State. Wrap around moisture on the backside will also lead to more
showers into Sunday as well.

A very strong northern stream upper level wave tracking through
Central Canada then progged to merge/phase with our departing 500 MB
low early next week and lead to an unusually amplified (for summer
standards) eastern North American trough. Southeast Michigan looks
to be on the western fringe of the cold air, with expansive high
pressure in control through at least mid week.

MARINE...

Benign marine conditions this morning transition toward a more
unsettled pattern throughout the day as an upper low and leading
thunderstorm complex accelerate toward the Great Lakes. Most of the
day remains dry with flow organizing out of the southeast as the
gradient tightens. Rain chances to then ramp up late this evening
with coverage increasing overnight as elevated portions of the warm
front lift into the area. Gusty winds approaching 25-30 knots are
possible until the warm front passes through Friday morning. Small
Craft Advisories may therefore be necessary late tonight through
Friday morning. Attention Friday afternoon-evening turns to
organized thunderstorm potential, though there is uncertainty in
timing, coverage, and intensity as several waves of convection will
be plausible. Governing upper low will slowly drift across the Great
Lakes through the weekend, extending shower and thunderstorm
potential through most of the weekend.

HYDROLOGY...

Periods of showers this evening right through Sunday, with embedded
thunderstorms from time to time to enhance rainfall. Total Rainfall
over the 3 day stretch is expected to be near 1 inch, but any strong
thunderstorms will lead to enhanced totals of 2+ inches. Localized
minor flooding of urban, low-lying, and otherwise flood prone areas
remains possible in the strong thunderstorms, but the off and on
nature of the rainfall is not expected to cause significant
flooding.

&&

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

$$

AVIATION.....MR
DISCUSSION...SF
MARINE.......MV
HYDROLOGY....SF


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