791
FXUS63 KDTX 162230
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
630 PM EDT Mon Sep 16 2024

.KEY MESSAGES...

- Seasonably warm and mainly dry conditions prevail through the
workweek and most of the weekend.

- Patchy morning fog develops Tuesday morning followed by increasing
cloud cover Tuesday night and Wednesday.

&&

.AVIATION...

Expansive area of high pressure maintains influence this period.
This ensures dry and stable conditions, precluding lower cloud
development. Shallow ground fog will again be possible at daybreak
Tuesday due to favorable radiative cooling conditions. Light winds
generally from the southeast persist.

For DTW/D21 Convection... Thunderstorms are not in the forecast for
the foreseeable future.

 DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 300 PM EDT Mon Sep 16 2024

DISCUSSION...

Extended stretch of mild and dry weather continues for at least the
next 48 hours as the longwave pattern remains blocked by a
protruding 590 dam ridge encompassing the Great Lakes/Northeast
while upper lows over the Lower Mississippi Valley and The Carolinas
interact over the south. Thermodynamic profiles have been largely
unchanged from day to day marked by H8 temps in the low-mid teens
and surface dewpoints in the upper 50s to around 60s. Deep-layer
subsidence continues to offer mainly clear skies while the lowest
dewpoint depression through the column is found near the top of the
boundary-layer. With the exception of perhaps a few shallow diurnal
cumulus clouds today/tomorrow and lingering/trapped wildfire smoke
well above the surface, low aerosol optical depths support largely
unencumbered insolation lending highs of 5-10F above normal today and
Tuesday. More typical nocturnal readings arise both nights with
broad radiational cooling window. See no reason to veer from
previously included patchy fog mention around sunrise Tuesday.

Primary forecast consideration for this week maintains focus on a
(sub-)tropical cyclone that is now tracking west across The
Carolinas with improving vertical continuity through the
troposphere. This system fully closes off tonight and remains
positioned downstream of more meaningful steering dynamics which are
revolving around western CONUS. Underwhelming split-flow
configuration aloft allows the aforementioned low to drift northwest
across southern Appalachia and toward the Ohio Valley with little
resistance. Latest guidance shows reduced variance in the northwest
extent of the system as a more rapid collapse unfolds Tuesday night
and Wednesday morning lending higher confidence in locally dry
conditions through the end of the work week, and potentially through
the weekend. For context, the official Detroit Area rainfall total
for this month stands at 0.06 inches, all of which fell on September
6th. If the dry forecast holds, it would mark the driest recorded
September (through the 22nd) since 1908.

MARINE...

Sprawling high pressure continues to govern conditions for the
central Great Lakes through the forecast period offering mainly dry
weather and light southeast winds (AOB 15 knots). A (sub-)tropical
cyclone that is now tracking west across The Carolinas fully closes
off tonight but remains positioned downstream of the more meaningful
steering dynamics over western CONUS. Latest guidance shows a rapid
collapse unfolding Tuesday night and Wednesday morning over the Ohio
Valley keeping the resident ridge of high pressure in control
through the workweek. This ensures persistent light easterly
composed flow yielding favorable marine conditions into the weekend.

&&

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

$$

AVIATION.....MR
DISCUSSION...KGK
MARINE.......KGK

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at www.weather.gov/detroit.