Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 10/17/23

Area Forecast Discussion

National Weather Service Detroit/Pontiac MI

 1151 PM EDT Mon Oct 16 2023

.AVIATION...

A brief window of drying within prevailing northerly flow may offer
a window for the existing stratus to vacate through the early
morning hours. Based on latest satellite trends, greater potential
will exist from PTK northward, with less confidence in the Detroit
corridor. Daytime heating will likely initiate another round of
expansive stratocumulus by late morning into the afternoon Tuesday.
General expectation for a cloud base at MVFR initially, before
transitioning to lower VFR late in the day. Modest winds from the
northwest overnight, then backing to westerly through the daylight
period.

.DTW THRESHOLD PROBABILITIES...

* Medium for ceiling at or below 5000 ft through Tuesday morning.
  High Tuesday afternoon and evening.

&&

.PREV DISCUSSION...
Issued at 347 PM EDT Mon Oct 16 2023

DISCUSSION...

Most of Michigan remains encased underneath an expansive stratus
deck which is no surprise given the strong inversion observed between
h850-h800 via the latest ACARS soundings. Low-level flow will back
slightly tonight from N to NNW tonight which will allow dry Canadian
air to filter into SE MI. Model guidance suggest the intrusion of
dry air will allow for some partial clearing of cloud cover this
evening and into the early morning hours, particularly for the Tri-
Cities, and satellite data backs this up given the aggressive
clearing now being observed across northern lower Michigan.

Otherwise, the lake effect rain band that has affected portions of
the Lake Huron shoreline into Port Huron is now starting to shift
offshore as low-level winds continue to gradually back from north to
north-northwest. This will lead to dry conditions overnight for all
of SE MI. Lows drop in the upper 30s to lower 40s for most spots,
although mid-30s is not out of the question for the Tri-Cities given
the ongoing clearing trends.

An upper-level wave currently over Manitoba is projected to drop
into the northern Great Lakes tomorrow morning and will briefly
reinforce a shortwave ridge across SE MI through the early afternoon
before traversing over the cwa through the evening. Passage of the
wave is not expected to produce precipitation given the antecedent
dry conditions. Low-level flow does back from the northwest to west-
southwest following the passage of the wave which will release some
lake Michigan moisture inland Wednesday morning. Some drizzle will
be possible with this moisture, but shallow moisture depths up to
5kft and subsidence behind the wave will be a limiting factor for any
robust shower activity.

The wave now offshore Washington will be the initial source for the
next round of widespread showers, which are expected to fill
starting late Wednesday night into Thursday morning across SE MI.
This wave is projected to arrive onshore this evening and will
travel east across the northern Plains by late tomorrow night.
Shortwave ridging fills in across the Great Lakes Wednesday
afternoon in advance of the wave, before the wave and associated
clipper low pressure system arrives on Thursday. The longwave
pattern turns a little less certain with regards to timing of
additional waves dropping in from the Canadian Provinces, but this
more active pattern does look to hold through at least Saturday, so
additional rain chances will remain in the forecast to end the week.

MARINE...

Weak high pressure is building into the area, but rough conditions
remain in place for most of the near-shore areas of Southern Lake
Huron. The Small Craft Advisory for inner Saginaw Bay will be
allowed to expire, as conditions have dropped below Small Craft
criteria for that area. Small Craft Advisories for the rest of
southern Lake Huron are still in effect through this evening, as
high waves are still a concern. The high pressure will quickly be
pushed out of the region by the next low pressure, causing winds to
shift to become southwesterly. The low pressure system is currently
expected to bring showers to the area in the latter half of the
week.

&&

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

$$

AVIATION.....MR
DISCUSSION...AM
MARINE.......BC

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at www.weather.gov/detroit.