533
FXUS63 KDTX 161725
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
125 PM EDT Thu May 16 2024

.KEY MESSAGES...

- Dry and warm today with widespread 70s.

- Scattered showers tonight with additional scattered to numerous
  showers and possible embedded thunderstorms daytime Friday.

- Low chances for showers and thunderstorms Saturday, mainly south
  of M-59, with an active weather pattern looking likely to set up
  early to middle of next week.

&&

.AVIATION...

Clear skies early this afternoon ahead of a low pressure system to
the east bringing showers to the area by this evening. Thunder is
possible with these showers, but potential remains low, and any
mention of thunder has been left out of the TAFs. MVFR ceilings will
accompany these showers, dropping gradually through the overnight
hours. MBS will see the start of these showers shortly after
midnight, while the rest of the TAF sites will first see chances for
rain beginning around 3am. Both showers and light fog present Friday
morning, with MVFR ceilings potentially dropping to IFR levels
briefly around daybreak. MVFR ceilings will be present through the
remainder of the TAF period. Hi-res guidance suggests a possible
redevelopment of isolated rain showers Friday afternoon, but
confidence remains low at this time on how these secondary showers
will develop.

For DTW/D21 Convection... An isolated thunderstorm is possible
within a broader area of showers late tonight. The storms will be
elevated and weak but capable of a brief lower visibility downpour
through Friday morning.

DTW THRESHOLD PROBABILITIES...

* Moderate for ceiling 5000 ft or less late tonight and Friday
  morning.

* Low for thunderstorms late tonight and Friday morning.

&&

.PREV DISCUSSION...
Issued at 249 AM EDT Thu May 16 2024

DISCUSSION...

Southern fringe of surface high pressure over the Hudson Bay builds
into southern lower MI today as mid-level ridging slides over-top.
This maintains lighter winds as surface flow turns more
southeasterly in response to a weakening trough lifting into the
upper Midwest. Widespread 70s are expected as a result for the
majority of SE MI with cooler temps more confined to the shorelines,
relative to yesterday. Height falls tied to the aforementioned
trough begin working into the area by this afternoon as southwest
low level flow promotes respectable moisture advection- PW values
climb from ~0.6" this morning to over 1" by latter part of this
evening. Increasing cloud cover accompanies this moisture surge with
skies turning mostly cloudy around sunset. Lead ribbon of
diminishing vorticity rounds the trough into lower MI tonight
supporting generally scattered shower chances. Little to no thunder
expected with this activity as instability looks to remain confined
to west MI, at least through the overnight period. Better potential
for wider spread showers as well as scattered thunderstorms arrives
daytime Friday as instability shifts eastward in advance of the
approaching washing out cold front. CAMs have trended a bit more
bullish on available MLCAPE with values closer to the 750-1000 J/kg
range supporting a better shot at thunder development; though sub-
par mid-level lapse rates, shear holding closer to 25-30kts, and
weaker frontal forcing, storms that fire are expected to be sub-
severe.

Saturday southern lower MI comes under the influence by the
periphery of southern stream mid-level troughing that will be
traversing the Ohio Valley. This could provide just enough lift atop
a warm, humider airmass (Td in the lower 60s) to offer a low-end
chance for isolated pop-up convection during afternoon peak heating.
Instability supportive of this scenario looks to generally be hold
to the southern CWA (south of M-59), collocated where the trough`s
influence is `strongest`, so have trimmed slight chance PoPs from
northern areas. Even for these southern areas, most likely will not
see any precip.

Northern stream trough that had been progged to track across the
upper Midwest instead is now favored to slide further north
along/north of the international border into northern Ontario. This
places supporting shortwave energy likewise further north and
further away from SE MI as its surface cold front drives across
southern lower MI Sunday. With rain chances already slim in the
original setup, this northerly drift should result in a completely
dry Sunday for our area. Active pattern is still possible for the
first half of next work week as a deepening longwave trough ejecting
out of the Rockies into the Plains looks supportive to send a series
of shortwaves through the Great Lakes.

MARINE...

A ridge of high pressure extends south across the Great Lakes this
morning, maintaining quiet marine conditions with light north wind
that gradual turns more easterly today. A weakening low pressure
system will track into western Lake Superior today, sending a
dissipating and slow-moving frontal boundary across the rest of the
region by late tonight. This may produce scattered showers overnight
into Friday with an isolated non-severe storm possible as well. A
diffuse pressure pattern maintains weak winds at or below 10 knots
through the weekend with a more active pattern likely to set up
early next week.

&&

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

$$

AVIATION.....BC
DISCUSSION...KDK
MARINE.......TF


You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.