177
FXUS63 KDTX 231723
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
123 PM EDT Thu May 23 2024

.KEY MESSAGES...

- Friday brings more nice weather to kick off the holiday weekend,
mostly sunny with highs in the lower 80s.

- Showers and thunderstorms move in Friday night (60-70%) and
continue into Saturday morning.

- Rain ends Saturday afternoon through Saturday night.

- Showers are likely again with a chance of thunderstorms Sunday
afternoon and Sunday night.

- The Memorial Day outlook calls for cool temperatures with showers
likely Monday and Monday night.

&&

.AVIATION...

Mainly clear sky conditions today with the exception of a few
diurnal cumulus and some high cirrus. High pressure to the south
keeps stable, dry conditions in place. Westerly winds remain gentle
through the rest of the day today, with occasional gusts reaching 15
knots. Light and variable winds in the early morning hours tomorrow
as the center of the high pressure centers overhead. Winds flip to
become southeasterly tomorrow behind the high, with skies remaining
clear. The next system is expected to move in Friday night/Saturday
morning and bring showers and storms, although the start time for
these storms remains just outside the TAF period for now.

DTW THRESHOLD PROBABILITIES...

*  None

&&

.PREV DISCUSSION...
Issued at 327 AM EDT Thu May 23 2024

DISCUSSION...

Northern periphery of a high pressure system under relatively zonal
mid-level flow will ensure dry weather today under plenty of
sunshine, allowing temperatures to rise into the upper 70s, up to
about 80 degrees for a high. Once afternoon mixing commences, dew
points drop into the low to mid 40s as wind speeds increase, gusting
around 20-25 mph for most locations, up to around 30 mph for the Tri-
Cities and northern Thumb. This will make for a comfortable day
despite temperatures still a little above normal values for this
time of year.

Water vapor imagery highlights an upper-level wave now entering
Wyoming, which will progress into the Dakotas tonight, amplifying an
upper-level ridge across the Great Lakes. The amplitude of the ridge
will reach its peak over Michigan by tomorrow afternoon, bolstering
subsidence and bringing clear skies for the first half of the day.
Not much change to the overall thermal profile, but very subtle warm
air advection will help support highs in the lower 80s with light
winds. Mid to upper-level clouds will then start to fill in from the
west derived from upstream activity associated with the approaching
wave. A piece of shortwave energy just ahead of the main vort lobe
will bring the chance for showers and thunderstorms Friday night
into Saturday morning. Moisture transport vectors are maximized over
SE MI just ahead of this wave, bringing a quick window to see h850
dew points increase to around 12C. But between the tail-end of the
hi-res suite, the degree of moisture transport (and thus
instability) does display larger variations, with better confidence
for meaningful CAPE residing over the southwest portion of the state.
Shower and storm potential will more than likely remain elevated
across SE MI, or will have limited surface based CAPE to work with.

High pressure builds in behind this wave bringing another period of
dry weather later in the day Saturday into Sunday, but dry weather
will likely be short-lived with a low pressure system that is
expected to fill in somewhere across the western Great Lakes or
southeast into the northern Ohio River Valley. A southern stream
upper-level wave will come onshore around Baja California and will
aid in cyclogenesis around the TX/OK panhandles, where low pressure
will then push towards the Great Lakes. This will bring another
chance for widely scattered to numerous showers and possible
embedded thunderstorms, pending the final position of the low. If
the low tracks into northern lower, as per the ECMWF, the warm
sector will drop showalter indices will drop below 0 with the rising
instability. The solutions that target southern MI will have less
favorable chances for thunderstorms. In either case, the large scale
forcing, including the mid-level wave and a window for favorable
left exit jet streak dynamics, will support likely PoPs (60-70%) for
late Sunday into Monday morning. Continued rain chances (50-60%)
hold through the remainder of Monday with moisture wrapping around
the low, interacting with the trailing upper-level wave.

MARINE...

Low pressure slows over Ontario today with modest southwest gradient
winds. Winds then flip to the east over the weekend and remain
modest as a surface ridge builds. Another wave ejects across the
Upper Midwest Friday into Saturday with a secondary low developing
along the system`s cold front. Active pattern continues early next
week with additional Small Craft Advisories possible across Saginaw
Bay.

&&

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

$$

AVIATION.....BC
DISCUSSION...AM
MARINE......LM


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at www.weather.gov/detroit.