000
FXUS63 KDTX 142333
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
733 PM EDT Sun Apr 14 2024

.KEY MESSAGES...

- Temperatures will drop into the 40s and 50s this evening.

- Monday and Tuesday will be dry.

- Showers are expected Tuesday night and Wednesday. There is a
chance for thunderstorms Tuesday afternoon and evening.

&&

.AVIATION...

A lake modified cold front will backdoor off of Lake Huron and
herald building surface high pressure across Southeast Michigan
tonight. Low level flow trajectories will become increasingly
anticyclonic leading to system relative isentropic downglide through
approximately 18Z Monday. High confidence in VFR conditions. Surface
winds are expected to emerge again out of the northwest at 10
knots for Monday.

.DTW THRESHOLD PROBABILITIES...

*  None.

&&

.PREV DISCUSSION...
Issued at 300 PM EDT Sun Apr 14 2024

DISCUSSION...

High pressure will expand across Lower Michigan tonight within
confluent mid level northwest flow. Sfc winds will turn toward the
north-northeast in advance of the sfc ridge and will help drive the
Lake Huron marine layer inland during the course of the evening.
Portions of the forecast area will see a 15 to 25 degree drop in
temps during the course of the evening with this cold front. A
weakening of the winds and clear skies overnight will prompt ideal
radiational cooling, supporting min temps down into the 40s.

The upper low now over the west coast is forecast to invoke
downstream ridge amplification across the Great Lakes. This will
sustain sfc high pressure across Lower Mi into Tuesday, maintaining
dry and tranquil conditions. The airmass will be much cooler across
Se Mi on Monday as 850mb temps will be a good 10 degrees colder than
today. Model soundings indicate afternoon mixing depths up to 6k
feet which should equate to afternoon highs into the 60s. A little
more moisture near the top of the mixed layer may support some
degree of afternoon cu on Monday. Light winds and clear skies will
then support another decent radiational cooling night Monday night,
supportive of forecast mins in the upper 30s to mid 40s. The surface
ridge axis will shift northeast of the area on Tuesday. Prevailing
east flow off the lakes and increasing mid/high clouds will warrant
slightly cooler afternoon highs (upper 50s to low 60s).

The 12Z model suite continue to show the upper low lifting across
the Upper Great Lakes Wed into Wed night, with the associated sfc
low forecast to occlude across the Upper Mississippi Valley by
Wednesday morning. A lead push of mid level moisture/isentropic
ascent will be driven across Se Mi late Tues/Tuesday night within a
region of respectable upper level divergence. While low level dry
air is likely to delay the onset of the rain on Tuesday, the
strength of the ascent and moisture transport will warrant a good
chance of rain Tues night. The main point of uncertainty in the
forecast revolves around the timing of the occlusion process and
whether or not the warm sector instability axis is able to lift into
Se Mi or remains south of the state. Both deterministic runs and
ensemble members show ample variations to maintain a good deal of
forecast uncertainty as to the amount of instability over Se Mi and
thus the severe weather risk if any. The large scale ascent
along/ahead of the sfc front and at least some weak elevated
instability will be enough to support high chances of showers and
thunderstorms.

This entire system is forecast to rapidly weaken as it lifts
northeast of the region Wed night/Thursday as a polar low tracks
across across southern Canada late in the week. This system will
deliver a seasonally cool airmass to Great Lakes region late week
and next weekend.

MARINE...

Dry cold front clearing southeast Michigan this afternoon, with
westerly wind gusts along the shorelines flirting with 25 knots.
Winds have already topped out and will be diminishing the rest of
evening as a ridge of high pressure builds into Lower Michigan
tonight. Light winds persist Monday before easterly winds begin to
ramp on Tuesday ahead of the next low pressure system moving into
the Central Great Lakes on Wednesday. A period of easterly gales is
possible Tuesday night into Wednesday, mainly over the northern half
of Lake Huron. A good deal of warm air will be spreading in,
supporting neutral to stable low level profiles, thus gales look to
be marginal, and still too far out to issue watch. An extended
period of widespread showers late Tuesday night through Wednesday
Night, along with a slight chance of thunderstorms.

Another weak cold front to swing through to end the work week, with
just light to moderate winds to follow the passage for the Weekend.

&&

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

$$

AVIATION.....CB
DISCUSSION...SC
MARINE.......SF


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