111
FXUS63 KDTX 081738
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
138 PM EDT Wed May 8 2024

.KEY MESSAGES...

- Warm and breezy today.

- Much cooler on Thursday with rain expected south of M-59 and a
chance north.

&&

.AVIATION...

Breezy westerly flow with gusts of 25 to 30 knots is in place this
afternoon across Southeast Michigan this afternoon as flattened
ridge is suppressed to the Southeast United States. Surface high
pressure is shown to build southward in response to differential
heating and mesohigh forcing which will in turn cause a cold front
to backdoor off Lake Huron and Lake St Clair this evening. Expect an
abrupt wind shift with winds turning to the northeast around 01-02Z.
A deep upper level trough axis will then settle into portions of
northern Lower Michigan Thursday. Increased midlevel deformation and
frontogenesis is expected to result in a widespread coverage of rain
showers after 15Z for all of Southeast Michigan.

DTW THRESHOLD PROBABILITIES...

* Low in crosswind thresholds being exceeded this afternoon.

&&

.PREV DISCUSSION...
Issued at 245 AM EDT Wed May 8 2024

DISCUSSION...

Massive/West-East elongated upper level low/trough centered over the
Dakotas early this morning. In fact, 00z Bismark raob indicated a
500 MB height of 537 DAM, which looks like it set the daily min
record. As this upper level low weakens today, a big pattern shift
will occur for us, as the warm and deep southwest-west flow in place
transitions to predominately northwest flow to end the work week
into the weekend.

Weak surface wind fields early this morning, coupled with last
evening`s rainfall, and dew pts in the 50s has lead to a little light
fog in spots. Still looks very shallow and should not have a much of
impact on max temperatures. Increasing westerly flow today with a
north-south gradient in place, as 850 MB temps this afternoon look
to be in the mid/upper single number north of I-69, with lower teens
toward the southern Michigan border. The I-94 corridor will likely
mix to 725 MB, where 2-3 C is forecasted, supportive of highs around
80 degrees/lower 80s, otherwise 70s should work for much of the
rest of the CWA. Huron county looks to have more clouds, cooler
influence from Saginaw Bay and perhaps a stray shower to keep temps
down in the upper 60s/near 70. With the deeper boundary layer mixing
expected, inherited wind gusts of 25-30 knots also appears fine.

Much cooler air for the entire CWA arrives on Thursday as positive
tilted trough axis drops south from Eastern Canada, and low level
winds out of the northeast increase off Lake Huron. Highs
predominately in the 55-60 degree range expected. It does
appear the upper level wave coming out of the Midwest will
subsequently be deflected farther south, through the Ohio Valley.
850-700 MB Theta-E ridge axis looks to be straddled along or just
south of the southern Michigan border, with moisture quickly
diminishing as one heads north, calling into question the rain
showers developing for northern areas of the CWA (see 00z regional
GEM, NAM, ICON, and UKMET especially). Planning on sharping up the
south-north pop gradient significantly.

Dry Friday as shortwave ridging builds over the Central Great Lakes,
but nthe ext upper level wave/trough embedded within the northwest
flow arrives by Saturday morning, supportive of a chance of showers
despite limited moisture available, and perhaps an isolated
thunderstorm as the showalter index lowers toward zero and several
hundreds of MUcape indicated.

MARINE...

Low pressure tracks near the Straits this morning setting up modest
(~15-20kt) westerly flow across the region in its wake. A secondary
low develops over the Ohio Valley tonight resulting in local winds
shifting to out of the northeast. With a marginally cooler airmass
drawn south, peak wind gusts Thursday over the central portion of
Lake Huron reach 20-25kts with near 30kts possible over the Saginaw
Bay due to funneling down the bay. Small craft advisories may be
needed around the Thumb nearshore waters daytime Thursday as waves
increase given the wind direction. System vacates by Thursday night
bringing lighter winds and ending further shower chances.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory until 10 PM EDT this evening for LHZ421-422-
     441>443.

Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

AVIATION.....CB
DISCUSSION...SF
MARINE.......KDK


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