300
FXUS63 KDTX 080645
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
245 AM 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.

&&

.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.

&&

.PREV DISCUSSION...
Issued at 1201 AM EDT Wed May 8 2024

AVIATION...

Bulk of convection has cleared out of Southeast Michigan late this
evening while a wave of subsidence leads to aggressive dissipation of
clouds. Wind speeds trend lower for several more hours offering
potential for periods of MVFR fog. After evening rainfall moistened
the near surface layer, air temperatures should largely cool-down
and approach the dewpoint temperatures, thus the current TEMPO.
Can`t completely rule out areas of IFR fog given the underachieving
gradient wind (and nearby obs), but low confidence exists. Sunny and
breezy conditions arrive Wednesday afternoon with gusts in excess of
25 knots.

For DTW/D21 Convection...

A line of storms crossing Lake Michigan will dissipate before
reaching the immediate airspace between 06Z and 08Z. Showers, and
perhaps a rumble of thunder, possible early Thursday morning with
the next system.

DTW THRESHOLD PROBABILITIES...

* Low for ceiling at or below 5000 feet this morning.


&&

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

$$

DISCUSSION...SF
MARINE.......KDK
AVIATION.....KGK


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