587
FXUS63 KDTX 092327
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
627 PM EST Sat Nov 9 2024

.KEY MESSAGES...

- A round of showers expected Sunday morning.

- Breezy conditions (wind gusts around 35 mph) on Monday as a cold
  front tracks through.

- Short-lived cooler/seasonable airmass Monday evening-Tuesday,
followed by above normal temperatures once again for the rest of the
work week.

&&

.AVIATION...

Dynamic closed upper level low pressure system will center upon
Lower Michigan Sunday sending an area of 1000-500mb height falls
directly through the state. Residual high static stability in the
lowest 10.0 kft agl will be slow to saturate through 09-10Z.
Thereafter, favorable right entrance region dynamics for ascent and
meridional moisture transport will result in prevailing IFR to MVFR
rain through approximately 16Z. Diurnal mixing may promote higher
ceiling heights during the middle of the day Sunday before a cold
front brings the potential for shallow topped convection and showers
sometime between 23-02Z. Very low confidence in any TSRA during the
fropa.

For DTW...Shallow low topped convective showers are expected between
23Z 11/10 and 02Z 11/11.

DTW THRESHOLD PROBABILITIES...

*  High for ceilings aob 5kft Sunday.

&&

.PREV DISCUSSION...
Issued at 250 PM EST Sat Nov 9 2024

DISCUSSION...

Very dry airmass in place today over southeast Michigan, as the 12z
DTX raob revealed an 49 C dew pt depression at 850 MB with a PW
value of 0.3 inches. Outside of a short lived cold shot in the late
Monday-Tuesday time frame, temperatures expected to continue to run
above normal. With an average temperature of 54.9 inches during the
first 8 days of November, Detroit running 8th warmest on record thus
far.

Large and symmetric mid-upper level low centered over the Central
Plains will be booted off to the northeast as the Pacific shortwave
trough/upper level energy pushes through British Columbia/Pacific
Northwest. The Plains 500 MB low looks to be tracking near/through
the Straights toward 00z Monday. Warm advection/isentropic ascent
and excellent moisture advection late tonight, as moisture axis (3+
C dew pt at 700 MB/10+ C at 850 MB) tracks through southeast
Michigan Sunday morning. Local probabilistic guidance indicates a
high probability (near 100 percent) of showers moving through Sunday
morning. Showalter index does fall to near zero, so can`t totally
rule out a stray thunderstorm as the 40+ knot low level jet works
through the region. Main impact would be just an enhancement to the
downpour, as basin average rainfall around quarter of an inch
appears reasonable, with potential to reach half an inch toward the
southern Michigan border.

Fast moving but potent upper level wave coming from the British
Columbia energy then swings through the northern Great Lakes on
Monday, driving what looks to be a mostly dry cold front through
southern Lower Michigan, as the mid level dry slot looks to overtake
the low level frontal boundary. The favorable diurnal timing and
good level cold advection (850 MB temps dropping into negative low
single numbers) during Monday afternoon/evening, likely to result in
wind gusts 30-35 MPH, with potential of 40 MPH across locations near
Saginaw Bay. Will also have to watch for the potential of lake
effect showers to impact eastern Thumb region, but tough to gauge
which side of due north low level winds will end up being Monday
night. Large and expansive high pressure building into the Central
Great Lakes on Tuesday will quickly shut off any potential shower
activity. Strong southerly return flow for mid week period will draw
moist and warm air, with another round of showers likely in the
Wednesday night/Thursday time period.

MARINE...

A high pressure system which quickly moved over the Great Lakes this
morning is now departing into New England, which will reinforce
southeast flow through the day. A low pressure system then remains
on track to move from the central Plains into the northern Great
Lakes by tomorrow afternoon and evening. This will further back wind
direction from the SE to the SW late in the day tomorrow, with
widespread rain showers preceding the wind shift.

Additional showers will be likely Monday across Lake Huron as an
upper-level disturbance and cold front moves over the Great Lakes.
The intrusion of cold Canadian air behind the front will boost over-
lake instability and will support wind gusts around 25 knots
starting tomorrow night, with higher end potential around 30 to 35
knots later in the day on Monday. Small Craft Advisories will be
likely for portions of all of the nearshore zones. Additionally,
gale potential has been increasing across north to north-central
Lake Huron. A Gale Watch will likely be issued for the late evening
marine package tonight. High pressure will quickly build in over the
lake on Tuesday, rapidly diminishing wind speed and gust potential
by Tuesday afternoon.

&&

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

$$

AVIATION.....CB
DISCUSSION...SF
MARINE.......AM


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